Tertiary amyl methyl ether (TAME) is an oxygenate with a potential role as a component in reformulated gasolines. The genotoxic potential of TAME was assessed in an Ames assay and a mouse micronucleus assay. The Ames assay was carried out using five standard salmonella strains and doses ranging from 100 to 10,000 micrograms per plate. Tertiary amyl methyl ether was not mutagenic in any of the strains, either with or without metabolic activation. In the micronucleus assay, mice were given a single intraperitoneal injection of TAME at doses of 0.15, 0.375 or 0.75 g kg-1. Bone marrow samples were collected and evaluated for micronucleus formation at 24, 48 and 72 h after dosing. No elevation in micronucleus frequency was observed at any dose or at any of the collection times. Thus, TAME was not clastogenic to mouse bone marrow under the conditions of this study. Preliminary test data indicated that the acute oral LD50 for TAME in Sprague-Dawley rats was ca. 2.1 g kg-1. In the 28-day subchronic study, Sprague-Dawley rats of both sexes were dosed orally with vehicle, 0.125, 0.5 or 1.0 g kg-1 day-1 TAME in corn oil at a dose volume of 2 ml/kg-1. Dosing continued 7 days a week for a period of 28 days. Deaths of two out of 10 animals in the high-dose group (1 g kg-1 day-1) appeared to be compound related. Food consumption and body weights were reduced in the high-dose male group relative to controls; otherwise, clinical observations were minimal.(ABSTRACT TRUNCATED AT 250 WORDS)