Use of in vitro (Ames and Mutatox tests) and in vivo (Amphibian Micronucleus test) assays to assess the genotoxicity of leachates from a contaminated soil

Two in vitro bacterial assays (Ames test and Mutatox test) and one in vivo Micronucleus test on amphibians were used to assess the genotoxicity of aqueous leachates from a soil sample contaminated with polycyclic aromatic hydrocarbons (PAHs) and heavy metals. Positive results were obtained with the three tests, suggesting that this contaminated soil may be a threat to the aquatic environment. The test sensitivity was shown to be influenced by the experimental conditions. The response was higher with the nonfiltered leachate than with 0.45 μm filtered one, which was the standard protocol (Norm X31-210). This standard procedure must be reconsidered in order to account for the pollutants adsorbed on solid particles which were biologically active. Incubation of bacteria in a liquid medium enhanced the sensitivity of the Ames test, by increasing the bioavailability of pollutants in comparison with the agar plate method. Biological tests appeared to be a useful complement to physico-chemical analysis, since they account for bioavailability and bioaccumulation of chemicals, and interactions between pollutants.