Evidence that epichlorohydrin is not a toxic metabolite of 1,2-dibromo-3-chloropropane

Abstract

1. The major urinary metabolite of ¹⁴C-epichlorohydrin, after oral administration to rats, was identified previously (Gingell et al. 1985) to be N-acetyl-S-(3-chloro-2-hydroxypropyl)-L -cysteine (ACPC) at 36% of the administered dose. In a similar study reported here, 1,2-dibromo-3-chloropropane (DBCP) was metabolized to at least 20 radioactive urinary metabolites. ACPC was only a minor metabolite (4%) of DBCP.

2. Epichlorohydrin was metabolized in vitro by rat liver microsomes to α-chlorohydrin but DBCP was not metabolized to epichlorohydrin or α-chlorohydrin under similar conditions. Covalent binding of radioactivity to liver microsomal proteins occurred for both substrates, but was less for ¹⁴C-epichlorohydrin than for ¹⁴C-DBCP. Addition of 3,3,3-trichloropropylene oxide, an inhibitor of epoxide hydrolase, increased the extent of protein binding of epichlorohydrin, but decreased the amount of ¹⁴C-DBCP which was bound.

3. The data indicate the epichlorohydrin is not a significant in vivo nor in vitro metabolite of DBCP in the rat, and is unlikely to be responsible for the toxicity of DBCP.