2,4-Toluene Diisocyanate

CAS RN:584-84-9

Exposure Summary

2,4-Toluene diisocyanate's production and use in the manufacture of polyurethane foams and other elastomers may result in its release to the environment through various waste streams. Commercial toluene diisocyanate (TDI) typically contains 80% of 2,4-toluene diisocyanate. If released to air, a vapor pressure of 8X10-3 mm Hg at 25 deg C indicates 2,4-toluene diisocyanate will exist solely as a vapor in the ambient atmosphere. Vapor-phase 2,4-toluene diisocyanate 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 1.7 days. Atmospheric degradation may also occur through contact with clouds, fog or rain. 2,4-Toluene diisocyanate does not contain chromophores that absorb at wavelengths >290 nm, and therefore is not expected to be susceptible to direct photolysis by sunlight. If released to moist soil, 2,4-toluene diisocyanate is not expected to leach or adsorb to solids due to its rapid degradation reaction with water. 2,4-Toluene diisocyanate is not expected to volatilize from dry soil surfaces based upon its vapor pressure. A 0% of its theoretical BOD in four weeks using an activated sludge inoculum in the Japanese MITI test suggests that biodegradation is not an important environmental fate process in soil or water. Based upon data for the mixture, if spilled on wet land, 2,4-toluene diisocyanate is rapidly degraded by reaction with moisture. If released into water, a crust forms around the liquid TDI and <0.5% of the original material remains after 35 days. Low concentrations of TDI hydrolyze in the aqueous environment in approximately a day. Occupational exposure to 2,4-toluene diisocyanate occurs through inhalation of vapors and aerosols and through dermal contact with this compound and other products containing 2,4-toluene diisocyanate. The general population may be exposed to 2,4-toluene diisocyanate through the use of commercially available urethane adhesives containing this compound. (SRC)
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