Title 40 -- Protection of Environment

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Appendix A to Subpart O of Part 141 -- Regulated Contaminants

Link to an amendment published at 65 FR 76749, December 7, 2000.

 
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                                  Traditional MCL     To convert for                                            Major sources in       Health effects
      Contaminant (units)             in mg/L        CCR, multiply by   MCL in CCR units         MCLG            drinking water           language
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Microbiological contaminants:
    Total Coliform Bacteria....  MCL: (systems      .................  MCL: (systems      0.................  Naturally present in  Coliforms are
                                  that collect                          that collect                           the environment.      bacteria that are
                                  >=40 samples/                         >=40 samples/                                                naturally present
                                  month) 5% of                          month) 5% of                                                 in the environment
                                  monthly samples                       monthly samples                                              and are used as an
                                  are positive;                         are positive;                                                indicator that
                                  (systems that                         (systems that                                                other, potentially-
                                  collect <40                        collect <40                                               harmful, bacteria
                                  samples/month) 1                      samples/month) 1                                             may be present.
                                  positive monthly                      positive monthly                                             Coliforms were
                                  sample.                               sample.                                                      found in more
                                                                                                                                     samples than
                                                                                                                                     allowed and this
                                                                                                                                     was a warning of
                                                                                                                                     potential problems.
    Fecal coliform and E. coli.  0................  .................  0................  0.................  Human and animal      Fecal coliforms and
                                                                                                               fecal waste.          E. coli are
                                                                                                                                     bacteria whose
                                                                                                                                     presence indicates
                                                                                                                                     that the water may
                                                                                                                                     be contaminated
                                                                                                                                     with human or
                                                                                                                                     animal wastes.
                                                                                                                                     Microbes in these
                                                                                                                                     wastes can cause
                                                                                                                                     short-term effects,
                                                                                                                                     such as diarrhea,
                                                                                                                                     cramps, nausea,
                                                                                                                                     headaches, or other
                                                                                                                                     symptoms. They may
                                                                                                                                     pose a special
                                                                                                                                     health risk for
                                                                                                                                     infants, young
                                                                                                                                     children, some of
                                                                                                                                     the elderly, and
                                                                                                                                     people with
                                                                                                                                     severely-
                                                                                                                                     compromised immune
                                                                                                                                     systems.
    Total organic carbon (ppm).  TT...............  .................  TT...............  N/A...............  Naturally present in  Total organic carbon
                                                                                                               the environment.      (TOC) has no health
                                                                                                                                     effects. However,
                                                                                                                                     total organic
                                                                                                                                     carbon provides a
                                                                                                                                     medium for the
                                                                                                                                     formation of
                                                                                                                                     disinfection by
                                                                                                                                     products. These
                                                                                                                                     byproducts include
                                                                                                                                     trihalomethanes
                                                                                                                                     (THMs) and
                                                                                                                                     haloacetic acids
                                                                                                                                     (HAAs). Drinking
                                                                                                                                     water containing
                                                                                                                                     these byproducts in
                                                                                                                                     excess of the MCL
                                                                                                                                     may lead to adverse
                                                                                                                                     health effects,
                                                                                                                                     liver or kidney
                                                                                                                                     problems, or
                                                                                                                                     nervous system
                                                                                                                                     effects, and may
                                                                                                                                     lead to an
                                                                                                                                     increased risk of
                                                                                                                                     getting cancer.
    Turbidity (NTU)............  TT...............  .................  TT...............  N/A...............  Soil runoff.........  Turbidity has no
                                                                                                                                     health effects.
                                                                                                                                     However, turbidity
                                                                                                                                     can interfere with
                                                                                                                                     disinfection and
                                                                                                                                     provide a medium
                                                                                                                                     for microbial
                                                                                                                                     growth. Turbidity
                                                                                                                                     may indicate the
                                                                                                                                     presence of disease-
                                                                                                                                     causing organisms.
                                                                                                                                     These organisms
                                                                                                                                     include bacteria,
                                                                                                                                     viruses, and
                                                                                                                                     parasites that can
                                                                                                                                     cause symptoms such
                                                                                                                                     as nausea, cramps,
                                                                                                                                     diarrhea and
                                                                                                                                     associated
                                                                                                                                     headaches.
Radioactive contaminants:
    Beta/photon emitters (mrem/  4 mrem/yr........  .................  4................  N/A...............  Decay of natural and  Certain minerals are
     yr).                                                                                                      man-made deposits.    radioactive and may
                                                                                                                                     emit forms of
                                                                                                                                     radiation known as
                                                                                                                                     photons and beta
                                                                                                                                     radiation. Some
                                                                                                                                     people who drink
                                                                                                                                     water containing
                                                                                                                                     beta and photon
                                                                                                                                     emitters in excess
                                                                                                                                     of the MCL over
                                                                                                                                     many years may have
                                                                                                                                     an increased risk
                                                                                                                                     of getting cancer.
