The developmental toxicity of diethylene and triethylene glycol dimethyl ethers in rabbits.

Diethylene glycol dimethyl ether (diEGdiME) and triethylene glycol dimethyl ether (triEGdiME), widely used organic solvents, are structurally related to several compounds that produce reproductive and developmental toxicity, including teratogenicity in laboratory animals. In the present studies, diEGdiME (0, 25, 50, 100, or 175 mg/kg/day) or triEGdiME (0, 75, 125, 175, or 250 mg/kg/day) were administered by gavage in distilled water to timed-pregnant New Zealand white rabbits (15-25 dams/group) during major organogenesis [Gestational Days (gd) 6-19]. Treated females were euthanized on gd 30, uterine contents were examined, and live fetuses were examined for morphological alterations. In the diEGdiMe study, evidence of maternal toxicity, per se, was observed only at 175 mg/kg/day with 15% mortality among treated females compared to 4% among controls. No significant maternal toxicity was observed in the 25 mg/kg/day group, and only minimal maternal toxicity (decreased maternal weight gain during treatment) was observed at 50 and 100 mg/kg/day compared to the vehicle control group. The no-observed-adverse-effect level for developmental toxicity in rabbits for diEGdiME was 50 mg/kg/day. The incidences of prenatal mortality and malformed live fetuses were significantly above controls at 100 and 175 mg/kg/day. Malformations observed most frequently included fusion of ribs to each other and hydronephrosis; clubbing of the limbs without underlying bone deformities, a variation, was also observed. In the triEGdiME study, clinical signs of toxicity were minimal and there was no increased maternal mortality. Maternal body weight and gravid uterine weight were significantly reduced at 250 mg/kg/day, whereas maternal weight gain during treatment was significantly depressed at doses of 175 mg/kg/day and above.(ABSTRACT TRUNCATED AT 250 WORDS)