The use of a urine mutagenicity assay in the monitoring of environmental exposure to genotoxins

Abstract

Urinary bacterial mutagenicity was used as a biomarker of exposure to ambient air pollution in a group of women working outdoors in the city of Teplice (TP; Northern Bohemia) with higher levels of air pollution than a similar group of women in the city of Prachatice (PT; Southern Bohemia). The Salmonella typhimurium plate incorporation assay with the TA98 and YG1041 strains and microsuspension assay with the YG1041 strain were used for testing the urinary mutagenicity. PAH and their metabolites were analyzed by HPLC and GC/MS methods. The significantly higher values of most PAHs/metabolites detected in a TP group confirmed the differences of PAH exposures between both groups. In the plate incorporation assay, the TA98 strain was not able to detect the increase in urinary mutagenicity, but, for the YG1041 strain, the urinary mutagenicity was clearly determined with a significant difference in number of YG1041 + S9 revertants between the TP and PT groups. The microsuspension assay increased the mean response by about 10-fold over the standard plate test; however, no statistical difference between TP and PT groups was found due to high interindividual variability and small sample size. Comparing the urinary PAH/metabolites to urinary mutagenicity, significant correlations were observed between the plate incorporation mutagenicity results with the YG1041 revertants in the presence of metabolic activation and several of the urinary PAH/metabolites. On the contrary, in the microsuspension assay, several urinary PAH/metabolites correlated significantly with the YG1041 revertants only in the absence of metabolic activation. This may indicate the influence of different treatment conditions of assays on the urinary mutagenicity results. The results suggest the insufficient sensitivity of the TA98 tester strain to determinate low urinary level of mutagens. On the contrary, the use of the YG1041 tester strain increases the probability of detecting an effect of environmental exposure and seems to be applicable to biological monitoring. To definitely replace the standard plate incorporation assay with the microsuspension method is not possible without further comparative studies.