    Alpha emitters (pCi/l).....  15 pCi/l.........  .................  15...............  N/A...............  Erosion of natural    Certain minerals are
                                                                                                               deposits.             radioactive and may
                                                                                                                                     emit a form of
                                                                                                                                     radiation known as
                                                                                                                                     alpha radiation.
                                                                                                                                     Some people who
                                                                                                                                     drink water
                                                                                                                                     containing alpha
                                                                                                                                     emitters in excess
                                                                                                                                     of the MCL over
                                                                                                                                     many years may have
                                                                                                                                     an increased risk
                                                                                                                                     of getting cancer.
    Combined radium (pCi/l)....  5 pCi/l..........  _................  5................  N/A...............  Erosion of natural    Some people who
                                                                                                               deposits.             drink water
                                                                                                                                     containing radium
                                                                                                                                     226 or 228 in
                                                                                                                                     excess of the MCL
                                                                                                                                     over many years may
                                                                                                                                     have an increased
                                                                                                                                     risk of getting
                                                                                                                                     cancer
Inorganic contaminants:
    Antimony (ppb).............  .006.............  1000.............  6................  6.................  Discharge from        Some people who
                                                                                                               petroleum             drink water
                                                                                                               refineries; fire      containing antimony
                                                                                                               retardants;           well in excess of
                                                                                                               ceramics;             the MCL over many
                                                                                                               electronics; solder.  years could
                                                                                                                                     experience
                                                                                                                                     increases in blood
                                                                                                                                     cholesterol and
                                                                                                                                     decreases in blood
                                                                                                                                     sugar.
    Arsenic (ppb)..............  \1\ 0.010........  1000.............  \1\ 10...........  \1\ 0.............  Erosion of natural    Some people who
                                                                                                               deposits; Runoff      drink water
                                                                                                               from orchards;        containing arsenic
                                                                                                               Runoff from glass     in excess of the
                                                                                                               and electronics       MCL over many years
                                                                                                               production wastes.    could experience
                                                                                                                                     skin damage or
                                                                                                                                     problems with their
                                                                                                                                     circulatory system,
                                                                                                                                     and may have an
                                                                                                                                     increased risk of
                                                                                                                                     getting cancer.
    Asbestos (MFL).............  7 MFL............  .................  7................  7.................  Decay of asbestos     Some people who
                                                                                                               cement water mains;   drink water
                                                                                                               Erosion of natural    containing asbestos
                                                                                                               deposits.             in excess of the
                                                                                                                                     MCL over many years
                                                                                                                                     may have an
                                                                                                                                     increased risk of
                                                                                                                                     developing benign
                                                                                                                                     intestinal polyps.
    Barium (ppm)...............  2................  .................  2................  2.................  Discharge of          Some people who
                                                                                                               drilling wastes;      drink water
                                                                                                               Discharge from        containing barium
                                                                                                               metal refineries;     in excess of the
                                                                                                               Erosion of natural    MCL over many years
                                                                                                               deposits.             could experience an
                                                                                                                                     increase in their
                                                                                                                                     blood pressure.
    Beryllium (ppb)............  .004.............  1000.............  4................  4.................  Discharge from metal  Some people who
                                                                                                               refineries and coal-  drink water
                                                                                                               burning factories;    containing
                                                                                                               Discharge from        beryllium well in
                                                                                                               electrical,           excess of the MCL
                                                                                                               aerospace, and        over many years
                                                                                                               defense industries.   could develop
                                                                                                                                     intestinal lesions
    Bromate (ppb)..............  .010.............  1000.............  10...............  0.................  By-product of         Some people who
                                                                                                               drinkig water         drink water of
                                                                                                               disinfection.         containing bromate
                                                                                                                                     in excess of the
                                                                                                                                     MCL over many years
                                                                                                                                     may have an
                                                                                                                                     increased risk of
                                                                                                                                     getting cancer.
    Cadmium (ppb)..............  .005.............  1000.............  5................  5.................  Corrosion of          Some people who
                                                                                                               galvanized pipes;     drink water
                                                                                                               Erosion of natural    containing cadmium
                                                                                                               deposits; Discharge   in excess of the
                                                                                                               from metal            MCL over many years
                                                                                                               refineries; Runoff    could experience
                                                                                                               from waste            kidney damage.
                                                                                                               batteries and
                                                                                                               paints.
    Chloramines (ppm)..........  MRDL=4...........  .................  MRDL=4...........  MRDLG=4...........  Water additive used   Some people who use
                                                                                                               to control microbes.  water containing
                                                                                                                                     chloramines well in
                                                                                                                                     excess of the MRDL
                                                                                                                                     could experience
                                                                                                                                     irritating effects
                                                                                                                                     to their eyes and
                                                                                                                                     nose. Some people
                                                                                                                                     who drink water
                                                                                                                                     containing
                                                                                                                                     chloramines well in
                                                                                                                                     excess of the MRDL
                                                                                                                                     could experience
                                                                                                                                     stomach discomfort
                                                                                                                                     or anemia.
