The role of isocyanates in fire toxicity

Isocyanates are a group of low molecular weight, highly reactive compounds with a functional isocyanate group. The main human exposure route is via inhalation of airborne isocyanates, although dermal exposure has also been reported. The inhalation of isocyanates is associated with severely adverse health effects such as asthma, inflammation in the respiratory tract and cancer. During thermal degradation of polyurethane materials, airborne isocyanates can be sampled in the fire effluent. This paper discusses the reactivity and commercial applications of isocyanates and the generation of airborne isocyanates during thermal degradation, the human health effects as well as the environmental fate of some of the most commercially important isocyanates. This is followed by a review of the generation of isocyanates from large-scale fire testing and bench-scale test methods as well as sampling techniques and derivatisation agents necessary to stabilise the isocyanates and analysis.