Acute, 9-Day, and 13-Week Vapor Inhalation Studies on Ethylene Glycol Monohexyl Ether

Acute, 9-Day, and 13-Week Vapor Inhalation Studies on EthyleneGlycol Monohexyl Ether. KLONNE, D. R., DODD, D. E., PRITTS,I. M., TROUP, C. M., NACHREINER, D. J., and BALLANTYNE, B. (1987).Fundam. Appl. Toxicol. 8, 198–206. At ambient conditions,the low vapor pressure of ethylene glycol monohexyl ether (EGHE)allows for a maximum vapor concentration of approximately 85ppm. In an acute inhalation study on Wistar albino rats, a 4-hrexposure to 83 ppm EGHE produced no clinical signs, body weighteffects, mortality, or macroscopic lesions in thoracic or abdominalorgans. Fischer 344 rats exposed for 9 days (6 hr/day) overan 11-day period, to 0 (control), 19, 41, or 84 ppm EGHE haddecreased body weight gains and increased liver to body weightvalues at 84 ppm EGHE. No alterations of the hematology parametersor the morphology of the testes or liver were observed. In asubsequent study, rats were exposed to mean EGHE concentrationsof 0 (control), 20, 41, or 71 ppm for 6 hr/day, 5 days/week,for 13 weeks. Urogenital wetness was observed in all EGHE-exposedgroups of females and in males of the 71-ppm group. Decreasedbody weight gains were observed in both sexes of the 71-ppmgroup, and a slight decrease was also observed in females ofthe 41-ppm group. Increased absolute and/or relative liver weightswere observed in both sexes of the 71-ppm group and to a lesserextent in the 41-ppm group. Possibly related to these findingsin the liver were decreases in serum transaminases (aspartateand alanine aminotransferase) and sorbitol dehydrogenase, withan increase in alkaline phosphatase observed in the 71-ppm groupof female rats. However, there were no gross or histopathologiclesions found to indicate impairment of the liver. Increasesin absolute and/or relative kidney weights were primarily observedin the 41-and 71-ppm groups of males but no gross or histopathologiclesions were found to explain these findings. The principalEGHE-related effect observed in animals maintained for a 1-monthrecovery period after cessation of exposures was a continuedincrease in the absolute and/or relative liver weights of the71-ppm group. Hematologic abnormalities and testicular atrophyobserved with some shorter chain alkyl glycol ethers were notobserved with EGHE. Based on the data from the 13-week inhalationstudy, subchronic inhalation exposure to 71 ppm EGHE producedminimal but biologically significant toxicity, while exposureto 41 ppm EGHE is considered to be a concentration at whichno biologically significant toxic effects were observed.