    Chlorine (ppm).............  MRDL=4...........  .................  MRDL=4...........  MRDLG=4...........  Water additive used   Some people who use
                                                                                                               to control microbes.  water containing
                                                                                                                                     chlorine well in
                                                                                                                                     excess of the MRDL
                                                                                                                                     could experience
                                                                                                                                     irritating effects
                                                                                                                                     to their eyes and
                                                                                                                                     nose. Some people
                                                                                                                                     who drink water
                                                                                                                                     containing chlorine
                                                                                                                                     well in excess of
                                                                                                                                     the MRDL could
                                                                                                                                     experience stomach
                                                                                                                                     discomfort.
    Chlorine dioxide (ppb).....  MRDL=.8..........  1000.............  MRDL=800.........  MRDLG=800.........  Water additive used   Some infants and
                                                                                                               to control micorbes.  young children who
                                                                                                                                     drink water
                                                                                                                                     chlorine dioxide in
                                                                                                                                     excess of the MRDL
                                                                                                                                     could experience
                                                                                                                                     nervous system
                                                                                                                                     effects. Similar
                                                                                                                                     effects may occur
                                                                                                                                     in fetuses of
                                                                                                                                     pregnant women who
                                                                                                                                     drink water
                                                                                                                                     containing chlorine
                                                                                                                                     dioxide in excess
                                                                                                                                     of the MRDL. Some
                                                                                                                                     people may
                                                                                                                                     experience anemia.
    Chlorite (ppm).............  1................  .................  1................  0.8...............  By-product of         Some infants and
                                                                                                               drinking water        young children who
                                                                                                               disinfection.         drink water
                                                                                                                                     containing chlorite
                                                                                                                                     in excess of the
                                                                                                                                     MCL could
                                                                                                                                     experience nervous
                                                                                                                                     system effects.
                                                                                                                                     Similar effects may
                                                                                                                                     occur in fetuses of
                                                                                                                                     pregnant women who
                                                                                                                                     drink water
                                                                                                                                     containing chlorite
                                                                                                                                     in excess of the
                                                                                                                                     MCL. Some people
                                                                                                                                     may experience
                                                                                                                                     anemia.
    Chromium (ppb).............  .1...............  1000.............  100..............  100...............  Discharge from steel  Some people who use
                                                                                                               and pulp mills;       water containing
                                                                                                               Erosion of natural    chromium well in
                                                                                                               deposits.             excess of the MCL
                                                                                                                                     over many years
                                                                                                                                     could experience
                                                                                                                                     allergic
                                                                                                                                     dermatitis.
    Copper (ppm)...............  AL=1.3...........  .................  AL=1.3...........  1.3...............  Corrosion of          Copper is an
                                                                                                               household plumbing    essential nutrient,
                                                                                                               systems; Erosion of   but some people who
                                                                                                               natural deposits.     drink water
                                                                                                                                     containing copper
                                                                                                                                     in excess of the
                                                                                                                                     action level over a
                                                                                                                                     relatively short
                                                                                                                                     amount of time
                                                                                                                                     could experience
                                                                                                                                     gastrointestinal
                                                                                                                                     distress. Some
                                                                                                                                     people who drink
                                                                                                                                     water containing
                                                                                                                                     copper in excess of
                                                                                                                                     the action level
                                                                                                                                     over many years
                                                                                                                                     could suffer liver
                                                                                                                                     or kidney damage.
                                                                                                                                     People with
                                                                                                                                     Wilson's disease
                                                                                                                                     should consult
                                                                                                                                     their personal
                                                                                                                                     doctor.
    Cyanide (ppb)..............  .2...............  1000.............  200..............  200...............  Discharge from steel/ Some people who
                                                                                                               metal factories;      drink water
                                                                                                               Discharge from        containing cyanide
                                                                                                               plastic and           well in excess of
                                                                                                               fertilizer            the MCL over many
                                                                                                               factories.            years could
                                                                                                                                     experience nerve
                                                                                                                                     damage or problems
                                                                                                                                     with their thyroid.
    Fluoride (ppm).............  4................  .................  4................  4.................  Erosion of natural    Some people who
                                                                                                               deposits; Water       drink water
                                                                                                               additive which        containing fluoride
                                                                                                               promotes strong       in excess of the
                                                                                                               teeth; Discharge      MCL over many years
                                                                                                               from fertilizer and   could get bone
                                                                                                               aluminum factories.   disease, including
                                                                                                                                     pain and tenderness
                                                                                                                                     of the bones.
                                                                                                                                     Fluoride in
                                                                                                                                     drinking water at
                                                                                                                                     half the MCL or
                                                                                                                                     more may cause
                                                                                                                                     mottling of
                                                                                                                                     children's teeth,
                                                                                                                                     usually in children
                                                                                                                                     less than nine
                                                                                                                                     years old.
