Dicrotophos

CAS RN:141-66-2

Exposure Summary

Dicrotophos' production may result in its release to the environment through various waste streams; its use as an insecticide and acaricide will result in its direct release to the environment. If released to air, a vapor pressure of 1.6X10-4 mm Hg at 25 deg C indicates dicrotophos will exist in both the vapor and particulate phases in the atmosphere. Vapor-phase dicrotophos will be degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals and ozone; the half-lives for these reactions in air are estimated to be 7.4 and 24 hours, respectively. Particulate-phase dicrotophos will be removed from the atmosphere by wet or dry deposition. Dicrotophos contains chromophores that absorb at wavelengths >290 nm and, therefore, may be susceptible to direct photolysis by sunlight. If released to soil, dicrotophos is expected to have very high to moderate mobility based upon Koc values of 16-188. Volatilization from moist soil surfaces is not expected to be an important fate process based upon a Henry's Law constant of 5.03X10-11 atm-cu m/mole. Dicrotophos has been classified as a non-persistent pesticide with an estimated soil half-life of less than 0.5 months. Soil surface and aqueous photolysis studies showed that the degradation of dicrotophos was not induced by light exposure. If released into water, dicrotophos is expected to adsorb to suspended solids and sediment based upon the Koc values. Volatilization from water surfaces is not expected to be an important fate process based upon this compound's Henry's Law constant. An estimated BCF of 3 suggests the potential for bioconcentration in aquatic organisms is low. Dicrotophos' decomposition in aqueous environments is primarily by hydrolysis. Half-lives for the hydrolysis of dicrotophos were 117, 72, and 28 days at pH 5, 7, and 9 at 25 deg C, respectively. Occupational exposure to dicrotophos may occur through inhalation and dermal contact with this compound at workplaces where dicrotophos is produced or used. Monitoring data indicate that the general population may be exposed to dicrotophos via ingestion of food. (SRC)
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