Genotoxicity of trichloroethylene in the natural milieu

Trichloroethylene (TCE) is a suspected genotoxic and carcinogenic compound which is usually present in the air, soil and water as pollutant. To estimate the genotoxic potential of TCE in a pure chemical form as well as an ingredient of the complex sample, Ames fluctuation test using TA98 and TA100 strains and Allium cepa genotoxicity assay were performed. For the genotoxicity analysis of TCE in natural milieu, the above mentioned tests were performed on the waste waters collected from two different stations of northern India namely Saharanpur and Aligarh, U.P., and these waste waters were supplemented with 50 and 100 mg/l of trichloroethylene. TCE alone was found to be non-genotoxic by both the testing system up to the range of 1000 mg/l concentration (data not shown). However, the test water samples supplemented with 100 mg/l of TCE, exhibited a significant increase in the genotoxicity compared with control by both the testing systems. In Ames fluctuation test, Mi(f) value was found to be increased by 41% and 53% with 100 mg/l of TCE supplemented Saharanpur and Aligarh waste water samples respectively, in the presence of S9 fraction compared with their respective controls. Allium cepa genotoxicity test also showed around 25% increase in total chromosomal aberration frequency following 100 mg/l TCE supplementation. However, supplementation of 50 mg/l TCE to the test water samples could not enhance the genotoxicity to a significant extent. From these results, we can conclude that TCE itself was non-genotoxic but it may promote mutation and/or DNA damage at a concentration of 100 mg/l under certain environmental conditions. We suggest that some chemicals in the test water samples might be interacting with TCE and/or metabolite(s) to cause the enhancement in genotoxicity. The mechanism of these synergistic effects should be explored further.