SPECTRUM

Chemical Fact Sheet

Chemical Abstract Number (CAS #) 563122
CASRN 563-12-2
SynonymsEthion
Phosphorodithioic acid, S,S'-methylene O,O,O',O'-tetraethyl ester
Bladan
Nialate
Analytical Method EPA Method 8141A
Molecular FormulaC9H22O4P2S4

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

Use INSECTICIDE AND ACARICIDE FOR CITRUS FRUIT, APPLES, NUTS, OTHER FRUIT, & COTTON It is used as a cattle dip for ticks and as a treatment for buffalo flies. /IT IS USED FOR CONTROL OF APHIDS, MITES (INCLUDING ERIOPHYD MITES), SCALES, THRIPS, LEAFHOPPERS, MAGGOTS, AND FOLIAR FEEDING LARVAE. ON A WIDE VARIETY OF FOOD, FIBER, & ORNAMENTAL CROPS. ETHION IS A NON-SYSTEMIC INSECTICIDE & ACARICIDE USED ON APPLES, PARTICULARLY WITH PETROLEUM OILS ON DORMANT TREES, TO KILL EGGS & SCALES. IT IS ALSO USED IN CONTROL OF BOOPHILUS SPP ON CATTLE IT IS NON-PHYTOTOXIC EXCEPT TO APPLE VARIETIES MATURING WITH OR BEFORE EARLY MCINTOSH. A series of pesticides were classified as follows: those which are non-toxic to both spores and mycelia of Trichoderma viride (group I), those which are moderately toxic to spores and mycelia, or toxic either to spores or mycelia (group II), and those which are toxic both to spores and to mycelia (group III). Ethion was found to be a member of group I and could be used with T viride in soil-borne fungal pathogen control.
Consumption Patterns 70% AS AN INSECTICIDE & ACARICIDE ON CITRUS FRUIT; 30% AS AN INSECTICIDE & ACARICIDE ON OTHER FRUIT, NUTS, & COTTON (EST) (1974) Applied to melons, 50.1%; Tree fruits, 2.6%; Citrus, 12.8%; Grapes, 4.5%; Other vegetables, nuts, and fruits account for remainder (1984) California use, calculated from table (1984) 4.68X10 7 g used in California (1984) 4.68X10 7 g used in California
Apparent Color COLORLESS TO AMBER-COLORED LIQUID
Melting Point -12 TO -13 DEG C
Molecular Weight 384.48
Density 1.220 @ 20 DEG C/4 DEG C
Environmental Impact Ethion is released directly into the environment in its application as an insecticide and acaricide. If released to soil, microbial degradation may be an important process for the removal of ethion based on degradation studies with sterile versus nonsterile soils. Ethion is susceptible to slow aqueous hydrolysis at acidic and neutral conditions with the hydrolysis becoming relatively rapid at pHs approaching 9 and above; therefore, hydrolysis may be the dominant transformation mechanism in very alkaline moist soils. Based on measured Koc values of 6451 to 15435, ethion is not expected to leach in soil. The persistence half-life of ethion in various soils under laboratory conditions has been found to vary from 1.3 to 8 weeks. Greenhouse and field studies with an organic soil have found half-lives of 16 to 49 weeks and significant carry-over from one planting season to the next. If released to water, microbial degradation may not be important in relation to abiotic processes based on degradation studies with natural waters versus sterilized natural waters. The hydrolysis half-lives of ethion at 25 deg C are 63, 58, 25, and 8.4 weeks at pHs 5, 6, 7, and 8, respectively, with a half-life of 1 day at pH 10 and 30 deg C. Ethion may be susceptible to some photooxidation in sunlit natural water. The high measured Koc values suggest that adsorption to sediment will be an important transport process. Based on a measured log Kow of 5.073, bioconcentration is potentially significant. Volatilization of ethion from water is not expected to be important, with the possible exception of rapidly moving shallow streams. The persistence half-life of ethion in three different natural waters under laboratory conditions was found to vary from 4 to 22 weeks; it was suggested that the faster rate of degradation in one of the natural waters was due to the presence of dissolved ions which caused an unidentified catalytic effect. If released to the atmosphere, ethion will exist in both the vapor-phase and adsorbed-phase, although the adsorbed-phase may dominate. In the vapor-phase, ethion will react rapidly with photochemically produced hydroxyl radicals at an estimated half-life rate of 6.95 hours. Ethion in the adsorbed-phase will be subject to wet and dry deposition. General population exposure to ethion may occur through ingestion of contaminated food, particularly fruits and root vegetables. Occupational exposure may occur through inhalation and dermal routes associated with the insecticidal use of ethion.
