OCCUPATIONAL ASTHMA DUE TO ISOCYANATES - NEW RESEARCH ORIENTATIONS ININDUSTRIAL-HYGIENE

The replacement of the HDI monomer by less volatile prepolymers is not accompanied by a decrease of the incidence of occupational asthma in Switzerland. Field measurements show that the prepolymer concentration levels may be high although the monomer is hardly detectable or compl ies with the norm. Our researches are focused on the improvement of ge neration and measurement techniques (international quality control), o n the characterization of the prepolymers to study their transformatio n in biological media. Field surveys will be conducted to establish th e prepolymer concentration profiles. We recommend for the introduction in Switzerland of threshold limit values for HDI-biuret and isocyanur ate.