A review of the literature on the mutagenicity/genotoxicity of surface waters is presented in this article. Subheadings of this article include a description of sample concentration methods, mutagenic/genotoxic bioassay data, and suspected or identified mutagens in surface waters published in the literature since 1990. Much of the published surface water mutagenicity/genotoxicity studies employed the Salmonella/mutagenicity test with strains TA98 and/or TA100 with and/or without metabolic activation. Among all data analyzed, the percentage of positive samples toward TA98 was approximately 15%, both in the absence and the presence of S9 mix. Those positive toward TA100 were 7%, both with and without S9 mix. The percentage classified as highly mutagenic (2500-5000 revertants per liter) or extremely mutagenic (more than 5000 revertants per liter) was approximately 3-5% both towards TA98 and TA100, regardless of the absence or the presence of S9 mix. This analysis demonstrates that some rivers in the world, especially in Europe, Asia and South America, are contaminated with potent direct-acting and indirect-acting frameshift-type and base substitution-type mutagens. These rivers are reported to be contaminated by either partially treated or untreated discharges from chemical industries, petrochemical industries, oil refineries, oil spills, rolling steel mills, untreated domestic sludges and pesticides runoff. Aquatic organisms such as teleosts and bivalves have also been used as sentinels to monitor contamination of surface water with genotoxic chemicals. DNA modifications were analyzed for this purpose. Many studies indicate that the 32P-postlabeling assay, the single cell gel electrophoresis (comet) assay and the micronucleus test are sensitive enough to monitor genotoxic responses of indigenous aquatic organisms to environmental pollution. In order to efficiently assess the presence of mutagens in the water, in addition to the chemical analysis, mutagenicity/genotoxicity assays should be included as additional parameters in water quality monitoring programs. This is because according to this review they proved to be sensitive and reliable tools in the detection of mutagenic activity in aquatic environment. Many attempts to identify the chemicals responsible for the mutagenicity/genotoxicity of surface waters have been reported. Among these reports, researchers identified heavy metals, PAHs, heterocyclic amines, pesticides and so on. By combining the blue cotton hanging method as an adsorbent and the O-acetyltransferase-overproducing strain as a sensitive strain for aminoarenes, Japanese researchers identified two new type of potent frameshift-type mutagens, formed unintentionally, in several surface waters. One group has a 2-phenylbenzotriazole (PBTA) structure, and seven analogues, PBTA-type mutagens, were identified in surface waters collected at sites below textile dyeing factories and municipal wastewater treatment plants treating domestic wastes and effluents. The other one has a polychlorinated biphenyl (PCB) skelton with nitro and amino substitution group and it was revealed to be 4-amino-3,3'-dichloro-5,4'-dinitrobiphenyl derived from chemical plants treating polymers and dye intermediates. However, the identification of major putative mutagenic/genotoxic compounds in most surface waters with high mutagenic/genotoxic activity in the world have not been performed. Further efforts on chemical isolation and identification by bioassay-directed chemical analysis should be performed.

Mutagens in surface waters: a review

Wastewater effluents, groundwater, surface water, sediments, soils and air particulate matter are often contaminated by a multitude of chemicals. Since often no a priori knowledge of relevant toxicants exists, chemical analysis alone is not an appropriate tool for hazard assessment. Instead, a linkage of effect data and hazardous compounds is required. For that purpose, effect-directed analysis (EDA) was developed, which is based on a combination of biotesting, fractionation procedures and chemical analytical methods. Since a controversial discussion about the prospects of success in relation to the expense exists, the current methodological state of EDA for organic toxicants in complex mixtures and important results are reviewed in this paper with the aim of establishing criteria for the successful use of this promising tool. While EDA is a powerful tool to identify specifically acting individual toxicants close to the source of emission, it is inappropriate for screening purposes and often may fail in remote areas where the concentrations of specific toxicants are too low relative to the nonspecific toxicity of the whole mixture of natural and anthropogenic compounds. The biological tools have to be carefully selected with respect to their ability to detect specific effects and their significance in hazard assessment. Sophisticated chemical tools are required to identify individual toxicants in mixtures of thousands of compounds, which are typical for contaminated environments.

Effect-directed analysis: a promising tool for the identification of organic toxicants in complex mixtures?

The contribution of azo dyes to the mutagenic activity of the Cristais River.

ObjectivesAccording to the 2007 National Research Council report Toxicology for the Twenty-First Century, modern methods (e.g., “omics,” in vitro assays, high-throughput testing, computational meth...

The Salmonella Mutagenicity Assay: The Stethoscope of Genetic Toxicology for the 21st Century

Benzotriazole: An overview on its versatile biological behavior

Water samples from the Nishitakase River in Kyoto, Japan, especially taken at sites below sewage plants, show significantly high mutagenicity in the Ames test. In the present study, mutagens in the river water were adsorbed to 24 g of blue rayon, extracted, and separated by HPLC on ODS columns. Five mutagenic compounds (I-V) were isolated, and they accounted for 21%, 17%, 11%, 12%, and 6%, respectively, of the total mutagenicity of the blue rayon-adsorbed materials. With compound I obtained from adsorbate to 24 g of blue rayon as a marker, a large quantity (1.1 mg) of mutagenic compound I was isolated by Sephadex LH-20 column chromatography and HPLC on ODS columns from material adsorbed to 27 kg of blue cotton. X-ray crystal analysis was carried out with the debrominated derivative of compound I. Based on this X-ray crystallography data and the UV, mass, and 1H-NMR spectra of both the derivative and compound I, the structure of compound I was determined to be 2-[2-(acetylamino)-4-[bis(2-methoxyethyl)amino]-5-methoxyphenyl]-5-amino - 7-bromo-4-chloro-2H-benzotriazole (PBTA-1). PBTA-1 is a newly identified potent mutagen, inducing 1,200,000 revertants of Salmonella typhimurium YG1024 per microgram in the presence of S9 mix.

Kiyoka Kiyokawa

Papers

Isolation and chemical-structural determination of a novel aromatic amine mutagen in water from the Nishitakase River in Kyoto.