Rats, 4 per sex/dose were administered 4-Amino-2-Hydroxytoluene via gavage in dose levels of 0, 0.4, 1, 2.5 or 6.4 g/kg bw. To determine the median lethal dose more precisely dosing was extended to a larger group, and additional groups of 5 rats per dose/sex, were administered the test substance via gavage in dose levels of 0, 1.6, 2.5, 4.0 or 6.4 g/kg bw. Shortly after dosing clinical signs observed were lethargy, piloerection and decreased respiration rate. Above 1.6 g/kg these signs were accompanied by ataxia, and in rats dosed above 2.5 mg/kg also fine body tremors and increased lacrimation was observed. The acute median lethal oral dose of 4-amino-2-hydroxytoluene in rats was calculated to be 3.6 (95% confidence limits: 3.1-4.0) g/kg bw.

A genotoxic potential of 4-Amino-2-Hydroxytoluene was observed after 48 hours of incubation with V79 cells starting at the lowest concentration tested (10 ug/ml), while DNA damage in both V79NAT1*4 and HaCaT cells started at substantially higher concentrations, 100 and 31,6 ug/ml, respectively.