Developmental toxicity of dimethylacetamide in rabbits following inhalation exposure.

(1) Dimethylacetamide was tested for developmental toxicity after inhalation exposure of pregnant Himalayan rabbits. Fifteen female rabbits per main group were exposed to dimethylacetamide vapours at concentrations of 0, 0.2, 0.7 or 2.0 mg/l (equivalent to 0, 57, 199.5 or 570 ppm) and five female rabbits per satellite group to 0 or 2.0 mg/l 6 h/day from day 7 post-insemination (p.i.) to day 19 p.i. All animals were observed until day 29 p.i. (2) No signs of maternal toxicity were seen in the does of the main groups (body weight and gross pathology) or in the does of the satellite groups (body weight, blood chemistry, histopathological findings of the liver). (3) Fetotoxic effects were caused at a concentration of 0.7 mg/l (e.g., increased skeletal variations) and 2.0 mg/l (e.g., significantly decreased fetal and placental weights, increase in soft tissue and skeletal variations). At 2.0 mg/l, there were also signs of a weak teratogenic effect expressed as a marginal, statistically not significant increase in soft tissue malformations (regarding the heart and great vessels). No compound-related effects were observed in the fetuses after exposure to 0.2 mg/l. (4) The highest concentration tested under these conditions (2.0 mg/l) was found to be a no-observable-adverse-effect-level (NOAEL) for the maternal Himalayan rabbit, whereas 0.2 mg/l was defined as the NOAEL for the developing organism.