Drinking water quality: An in vitro approach for the assessment of cytotoxic and genotoxic load in water sampled along distribution system

An in vitro approach was performed to assess the quality of drinking water collected at two treatment/distribution networks located near the source (Plant #1) and the mouth of River Po (Plant #2). The water was sampled at different points of each distribution network, before (raw water) and after the chlorine dioxide disinfection, and in two points of the pipeline system to evaluate the influence of the distribution system on the amount and quality of the disinfection by-product. Cytotoxicity and genotoxicity of water extracts were evaluated in human peripheral lymphocytes and Hep-G2 cells by the use of the micronucleus (MN) test and Comet assay. Raw water samples of both plants induced cytotoxic effects, but not the increases of MN frequency in Hep-G2 cells and in human lymphocytes. Increases of DNA damage in human leukocytes was detected by Comet assay for raw water of Plant #2 at concentration ≥ 0.25 Leq/mL. The disinfection process generally has reduced the toxicity of water samples, even if potential direct DNA-damaging compounds have been detectable in drinking water samples. The proposal approach, if currently used together with chemical analysis, can contribute to improve the monitoring drinking water.     

Genetic biomonitoring of an urban population exposed to mutagenic airborne pollutants

Biomonitoring studies have increased as a consequence of risks and effects to human health on exposure to environmental contaminants, mainly air pollutants. Genetic biomarkers are useful tools for the early assessment of exposure to occupational and environmental pollution. The objective of the present study was to investigate genotoxic effects on people residing and/or working downwind from an oil refinery in southern Brazil and the mutagenic activity of airborne particulate matter (PM10). Samples of peripheral blood and buccal mucosa cells were evaluated using the single-cell gel electrophoresis assay (comet assay) and the micronucleus (MN) assay, respectively. PM10 samples were collected in the target site and the organic matter extraced with dichloromethane was assessed for mutagenic activity in the Salmonella/microsome assay. The exposed group (n = 37) was compared to a reference group (n = 37) of subjects living in an urban area with limited traffic and industrial influence, located far from the main industrial areas. All PM10 organic extracts showed mutagenic positive responses and the effect decreased in the presence of S9 mix indicating that the predominant compounds present were direct-acting mutagens. The responses of YGs strains are consistent with aromatic amines and nitroarenes being present in the PM10 extracts. The group in the area under the influence of the oil refinery (exposed group) showed significantly higher DNA damage in lymphocytes than the reference group. The MN frequencies in buccal mucosa were very low for both groups and no difference between groups was observed. No association was found between age and tobacco smoking habit and level of DNA damages measured by the comet assay. The results indicate that the comet assay was a sensitive tool to detect DNA damage in subjects under the influence of an oil refinery, with marked genotoxic activity in the atmospheric environment.     

Cellular damages in the Allium cepa test system, caused by BTEX mixture prior and after biodegradation process

Petroleum and derivatives have been considered one of the main environmental contaminants. Among petroleum derivatives, the volatile organic compounds benzene, toluene, ethylbenzene and xylene (BTEX) represent a major concern due to their toxicity and easy accumulation in groundwater. Biodegradation methods seem to be suitable tools for the clean-up of BTEX contaminants from groundwater. Genotoxic and mutagenic potential of BTEX prior and after biodegradation process was evaluated through analyses of chromosomal aberrations and MN test in meristematic and F₁ root cells using the Allium cepa test system. Seeds of A. cepa were germinated into five concentrations of BTEX, non-biodegraded and biodegraded, in ultra-pure water (negative control), in MMS 4 × 10⁻⁴ M (positive control) and in culture medium used in the biodegradation (blank biodegradation control). Results showed a significant frequency of both chromosomal and nuclear aberrations. The micronucleus (MN) frequency in meristematic cells was significant for most of tested samples. However, MN was not present in significant levels in the F₁ cells, suggesting that there was no permanent damage for the meristematic cell. The BTEX effects were significantly reduced in the biodegraded samples when compared to the respective non-biodegraded concentrations. Therefore, in this study, the biodegradation process showed to be a reliable and effective alternative to treat BTEX-contaminated waters. Based on our results and available data, the BTEX toxicity could also be related to a synergistic effect of its compounds.     

Adaptive response in frogs chronically exposed to low doses of ionizing radiation in the environment

Using the micronucleus assay, decreased levels of DNA damage were found after high dose ionizing radiation exposure of liver cells taken from frogs inhabiting a natural environment with above-background levels of ionizing radiation, compared to cells taken from frogs inhabiting background areas. The data obtained from a small number of animals suggest that stress present in the above-background environment could induce an adaptive response to ionizing radiation. This study did not reveal harmful effects of exposure to low levels of radioactivity. On the contrary, stress present in the above-background area may serve to enhance cellular defense mechanisms.     

助动车尾气对哺乳动物的致突变作用

对３种牌号助动车排出尾气中的颗粒提取物，采用小鼠微核试验进行研究。结果表明，３种牌号助动车排出的颗粒提取物有导致小鼠微核出现的提高，且有一定的剂量一反应关系，提示助动车排出的颗粒提取物对哺乳类动物染色体有损伤作用。研究中未发现各牌号车型之间 核出现率的明显差别。     

东大湖养鱼场水质遗传毒理的检测研究

本文报道了利用蚕豆根尖微核技术和鱼周血有核红细胞微核技术检测东大潮5个渔场的水质污染情况。结果为：各渔场蚕豆根尖MCN‰与对照（自来水）存在显著差异（F＞F(0．01)，P＜0．01），根据污染指数划分：A、B两渔场为重污染，C、D为中度污染，E为轻污染。各渔场鱼周血有核红细胞MCN‰与无明显污染源水体（柏录）存在着显著性差异（F＞F(0．01)，P＜0．01）。两种方法检测结果呈一致性，污染程度为A≈B＞C≈D＞E。微核率变化主要受污染源性质及位置的影响。将两种遗传毒性检测方法与化学方法检测相配合．能全面、准确、快速地监测水体污染状况，具有广泛的应用前景。     

用人淋巴细胞微核试验检测地面水致突变性

用胞质阻断微核试验（CBMN）来检测浙江某地区地面水有机提取物的致突变性,并与Ames试验结果进行了比较。结果表明,该水样中含有微量致突变物,CBMN试验和Ames试验结果基本相符,说明CBMN试验用作检测地面水致突变性是可行的,但灵敏度略低于Ames试验。