Experience with early detection of toluene diisocyanate-associated occupational asthma

There is good reason to expect that regular respiratory surveillance and early removal of workers who develop toluene diisocyanate (TDI)-associated occupational asthma can effectively protect these workers from accelerated pulmonary function decline. Application of this simple principle in operating industrial workplaces presents numerous challenges. The experience of one corporation is presented. One approach is to remove from future diisocyanate work, all workers who develop symptoms consistent with occupational asthma. However, the experience within this one corporation concurs with earlier, more carefully controlled investigations that such a strategy would be unduly restrictive of workers' occupational options. Fewer than half of the workers, who might have triggered such a practice, have required removal after more thorough occupational medical evaluation. Diisocyanates are such well known occupational asthmagens that other exposures tend to be ignored when considering respiratory health problems in a workplace. A small series of workers with work-related respiratory symptoms will be discussed. The usual industrial hygiene air monitoring demonstrated excellent control of the polyisocyanate hazard. Further investigation demonstrated poor control of a mold-release solution. Control of that exposure has allowed previously restricted workers to return to their former work making polyurethane parts. The number of cases available for analysis and discussion from this single, albeit large, corporation is small. Significant advances in understanding whether time-weighted average (TWA), task-specific, or dermal exposures to TDI and other polyisocyanates are most hazardous will require either many more years of experience within one corporation, or pooling of experience across the industry.