| Chemical Abstract Number (CAS #) |
759944
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| Synonyms | EPTC |
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Carbamothioic acid, dipropyl-, S-ethyl ester | Eptam | Alirox | Niptan | Witox | Farmarox | S-Ethyl dipropylthiocarbamate |
| Analytical Method |
EPA Method 634 |
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| Molecular Formula | C9H19NOS |
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| Use | SOIL FUMIGANT
SELECTIVE HERBICIDE FOR CONTROL OF A VARIETY OF WEEDS
For annual grassy weeds, perennial weeds, some broadleaf weeds in beans, forage, legumes,
potatoes, corn, sweet potatoes in some areas.
Control of grasses and weeds in peas, beetroot, sugarbeet, lucerne, trefoil, clover,
cotton, flax, almonds, walnuts, ornaments, pineapples, pine nurseries, and other crops.
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| Consumption Patterns | HERBICIDE, OF WHICH APPROXIMATELY 59% IS USED ON CORN, 31% ON
VEGETABLES, 10% ON SUGAR BEETS (1975)
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| Apparent Color | CLEAR LIQUID ; Pale-dark yellow liquid
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| Odor | AROMATIC ODOR
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| Boiling Point | 232 DEG C @ 760 MM HG
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| Molecular Weight | 189.35
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| Density | 0.955 @ 30 DEG C
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| Sensitivity Data | SRP: Exposure to dusts, sprays, solutions, wettable powder suspensions or emulsions of
these agents may lead to skin and mucous membrane irritation.
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| Environmental Impact | Eptam is released directly to the environment through its use and application asan
agricultural herbicide. After application, it may undergo surface runoff (via rainfall or irrigation),
with transport to rivers and lakes. If released tosoil, microbial degradation is reported to be a
major removal process. Furthermore, volatilization from soil surfaces will be an important fate
process (estimated half-life of 3.4 hrs from a soil surface) if Eptam is applied when the surface is
wet at the time of application and the herbicide is not immediately incorporated into the soil.
Eptam has moderate-high mobility in soil (Kocs of 109-283); its detection in groundwater
demonstrates that it can leach. The half-life in soil typically ranges from 6 to 35 days; the US Dept
of Agriculture's Pesticide Properties Database lists a soil half-life of 6 days. If released to water,
Eptam may degrade through microbial degradation. Volatilization will be important (estimated
volatilization half-lives of 2.4 and 82 days from a model river and environmental pond,
respectively). Hydrolysis and bioconcentration will not be important. If released to the
atmosphere, Eptam will exist almost entirely in the vapor phase; vapor phase Eptam readily
degrades by reaction with photochemically produced hydroxyl radicals (estimated half-life of 14
hours). Physical removal from the atmosphere occurs through wet deposition. Worker exposure
to Eptam occurs through dermal contact and inhalation of vapor and dust.
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| Environmental Fate | A REDUCTION OF EPTC PERSISTENCE WHEN IT WAS DISSOLVED IN
KEROSENE & AN INCR OF PERSISTENCE BY THE ADDITION OF SPECIFIC
SURFACTANTS WAS REPORTED/. EPTC WAS INACTIVATED ABOUT 1/3 AS
RAPIDLY IN AUTOCLAVED AS IN NONAUTOCLAVED SOIL
TERRESTRIAL FATE: The degradation half-life of Eptam (initial concn of 5 ppm) at 25 deg C
in Regina heavy clay soil (pH 7.5) and Weyburn loam (pH 7.0) was 4-5 wks and 4 wks,
respectively . The half-life in moist loam soil at 21-27 deg C is about 1 week . Eptam was
reported to persist in soil for 4 wks . According to the US Dept of Agriculture's Pesticide
Properties Database, the soil half-life of Eptam is 6 days . Microbial breakdown is reported as a
main removal process of Eptam from soil . Furthermore, volatilization from soil surfaces will be
an important fate process (estimated half-life of 3.4 hrs from a wet soil surface ) if Eptam is
applied when the surface is wet at the time of application and the herbicide is not immediately
incorporated into the soil(3,SRC). In a loam soil at 25 deg C inoculated with Eptam degraders,
approximately 100% Eptam was removed from the soil within 15 days; 45% resulted from
biodegradation(6). The sterile sample in this study resulted with 55% removal by volatilization(6).
TERRESTRIAL FATE: A Koc value of 200 indicates high mobility in soil; however,
Eptam is adsorbed to dry soil . Detection in US groundwater demonstrates that leaching is
potentially an important transport process. The amount of leaching decreases as clay and
organic matter increases . In sandy soils in glass columns, eptam moved to a depth of 23-38 cm
when 20 cm of water was applied . In loam and clay soils, Eptam moved to a depth of 8-15 cm
when 20 cm of water was applied .
AQUATIC FATE: Volatilization will be an important removal process of Eptam from aquatic
ecosystems; estimated Henry's Law constant of 2.26x10 atm-cu m/mole at 25 deg C.
Volatilization half-lives of 2.4 and 82 days have been estimated for a model river (one meter deep)
and a model environmental pond, respectively(1-2). Hydrolysis and bioconcentration in fish
(estimated BCF range of 12-22 ) will not be important. An experimental Koc of 240
indicates weak adsorption to sediments. Based on biodegradation studies in soil(4-7),
microbial degradation may occur.
ATMOSPHERIC FATE: Based upon an experimental vapor pressure of 0.034 mm Hg at 25 deg
C , Eptam is expected to exist almost entirely in the vapor phase in the ambient
atmosphere(2,SRC). It will degrade in the vapor phase by reaction with photochemically
produced hydroxyl radicals with an estimated half-life of about 14 hrs(3,SRC). Physical removal
from air by wet deposition (dissolution in clouds, rainfall, etc) will occur. Eptam has been
detected in widespread rainwater monitoring studies(4-5); degradation rates associated with
rainwater and clouds are unknown; these monitoring studies suggest that widespread
atmospheric dispersal is possible .
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| Drinking Water Impact | SURFACE WATER: During 1986 to 1991, Eptam maximum concns in Lake Erie
tributaries, which drain agricultural watersheds, were: 3.99 ug/l in the Maumee River, 14.186 ug/l
in the Sandusky River, 5.696 ug/l in Honey Creek, 7.639 ug/l in Rock Creek, 21.065 ug/l in Lost
Creek, 0.865 ug/l in the Cuyahoga River, and 0.119 ug/l in the Raisin River . Eptam was
detected in Shell Creek, a tributary to the Platte River in Nebraska, at a concn range of 0.1-1 ug/l
in 7 samples taken about 96 hrs after a spring rainstorm; no Eptam was detected in the creek prior
to the storm . During the months May-August, 1981-85, the Eptam concn was 0.1 ug/l in 1 of
41 samples drawn at the mouth of the Saugeen River, Ontario, Canada . In 1977, Eptam was
qualitatively identified in water from Lake Erie .
RAIN/SNOW: Eptam was detected in 1985 at a concn less than 0.1 ug/l in 1 of 14 rain samples
taken in West Lafayette, IN . Eptam was quantified in 5 of 318 Iowa rain samples at an average
concn of 1.07 ug/l during November, 1987-September, 1990 .
GROUNDWATER: Eptam was detected at a maximum concn of 2.9 ug/l in groundwater from
Wisconsin; it was qualitatively detected in groundwater from Minnesota .
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