|Chemical Abstract Number (CAS #)||
|Synonyms||Dimethoate||Phosphorodithioic acid, O,O-dimethyl S-[2-(methylamino)-2-oxoethyl] ester||Cygon
||EPA Method 8141|
Link to the National Library of Medicine's Hazardous Substances
Database for more details
on this compound.
|Use|| Systemic insecticide-acaricide used for a wide range of insects such as aphids, thrips,
planthoppers, white flies, mites on ornamental plants, alfalfa, apples, corn, cotton, grapefruit,
grapes, lemons, melons, oranges, pears, pecans, safflower, sorghum, soybeans, tangerines,
tobacco, tomatoes, watermelons, wheat, other vegetables; residual wall spray in farm buildings for
INSECTICIDE FOR DECIDUOUS FRUITS & NUTS & COMMERCIAL/INDUSTRIAL
It is effective against Diptera of medical importance
FOR FRUIT FLY LARVAE
|Consumption Patterns|| INSECTICIDE FOR VEGETABLES, 31%; CITRUS, 23%; DECIDUOUS FRUITS &
NUTS, 15%; ALFALFA, 8%; COTTON, 8%; WHEAT, 8%; OTHER FIELD CROPS-EG,
SORGHUM & SOYBEANS, 8% (1982)
|Apparent Color|| Colorless crystals
|Odor|| CAMPHOR-LIKE ODOR; Mercaptan odor
|Boiling Point|| 107 deg C at 0.05 mm Hg From table/
|Melting Point|| 51-52 DEG C
|Molecular Weight|| 229.28
|Density|| 1.277 @ 65 DEG C
|Sensitivity Data|| May cause eye irritation.
|Environmental Impact|| Release of dimethoate to the environment will result from its production and use as a
contact and systemic insecticide. If it is released to the soil it will not adsorb to the soil and will be
subject to considerable leaching. Evaporation from dry soil and other surfaces and biodegradation
may be significant processes. Soil half-lives of approximately 4 and 2.5 days were reported during
drought and moderate rainfall conditions. If released to water dimethoate will not be expected to
sorb to sediment, hydrolyze, or to bioconcentrate in aquatic organisms; direct photolysis and
evaporation from water are not expected to be important processes. It may be subject to
biodegradation in natural waters based on a half-life of 8 weeks for degradation in raw river
water. If dimethoate is released to the atmosphere it may be subject to oxidation. The estimated
vapor phase half-life in the atmosphere is 2.83 days as a result of H atom abstraction by
photochemically produced hydroxyl radicals. Exposure to dimethoate will result mainly from
occupational contact during its production and use as a contact and systemic insecticide. General
population exposure may also occur through the ingestion of contaminated foods.
|Environmental Fate|| TERRESTRIAL FATE: If dimethoate is released to the soil, it will not adsorb to the soil
and will be subject to considerable leaching . It should not be susceptible to hydrolysis in soils.
Evaporation from dry soil and other surfaces may be a significant process with 23.0-40.4% losses
reported due to evaporation from uncovered columns of soils with varying organic content .
Biodegradation may be an important fate process with 77% degradation reported in clay loam soil
in 2 weeks compared to 18 and 20% degradation in the same soil that had been autoclaved or
irradiated . Soil half-lives of approx 4 and 2.5 days were reported during drought and moderate
rainfall conditions ; a range of 4-16 days for the half-life in soil was reported(3,SRC).
AQUATIC FATE: If released to water, dimethoate will not be expected to sorb to sediment, to
hydrolyze, or to bioconcentrate in aquatic organisms. Direct photolysis and evaporation of
dimethoate from water are not expected to be important processes. It may be subject to
biodegradation based on a half-life of 8 weeks in raw river water .
ATMOSPHERIC FATE: If dimethoate is released to the atmosphere, it may be subject to
oxidation. The estimated vapor phase half-life in the atmosphere is 2.83 days as a result of H atom
abstraction by photochemically produced hydroxyl radicals.
When applied to plants, dimethoate was decomposed on surface by hydrolysis &
oxidation. On the plant surface, dimethoate underwent non-enzymatic oxidation to the oxygen
analog & hydrolysis to water sol deriv identified as dimethyl phosphoric & O,O-dimethyl
phosphorothioic acids, desmethyl dimethoate
|Drinking Water Impact|| DRINKING WATER: Not detected in water from 54 wells in California, in an area
where it was used for at least 15 years . Not detected in 82 samples from 80 stations in New
York State, 1964-66, including wells, groundwater, and surface water .
SURFACE WATER: Not detected in 82 samples from 80 stations in New York State, 1964-66,
including wells, groundwater, and surface water . West Germany, Rhine River, 1-10 ppb .