| Chemical Abstract Number (CAS #) |
75990
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| Synonyms | Dalapon |
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2,2-Dichloropropanoic acid |
| Analytical Methods |
EPA Method 515.1 |
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EPA Method 552.1 |
EPA Method 615 |
EPA Method 8150B |
EPA Method 8151 |
| Molecular Formula | C3H4Cl2O2 |
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| Use | IN NON-CROP AREAS SUCH AS ROADSIDES, RAILWAYS, DITCHES. ALSO IN
CERTAIN ESTABLISHED CROPS SUCH AS ALFALFA, ASPARAGUS, FLAX,
POTATOES, RAPE SEED, SUGAR BEETS.
For quackgrass, bermudagrass, johnsongrass, other perennial and annual grasses, cattails, rushes.
Often preplant for established perennial grasses in cropland, noncropland areas, irrigation ditch
banks. Translocates to the roots of most species as a growth regulator.
Selective herbicide; growth regulator
HERBICIDE SODIUM SALT
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| Consumption Patterns | Non-food use, 92.9% (89.9% use on rights of way); main food crop treated was
sugarbeet (6.7% of total) (1984) California use, calculated from table
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| Apparent Color | LIQUID; COLORLESS
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| Odor | Acrid
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| Boiling Point | 190 deg C
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| Melting Point | 20 DEG C
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| Molecular Weight | 142.97
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| Density | 1.4014 @ 20 DEG C
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| Odor Threshold Concentration | 2,500 mg/cu m
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| Sensitivity Data | SKIN - MODERATE IRRITATION UPON REPEATED PROLONGED CONTACT.
EYES - MODERATE IRRITATION . INHALATION - DUSTS MAY BE IRRITATING TO
UPPER RESP TRACT.
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| Environmental Impact | Dalapon is released directly to the environment in its use as a herbicide for the control of
annual and perennial grasses. 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, adsorption to sediments, or bioconcentration 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.
Occupational exposure to dalapon may occur through dermal and inhalation routes associated
with the formulation and application of dalapon herbicide.
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| Environmental Fate | TERRESTRIAL FATE: Microbial degradation and leaching appear to be the important
fate processes in soil with respect to dalapon. Dalapon leaches readily in soils. 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 . Dalapon has been
observed to breakdown completely in Hawaiian soils within a few weeks . Using a plant
bioassay under greenhouse conditions (28 deg C), dalapon persisted only 4-8 days in muck soil,
8-16 days in loam and silty clay loam soils, 16-32 days in sandy loam soil, and 32-64 days in silt
clay soil . The speed of degradation is greatly dependent on soil conditions favorable to
microorganisms, with favorable conditions being temperatures of 20 to 30 deg C, adequate soil
moisture, and a pH range of 5.3 to 7.5 . The persistence of dalapon in the soil of various forests
and tree nurseries has been observed to be as long as 6 months(4,SRC).
AQUATIC FATE: The environmental fate processes which are potentially important for
removing dalapon from natural waters include hydrolysis, microbial degradation, and photolysis.
The hydrolysis half-life of dalapon and its salts 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 significance of chemical hydrolysis . Direct photolysis of
dalapon in water is possible since it absorbs UV light above 290 nm; however, rates of photolysis
has not been investigated under environmental conditions. Aquatic volatilization, adsorption to
sediments, or bioconcentration are not expected to be significant.
ATMOSPHERIC FATE: The vapor-phase reaction of dalapon with photochemically produced
hydroxyl radicals has been estimated to be 72.3 days in typical atmosphere . Since dalapon is
extremely water soluble (> 80 g/100 g water at 25 deg C) , atmospheric removal via washout
may be possible.
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| Drinking Water Impact | NEGLIGIBLE CONCN OF DALAPON WOULD REMAIN IN WATER AFTER
WATER TRAVELED DISTANCE OF 32.2-40.2 KM .
DRINKING WATER: Dalapon has been detected in drinking water concentrates collected from
Cincinnati OH (in Oct 1978 and Jan 1980) and Seattle WA (in Nov 1976) . Dalapon was
detected in 1 out of 237 wells sampled during 1969-78 in Ontario, Canada at a concentration
range of 0.1-1 ppb .
EFFL: Dalapon has been detected in effluent concentrates collected from advanced waste
treatment facilities in Lake Tahoe CA (in Nov 1974) and Washington DC (in Sept 1974) .
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