                                                                                                                                     Mottling, also
                                                                                                                                     known as dental
                                                                                                                                     fluorosis, may
                                                                                                                                     include brown
                                                                                                                                     staining and/or
                                                                                                                                     pitting of the
                                                                                                                                     teeth, and occurs
                                                                                                                                     only in developing
                                                                                                                                     teeth before they
                                                                                                                                     erupt from the
                                                                                                                                     gums.
    Lead (ppb).................  AL=.015..........  1000.............  AL=15............  0.................  Corrosion of          Infants and children
                                                                                                               household plumbing    who drink water
                                                                                                               systems; Erosion of   containing lead in
                                                                                                               natural deposits.     excess of the
                                                                                                                                     action level could
                                                                                                                                     experience delays
                                                                                                                                     in their physical
                                                                                                                                     or mental
                                                                                                                                     development.
                                                                                                                                     Children could show
                                                                                                                                     slight deficits in
                                                                                                                                     attention span and
                                                                                                                                     learning abilities.
                                                                                                                                     Adults who drink
                                                                                                                                     this water over
                                                                                                                                     many years could
                                                                                                                                     develop kidney
                                                                                                                                     problems or high
                                                                                                                                     blood pressure.
    Mercury [inorganic] (ppb)..  .002.............  1000.............  2................  2.................  Erosion of natural    Some people who
                                                                                                               deposits; Dis         drink water
                                                                                                               charge from           containing
                                                                                                               refineries and        inorganic mercury
                                                                                                               factories; Runoff     well in excess of
                                                                                                               from landfills;       the MCL over many
                                                                                                               Runoff from           years could
                                                                                                               cropland.             experience kidney
                                                                                                                                     damage.
    Nitrate (ppm)..............  10...............  .................  10...............  10................  Runoff from           Infants below the
                                                                                                               fertilizer use;       age of six months
                                                                                                               Leaching from         who drink water
                                                                                                               septic tanks, sew     containing nitrate
                                                                                                               age; Erosion of       in excess of the
                                                                                                               natural deposits.     MCL could become
                                                                                                                                     seriously ill and,
                                                                                                                                     if untreated, may
                                                                                                                                     die. Symptoms
                                                                                                                                     include shortness
                                                                                                                                     of breath and blue
                                                                                                                                     baby syndrome.
    Nitrite (ppm)..............  1................  .................  1................  1.................  Runoff from           Infants below the
                                                                                                               fertilizer use;       age of six months
                                                                                                               Leaching from         who drink water
                                                                                                               septic tanks, sew     containing nitrite
                                                                                                               age; Erosion of       in excess of the
                                                                                                               natural deposits.     MCL could become
                                                                                                                                     seriously ill and,
                                                                                                                                     if untreated, may
                                                                                                                                     die. Symptoms
                                                                                                                                     include shortness
                                                                                                                                     of breath and blue
                                                                                                                                     baby syndrome.
    Selenium (ppb).............  .05..............  1000.............  50...............  50................  Discharge from        Selenium is an
                                                                                                               petroleum and metal   essential nutrient.
                                                                                                               refineries; Erosion   However, some
                                                                                                               of natural            people who drink
                                                                                                               deposits; Discharge   water containing
                                                                                                               from mines.           selenium in excess
                                                                                                                                     of the MCL over
                                                                                                                                     many years could
                                                                                                                                     experience hair or
                                                                                                                                     fingernail losses,
                                                                                                                                     numbness in fingers
                                                                                                                                     or toes, or
                                                                                                                                     problems with their
                                                                                                                                     circulation.
    Thallium (ppb).............  .002.............  1000.............  2................  0.5...............  Leaching from ore-    Some people who
                                                                                                               processing sites;     drink water
                                                                                                               Discharge from        containing thallium
                                                                                                               electronics, glass,   in excess of the
                                                                                                               and drug factories.   MCL over many years
                                                                                                                                     could experience
                                                                                                                                     hair loss, changes
                                                                                                                                     in their blood, or
                                                                                                                                     problems with their
                                                                                                                                     kidneys,
                                                                                                                                     intestines, or
                                                                                                                                     liver.
Synthetic organic contaminants
 including pesticides and
 herbicides:
    2,4-D (ppb)................  .07..............  1000.............  70...............  70................  Runoff from           Some people who
                                                                                                               herbicide used on     drink water
                                                                                                               row crops.            containing the weed
                                                                                                                                     killer 2,4-D well
                                                                                                                                     in excess of the
                                                                                                                                     MCL over many years
                                                                                                                                     could experience
                                                                                                                                     problems with their
                                                                                                                                     kidneys, liver, or
                                                                                                                                     adrenal glands.
    2,4,5-TP [Silvex](ppb).....  .05..............  1000.............  50...............  50................  Residue of banned     Some people who
                                                                                                               herbicide.            drink water
                                                                                                                                     containing silvex
                                                                                                                                     in excess of the
                                                                                                                                     MCL over many years
                                                                                                                                     could experience
                                                                                                                                     liver problems.
