Are Mouse Strains Differentially Susceptible to the Reproductive Toxicity of Ethylene Glycol Monomethyl Ether? A Study of Three Strains

Most rodent reproductive toxicology studies utilize strains of high fecundity. These studies were conducted to examine the possibility that mouse strains of differing fecundity would respond differently to a known reproductive toxicant. Thirty pairs each of Swiss CD-1, C57B1, and C3H mice were cohabited for 14 weeks while consuming 0, 0.03, 0.10, or 0.30% EGME in the drinking water. Litter data were collected during cohabitation. Body and organ weights, and various sperm data, were collected at necropsy, and second-generation fertility was evaluated. The data show that the most fecund strain (Swiss) was affected the least by exposure to EGME, while the least fecund strain (C3H) suffered the greatest declines in fertility. These differences might alter interspecies extrapolation factors, or the permissible exposure levels for humans.