Rats were gavaged with 60, 48, 38, 30, or 24 ml/kg of either petroleum (P) or shale (S)-derived distillate fuel, marine (DFM). Surviving rats were killed 14 days after dosing. There was a slight difference in toxicity of the two fuels but neither fuel was very toxic. The LD50/14 was 43 ml/kg for P-DFM and 50 ml/kg for S-DFM. Lesions in rats that died indicated hepatic and renal toxicity. In another study, rats were gavaged with 24 ml/kg of either P- or S-DFM and killed at 1, 2, or 3 days after dosing. Prominent clinicopathologic findings included loss of body weight, hematologic evidence of dehydration, transient leukopenia, and serum chemistry and histopathologic alterations indicative of mild hepatic and renal toxicity.