Environmental Fate Aquatic Fate: Degradation of ethion in irrigation canal waters draining a citrus grove in South Florida occurred readily by hydrolysis with a half-life of 26 days. The reaction was pH independent from pH 4-7 with a pseudo-1st-order rate constant of 4.8/days. Adsorption to canal sediments was negligible and desorption was rapid. Ethion did not accumulate in the sediment and water sample levels, never exceeded 0.017 mg/l in the water or 0.03 mug/g (dry wt) in the sediments. Hydrolysis may have been a significant mechanism in the loss of ethion from irrigation canal waters. Terrestrial Fate: Ethion, fonofos, fensulfothion, carbofuran, or chlorpyrifos were applied as a commercial granular formulations at rates equivalent to 2.24, 1.12, 1.12, 1.68, and 1.68 kg AI (active ingredient)/ha, respectively, to furrows in a greenhouse and subjected to 4 different watering schedules (normal, 0.5, 1.0, and 1.5 ml/sq cm). Persistence & movement were measured. Ethion moved slightly faster in the 2 wetter soils. Unretained water did not contain significant concn of pesticides. Plots were treated with insecticide & seeded with onions for 3 successive yr. Residue (ethion) in the soil after 3 yr was 7.6 ppm. TERRESTRIAL FATE: Under laboratory conditions, the half-lives of ethion in a sandy loam soil and organic soil were found to be 7 and 8 weeks, respectively , while the half-life in red, black, and laterite soil was 9.0-15.5 days in the laboratory . In greenhouse tests using an organic soil, the half-life of ethion varied from 16 to 49 weeks depending upon the degree of watering ; field tests using the same organic soil over a 3-year period (with ethion application in the spring of each year) found a significant carry-over of ethion residue from the autumn to the following spring with eventual accumulation of ethion in the soil in the 2nd and 3rd year . When applied to an organic soil in granular form in the spring, about 25% of the ethion was carried over to the following spring in field tests in Ontario . Microbial degradation of ethion may be an important process in its removal from soil based on degradation studies with nonsterile versus sterile soils. Ethion is susceptible to slow aqueous hydrolysis at acidic and neutral conditions with the hydrolysis becoming relatively rapid at pHs approaching 9 and above; therefore, in very alkaline moist soils, hydrolysis will probably be the dominant removal mechanism. Based on measured Koc values of 6451 to 15435, ethion is not expected to leach in soil. . AQUATIC FATE: Degradation studies with natural waters versus sterilized natural waters have suggested that microbial degradation of ethion is not important in relation to abiotic processes. The hydrolysis half-lives of ethion at 25 deg C are 63, 58, 25, and 8.4 weeks at pHs 5, 6, 7, and 8, respectively, with a half-life of 1 day at pH 10 and 30 deg C. Since ethion is susceptible to rapid photooxidation in the vapor-phase and slow oxidation in the solid-phase, photooxidation in sunlit natural water may be possible, although the relative significance of this process has not been estimated. Based on high measured Koc values (6451-15435), adsorption to sediment and particulate organic matter in water is expected to be a significant fate process. The volatilization half-life from a river one meter deep flowing 1 m/sec with a wind velocity of 3 m/sec has been estimated to be 14.6 weeks, however, adsorption to sediment may significantly attenuate the potential rate of volatilization. In addition, the rate of volatilization will be significantly slower in deeper bodies of water or in more stagnant bodies of water; therefore, ethion volatilization is not expected to be an important fate process, with the possible exception of shallow, rapidly moving streams. Based on a measured log Kow of 5.073, bioconcentration is potentially significant. The persistence half-life of ethion in three different natural waters under laboratory conditions was found to vary from 4 to 22 weeks(1,2,3). It was suggested that the faster rate of degradation in one of the natural waters was due to the presence of dissolved ions which caused an unidentified catalytic effect(1,SRC). ATMOSPHERIC FATE: Based on a vapor pressure of 1.5X10-6 mm Hg at 25 deg C , ethion will exist in both the vapor-phase and adsorbed-phase in the ambient atmosphere, although the adsorbed-phase may dominate(2,SRC). In the vapor-phase, ethion will react rapidly with photochemically produced hydroxyl radicals at an estimated half-life rate of 6.95 hours. Ethion in the adsorbed-phase will be subject to wet and dry deposition .
Drinking Water Impact DRINKING WATER: Ethion has reportedly been identified in German drinking water . SURFACE WATER: Ethion was detected in 0.1% of 2823 water samples collected at 174 stations of the US Geological Survey-USEPA Pesticide Monitoring Network between 1975 and 1980 . Ethion has been qualitatively identified in tributaries feeding Lake Erie, Lake Huron and Lake St. Clair . Ethion was detected to 0.4% of all water samples collected from 11 agricultural watersheds in Ontario in 1975-1976 monitoring and had a maximum concn of 0.04 ppb; it was not detected in 1976-1977 monitoring .

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