A study of developmental toxicity of hydroquinone in the rabbit

To obtain information on potential developmental toxicity, hydroquinone (HQ) was administered to pregnant New Zealand White rabbits (18 mated per dose group) in aqueous solution (0, 25, 75, or 150 mg HQ/kg/day) by gavage on Gestation Days (GD) 6 to 18. Caesarean sections were performed on GD 30. Doses of 75 and 150 mg/kg/day adversely affected feed consumption and/or body weights of dams during the treatment period. At these doses, however, treatment-related effects were not evident from physical observations, liver and kidney weights, premature delivery incidence, and caesarean sectioning data. The NOEL for maternal toxicity was 25 mg/kg/day. In the 150 mg/kg/day dose group, total incidences of external, visceral, and skeletal findings for fetuses did not differ statistically from controls. Slight, statistically insignificant, increases were found, however, in the incidences of ocular and minor skeletal malformations (micro-ophthalmia, vertebral/rib defects, angulated hyoid arch) on both a per fetus and a per litter basis. Under the conditions of this study, HQ at 150 mg/kg/day produced minimal developmental alterations in the presence of maternal toxicity. The NOEL for developmental toxicity was 75 mg/kg/day.