| Chemical Abstract Number (CAS #) |
1918167
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| Synonyms | Propachlor |
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Acetamide, 2-chloro-N-(1-methylethyl)-N-phenyl- | 2-Chloro-N-isopropylacetanilide | Ramrod |
| Analytical Methods |
EPA Method 508 |
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EPA Method 8081 |
| Molecular Formula | C11H14ClNO |
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| Use | HERBICIDE FOR GRASSES & BROADLEAF WEEDS ON CORN, SORGHUM,
SOYBEANS, SUGAR BEETS AND OTHER FIELD CROPS, FORAGE CROPS, PASTURE
LAND, & RANGE LAND, SUMMER FALLOW, & ON VEGETABLES
Herbicide effective against annual grasses and some broad-leaved weeds in beans, brassicas,
cotton, groundnuts, leeks, maize, onions, peas, roses, ornamental trees and shrubs, and sugarcane
.
Selective herbicide for control of annual grasses and some annual broad-leaved weeds in
garlic, fennel, flower crops, flax, oilseed rape, strawberries, pumpkins .
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| Consumption Patterns | AS A HERBICIDE FOR ANNUAL GRASSES & BROADLEAF WEEDS: 90% USED
ON CORN; 6% ON SORGHUM; 2% ON SOYBEANS; 1% ON VEGETABLES; & 1% IN
OTHER APPLICATIONS (ON SUGAR BEETS & OTHER FIELD CROPS, FORAGE CROPS,
PASTURE & RANGE LAND, & SUMMER FALLOW) (1971)
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| Apparent Color | LIGHT TAN SOLID ; WHITE, CRYSTALLINE SOLID
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| Boiling Point | 110 DEG C @ 0.03 MM HG
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| Melting Point | 67-76 DEG C
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| Molecular Weight | 211.71
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| Density | 1.242 G/ML @ 25 DEG C
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| Environmental Fate | Propachlor was applied to soil and to onions as pre- and post-emergence treatments.
Residues of free N-isopropylaniline or propachlor were not present in the onions when harvested
nor in soil when sampled one year afer treatment. Analyses of the onions and soil, however, did
show the presence of a conjugated metabolite which was shown after hydrolysis to be
N-isopropylaniline. Residues of this conjugate were present as much as 2 years after application.
Ring-(14)C-labeled alachlor and propachlor were studied in a model eco-system. Alachlor was
degraded into eight compounds and propachlor into seven compounds. None were identified. In
each case some of the material was unextractable. There was no evidence of magnification of the
two compounds or their metabolites in the food chain.
TERRESTRIAL FATE: Biodegradation may control the fate of propachlor in soil(1-2). The
biodegradation may proceed either by cometabolism leading to the formation of several
metabolites or to complete mineralization of propachlor . Both increase in soil temperature and
moisture content will accelerate biodegradation of propachlor in soil . Photodegradation of
soil-bound propachlor by sunlight is not expected to be important . The loss of propachlor from
dry soil by volatilization will not be important, the volatilization may become important in some
moisture-saturated soil under windy conditions .
TERRESTRIAL FATE: Both soil thin layer chromatographic studies and Koc values in the
range 45-794(1-3) suggests that propachlor will be highly to moderately mobile in most soils. The
half-life of propachlor in most soils under field conditions is 4 to 14 days , but the metabolites
of propachlor may persist in soil much longer(5,SRC).
AQUATIC FATE: Photolysis of the compound in water by sunlight may not be important, but the
presence of sensitizers may accelerate the rate of photolysis . The estimated Koc value in the
range 45-794(2-4) suggests that adsorption to suspended solids and sediment may be of low to
moderate importance for the removal of propachlor from water. Based on a value of 1.09X10-7
atm-cu m/mole for Henry's Law constant , the volatilization of propachlor from water will not
be important(6,SRC).
AQUATIC FATE: THe major process for the loss of propachlor from water is
biodegradation(6-7). Both the experimental and the estimated bioconcentration factor in the range
1-17(1-3) indicates that bioconcentration of propachlor in aquatic organisms not be important.
Only 15.5% of propachlor was lost from a lake water in 30 days . In another lake water, 59%
of propachlor metabolized in 6 weeks .
ATMOSPHERIC FATE: Based on a vapor pressure of 2.3X10-4 mm Hg at 25 deg C ,
propachlor may exist predominantly in the vapor phase in the atmosphere(2,SRC). Based on an
estimation method , vapor phase propachlor may be removed from the atmosphere with a
half-life of 5.7 hrs due to reaction with photochemically produced hydroxyl radicals. Partial
removal of particulate propachlor from the air may occur by dry deposition. The fact that
propachlor has been detected in rainwater suggests it will be removed from the atmosphere by
wet deposition as well.
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| Drinking Water Impact | LABILE IN AQ ENVIRONMENT, & THERE IS NO EVIDENCE TO INDICATE
THAT METABOLITES OR DEGRADATION PRODUCTS WERE ACCUM IN BIOTA.
SURFACE WATER: Propachlor was detected in 1 of 7 samples from lower Tuttle Creek Lake,
KS at a concn 0.25 ug/l . It was also detected in Mississippi River water near Memphis, TN at a
concn 13 ng/l . On a nationwide basis, propachlor was found in 34 of 1690 surface water
samples at a max concn of 10 ug/l .
GROUNDWATER: Propachlor was detected in an average of 1.2% of groundwater samples
collected from IL, IA and MN . The max propachlor concn in groundwaters from IL, IA and
MN were 2.98 ug/l, 1.75 ug/l and 0.52 ug/l, respectively . Propachlor was also detected in 12%
groundwater samples from NE at a median concn of 1.65 ug/l . In a nationwide survey,
propachlor was detected in 2 of 99 groundwater samples collected from 94 wells at a max
concn of 0.12 ug/l .
RAIN WATER: Propachlor was detected in 3.1% of rain water samples from IA at a max. and
median concn of 0.88 and 0.17 ug/l, respectively .
EFFL: Propachlor was detected in 1.4% of tile drainage water from agricultural lands in IA at a
max concn of 1.7 ug/l .
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