NTP toxicology and carcinogensis studies of dipropylene glycol (CAS No. 25265-71-8) in F344/N rats and B6C3F1 mice (drinking water studies).

Background: Dipropylene glycol is found in antifreeze, air fresheners, cosmetic products, solvents, and plastics. We studied the effects of dipropylene glycol on male and female rats and mice to identify potential or cancer-related hazards to humans.

Methods: We gave groups of 50 male and female mice drinking water containing dipropylene glycol at concentrations of 10,000, 20,000, or 40,000 parts per million (corresponding to 1%, 2%, or 4%) for two years. Male and female rats received concentrations of 2,500, 10,000, or 40,000 parts per million. Other groups received untreated water and were the control group. Tissues from more than 40 sites were examined for every animal.

Results: The groups of animals receiving 40,000 ppm dipropylene glycol weighed less than the control animals. All the make rats receiving 40,000 ppm dipropylene glycol died before the end of the study, mainly because of kidney disease. All the other animal group survived as well as the controls. No increase in tumor rates were seen in any of the groups of rats or mice.

Conclusions: We conclude that dipropylene glycol did not cause cancer in male or female rats or mice. Exposure to dipropylene glycol did increase the rate and severity of kidney nephropathy and inflammation of the liver and salivary gland in male rats and some atrophy of the epithelial tissue of the nose in male and female rats.