CAS RN: 505-60-2

Exposure Summary

Bis(2-chloroethyl)sulfide's former use as a vesicant in chemical warfare resulted its direct release to the environment. Bis(2-chloroethyl)sulfide's production and use as a model compound in biological studies on alkylating agents, medicinal use to control hyper-proliferation of psoriatic keratinocytes and in organic synthesis may result in its release to the environment through various waste streams. If released to air, a vapor pressure of 0.11 mm Hg at 25 deg C indicates bis(2-chloroethyl)sulfide will exist solely as a vapor in the atmosphere. Vapor-phase bis(2-chloroethyl)sulfide will be degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals; the half-life for this reaction in air is estimated to be about 2 days. Bis(2-chloroethyl)sulfide absorbs UV very weakly at wavelengths >290 nm; therefore, direct photolysis, while possible, is not expected to be an important fate process. Vapor-phase bis(2-chloroethyl)sulfide is relatively stable to water vapor in air, however, it may dissolve in liquid-phase water with resulting hydrolysis. If released to soil, bis(2-chloroethyl)sulfide is expected to have moderate mobility based upon an estimated Koc of 240. It has been observed to bind through a reversible interaction with dry soil. Volatilization from moist soil surfaces is expected to be an important fate process based upon a Henry's Law constant of 2.45X10-5 atm-cu m/mole. Evaporation can be an important dissipation mechanism for bis(2-chloroethyl)sulfide from soil. After application to soil, bis(2-chloroethyl)sulfide degradation occurs mainly through chemical hydrolysis with microbiological degradation being the important fate process for degradation of the hydrolysis products. Although hydrolysis can occur rapidly, hydrolysis can be retarded or terminated by encapsulation of the bis(2-chloroethyl)sulfide by degradation adducts. Bis(2-chloroethyl)sulfide can be highly persistent in soil under conditions of low temperature and moisture. The persistence of bis(2-chloroethyl)sulfide sprayed on several soils at a variety of weather conditions ranged from 31 to 51 hr at 25 deg C and 50 to 92 days at 0 deg C. Persistence on snow ranges from 14-56 days. There are examples of bis(2-chloroethyl)sulfide persisting in the environment for many years, or even decades. If released into water, bis(2-chloroethyl)sulfide is expected to adsorb moderately to suspended solids and sediment based upon the estimated Koc. Volatilization from water surfaces is expected to be an important fate process based upon this compound's Henry's Law constant. Estimated volatilization half-lives for a model river and model lake are 49 hours and 19 days, respectively. An estimated BCF of 12 suggests the potential for bioconcentration in aquatic organisms is low. Bis(2-chloroethyl)sulfide hydrolyzes rapidly when dissolved in water with a half-life on the order of 4 to 8 minutes at 25 deg C. However, hydrolytic destruction can be limited by a very slow rate dissolution into the water. At 0, 25, and 40 deg C, the half-lives of bis(2-chloroethyl)sulfide when dissolved in large amounts of water are 1.75 hr, 4 minutes, and 43 seconds, respectively. Occupational exposure to bis(2-chloroethyl)sulfide may occur through inhalation and dermal contact with this compound at workplaces where bis(2-chloroethyl)sulfide is produced or used. Military personnel may be exposed during the transport and storage of this chemical as well as when used as a chemical warfare agent. Non-occupational exposure may occur around sites where the agent was released during warfare (e.g. Belgium, Morocco, Ethiopia, China, Iraq, and the Islamic Republic of Iran), where munitions are buried or where contaminated soils containing mustard gas are disturbed during excavation activities. (SRC)
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