Diphenylmethane diisocyanate (MDI), 4,4′-

Abstract

Methylenediphenyl diisocyanate (MDI) is an odorless white solid comprised of about 98% monomeric 4,4′-MDI (101-68-8) with a small percentage of 2,4′- and 2,2′-MDI monomers. The free isocyanate groups of MDIs are highly reactive. Isocyanates and thioisocyanates, such as DIPHENYLMETHANE-4,4′-DIISOCYANATE, are incompatible with many classes of compounds, reacting exothermically to release toxic gases. This reactivity is responsible for the behavior of MDI in environmental and biological systems. MDI is commonly reacted with compounds in the production of rigid and flexible polyurethane foam. The primary human health concerns are irritation at the point of contact and sensitization. 4,4′-methylenediphenyl diisocyanate (MDI) is used to produce polyurethane foams. Exposure via inhalation of high concentrations of MDI may cause sensitization and asthma in humans. Acute skin contact can cause dermatitis and eczema in workers. Long-term chronic inhalation exposure may cause asthma, dyspnea, and other pulmonary symptoms. Effects of this compound on the reproductive, developmental, or carcinogenic effects in humans has not been clearly established. EPA has classified MDI as a Group D, not classifiable as to human carcinogenicity. There is no known antidote for this compound and supportive measures are the only way to treat over-exposed patients.