Induction of single-strand breaks in DNA of mice by trichloroethylene and tetrachloroethylene.

Trichloroethylene (TRI) (4-10 mmol/kg body wt) and tetrachloroethylene (PER) (4-8 mmol/kg body wt) were given to male mice by i.p. injection. The induction of single-strand breaks (SSB) in DNA of liver, kidney and lung was studied by the DNA unwinding technique. There was a linear increase of the level of SSB in kidney and liver DNA but not in lung DNA 1 h after administration. The damage was completely repaired 24 h after injection. The capability of TRI and PER to induce SSB in liver DNA is compared to that of three other substances, i.e., methyl methanesulfonate (MMS), styrene-7,8-oxide and styrene, which have been studied earlier by the same technique. The potency of the substances for induction of SSB was in the following order: MMS greater than styrene-7,8-oxide greater than styrene greater than PER greater than TRI.