United States
                             Environmental Protection
                                                      Office of Water
            EPA 811-F-95-003J-T
                  October 1995
                             National  Primary Drinking
                            Water Regulations
                                 DENSITY/SPEC. GRAV.: 1.4 at 15° C
 CAS NUMBER: 75-99-0
                                 SOLUBILITY: 800 g/L of water at 25° C;
                                   Very soluble in water
    Colorless liquid with an acrid odor; sold  SOIL SORPTION COEFFICIENT:
    as sodium or magnesium salt           K°c N/A; very high mobility in soil

                                 ODOR/TASTE THRESHOLDS:  N/A
 M.P.: 20° C    B.P.:  190°C


    Log Kow = 0.778
                                 BlOCONCENTRATION FACTOR:
                                   BCF =1 to 3; not expected to biocon-
                                   centrate in aquatic organisms.
  6.3x10-8 atm-cu m/mole

TRADE NAMES/SYNONYMS:   2,2-dichloro-
  proprionic acid; 2,2-DPA; Revenge;
  Alatex; Basfapon; Basinex; Crisapon;
  Dawpon-RAE; Ded-Weed; Dowpon;
  Gramevin; Kenapon; Liropon; Propon;
  Radapon; Unipon; S-1315; S-95
                                                of the sodium and magnesium salts.
                                                  Domestic production of dalapon in 1982 ranged be-
                                                tween 7 and 9 million Ibs. active ingredient. In 1984, its
                                                use in California was reported as follows: Non-food use,
                                                92.9% (89.9% use on rights of way); main food crop
                                                treated was sugarbeet (6.7% of total).
  MCLG:      0.2 mg/L
  Met:       0.2 mg/L
  HAL(child):  1- to 10-day: 3 mg/L
             longer-term: 0.3 mg/L

  Acyte/EPAhasfounddalapontopotentiallycausethe   Da|apon is released directly to the environment in its
following health effects from acute exposures at levels use as a herbicide for the control of annual and perennial
above the MCL: no effects, but readily absorbed into and grasses
widely distributed throughout the body.                              .                 .    .        .
                                                  Since dalapon is not  a listed chemical in the Toxics
  Drinking water levels which are considered "safe" for Re|ease Inventory, data on releases during its manufac-
short-term exposures: For a 10-kg (22 Ib.) child consum- ture and hand|ing are not available.
ing 1 liter of water per day, up to a ten-day exposure to 3
mg/L or up to a 7-year exposure  to 0.3 mg/L.
                                                ENVIRONMENTAL FATE
  Chronic:   Dalapon has the potential to cause the                .,-,_.,.,'_,.      .,,   u-
following  health effects from long-term exposures  at   If reteased.to soil, microbial degradation and leaching
levels above the MCL: increased kidney-to-body weight ??Pear to be tne important environmental fate processes.
                                                Dalapon leaches readily in soil; however, under condi-
  Cancer: There is inadequate evidence to state whether tjons favorab|e for microbial growth, microbial degrada-
or not dalapon has the potential to cause cancer from tjon wj|| proDab|y proceed at a faster rate than leaching.
lifetime exposure in drinking water.                  in the absence of mjCrobial action, dalapon degradation
                                                in soil is  slow. The resultant average persistence of
USAGE PATTERNS                                  dalapon at recommended rates of application has been
  Dalapon is a herbicide used to control grasses in a reported to be two to four weeks in most agricultural soils
•ride variety of crops, including fruit trees, beans, coffee, durin9the 9rowin9 season- althou9h a Persistence of six
corn, cotton and peas. It  is also  registered for use in a months has been observed in soils of various forests and
numberof non-crop applications such as lawns, drainagetree nurseries.
ditches, along railroad tracks, and in industrial areas.   If released to water, microbial degradation,  hydrolysis,
Dalapon is marketed as the sodium salt or as a mixture and photolysis are potentially important in the removal of
October 1995
                                         Technical Version
             Printed on Recycled Paper

dalapon. The hydrolysis half-life of dalapon and its salts
in water is on the order of several months at temperatures
less than 25 deg C, with the hydrolysis forming pyruvic
acid. Under conditions favorable for microbial growth,
dalapon decomposition via microorganisms will probably
be complete within one  month which will diminish the
importance of chemical hydrolysis. Direct photolysis in
water may be possible, although photolytic rates  have
not been investigated  under environmental conditions.
Aquatic volatilization and adsorption to sediments are not
expected to be significant.
  If released to the atmosphere, dalapon will react in the
vapor-phase with photochemically produced hydroxyl
radicals at an estimated half-life rate of 72.3 days. Atmo-
spheric removal via washout may be possible  since
dalapon is extremely water soluble:
  Bioconcentration is not expected to be significant. The
BCF measured for dalapon (sodium salt) during a 3-day
exposure in an aquarium was 3 for fish and less than one
for snails. BCF's of less than one have been measured for
poultry, rodents, dogs, and cows.
  Occupational exposure to dalapon may occur through
dermal  and inhalation routes associated with the formu-
lation and application of dalapon herbicide.
                                                         OTHER REGULATORY INFORMATION

                                                         FOR GROUND/SURFACE WATER SOURCES:
                                                           INITIAL FREQUENCY-  4 quarterly samples every 3 years
                                                           REPEAT FREQUENCY- If no detections during initial round:
                                                                         2 quarterly per year if serving >3300 persons;
                                                                         1 sample per 3 years for smaller systems
                                                         TRIGGERS - Return to Initial Freq. if detect at > 0.001 mg/L

                                                         REFERENCE SOURCE             METHOD NUMBERS
                                                         EPA 600/4-88-039             515.1; 552.1

                                                         BEST AVAILABLE TECHNOLOGIES
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                                                         FOR ADDITIONAL INFORMATION:
                                                         4 EPA can provide further regulatory and other general information:
                                                         • EPA Safe Drinking Water Hotline - 800/426-4791

                                                         * Other sources of lexicological and environmental fate data include:
                                                         • Toxic Substance Control Act Information Line - 202/554-1404
                                                         • Toxics Release Inventory, National Library of Medicine - 301/496-6531
                                                         • Agency for Toxic Substances and Disease Registry - 404/639-6000
                                                         • National Pesticide Hotline - 800/858-7378
October 1995
Technical Version
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