Toxicity and genotoxicity enhancement during polycyclic aromatic hydrocarbons' biodegradation

Several laboratory column percolators were operated in order to study the bioremediation potential of polycyclic aromatic hydrocarbons (PAH)‐contaminated soils. The columns contained either soil artificially amended with specific PAH mixtures or contaminated soil from a site in Karlsruhe, Germany. In all cases, biodegradative processes led to the elimination of the original contaminants. This, however, was accompanied by a marked increase in genotoxic activity of the column effluents as determined by the Mutatox^TM assay. Genotoxicity was practically abolished, however, when a surfactant was added to the percolating fluids. While in some cases the changes in genotoxicity were paralleled by toxicity (Microtox^TM) data, in others the trend was opposite. It is concluded that when degradation is incomplete, the potential exists for toxicity and genotoxicity enhancement, with the latter hazard not always predictable by short‐term toxicity assays. Routine genotoxicity monitoring is thus advocated for bioremediation projects; the Mutatox^TM assay appears to be a convenient tool for this purpose. © 1994 by John Wiley & Sons, Inc..