Changes in hepatic microsomal enzyme function in workers exposed to mixtures of chemicals.

Antipryine clearance was measured during occupational exposure and after an exposure-free interval of 3 wk in 26 spray painters, 44 workers in a herbicide-producing (phenoxyacids) plant, and 10 pesticide-exposed greenhouse gardeners. A control group of 39 workers were investigated simultaneously. A noninvasive simplified antipyrine clearance was used. Antipyrine clearance was greater in pesticide-exposed persons, but it was 15% less in workers exposed to spray paints compared to 3 wk after discontinuation of exposure. Clearance was unchanged in the control group examined at the same interval. Thus, the combined action of different spray paints, grinding dust, and cleaners may inhibit, and phenoxyacids, chlorophenols, and various pesticides may induce, the microsomal enzyme function. The workers had been exposed to the chemicals for years, but the change in antipyrine clearance apparently was reversible.