Absorption, distribution, metabolism and excretion of intravenously and dermally administered triethanolamine in mice

Triethanolamine (TEA) is an amino alcohol having widespread applications in consumer goods and as an industrial chemical. A number of relatively high- dose dermal toxicity studies have been conducted in rats and mice reflectin g the principal route of human exposure to TEA. The absorption, distributio n, metabolism and excretion (ADME) of C-14-TEA derived radioactivity were d etermined in male C3H/HeJ mice following dermal application of 2000 mg/kg ( neat) or, to characterize blood kinetics, intravenous (iv) injection of 1 m g/kg C-14-TEA, Balance and excretion data were also collected in mice utili zing several dermal dosing scenarios (1000 mg/kg in acetone, 2000 mg/kg nea t, 2000 mg/kg in water) and, for comparative purposes, in male Fischer 344 rats dosed dermally with 1000 mg/kg neat C-14-TEA. Urine, feces, expired CO 2 (iv) and, where appropriate, blood were collected over a 24- or 48-hour p eriod post-dosing. The half-life for dermal absorption of radioactivity was estimated to be 1.3 hours. Intravenously administered radioactivity was el iminated in a biphasic manner with a prominent initial phase (half-life of 0.3 hr) followed by a slower terminal phase (half-life of 10 hr). Radioacti vity was excreted primarily via the urine (49-69%) as unmetabolized TEA, re gardless of dosage, route or vehicle used, Fecal excretion of radioactivity comprised 16-28% of dose administered, The body burden at sacrifice (sum o f liver, kidney, carcass and non-application site skin) ranged from 3 to 6% of the dose. It was concluded that TEA is absorbed extensively following d ermal application to mice at dosages relevant to toxicity testing and that acetone or water vehicles do not appear to significantly alter total uptake . Significantly, the blood kinetics and ADME of TEA in mice and/or rats dif fers from that of a related chemical, diethanolamine, which appears to be m ore toxic to rodents than TEA. (C) 2000 Elsevier Science Ltd. All rights re served.