Teratogenic evaluation of p-tert-butylphenol formaldehyde resin (novolak type) in rats following oral exposure.

The teratogenicity of p-tert-butylphenol formaldehyde resin, novolak type, (PTBP-FR) was examined in Wistar rats. Pregnant rats were fed diets containing 0, 2.5, 5 or 10% of PTBP-FR ad libitum from day 6 to day 15 of pregnancy. Maternal toxicity, as evidenced by a decreased maternal body weight gain and food consumption, was observed in the 5 and 10% dose groups. However, treatment-related clinical signs were not observed. No significant reductions in the fetal body or placental weights were observed in any dose group. There were no significant differences in the number of live fetuses, intrauterine deaths (dead fetuses and resorptions), or fetal sex ratios found between the PTBP-FR-treated and control groups. Although external and internal malformations including short tail, dilatation of the cerebral ventricle and the renal pelvis and dextrocardia, and some skeletal variations were observed in fetuses at some groups treated with PTBP-FR, the incidences of these morphological alterations were not statistically different from controls. In conclusion, PTBP-FR administered orally to Wistar rats during days 6-15 of gestation produced no related signs of developmental toxicity.