SPECTRUM

Chemical Fact Sheet

Chemical Abstract Number (CAS #) 30560191
CASRN 30560-19-1
SynonymsAcephate
Phosphoramidothioic acid, acetyl, O,S-dimethyl ester
Orthene
Acetamidophos
O,S-Dimethyl acetylphosphoramidothioate
Molecular FormulaC4H10NO3PS

Link to the National Library of Medicine's Hazardous Substances
Database for more details on this compound.

Use Contact and systemic insecticide. Effective against alfalfa looper, aphids, armyworms, bagworms, bean leafbeetle, bean leafroller, blackgrass bugs, bollworm, budworm, cabbage looper, cankerworms, corn earworm, cutworms, diamond back moth, European corn borer, fireworms, fleahooper, grasshoppers, green cloverworm, gypsy moth, hornworm, imported cabbage worm, imported fire ants, lace bugs, leafminers, leafhoppers, leafrollers, lygus, Mexican bean beetle, Mormon crickets, oak moth, saltmarsh caterpillar, soybean looper, spanworms, sparganothis, stinkbugs, tent caterpillars, three-cornered alfalfa hopper, thrips, tobacco hornworm, velvetbean caterpillar, webworms, and whitefly. For bell and non-bell peppers, Brussel sprouts, cauliflower, celery, cotton, cranberries, dry beans, head lettuce, mint, peanuts, soybeans, and succulent beans. Cockroach control (spot treatment only) in residential and industrial buildings and insect control in forests, tobacco, and on ornamentals. Acephate is used to control insects and aphids in ornamentals, where it has a reasonably broad spectrum. It is also cleared for use on beans, cotton, head lettuce, celery, soybeans, and bell peppers. It controls parasites of cattle, goats, hogs, horses, poultry, and sheep, where tolerances have been set for milk, eggs, fat, and meat. Acephate is used for household use or golf course spray. From table
Consumption Patterns 2.2 Million lbs US consumption (1982).
Apparent Color Colorless solid Technical grade 80-90% pure/; White solid (technical); White crystals
Melting Point 82-89 deg C Technical grade 80-90% purity/
Molecular Weight 183.16
Sensitivity Data Organophosphorus cmpd can produce dermal irritation but most are weak sensitizers. /Organophosphorus cmpd
Environmental Impact Acephate's use as an insecticide releases the compound directly to the soil environment through applications (usually spraying) to protect crops and seeds. If released to soil or water, acephate will degrade by microbial degradation and aqueous hydrolysis. The rate of hydrolysis increases with increasing pH; therefore, degradation can occur more rapidly in alkaline media than in acidic media. Estimated Koc values of 2-8 suggest that acephate will leach readily in soil. A review of available literature has determined that the average soil half-life of acephate is about 3 days. If released to the atmosphere, acephate can exist in both the vapor and particulate-phases; vapor-phase acephate degrades rapidly by reaction with photochemically produced hydroxyl radicals (estimated half-life of 6 hours). Physical removal from the atmosphere may occur through wet and dry deposition. Occupational exposure to acephate occurs through dermal contact and inhalation of dust. The general population is exposed to acephate through consumption of foods containing pesticide residues of the compound.
Environmental Fate TERRESTRIAL FATE: Laboratory degradation studies have demonstrated that acephate can degrade through microbial degradation and aqueous hydrolysis . Since the rate of hydrolysis increases with increasing pH , degradation may occur more rapidly in alkaline soil than in acidic soil. A review of available literature determined that the average soil half-life of acephate is about 3 days . A laboratory study of rice paddy soil found a half-life of 3-4 days in aerobic conditions and 13-14 days in anaerobic (flooded) conditions suggesting a longer persistence in anaerobic conditions. The persistence half-life on a variety of foliage is reported to range from 0.7 to 8.2 days . Estimated Koc values of 2-8 suggest that acephate will leach readily(5,SRC). AQUATIC FATE: Laboratory degradation studies have demonstrated that acephate can degrade through microbial degradation and aqueous hydrolysis . Since the rate of hydrolysis increases with increasing pH , degradation will occur more rapidly in alkaline water than in acidic water. DMPT (O,S-dimethyl phosphorothiolate) has been identified as the major hydrolysis product ; methamidophos and OMPT (O-methylacetyl phosphoramidothiolate) have been identified as minor hydrolysis products . Aquatic volatilization, bioconcentration, direct photolysis and adsorption to sediment are not expected to be important environmental fate processes. ATMOSPHERIC FATE: Based upon a vapor pressure of 1.7X10-6 mm Hg at 25 deg C , acephate can exist in both the vapor and particulate-phases in the ambient atmosphere(2,SRC). It will degrade rapidly in the vapor-phase by reaction with photochemically produced hydroxyl radicals with an estimated half-life of 6 hr(3,SRC). Acephate is very soluble in water , therefore, physical removal from air by wet deposition (dissolution in clouds, rainfall, etc) is possible. Physical removal of particulates by dry deposition (settling) will also occur. TERRESTRIAL FATE - Acephate if rapidly degraded in soil, with a half-life of 0.5-4 days for most soil types and 6-13 days in organic muck. EFFL: An acephate concn of 134 mg/L was detected in the rinsate effluent from washing (rinsing) an airplane tank used to hold the insecticide during s

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