Evaluation of 10 aliphatic halogenated hydrocarbons in the mouse bone marrow micronucleus test

Ten halogenated aliphatic hydrocarbons (carbon tetrachloride, 1-chlorohexan e, 2,3-dichlorobutane, 1,2-dichloroethane, 1,2-dichloroethylene, 1,3-dichlo ropropane, hexachloroethane, 1,1,2- trichloroethane, 1,2,3- trichloropropan e and 1,1,3-trichloropropene), previously assayed in genetic assays in fung i, were evaluated in the mouse bone marrow micronucleus test in order to as sess their genotoxicity in vivo. All chemicals were administered once i.p. at 40 and 70-80% of their respective LD50 to male and female CD-1 mice, 24 and 48 h before killing. All treatments produced evident clinical symptoms, but no marked depression of bone marrow proliferation. No statistically si gnificant increases in the incidence of micronucleated polychromatic erythr ocytes over the control values were observed at any sampling time with any of the 10 halogenated hydrocarbons assayed. The comparison of the results o btained in this study with the findings provided by in vitro micronucleus a ssays on the same chemicals, reported by other authors, indicate that mouse bone marrow is weakly sensitive to the genotoxic effects induced by haloge nated hydrocarbons in other test systems. This suggests that the role of su ch an assay in carcinogen screening may be questionable for this chemical c lass. An examination of mouse bone marrow micronucleus test results with th e halogenated aliphatic hydrocarbons classified as carcinogens by IARC supp orts this conclusion.