Occupational genotoxicity assessment by mutagenicity assays

Biomonitoring of urine mutagenicity with the Ames test: improvement of the extraction/concentration method

Comparative extraction efficiency of the pre-packed Bakerbond-spe-SDB-1 resin and of Amberlite-AD2 (XAD-2) resin, for the preparation of urine extracts in biomonitoring studies. Urine extracts were prepared in parallel with the Bakerbond column and with the classical XAD-2 resin from urines (1) spiked with mutagenic chemicals, (2) collected from patients after chemotherapy, and (3) from smokers. Mutagenic activities were evaluated on Salmonella typhimurium tester strains TA97a, TA98, TA100 and TA102 with and without S9 mix. Mutagenic activities obtained with Bakerbond extracts were almost always higher or at least equivalent to those prepared on XAD-2 resin. Similar results were observed for the three urine sample groups. When fully validated, the use of the pre-packed columns will be more convenient and time-saving for large population studies.

A new sensitive test based on yeast cells for studying environmental pollution

Different tests based on yeast cells were developed for determination of mutagenic/carcinogenic action; however, they all showed lower sensitivity compared to bacterial tests, the main reason for this being the limited permeability of yeast cells. We found that general permeability of Saccharomyces cerevisiae cells can be increased by mutation and on this basis we developed a more sensitive test. The aim of this study was to prove the applicability of our test, called D7ts1, in environmental studies. Soil, water and air samples were taken during 1998 from regions in Bulgaria with declared low, average or high pollution levels and investigated for presence of mutagenic/carcinogenic activities in the bacterial test of Ames, the yeast D7 test of Zimmermann and our new D7ts1 test. Results obtained evidenced the following conclusions: (1) the usage of D7ts1 test instead of D7 test permits a clearer measurement of positive samples and detects mutagenic/carcinogenic activities undetectable by D7 test; (2) all samples with positive Ames test were positive in the D7ts1 test; however, some samples, clearly positive in the D7ts1, were negative in the Ames test; therefore, the simultaneous usage of D7ts1 and Ames tests in environmental studies is advantageous because it detects dangers for the human health activities to which bacterial cells do not respond; and (3) regions in Bulgaria declared clean were found to be polluted; particularly troubled are the whole-year positive data in the three tests for air samples from a 'clean' region.

Comet assay application in environmental monitoring: DNA damage in human leukocytes and plant cells in comparison with bacterial and yeast tests

Urban airborne particulate is a complex mixture of air pollutants, many of which have not been identified. However, short-term mutagenesis tests together with chemicophysical parameter analysis are able to better assess air quality and genotoxic load. The findings of continuous monitoring (January 1991-August 1998) of urban air genotoxicity of a Po Valley town (Italy) on Salmonella typhimurium and Saccharomyces cerevisiae are reported. During this period, various measures (catalytic devices, unleaded fuels, annual vehicle overhaul, etc.) to improve air-dispersed pollutant control were enforced. However, a continuous presence of genotoxic compounds is shown and more qualitative than quantitative changes are evident. We also demonstrate the ability of the Comet assay to detect DNA-damaging agents in airborne particulate samples. We applied the test to human leukocytes and, with major improvements, to plant cells (Allium cepa roots and epigean tissues of Impatiens balsamina). The first findings on human leukocytes confirm the sensitivity of this assay, its peculiarity and its applicability in assessing genotoxicity in environmental samples. The capability of plants to show the response of multicellular organisms to environmental pollutants largely counterbalances a probable lowering in sensitivity. Moreover, application of the Comet test to epigean tissues could be useful in estimating the bioavailability of and genotoxic damage by air pollutants, including volatile compounds (ozone, benzene, nitrogen oxides, etc.) to higher plants.