Asthma caused by diphenylmethane diisocyanate in foundry workers. Clinical, bronchial provocation, and immunologic studies.

Eleven foundry workers who developed asthmatic symptoms were studied with inhalation provocation tests with formaldehyde and diphenylmethane diisocyanate (MDI). These latter two chemicals are components of PepSet used for making molds for casting. Six subjects showed specific asthmatic reactions to MDI challenge (more than 20% fall in FEV1), 2 had a combined immediate and late reaction, and 4 had a predominantly late reaction.