[Diisocyanate exposure as a cause of occupational asthma].

Abstract

The authors present a summary of current knowledge on asthma caused by diisocyanates in workers under occupational exposure and introduce basic characteristics of these chemicals widely used in industry. Although they represent one of the main causes of occupational bronchial asthma (AB) in developed industrial countries, the number of reported asthma caused by diisocyanates is still relatively low in the Czech Republic--it represents less than ten percent of all reported occupational asthma. One of the possible reasons is demanding diagnostics and assessment of occupational impact of chemical noxae with combined effect mechanism characteristic of low-molecular diisocyanates. Studies concerned with presented topics support the concept that AB caused by diisocyanates shows clinical features of both atopic and nonatopic asthma. AB caused by DI is presented by mixed type of the TH1/TH2 response, influx and regulatory role of CD4+ and CD8+ T lymphocytes. Mixed immunopathological mechanism and toxic effect are combined. For the present, evaluation of elimination and reexposure tests appear as the most valuable of available diagnostic methods, respectively simulated reexposure test in a health care facility and assesment of serum IgG or IgE antibodies against diisocyanates can be used. Data on occurrence of the disease in the Czech Republic and detailed information on the sample of patients with respiratory allergic disease caused by diisocyanates reported by the Clinic of Occupational Diseases of the Faculty Hospital in Hradec Králové in 1994-2003 are presented. The disease was caused by evaporation of diisocyanates released during the production of polyurethanes and evaporation of adhesives containing toluendiisocyanate (TDI). In most cases, there were milder forms of asthma with significant improvement or elimination of difficulties occuring after occupational exposure was interrupted. Knowledge of the pathogenesis of AB caused by diisocyanates should accelerate the development of diagnostic tests and consequent treatment intervention, as early determination of diagnosis and interruption of occupational exposure are essential for following prognosis of disease.