Assessment of the genotoxicity of mine-dump material using the Tradescantia-stamen hair (Trad-SHM) and the Tradescantia-micronucleus (Trad-MCN) bioassays

The Tradescantia-stamen hair (Trad-SHM) and -micronucleus (Trad-MCN) bioass ays were used to determine the genotoxicity of two eluates derived from min e tailings. The goal was to test the suitability of the Tradescantia bioass ays as screening tools for this kind of waste material. Leachates obtained using the current standard German leaching test methods (S4 eluate) as well as leachates obtained using a new eluation method (pH(stat)4) were tested and compared. Concentration of heavy metals in the pH(stat)4 eluate were mu ch higher than in the S4 eluate. The chemical analysis corresponded well wi th the results of the bioassays. Exposure to solutions containing more than 1% pH(stat)4 eluate caused a significantly higher number of micronuclei. T he Trad-SHM bioassay also showed an increased pink mutation rate when plant s were exposed to 8 or 16% eluate solutions. In contrast, the S4 eluate onl y caused increased mutation rates when solutions containing more than 32% e luate were used. The low pH of the pH(stat)4 eluate was not responsible for the genotoxicity observed using both bioassays, as indicated by the lack o f significant mutation rates in the nitric acid controls. This demonstrates that the Tradescantia bioassays can be used as tools to assess the genotox ic potential of environmental samples with a wide range of pH values, witho ut the need for sample modification. (C) 1999 Elsevier Science B.V. All rig hts reserved.