Human Response to Low Concentrations of p,p-Diphenylmethane Diisocyanate (MDI)

The spray application of a polyurethane foam was monitored in an underground mine to determine the air concentrations of diisocyanate and the resultant human response. Results snowed that the majority of unreacted p,p-diphenylmethane diisocyanate (MDI) was contained in the particulate material generated by the spray mechanism. Nearly all the generated particles were shown to be in the respirable range. The immunochemical response of human subjects showed that an exposure of about 1.3 ppm-min resulted in an antibody response, whereas an exposure of about 0.9 ppm-min did not. This study indicates that detection of MDI antibodies in the serum of individuals is diagnostic proof of a recent exposure to isocyanates.