[Occupational sensitization to methylene diphenyl diisocyanate during the manufacture of polyurethane products]

A complex occupational hygienic and clinical allergologic investigation in a methylene-diphenyl diizocyanate (MDI)-based polyurethane products manufacture was carried out for the first time in this country. The average MDI concentrations for a shift are within the limits of TWA, but during short operations exceed STEL and reach 0.072-0.181 mg/m3. By clinical and immuno-allergologic methods, applied on 46 MDI-exposed workers and 42 controls, the sensibilizing effect on the respiratory system, skin and eyes was detected. The allergic reactions take the course of bronchial asthma (6.5%), rhinitis and rhinopharyngitis (37%), rhinosinusitis (13%), conjunctivitis (13%), and urticaria and dermatitis (17.4%), as in 12 cases (12%) the allergic illnesses are combined. The specific occupational sensibilization, proved by positive dermal allergy tests with MDI in 24 (52%) exposed workers, and increased MDI-IgE antibodies in 4 workers, is of high statistical reliability in comparison with the control group and supposes immune reactions of quick type (IgE) and mainly retarded type--cell mediated. Various prophylactic measures against the proven occupational sensibilization risk are proposed.