The following abstract presents results of a study conducted by a contract laboratory for the National Toxicology Program. The findings may not have been peer reviewed and were not evaluated in accordance with the levels of evidence criteria established by NTP in March 2009. For more information, see the Explanation of Levels of Evidence for Developmental Toxicity. The findings and conclusions for this study should not be construed to represent the views of NTP or the U.S. Government.
Dipropylene glycol is a high production glycol used in the manufacture of nitrocellulose solvent, lacquers, paints, printing inks, and shellac varnishes. In general, the toxicity of the glycols decreases as the molecular weight of the molecule increases. Therefore, it was expected that DPG would be less toxic than low molecular weight glycols such as ethylene glycol. This study was conducted to assess the potential for DPG to cause developmental toxicity and to compare its toxicity to other glycols. DPG was administered by gavage to artificially inseminated NZW rabbits (24 per group) on gestation days 6-19 at dose levels of 0, 200, 400, 800, or 1200 mg/kg body weight/day. Animals were observed daily for clinical signs of toxicity. Mean food and body weights were calculated for each group on gd 0, 6, 9, 12, 15, 19, 25, and 30. All animals were killed on gd 30 and examined for maternal body and organ weights, implant status, fetal weight, sex, and morphological development.
No maternal lethality occurred in this study. Pregnancy rates were 95%, 83%, 91%, 92%, and 82% in the control to high dose groups, respectively. No effect that could be attributed to exposure to DPG was noted on maternal body weight, food consumption, or clinical signs. Necropsy of the maternal animals revealed no effects on kidney and liver weights. In utero DPG exposure did not affect the frequency of post-implantation loss, mean fetal body weight per litter, or external, visceral, or skeletal malformations.
In summary, no maternal toxicity was observed in animals exposed to 1200 mg/kg/day of DPG from gd 6 through gd 19, although preliminary study data indicated that this exposure would be in the maternally toxic range for this species. No developmental toxicity was noted in the offspring of the animals from any group exposed to DPG during this study. The study established a no observed adverse effect level of at least 1200 mg/kg/day for both maternal and developmental toxicity of dipropylene glycol administered orally in rabbits.