Effect modification by inorganic lead in the dominant lethal assay.

Experimental evidence suggests that inorganic lead may modify mutagenic events. We examined the modifying effect of lead on mutagenic events in late spermatogenesis in the dominant lethal assay. Twelve NMRI male mice were given lead chloride in the drinking water and 12 male mice received tap water without lead chloride. Cyclophosphamide (120 mg/kg b.w., i.p.) was given to six males in the lead treatment group and six males in the tap water group 1 week before mating. This resulted in four treatment groups: control, lead, cyclophosphamide, and lead plus cyclophosphamide. Cyclophosphamide given to the males (with or without lead treatment) reduced the numbers of live implants in mated females. The most prominent effect of cyclophosphamide was an increase of resorbed implants. Females mated to lead exposed male mice showed a nonsignificantly lower frequency of resorptions compared to controls. The results give no support to the hypothesis that inorganic lead may influence the mutagenicity of cyclophosphamide in the dominant lethal test.