Toluene diisocyanate , health effect

Adams WG. 1975. Long-term effects on the health of men engaged in the manufaeture of toluene diisocyanate. Br J Ind Med 32(l) 72-78. 

Kazuyuki 0, Higashi T, Nakadate T, et al. 1992. Fom year follow-up of effects toluene diisocyanate exposure on the respiratory system in polyurethane foam manufacturing worker. Int Arch Occup Environ Health 63 565-569. 

Important commercial isocyanates include the diisocyanate monomers toluene diisocyanate (TDI), methylene diphenyl diisocyanate (MDI), hexamethylene diisocyanate (HDI), and MDI-, TDI-, and HDI-based isocyanates (e.g., prepolymers and polyisocyanates). World-wide production volume is estimated at over 12 billion lb. Isocyanates (diisocyanates, polyisocyanates, and prepolymers) all cause similar health effects, most commonly asthma [32]. Isocyanates are reported to be the leading attributable cause of work-related asthma [16]. Isocyanates are potent sensitizers that can trigger a severe and potentially fatal asthma attack in sensitized persons at very low isocyanate exposure levels [16]. Toluene diisocyanate is reasonably anticipated to be a human carcinogen by National Toxicology Program. 

Omae, K., Nakadate, T., Higashi, T., Nakaza, M., Aizawa, Y. Sakurai, H. (1992a) Four-year follow-up of effects of toluene diisocyanate exposure on the respiratoiy system in polyurethane foam manufacturing workers I. Study design and results of the first cross-sectional observation. Int. Arch, occup. environ. Health, 63, 559-564... 

Use and exposure Technical grade dinitrotoluene is an oily liquid and easily combustible. Dinitrotoluenes are used primarily as chemical intermediates in the production of toluene diamines, diisocyanates, polyurethane foams, dyes, propellants, and polymers, and in the explosives industry." " " Toxicity and health effects Dinitrotoluene is known to cause adverse health effects on the blood, liver, kidney, and CNS in laboratory animals after an acute oral exposure. The animals also showed cyanosis and ataxia. Prolonged periods of exposure caused muscular weakness, poor muscular coordination, tremors, convulsions, ataxia, and paralysis. Industrial workers have developed headache, appetite loss, giddiness, dizziness, nausea, insomnia, and tingling pains in the extremities after chronic exposure to dinitrotoluene. - ... 

PU are compounds formed by reacting the polyol component with an isocyanate compound, typically toluene diisocyanate (TDI) methylene diisocyanate (MDI) or hexamethylene diisocyanate. Polyols are relatively non-toxic (i.e., polyether type polyols are found to be safe, because they are low in oral toxicity with almost no irritation effect to the eyes and skin), however, isocyanates are highly toxic and the product can have a significant toxicity if remnants of isocyanate are in it, which manifests itself mainly as a respiratory (as well as a dermal) hazard. Exposure to the vapour of isocyanates directly may cause irritation for the eyes, respiratory tract and skin. Such an irritation may be too severe to produce bronchitis and pulmonary oedema. As health hazards of isocyanates are considered, one immediately remembers one of the worst industrial disasters of the 20th century, that occurred in Bhopal, India, because of the toxic cloud of methyl isocyanate was released accidentally from the Union Carbide pesticide factory in December 1984. An estimated 3,000 people died immediately with a final of some 20,000, most suffocating from the cloud s toxic chemicals, and some 50,000 were injured, most were residents living near the plant. 

The toxic route is primarily inhalation. The vapor pressure of this compound at ambient temperature is very low, 0.00014 torr at 25°C. However, when heated to about 75°C, the acute health hazard is greatly enhanced (Hadengue and Philbert 1983). The acute toxic symptoms were found to be similar to those of toluene-2,4-diisocyanate and other aromatic isocyanates. Inhalation of its vapors or particulates can cause bronchitis, coughing, fever, and an asthma-like syndrome. Other symptoms were nausea, shortness of breath, chest pain, insomnia, and irritation of the eyes, nose, and throat. The immunologic response, however, varied among humans. Exposure to 0.1-0.2 ppm for 30 minutes is likely to manifest the acute toxic effects in humans. 

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