Occupational dermatitis from exposure to polyurethane chemicals

In addition to asthma, contact dermatitis may also develop from occupational contact with polyurethane (PU) chemicals. 6 cases of allergic contact dermatitis from exposure to PU chemicals were diagnosed in 1974-1990. The present paper summarizes the results and gives detailed descriptions of 3 such patients. 3 patients were allergic to 5 different diisocyanates (DICs), including 4,4'-diphenylmethane DIC (MDI), toluene DIC (TDI), 1,6-hexamethylene DIC (HID), and furthermore to diaminodiphenylmethane (MDA). 3 patients were sensitized by exposure to MDI. 2 of these reacted to MDI and MDA, and 1 to TDI in addition. 1 of the 3 patients reacted only to MDA, possibly formed by hydrolysis of MDI. Primary sensitization to MDA and cross-allergy to MDI could explain the reactions of the patients exposed to MDI, but separate sensitization may also be possible. Patch tests with fresh petrolatum (pet.) mixtures were first made and a 2% concentration was recommended for MDI and TDI. In order to determine the stability of DIC test substances, the last 2 patients were tested with old test substances. Tests with MDI 1.5% pet. and TDI 1.5% pet., 5.5 months and 15.5 months old, were positive. The results suggest that, when allergy to PU chemicals is suspected, patch tests should include, in addition to MDA, at least MDI and TDI 1.5-2% pet. They also suggest that test substances can be used for over a year, and that allergy to MDA may point to MDI exposure contained in PU chemicals.