    Acrylamide.................  TT...............  .................  TT...............  0.................  Added to water        Some people who
                                                                                                               during sewage/        drink water
                                                                                                               wastewater            containing high
                                                                                                               treatment.            levels of
                                                                                                                                     acrylamide over a
                                                                                                                                     long period of time
                                                                                                                                     could have problems
                                                                                                                                     with their nervous
                                                                                                                                     system or blood,
                                                                                                                                     and may have an
                                                                                                                                     increased risk of
                                                                                                                                     getting cancer.
    Alachlor (ppb).............  .002.............  1000.............  2................  0.................  Runoff from           Some people who
                                                                                                               herbicide used on     drink water
                                                                                                               row crops.            containing alachlor
                                                                                                                                     in excess of the
                                                                                                                                     MCL over many years
                                                                                                                                     could have problems
                                                                                                                                     with their eyes,
                                                                                                                                     liver, kidneys, or
                                                                                                                                     spleen, or
                                                                                                                                     experience anemia,
                                                                                                                                     and may have an
                                                                                                                                     increased risk of
                                                                                                                                     getting cancer.
    Atrazine (ppb).............  .003.............  1000.............  3................  3.................  Runoff from           Some people who
                                                                                                               herbicide used on     drink water
                                                                                                               row crops.            containing atrazine
                                                                                                                                     well in excess of
                                                                                                                                     the MCL over many
                                                                                                                                     years could
                                                                                                                                     experience problems
                                                                                                                                     with their
                                                                                                                                     cardiovascular
                                                                                                                                     system or
                                                                                                                                     reproductive
                                                                                                                                     difficulties.
    Benzo(a)pyrene [PAH]         .0002............  1,000,000........  200..............  0.................  Leaching from         Some people who
     (nanograms/l).                                                                                            linings of water      drink water
                                                                                                               storage tanks and     containing
                                                                                                               distribution lines.   benzo(a)pyrene in
                                                                                                                                     excess of the MCL
                                                                                                                                     over many years may
                                                                                                                                     experience
                                                                                                                                     reproductive
                                                                                                                                     difficulties and
                                                                                                                                     may have an
                                                                                                                                     increased risk of
                                                                                                                                     getting cancer.
    Carbofuran (ppb)...........  .04..............  1000.............  40...............  40................  Leaching of soil      Some people who
                                                                                                               fumigant used on      drink water
                                                                                                               rice and alfalfa.     containing
                                                                                                                                     carbofuran in
                                                                                                                                     excess of the MCL
                                                                                                                                     over many years
                                                                                                                                     could experience
                                                                                                                                     problems with their
                                                                                                                                     blood, or nervous
                                                                                                                                     or reproductive
                                                                                                                                     systems.
    Chlordane (ppb)............  .002.............  1000.............  2................  0.................  Residue of banned     Some people who
                                                                                                               termiticide.          drink water
                                                                                                                                     containing
                                                                                                                                     chlordane in excess
                                                                                                                                     of the MCL over
                                                                                                                                     many years could
                                                                                                                                     experience problems
                                                                                                                                     with their liver or
                                                                                                                                     nervous system, and
                                                                                                                                     may have an
                                                                                                                                     increased risk of
                                                                                                                                     getting cancer.
    Dalapon (ppb)..............  .2...............  1000.............  200..............  200...............  Runoff from           Some people who
                                                                                                               herbicide used on     drink water
                                                                                                               rights of way.        containing dalapon
                                                                                                                                     well in excess of
                                                                                                                                     the MCL over many
                                                                                                                                     years could
                                                                                                                                     experience minor
                                                                                                                                     kidney changes.
    Di(2-ethylhexyl) adipate     .4...............  1000.............  400..............  400...............  Discharge from        Some people who
     (ppb).                                                                                                    chemical factories.   drink water
                                                                                                                                     containing di(2-
                                                                                                                                     ethylhexyl) adipate
                                                                                                                                     well in excess of
                                                                                                                                     the MCL over many
                                                                                                                                     years could
                                                                                                                                     experience toxic
                                                                                                                                     effects such as
                                                                                                                                     weight loss, liver
                                                                                                                                     enlargement or
                                                                                                                                     possible
                                                                                                                                     reproductive
                                                                                                                                     difficulties.
    Di(2-ethylhexyl) phthalate   .006.............  1000.............  6................  0.................  Discharge from        Some people who
     (ppb).                                                                                                    rubber and chemical   drink water
                                                                                                               factories.            containing di(2-
                                                                                                                                     ethylhexyl)
                                                                                                                                     phthalate well in
                                                                                                                                     excess of the MCL
                                                                                                                                     over many years may
                                                                                                                                     have problems with
                                                                                                                                     their liver, or
                                                                                                                                     experience
                                                                                                                                     reproductive
                                                                                                                                     difficulties, and
                                                                                                                                     may have an
                                                                                                                                     increased risk of
                                                                                                                                     getting cancer.
