Biomarker monitoring for health risk based on sensitivity to environmental mutagens

Mutagenicity of quaternary ammonium salts containing carbohydrate moieties

Quaternary ammonium salts are widely used in industrial, agricultural, healthcare and domestic applications. They are believed to be safe compounds, with little or no health hazard to humans. However, in this report, we demonstrate that a series of newly synthesized quaternary ammonium salts containing carbohydrate moieties reveal potent mutagenic activities, as assessed by using the Vibrio harveyi bioluminescence mutagenicity test. D-Gluco- and D-galacto-derivatives were found to have a higher mutagenic potential than D-manno-derivatives. Among the former groups of compounds, the N-[2-(D-glycopyranosyloxy)ethyl]-N,N,N-trimethylaminium salts were of the highest activity in the mutagenicity assay. These results suggest that the safety of quaternary ammonium salts may be lower than previously supposed, indicating a need for testing such compounds for their mutagenicity.

Rapid detection of mutagens accumulated in plant tissues using a novel Vibrio harveyi mutagenicity assay

Detection of mutagenic pollution in natural environment is difficult as there are thousands of known chemical mutagens, and they have mutagenic effects usually at very low concentrations. Plants are able to accumulate various substances, including mutagens, in their tissues. Here, we demonstrate that rapid detection of mutagenic activities of compounds accumulated in plant tissues is possible using a recently developed microbiological mutagenicity assay, based on induction of bioluminescence of a dim mutant of a marine bacterium Vibrio harveyi. Using this assay, it was possible to detect mutagenic activity in extracts from relatively small amounts of tissues (1.5 g) collected from plants, which were cultured in vitro for 30 days in the presence of nano-molar concentrations of various chemical mutagens. Moreover, contrary to control samples, cultured in vitro without any mutagens, significant mutagenicity was detected in several extracts of plant tissues collected from natural environment. The whole procedure was as short as 4 h or less.

The use of the Vibrio harveyi luminescence mutagenicity assay as a rapid test for preliminary assessment of mutagenic pollution of marine sediments

Mutagenic pollution of the natural environment is currently one of the most serious environmental problems. It includes the pollution of marine sediments. Therefore, rapid detection of the presence of mutagens is an important issue. Recently, we have developed a novel microbiological assay for rapid assessment of mutagenicity of samples from the natural environment. This assay is based on bioluminescence of a mutant Vibrio harveyi strain, and was shown to be useful in testing samples of marine water and plant tissues. Here we demonstrate the usefulness of this assay in preliminary assessment of mutagenic pollution of marine sediments. Mutagenicity of environmental samples taken from the Baltic Sea, is documented and compared here with a commercially available standard sediment sample (IAEA 383), which contains known amounts of mutagenic compounds. The whole procedure, from obtaining a sample in the laboratory to getting final results, is very short (less than 4 h).

Mutagen sensitivity assays in population studies

Human population monitoring studies are frequently conducted to determine if exposure to environmental mutagenic agents can cause health problems or not. In these studies, a variety of biomarkers are used to identify biological events that are predictive of health consequences. An emphasis in this report is on the use of mutagen sensitivity assays to understand health risk. The assay is based on the assumption that exposure to mutagenic chemicals or mixtures of chemicals for a long time can cause cellular changes that are expressed as mutagen sensitivity. From experience in using these assays in cancer patients and in mutagen-exposed populations, it is clear that the expression of mutagen sensitivity is based on the interactions between mutagen exposure and individual susceptibility. When studies are conducted under appropriate conditions, expression of mutagen sensitivity is suggestive of increased risk for environmental disease such as cancer.

Chromosomal aberrations under basal conditions and after treatment with X-ray in human lymphocytes as related to the GSTM1 genotype

The frequency of chromosomal aberrations (CAs) was evaluated in blood lymphocytes from 18 healthy subjects. Basal CA frequencies were not significantly different in GSTM1 positive and GSTM1 null subjects (P>0.05), whereas they were considerably higher in smokers than in non-smokers. After 1 Gy dose of X-ray challenge of blood samples, CA frequencies were significantly higher in GSTM1 null subjects, compared to GSTM1 positive subjects (P<0.005), and in smokers, compared to non-smokers. These effects are ascribed to the influence of GSTM1 genotype and of smoking status on DNA repair capacities. As the induction of CAs are associated with carcinogenesis, the challenge assay is able to detect enhanced susceptibility for CA caused by genetic predisposition of DNA repair deficiency.

An application of the challenge assay in boat builders exposed to low levels of styrene--a feasibility study of a possible biomarker for acquired susceptibility

Sensitivity to carcinogens and susceptibility for malignant diseases may be related to genetic predisposition, e.g. polymorphisms in toxicant-metabolizing enzymes or DNA repair deficiencies. The latter may also be acquired by exposure to substances that interfere with DNA repair processes. Application of the challenge assay to an exposed population may allow scientists to study the interference of DNA repair as an acquired susceptibility phenomenon. The assay was therefore used in a feasibility study to evaluate its application. A group of 14 workers exposed to low levels of styrene (mean < 100 mg/m3 styrene in air; 35 micrograms/l styrene in blood) and a reference of seven controls were investigated for structural chromosomal aberrations using FISH. The rate of exchange-type aberrations per 100 metaphases was 0.14 (95% CI, 0.05-0.31) in controls and 0.22 (95% CI, 0.13-0.36) in exposed workers. The difference is not statistically significant. Interaction with DNA repair was measured in the 14 workers and 2 historical controls using the challenge assay. Exchange-type aberrations per 100 metaphases after X-ray challenge of 1.66 Gy were 13.26 (10.53-16.50) and 16.19 (15.00-17.40) for the controls and exposed, respectively. The difference is statistically significant (p < 0.038). Among the exposed group, the challenge response was also significantly correlated with the cumulative lifetime exposure to styrene (R2 = 0.3996; p < 0.015) but not with the current exposure as measured in blood (R2 = 0.0226; p = 0.700). The challenge responses in the short-term and long-term exposed subgroups were 15.55 (14.23-16.96) and 17.90 (15.64-20.39), respectively, based on sample sizes of 5 and 9, respectively. The difference was not significant. Hence, data from our study are consistent with the hypothesis that long-term exposure to styrene can interfere with DNA repair activities. The lack of statistically significant differences in some of the data may be due to the small sample size and a possible confounding by age in our investigation. Additional data from our ongoing study should clarify this uncertainty.