Survey of Industrial Workers for Antibodies to Toluene Diisocyanate

A screening program was undertaken at a research and development facility of a large toluene-diisocyanate (TDI) manufacturing corporation. The purpose was to determine the occurrence of antibodies to TDI in selected worker populations. Sera were obtained at 6-month intervals from 103 employees who were exposed from 6 to 24 months to ambient workplace concentrations of TDI (0.02 ppm or less). With the use of RAST (radioallergosorbent test) containing p-tolyl isocyanate-human serum albumin as antigen, no tolyl-reactive IgE antibodies were detected in sera when workers were exposed only to ambient TDI concentrations. During the study, 20 workers had acute exposures to TDI as a result of spills or splashes. Antibody responses developed in three of four individuals whose acute exposures were accompanied by immediate respiratory symptomatology and a decrease in FEV, of 20% or greater. By contrast, an antibody response developed in only one of nine workers with immediate respiratory symptoms but no spirometric changes upon acute TDI exposure. No serologic response developed in the remaining workers whose acute exposure resulted in delayed-onset respiratory symptomatology without spirometric changes, or who were asymptomatic at exposure. In persons developing antibodies, an increase in tolyl-reactive IgE was observed within two months of exposure. Routine serologic screening of workers for tolyl-reactive antibodies may be of value in confirming suspected isocyanate exposure and in providing an early warning of developing TDI hypersensitivity.