Technical Factsheet on: DALAPON
List of Contaminants
As part of the Drinking Water and Health pages, this fact sheet is part of a larger publication:
National Primary Drinking Water Regulations
Drinking Water Standards
MCLG: 0.2 mg/L
MCL: 0.2 mg/L
HAL(child): 1- to 10-day: 3 mg/L; longer-term: 0.3 mg/L
Health Effects Summary
Acute: EPA has found dalapon to potentially cause the following
health effects from acute exposures at levels above the MCL: no
effects, but readily absorbed into and widely distributed
throughout the body.
Drinking water levels which are considered "safe" for short-term
exposures: For a 10-kg (22 lb.) child consuming 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.
Chronic: Dalapon has the potential to cause the following
health effects from long-term exposures at levels above the MCL:
increased kidney-to-body weight.
Cancer: There is inadequate evidence to state whether or not
dalapon has the potential to cause cancer from lifetime exposure
in drinking water.
Usage Patterns
Dalapon is a herbicide used to control grasses in a wide variety
of crops, including fruit trees, beans, coffee, corn, cotton and
peas. It is also registered for use in a number of non-crop
applications such as lawns, drainage ditches, along railroad
tracks, and in industrial areas. Dalapon is marketed as the
sodium salt or as a mixture of the sodium and magnesium salts.
Domestic production of dalapon in 1982 ranged between 7 and 9
million lbs. 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).
Release Patterns
Dalapon is released directly to the environment in its use as a
herbicide for the control of annual and perennial grasses.
Since dalapon is not a listed chemical in the Toxics Release
Inventory, data on releases during its manufacture and handling
are not available.
Environmental Fate
If released to soil, microbial degradation and leaching appear to
be the important environmental fate processes. Dalapon leaches
readily in soil; however, under conditions favorable for
microbial growth, microbial degradation will probably proceed at
a faster rate than leaching. In the absence of microbial action,
dalapon degradation in soil is slow. The resultant average
persistence of dalapon at recommended rates of application has
been reported to be two to four weeks in most agricultural soils
during the growing season, although a persistence of six months
has been observed in soils of various forests and tree nurseries.
If released to water, microbial degradation, hydrolysis, and
photolysis are potentially important in the removal of 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. Atmospheric 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 formulation and application
of dalapon herbicide.
Chemical/ Physical Properties
CAS Number: 75-99-0
Color/ Form/Odor: Colorless liquid with an acrid odor; sold as
sodium or magnesium salt
M.P.: 20 C B.P.: 190 C
Vapor Pressure: N/A
Octanol/Water Partition (Kow): Log Kow = 0.778
Density/Spec. Grav.: 1.4 at 15 C
Solubility: 800 g/L of water at 25 C; Very soluble in water
Soil sorption coefficient: Koc N/A; very high mobility in soil
Odor/Taste Thresholds: N/A
Bioconcentration Factor: BCF =1 to 3; not expected to
bioconcentrate in aquatic organisms.
Henry's Law Coefficient: 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
Other Regulatory Information
Monitoring 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>
Analysis:
| Reference Source |
Method Numbers |
| EPA 600/4-88-039 |
515.1; 552.1 |
Treatment- Best Available Technologies:
Granular Activated Charcoal
For Additional Information:
EPA can provide further regulatory and other general information:
EPA Safe Drinking Water Hotline - 800/426-4791
Other sources of toxicological 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
List of Contaminants
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