Comparative toxicities of coal- and shale-derived crude oils and a petroleum-derived fuel oil to the freshwater snails Helisoma trivolvis and Physa gyrina

Abstract

The water-soluble fractions (WSFs) of coal- and shale-derived crude oils and a No. 2 diesel fuel oil were tested for acute and chronic toxicity to the pulmonate snails Physa gyrina and Helisoma trivolvis. The 48-h LC 50s (WSF dilutions that killed 50% of the animals in 48 h) of coal oil WSF and shale oil WSF for adult H. trivolvis were 5·4% and 16%, respectively, and for adult P. gyrina they were 3% and 3·6%. Full-strength diesel fuel oil WSF did not kill adult snails of either species in 48 h. In the chronic toxicity tests, snail embryos were exposed continuously to sublethal WSF concentrations from the time of oviposition through 1 week post hatching (11–23 days). The lowest concentrations of coal oil, shale oil and diesel fuel oil WSFs that significantly reduced hatching of H. trivolvis were 0·125%, 0·5% and 32%, respectively, and for P. gyrina they were 1·1%, 2·5% and 8%. Some of the high WSF concentrations significantly delayed hatching of both snail species by about 2 days as compared with the controls. There were no effects of the WSFs on survival of hatched snails. The data suggest that the WSFs may be teratogenic for snail embryos.