    Dibromochloropropane (ppt).  .0002............  1,000,000........  200..............  0.................  Runoff/leaching from  Some people who
                                                                                                               soil fumigant used    drink water
                                                                                                               on soybeans,          containing DBCP in
                                                                                                               cotton, pineapples,   excess of the MCL
                                                                                                               and orchards.         over many years
                                                                                                                                     could experience
                                                                                                                                     reproductive
                                                                                                                                     problems and may
                                                                                                                                     have an increased
                                                                                                                                     risk of getting
                                                                                                                                     cancer.
    Dinoseb (ppb)..............  .007.............  1000.............  7................  7.................  Runoff from           Some people who
                                                                                                               herbicide used on     drink water
                                                                                                               soybeans and          containing dinoseb
                                                                                                               vegetables.           well in excess of
                                                                                                                                     the MCL over many
                                                                                                                                     years could
                                                                                                                                     experience
                                                                                                                                     reproductive
                                                                                                                                     difficulties.
    Diquat (ppb)...............  .02..............  1000.............  20...............  20................  Runoff from           Some people who
                                                                                                               herbicide use.        drink water
                                                                                                                                     containing diquat
                                                                                                                                     in excess of the
                                                                                                                                     MCL over many years
                                                                                                                                     could get
                                                                                                                                     cataracts.
    Dioxin [2,3,7,8-TCDD] (ppq)  .00000003........  1,000,000, 000...  30...............  0.................  Emissions from waste  Some people who
                                                                                                               incineration and      drink water
                                                                                                               other combustion;     containing dioxin
                                                                                                               Discharge from        in excess of the
                                                                                                               chemical factories.   MCL over many years
                                                                                                                                     could experience
                                                                                                                                     reproductive
                                                                                                                                     difficulties and
                                                                                                                                     may have an
                                                                                                                                     increased risk of
                                                                                                                                     getting cancer.
    Endothall (ppb)............  .1...............  1000.............  100..............  100...............  Runoff from           Some people who
                                                                                                               herbicide use.        drink water
                                                                                                                                     containing
                                                                                                                                     endothall in excess
                                                                                                                                     of the MCL over
                                                                                                                                     many years could
                                                                                                                                     experience problems
                                                                                                                                     with their stomach
                                                                                                                                     or intestines.
    Endrin (ppb)...............  .002.............  1000.............  2................  2.................  Residue of banned     Some people who
                                                                                                               insecticide.          drink water
                                                                                                                                     containing endrin
                                                                                                                                     in excess of the
                                                                                                                                     MCL over many years
                                                                                                                                     could experience
                                                                                                                                     liver problems.
    Epichlorohydrin............  TT...............  .................  TT...............  0.................  Discharge from        Some people who
                                                                                                               industrial chemical   drink water
                                                                                                               factories; An         containing high
                                                                                                               impurity of some      levels of
                                                                                                               water treatment       epichlorohydrin
                                                                                                               chemicals.            over a long period
                                                                                                                                     of time could
                                                                                                                                     experience stomach
                                                                                                                                     problems, and may
                                                                                                                                     have an increased
                                                                                                                                     risk of getting
                                                                                                                                     cancer.
    Ethylene dibromide (ppt)...  .00005...........  1,000,000........  50...............  0.................  Discharge from        Some people who
                                                                                                               petroleum             drink water
                                                                                                               refineries.           containing ethylene
                                                                                                                                     dibromide in excess
                                                                                                                                     of the MCL over
                                                                                                                                     many years could
                                                                                                                                     experience problems
                                                                                                                                     with their liver,
                                                                                                                                     stomach,
                                                                                                                                     reproductive
                                                                                                                                     system, or kidneys,
                                                                                                                                     and may have an
                                                                                                                                     increased risk of
                                                                                                                                     getting cancer.
    Glyphosate (ppb)...........  .7...............  1000.............  700..............  700...............  Runoff from           Some people who
                                                                                                               herbicide use.        drink water
                                                                                                                                     containing
                                                                                                                                     glyphosate in
                                                                                                                                     excess of the MCL
                                                                                                                                     over many years
                                                                                                                                     could experience
                                                                                                                                     problems with their
                                                                                                                                     kidneys or
                                                                                                                                     reproductive
                                                                                                                                     difficulties.
    Heptachlor (ppt)...........  .0004............  1,000,000........  400..............  0.................  Residue of banned     Some people who
                                                                                                               pesticide.            drink water
                                                                                                                                     containing
                                                                                                                                     heptachlor in
                                                                                                                                     excess of the MCL
                                                                                                                                     over many years
                                                                                                                                     could experience
                                                                                                                                     liver damage and
                                                                                                                                     may have an
                                                                                                                                     increased risk of
                                                                                                                                     getting cancer.
    Heptachlor epoxide (ppt)...  .0002............  1,000,000........  200..............  0.................  Breakdown of          Some people who
                                                                                                               heptachlor.           drink water
                                                                                                                                     containing
                                                                                                                                     heptachlor epoxide
                                                                                                                                     in excess of the
                                                                                                                                     MCL over many years
                                                                                                                                     could experience
                                                                                                                                     liver damage, and
                                                                                                                                     may have an
                                                                                                                                     increased risk of
                                                                                                                                     getting cancer.
