Tumor formation and sister chromatid exchange induction by ethyl carbamate: relationships among non-pregnant murine females, gravid dams, and transplacentally exposed offspring.

Abstract

Sister-chromatid exchange (SCE) induction and cell cycle kinetics alterations by ethyl carbamate in bone marrow of non-gravid murine Swiss Webster, ICR/Jcl, and C57Bl/6J dams were evaluated, and data from non-gravid females were compared with those previously reported for pregnant dams of the same strains. In addition, lung adenoma induction by ethyl carbamate in gravid Swiss Webster dams, their offspring, and in non-pregnant Swiss Webster females was also determined. Relative cytogenetic and tumor responses in non-gravid and gravid Swiss Webster females and their offspring were compared. In contrast to the increased sensitivity reported for gravid Swiss Webster dams versus ICR/Jcl and C57Bl/6J dams, SCE responses to 1.1, 2.2, or 3.3 mmol/kg of ethyl carbamate in non-gravid females were approximately equivalent among strains. In Swiss Webster and C57Bl/6J (but not ICR/Jcl) strains, SCE responses in non-gravid females at 2.2 and 3.3 were significantly lower than those of their pregnant counterparts. Tumor induction by 3.3 mmol/kg ethyl carbamate paralleled relative SCE induction with Swiss Webster dams, demonstrating a 5-fold increase in the number of tumors relative to their offspring and a 4-fold enhancement of tumor induction relative to their non-pregnant counterparts.