Exposure assessment and sensitisation in workers exposed to organic acid anhydrides

Objectives: To clarify whether the intensity of exposure to organic acid an hydrides (OAAs) is associated with the risk of sensitisation to these aller gens. Methods: The investigations were carried out in three different manuf acturing plants (A, BI and C) where OAAs were used in the production of epo xy resins. Methyltetrahydrophthalic acid anhydride (MTI-IPA) was used in al l three plants. The exposure assessment included stationary and ambient air monitoring (OAAs in the air) and biological monitoring (metabolites in uri ne). In plant A 20, in plant B 86 and in plant C 113 employees were examine d by a physician (anamnesis, skin-prick test, specific IgE, spirometry). In plants B and C, the exposure areas were classified as high, medium, and lo w, without the results of the exposure assessment being known. Results: The ambient air concentrations (in mu g/m(3)) of MTHPA were 37.2 and 58.5 in p lant A (number of samples n = 2), ranged from <0.5-26.2 in plant B (n = 5) and from 2.1-57.9 in plant C (n = 3) with stationary air collecting, and fr om 8-45 (n = 6), from <4.7-35.7 (n = 3) and from 2-37.8 (n = 3) with person al air collection. The metabolites of OAAs in urine (in nmol/mmol creatinin e) ranged from 5.7-645 (median of MTHPA: 346) in plant A, from <1-213 (medi an of MTI-IPA. 10.1) in plant B and from 0.1-830 (median of the sum of the OOA metabolites: 108.6) in plant C. The prevalence of sensitisation was 35% in plant A: 21% in plant B and 29% in plant C.A higher prevalence in the h ighly exposed areas, however. could not be seen. Levels of IgE specific for conjugates of MTHPA were not associated with the metabolites in the end of shift urine. Levels of IgG specific for conjugates of MTHPA, however, were associated with the metabolites in the end of shift urine. Conclusions: Th e data showed that biological monitoring is a useful tool in the exposure a ssessment of OAAs. Comparing the prevalence of sensitisation and the result s of biological monitoring, between the three plants, we found that sensiti sation increased with increasing exposure. Within a plant a higher risk of sensitisation in persons working in highly exposed areas at the time of the examination could not be seen, possibly due to frequent job rotation.