The metabolism and disposition of [2,3-'4C]acrolein was studied in Sprague-Dawley rats after oral or intravenous dosing. Four groups of ten rats (five male and five female) were dosed with radiolabeled acrolein intravenously at 2.5 mg kg-' (Group 2), orally by gavage at 2.5 mg kg-I, either as a single dose (Group 3) or after 14 daily doses of unlabeled acrolein (Group 4), or orally by gavage at 15 mg kg-' (Group 5). Urine, feces, expired air and organic volatiles were collected for 7 days, after which the animals were sacrificed and tissues collected. All samples were analyzed for total radioactivity. After 7 days, the excretory patterns of male and female rats were almost identical. Urinary excretion was highest in the intravenously dosed animals (6649%) and lowest in the Group 5 animals (3640%), whereas the reverse was true for feces (<2% for i.v. Group 2 animals and 28-30% for the Group 5 animals). Carbon dioxide expiration was comparable (26-31 %) across all groups. Tissue concentrations of radioactivity were minimal in all groups (<1.2%), but concentrations of radioactivity were highest in the intravenous Group 2 animals. The time course of excretion for all groups was similar with the exception of the high-dose animal group, which showed a pronounced delay in excretion during the first 12 h.