Methylene chloride: two-generation inhalation reproductive study in rats.

Abstract Reproductive parameters in Fischer 344 rats were evaluated following inhalation of methylene chloride (meCl 2 ) for two successive generations. Thirty male and female rats were exposed to 0, 100, 500, or 1500 ppm MeCL 2 for 6 hr/day, 5 days/week for 14 weeks and then mated to produce f 1 litters. After weaning, 30 randomly selected f 1 pups/sex/group were exposed to MeCl 2 for 17 weeks and subsequently mated to produce f 2 litters. Reproductive parameters examined included fertility, litter size and neonatal growth, and survival. All adults and selected weanlings were examined for grossly visible lesions. Tissues from selected weanlings were examined histopathologically. No adverse effects on reproductive parameters, neonatal survival, or neonatal growth were noted in animals exposed to methylene chloride in either the f 0 or f 1 generations. Similarly, there were no treatment-related gross pathologic observations in f 0 or f 1 adults or f 1 and f 2 weanlings. Histopathologic examination of tissues from f 1 and f 2 weanlings did not reveal any lesions attributed to methylene chloride. Thus, exposure of rats to concentrations as high as 1500 ppm methylene chloride, which has been shown in a 2-year study to produce treatment-related effects, did not affect any reproductive parameters.