An Evaluation of the Developmental Toxicity of 2,4-Pentanedione in the Fischer 344 Rat by Vapour Exposure

The developmental toxicity of 2,4-Pentanedione (2,4-PD; CAS No. 123-54-6), a widely used industrial chemical, was investigated by vapour exposure, because of its widespread use, and potential for human exposure. Timed-pregnant Fischer 344 rats were exposed on gestational days (gd) 6 to 15 inclusive to analytically measured concentrations (as mean ± SD) of 53 ± 1.6, 202 ± 4.7 and 398 ± 5.7 ppm 2,4-PD vapour. At sacrifice (gd 21) foetuses were examined for external, visceral and skeletal variations and malformations. There was no maternal mortality, and body weight was reduced only at 398 ppm. Histological examination of maternal brains from the 398 ppm group showed no abnormalities. No treatment-related effects were seen on number of corpora lutea; total, nonviable or viable implants per litter; pre-or post-implantation losses; or foetal sex ratio. Reduced foetal body weight per litter was seen at 398 ppm (males and females and all foetuses) and 202 ppm (males and all foetuses). There was no concentration-related, or statistically significant, increase in the incidence of individual malformations, malformations by category (external, visceral or skeletal), or total malformations. Partial foetal atelectasis was increased at 398 ppm, and the increased incidence of 17 skeletal variants (out of 79 observed) indicated a consistent pattern of fototoxicity at 398 ppm. In summary, at 398 ppm there was maternal toxicity (reduced body weight) and foetotoxicity (reduced body weight and ossification) and at 202 ppm there was foetotoxicity (reduced body weight). Embryotoxicity or teratogenicity were not seen at any concentration. The no-observable-effects concentration was 53 ppm for both maternal and developmental toxicity.