Dimethylethanolamine: Acute, 2-Week, and 13-Week Inhalation Toxicity Studies in Rats

Dimethylethanolamine (DMEA) is a volatile, water-soluble aminethat has applications in the chemical and pharmaceutical industries.These studies evaluated the acute and subchronic inhalationtoxicity of DMEA. Acute (4-hr) exposures of Wistar rats to DMEAvapor resulted in an LC5O value (95% confidence limits) of 1641(862–3125)ppm. Clinical signs of nasal and ocular irritation, respiratorydistress, and body weight loss were observed in rats exposedto 1668 ppm DMEA and higher. In the 2-week study, F-344 ratsexposed to 98, 288, or 586 ppm DMEA for 9 days (6 hr/day) duringan 11-day period also exhibited signs of respiratory and ocularirritation (except the 98 ppm group). All animals of the 586ppm group and 4 of 15 male rats of the 288 ppm group died. Bodyweight values for the 288 ppm group were reduced to about 75%of preexposure values, while the 98 ppm group gained 35% lessweight than controls. Statistically significant differencesin clinical pathology parameters (288 ppm group) and in organweight values (288 and 98 ppm groups) probably resulted fromthe decreased food consumption and not from specific targetorgan toxicity. In the groups evaluated histologically (the98 and 288 ppm groups) the eye and nasal mucosa were the primarytarget organs. In the 13-week subchronic study, F-344 rats wereexposed to 0, 8, 24, or 76 ppm DMEA for 6 hr/day, 5 days/weekfor 13 weeks. The principal exposure-related changes were transientcorneal opacity in the 24 and 76 ppm groups; decreased bodyweight gain for the 76 ppm group; and histopathologic lesionsof the respiratory and olfactory epithelium of the anteriornasal cavity of the 76 ppm group and of the eye of several 76ppm group females. Rats maintained for a 5-week recovery periodonly exhibited histological lesions of the nasal tissue, withthe lesions being decreased in incidence and severity. DMEAacts primarily as an ocular and upper respiratory tract irritantand toxicant at vapor concentrations of 76 ppm, while 24 ppmor less produced no biologically significant toxicity in rats.Thus, 24 ppm was considered to be the no-observable-effect level.