Communities near toluene diisocyanate sources: an investigation of exposure and health

Toluene diisocyanate (TDI) is a well-known cause of occupational asthma, but we know little about the potential for exposure and health effects among residents who live near facilities that release TDI. In the mid-1990's, the North Carolina Department of Health and Human Services and the Agency for Toxic Substances and Disease Registry investigated exposures to TDI and health outcomes in one community, which left some unanswered questions. This cross-sectional study evaluated the potential associations between living near a TDI source and the prevalence of three variables: asthma or asthma-like respiratory symptoms, antibodies specific to TDI, and verifiable levels of TDI in residential air. Results among North Carolina residents living near such facilities (five target communities) were compared with the results from residents living further away (five comparison communities). Overall, the prevalence of reporting either asthma or asthma-like respiratory symptoms was higher (odds ratio=1.60; 95% confidence interval=0.97–2.54) among residents in target communities than those in comparison communities. However, this difference was not statistically significant. Symptom prevalence varied greatly among the community populations. The prevalence of respiratory symptoms was higher near facilities with historically higher TDI emissions. Among the 351 participants who provided blood samples, only one had immunoglobulin G specific antibodies to TDI. This participant lived in a target area and may have had non-occupational exposure. TDI was detected at an extremely low level (1 ppt) in one of the 45 air samples from target communities. One ppt is one-tenth the EPA reference concentration. Overall, air sample and antibody test results are not consistent with recent or ongoing exposure to TDI.