Toluene diisocyanates (C6H3CH3 (NCO)2, TDIs) are synthetic low molecular-weight organic chemicals with two highly reactive isocyanate groups (-NCO). Exposure to TDI can cause irritation of the eyes, nose, and upper and lower respiratory tract, asthma-like responses, sensitive pneumonitis, and obstructive pulmonary function loss. In this paper, the exposure-effect relationships between long-term TDI exposure and its effect on pulmonary function are summarized by evaluating the results of cohort studies, including 2 cohort studies conducted by the author's research team, which were specially devoted to the exposure-effect relationships and were published at the end of 1992. By assessing the exposure-effect relationships, the current occupational exposure limit of TDI in Japan is discussed and a framework for the health checks on TDI-exposed workers is proposed.
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