Reproductive and developmental toxicity studies of toluene - II. Effects of inhalation exposure on fertility in rats

Male and female Sprague-Dawley rats were exposed to toluene vapor at 600 and 2000 ppm for 6 h/day, and effects on their fertility were investigated. Females were exposed from 14 days before mating until day 7 of gestation. Males were exposed for a total of 90 days, including the mating period; treatment was begun 60 days before pairing, and toxicity with respect to testicular and reproductive functions was examined. In females of the 2000 ppm-treated group, salivation and lacrimation that may have been caused by CNS depression were observed starting 20 days after exposure. Although no abnormalities were seen in mating behavior or fertility, fetal mortality and the number of dams with dead fetuses increased in the 2000 ppm group. In the males exposed to 2000 ppm toluene for 90 days, an increase in kidney weights and a decrease in thymus weights were observed. Basophilic changes and necrosis of kidney tubules were greater at the higher exposure level. Additionally, decreases in the weights of the epididymides and spermatic count were observed, indicating toxicity of toluene to the male reproductive system in vivo for the first time. In conclusion, embryo-fetal toxic effects were apparent in female rats exposed to toluene before and during the early stage of pregnancy. Subacute exposure to a high level (2000 ppm) of toluene vapor elicited mild toxic changes in the kidneys, thymus, and reproductive organs of males. Toxic effects on fertility and reproduction were thus demonstrated not only in females but also in males exposed to toluene vapor in the present study.