An in vitro investigation of the reductive metabolism of chloroform.

In hypoxic (1% pO2) and anoxic (0% pO2) incubations of CHCl3 with rat liver microsomes from PB-induced animals, no evidence of formation of monochloromethyl carbene could be found. Dichloromethane was detected as a volatile metabolite of CHCl3 in incubations with rat liver microsomes from PB-induced animals, under different oxygenation conditions (from 0% to 20% pO2). With uninduced microsomes, significant levels of dichloromethane were formed only in hypoxic (1% pO2) or anoxic incubations. The amount of dichloromethane measured was 2-6 times lower than the levels of adducts to the fatty acyl chains (FC) of microsomal phospholipid. The very low rate of dichloromethane formation suggests that the assay of expired dichloromethane is not suitable to detect the reductive metabolism of CHCl3 in vivo.