    Hexachlorobenzene (ppb)....  .001.............  1000.............  1................  0.................  Discharge from metal  Some people who
                                                                                                               refineries and        drink water
                                                                                                               agricultural          containing
                                                                                                               chemical factories.   hexachlorobenzene
                                                                                                                                     in excess of the
                                                                                                                                     MCL over many years
                                                                                                                                     could experience
                                                                                                                                     problems with their
                                                                                                                                     liver or kidneys,
                                                                                                                                     or adverse
                                                                                                                                     reproductive
                                                                                                                                     effects, and may
                                                                                                                                     have an increased
                                                                                                                                     risk of getting
                                                                                                                                     cancer.
    Hexachlorocyclopentadiene    .05..............  1000.............  50...............  50................  Discharge from        Some people who
     (ppb).                                                                                                    chemical factories.   drink water
                                                                                                                                     containing
                                                                                                                                     hexachlorocyclopent
                                                                                                                                     adiene well in
                                                                                                                                     excess of the MCL
                                                                                                                                     over many years
                                                                                                                                     could experience
                                                                                                                                     problems with their
                                                                                                                                     kidneys or stomach.
    Lindane (ppt)..............  .0002............  1,000,000........  200..............  200...............  Runoff/leaching from  Some people who
                                                                                                               insecticide used on   drink water
                                                                                                               cattle, lumber,       containing lindane
                                                                                                               gardens.              in excess of the
                                                                                                                                     MCL over many years
                                                                                                                                     could experience
                                                                                                                                     problems with their
                                                                                                                                     kidneys or liver.
    Methoxychlor (ppb).........  .04..............  1000.............  40...............  40................  Runoff/leaching from  Some people who
                                                                                                               insecticide used on   drink water
                                                                                                               fruits, vegetables,   containing
                                                                                                               alfalfa, livestock.   methoxychlor in
                                                                                                                                     excess of the MCL
                                                                                                                                     over many years
                                                                                                                                     could experience
                                                                                                                                     reproductive
                                                                                                                                     difficulties.
    Oxamyl [Vydate] (ppb)......  .2...............  1000.............  200..............  200...............  Runoff/leaching from  Some people who
                                                                                                               insecticide used on   drink water
                                                                                                               apples, potatoes      containing oxamyl
                                                                                                               and tomatoes.         in excess of the
                                                                                                                                     MCL over many years
                                                                                                                                     could experience
                                                                                                                                     slight nervous
                                                                                                                                     system effects.
    PCBs [Polychlorinated        .0005............  1,000,000........  500..............  0.................  Runoff from           Some people who
     biphenyls] (ppt).                                                                                         landfills;            drink water
                                                                                                               Discharge of waste    containing PCBs in
                                                                                                               chemicals.            excess of the MCL
                                                                                                                                     over many years
                                                                                                                                     could experience
                                                                                                                                     changes in their
                                                                                                                                     skin, problems with
                                                                                                                                     their thymus gland,
                                                                                                                                     immune
                                                                                                                                     deficiencies, or
                                                                                                                                     reproductive or
                                                                                                                                     nervous system
                                                                                                                                     difficulties, and
                                                                                                                                     may have an
                                                                                                                                     increased risk of
                                                                                                                                     getting cancer.
    Pentachlorophenol (ppb)....  .001.............  1000.............  1................  0.................  Discharge from wood   Some people who
                                                                                                               preserving            drink water
                                                                                                               factories.            containing
                                                                                                                                     pentachlorophenol
                                                                                                                                     in excess of the
                                                                                                                                     MCL over many years
                                                                                                                                     could experience
                                                                                                                                     problems with their
                                                                                                                                     liver or kidneys,
                                                                                                                                     and may have an
                                                                                                                                     increased risk of
                                                                                                                                     getting cancer.
    Picloram (ppb).............  .5...............  1000.............  500..............  500...............  Herbicide runoff....  Some people who
                                                                                                                                     drink water
                                                                                                                                     containing picloram
                                                                                                                                     in excess of the
                                                                                                                                     MCL over many years
                                                                                                                                     could experience
                                                                                                                                     problems with their
                                                                                                                                     liver.
    Simazine (ppb).............  .004.............  1000.............  4................  4.................  Herbicide runoff....  Some people who
                                                                                                                                     drink water
                                                                                                                                     containing simazine
                                                                                                                                     in excess of the
                                                                                                                                     MCL over many years
                                                                                                                                     could experience
                                                                                                                                     problems with their
                                                                                                                                     blood.
    Toxaphene (ppb)............  .003.............  1000.............  3................  0.................  Runoff/leaching from  Some people who
                                                                                                               insecticide used on   drink water
                                                                                                               cotton and cattle.    containing
                                                                                                                                     toxaphene in excess
                                                                                                                                     of the MCL over
                                                                                                                                     many years could
                                                                                                                                     have problems with
                                                                                                                                     their kidneys,
                                                                                                                                     liver, or thyroid,
                                                                                                                                     and may have an
                                                                                                                                     increased risk of
                                                                                                                                     getting cancer.
