Metabolic activity of antipyrine in workers occupationally exposed to trichloroethylene

Abstract

In order to investigate possible effects of occupational exposure to trichloroethylene (TRI) on the liver cytochrome P-450 dependent monooxygenases, the metabolic activity of salivary antipyrine was determined in workers (I; N = 32) employed in dry-cleaning shops (I-1; N = 17) and in an industrial metal degreasing process (I-2; N = 15). The studies were performed twice: (a) during the working period, (b) and after at least three weeks free of exposure. The control group (II) consisted of 29 subjects with no known exposure to chemicals. Analyses of the solvents used (TRI) showed them to be mixtures. Statistically significant differences were found (P less than 0.01) in antipyrine t1/2 and clearance within the exposed group (Ia:Ib), but not between the exposed (I) and control (II) group. A breakdown of antipyrine pharmacokinetic data by I-1 and I-2 subgroups demonstrated a statistically significant difference in t1/2 (P less than 0.02) and clearance (P less than 0.05) within I-1 subgroup (a:b), in contrast to the I-2 subgroup (a:b). The difference in antipyrine t1/2 between I-1,a and the control group (II) was also statistically significant (P less than 0.05). Although there was no difference in TRI exposure between I-1 and I-2 based on the biological parameters of TRI absorption, the TRI used in I-2 was of higher grade of purity. It can therefore be concluded that TRI itself is not an inducer of liver monooxygenases and that the monooxygenase induction in subgroup I-1 of TRI exposed workers could be due to TRI impurities.