Toluene diisocyanate (TDI) pulmonary disease: immunologic and inhalation challenge studies

Clinical and serologic effects of TDI exposure were studied in 112 occupationally exposed plant workers. Sera were obtained before and after commencement of TDI production. All subjects were skin-tested with common inhalant allergens and a TDI-HSA conjugate. Total eosinophil counts, immunoglobulin quantitations, and specific antibody assays by PCA, P-K, and radioimmunoassay were performed. Clinically "sensitive" individuals were tested by provocative inhalation challenge with from 0.005 ppm to the threshold limit value of 0.02 ppm TDI. No TDI-induced immunologic changes were noted with the exception of 3 individuals who demonstrated small positive wheal-and-erythema reactions to TDI-HSA but not to HSA alone. Inhalation challenge with TDI vapor produced airways obstruction, as measured by FEF (25-75). These responses were of the immediate, delayed, and dual type, and were provoked in some cases with levels as low as 0.005 ppm TDI.