Volatile organic contaminants:
    Benzene (ppb)..............  .005.............  1000.............  5................  0.................  Discharge from        Some people who
                                                                                                               factories; Leaching   drink water
                                                                                                               from gas storage      containing benzene
                                                                                                               tanks and landfills.  in excess of the
                                                                                                                                     MCL over many years
                                                                                                                                     could experience
                                                                                                                                     anemia or a
                                                                                                                                     decrease in blood
                                                                                                                                     platelets, and may
                                                                                                                                     have an increased
                                                                                                                                     risk of getting
                                                                                                                                     cancer.
    Carbon tetrachloride (ppb).  .005.............  1000.............  5................  0.................  Discharge from        Some people who
                                                                                                               chemical plants and   drink water
                                                                                                               other industrial      containing carbon
                                                                                                               activities.           tetrachloride in
                                                                                                                                     excess of the MCL
                                                                                                                                     over many years
                                                                                                                                     could experience
                                                                                                                                     problems with their
                                                                                                                                     liver and may have
                                                                                                                                     an increased risk
                                                                                                                                     of getting cancer.
    Chlorobenzene (ppb)........  .1...............  1000.............  100..............  100...............  Discharge from        Some people who
                                                                                                               chemical and          drink water
                                                                                                               agricultural          containing
                                                                                                               chemical factories.   chlorobenzene in
                                                                                                                                     excess of the MCL
                                                                                                                                     over many years
                                                                                                                                     could experience
                                                                                                                                     problems with their
                                                                                                                                     liver or kidneys.
    o-Dichlorobenzene (ppb)....  .6...............  1000.............  600..............  600...............  Discharge from        Some people who
                                                                                                               industrial chemical   drink water
                                                                                                               factories.            containing o-
                                                                                                                                     dichlorobenzene
                                                                                                                                     well in excess of
                                                                                                                                     the MCL over many
                                                                                                                                     years could
                                                                                                                                     experience problems
                                                                                                                                     with their liver,
                                                                                                                                     kidneys, or
                                                                                                                                     circulatory
                                                                                                                                     systems.
    p-Dichlorobenzene (ppb)....  .075.............  1000.............  75...............  75................  Discharge from        Some people who
                                                                                                               industrial chemical   drink water
                                                                                                               factories.            containing p-
                                                                                                                                     dichlorobenzene in
                                                                                                                                     excess of the MCL
                                                                                                                                     over many years
                                                                                                                                     could experience
                                                                                                                                     anemia, damage to
                                                                                                                                     their liver,
                                                                                                                                     kidneys, or spleen,
                                                                                                                                     or changes in their
                                                                                                                                     blood.
    1,2-Dichloroethane (ppb)...  .005.............  1000.............  5................  0.................  Discharge from        Some people who
                                                                                                               industrial chemical   drink water
                                                                                                               factories.            containing 1,2-
                                                                                                                                     dichloroethane in
                                                                                                                                     excess of the MCL
                                                                                                                                     over many years may
                                                                                                                                     have an increased
                                                                                                                                     risk of getting
                                                                                                                                     cancer.
    1,1-Dichloroethylene (ppb).  .007.............  1000.............  7................  7.................  Discharge from        Some people who
                                                                                                               industrial chemical   drink water
                                                                                                               factories.            containing 1,1-
                                                                                                                                     dichloroethylene in
                                                                                                                                     excess of the MCL
                                                                                                                                     over many years
                                                                                                                                     could experience
                                                                                                                                     problems with their
                                                                                                                                     liver.
    cis-1,2-Dichloroethylene     .07..............  1000.............  70...............  70................  Discharge from        Some people who
     (ppb).                                                                                                    industrial chemical   drink water
                                                                                                               factories.            containing cis-1,2-
                                                                                                                                     dichloroethylene in
                                                                                                                                     excess of the MCL
                                                                                                                                     over many years
                                                                                                                                     could experience
                                                                                                                                     problems with their
                                                                                                                                     liver.
    trans-1,2-Dichloroethylene   .1...............  1000.............  100..............  100...............  Discharge from        Some people who
     (ppb).                                                                                                    industrial chemical   drink water
                                                                                                               factories.            containing trans-
                                                                                                                                     1,2-
                                                                                                                                     dichloroethylene
                                                                                                                                     well in excess of
                                                                                                                                     the MCL over many
                                                                                                                                     years could
                                                                                                                                     experience problems
                                                                                                                                     with their liver.
    Dichloromethane (ppb)......  .005.............  1000.............  5................  0.................  Discharge from        Some people who
                                                                                                               pharmaceutical and    drink water
                                                                                                               chemical factories.   containing
                                                                                                                                     dichloromethane in
                                                                                                                                     excess of the MCL
                                                                                                                                     over many years
                                                                                                                                     could have liver
                                                                                                                                     problems and may