A battery of bioassays for the evaluation of phenanthrene biotoxicity in soil

A battery of bioassays was used to assess the ecotoxicological risk of soil spiked with a range of phenanthrene levels (0.95, 6.29, 38.5, 58.7, 122, and 303 μg g(-1) dry soil) and aged for 69 days. Multiple species (viz. Brassica rapa, Eisenia feotida, Vibrio fischeri), representing different trophic levels, were used as bioindicator organisms. Among acute toxicity assays tested, the V. fischeri luminescence inhibition assay was the most sensitive indicator of phenanthrene biotoxicity. More than 15 % light inhibition was found at the lowest phenanthrene level (0.95 μg g(-1)). Furthermore, comet assay using E. fetida was applied to assess genotoxicity of phenanthrene. The strong correlation (r (2) ≥ 0.94) between phenanthrene concentration and DNA damage indicated that comet assay is appropriate for testing the genotoxic effects of phenanthrene-contaminated soil. In the light of these results, we conclude that the Microtox test and comet assay are robust and sensitive bioassays to be employed for the risk evaluation of polycyclic aromatic hydrocarbon-contaminated soil.