A CLINICAL AND IMMUNOLOGICAL STUDY ON 92 WORKERS OCCUPATIONALLY EXPOSED TO ANHYDRIDES

This study aimed at investigating sensitizing and hazardous effects of a new acid anhydride, pyromellitic dianhydride (PMDA), in addition to those of phthalic anhydride, maleic anhydride and trimellitic anhydri de, in a group of 92 exposed workers in two German chemical plants. Of the 92 workers, 56 reported work-related complaints with a predominan ce of phlegm and dyspnoea in those exposed to anhydride dust for less than 1 year. Haemorrhagic rhinitis occurred only after a prolonged exp osure of more than 15 years. Specific IgE antibodies to anhydride-HSA conjugates could be detected in 15 exposed subjects, 12 of whom had wo rk-related symptoms. The IgE-positive group had significantly more imp aired lung function parameters than the IgE-negative group. The propor tion of IgE-positive subjects was highest in the groups with dyspnoea (5/18), cough (6/24) and rhinitis (11/44) whereas only 1 of 11 workers with haemorrhagic rhinitis had such antibodies. A follow-up study of 23 affected workers was performed after 10 months to assess clinical s ymptoms, lung function and IgE antibody levels. This follow-up study s howed the absence of obstructive ventilation patterns in three out of six subjects in addition to cessation of symptoms in most initially af fected workers who were no longer exposed. On the other hand, 14 worke rs under continuous exposure had comparable pathological findings on r e-examination. Our results confirm that anhydrides including the lesse r known PMDA, behave as respiratory irritants and as immediate-type se nsitizers. They predominantly induced reversible symptoms in workers w hose exposure stopped after a working period of about 0.7 years. Abnor mal lung function parameters normalized in nearly 50% of these subject s.