Dimitris Vlastos

Environmental and human risk assessment of landfill leachate: an integrated approach with the use of cytotoxic and genotoxic stress indices in mussel and human cells.

The present study investigates leachate hazardous effects on marine biota and human cells, with the use of a battery of assays, both under in vivo and in vitro conditions. According to the results, mussels exposed for 4 days to 0.01 and 0.1% (v/v) of leachate showed increased levels of DNA damage and micronuclei (MN) frequencies in their hemocytes. Similarly, enhanced levels of DNA damage were also observed in hemocytes treated in vitro with relevant concentrations of leachate, followed by a significant enhancement of both superoxide anions (O₂(-)) and lipid peroxidation products (malondialdehyde/MDA). On the other hand, human lymphocyte cultures treated with such a low concentrations of leachate (0.1, 0.2 and 1%, v/v), showed increased frequencies of MN formation and large MN size ratio, as well as decreased cell proliferation, as indicated by the use of the cytokinesis block micronucleus (CBMN) assay and Cytokinesis Block Proliferation Index (CBPI) respectively. These findings showed the clear-cut genotoxic and cytotoxic effects of leachate on both cellular types, as well as its potential aneugenic activity in human lymphocytes.

Effect of 910-MHz Electromagnetic Field on Rat Bone Marrow

Aiming to investigate the possibility of electromagnetic fields (EMF) developed by nonionizing radiation to be a noxious agent capable of inducing genotoxicity to humans, in the current study we have investigated the effect of 910-MHz EMF in rat bone marrow. Rats were exposed daily for 2 h over a period of 30 consecutive days. Studying bone marrow smears from EMF-exposed and sham-exposed animals, we observed an almost threefold increase of micronuclei (MN) in polychromatic erythrocytes (PCEs) after EMF exposure. An induction of MN was also observed in polymorphonuclear cells. The induction of MN in female rats was less than that in male rats. The results indicate that 910-MHz EMF could be considered as a noxious agent capable of producing genotoxic effects.

Evaluation of toxicity and genotoxicity of 2-chlorophenol on bacteria, fish and human cells.

Due to the extensive use of chlorophenols (CPs) in anthropogenic activities, 2-Chlorophenol (2-CP), among other CPs, can enter aquatic ecosystems and can be harmful to a variety of organisms, including bacteria, fish and humans, that are exposed directly and/or indirectly to such contaminated environments. Based on the existing knowledge and in order to move a step forward, the purpose of this study is to investigate the toxic and mainly the genotoxic effects of 2-CP using a combination of bioassays. The tests include the marine bacterium Vibrio fischeri and micronuclei induction in the erythrocytes of Carassius auratus as well as in cultured human lymphocytes. The results obtained reveal that 2-CP is able to induce dose-dependent toxic and genotoxic effects on the selected tested concentrations under the specific experimental conditions.

Genotoxicity study of photolytically treated 2-chloropyridine aqueous solutions.

2-Chloropyridine (2-CPY) has been identified as a trace organic chemical in process streams, wastewater and even drinking water. Furthermore, it appears to be formed as a secondary pollutant during the decomposition of specific insecticides. As reported in our previous work, 2-CPY was readily removed and slowly mineralised when subjected to ultraviolet (UV) irradiation at 254 nm. Moreover, 2-CPY was found to be genotoxic at 100 microg ml(-1) but it was not genotoxic at or below 50 microg ml(-1). In this work 2-CPY aqueous solutions were treated by means of UV irradiation at 254 nm. 2-CPY mineralisation history under different conditions is shown. 2-CPY was found to mineralise completely upon prolonged irradiation. Identified products of 2-CPY photolytic decomposition are presented. Solution genotoxicity was tested as a function of treatment time. Aqueous solution samples, taken at different photo-treatment times were tested in cultured human lymphocytes applying the cytokinesis block micronucleus (CBMN) assay. It was found that the solution was genotoxic even when 2-CPY had been practically removed. This shows that photo-treatment of 2-CPY produces genotoxic products. Upon prolonged irradiation solution genotoxicity values approached the control value.

Pesticide exposure and genotoxicity correlations within a Greek farmers' group

Humans are exposed to pesticides as a consequence of their use in fields or persistence in a variety of media, including air, water, soil, plants, and animals. The use of pesticides, to which humans are exposed, will possibly increase in the near future. This exposure has been related to several human diseases, including cancer. In the present study, we investigated whether occupational exposure to a complex mixture of pesticides is resulting in increased micronuclei (MN) frequency in peripheral blood lymphocytes. Exposed and control subjects were selected in southern Crete, where intensive use of pesticides is observed. Statistically significant differences in micronuclei frequencies in the studied groups were revealed from the obtained results. Comparison of MN frequencies on control and exposed subjects between smokers and non-smokers did not reveal any statistically significant differences. Further studies in other areas in Greece, enlarging the sample size and covering other farmer groups with different farming activities and levels of exposure, are needed to generalize the findings of this study.

A Multidisciplinary Assessment of River Surface Water Quality in Areas Heavily Influenced by Human Activities

The present study could serve as a multidisciplinary approach for the assessment of river surface water quality with the use of chemical and biological methods. Specifically, physicochemical parameters, heavy metals, and pesticides were measured in water samples from three different stations (sampling station S1, S2, and S3) along Asopos River (Greece). In parallel, algal species (primary producers)—such as Scenedesmus rubescens and Chlorococcum sp.; consumer invertebrate species, such as the fairy shrimp Thamnocephalus platyurus and the rotifer Brachionus calyciflorus; as well as human lymphocytes—were exposed to those samples for assessing their toxic and genotoxic/mutagenic effects. According to the results, although the values of almost all of the physicochemical parameters tested, heavy metals (zinc, cadmium, lead, and mercury) and pesticides were lower than or within the respective environmental quality standards, thus offering no clear evidence for their natural or anthropogenic origin. Values recorded for nickel, chromium, hexavalent chromium, and malathion represent a typical case of mixed influence from natural and anthropogenic enrichments. In contrast, the algal growth arrest, the acute toxic effects on the freshwater invertebrates, and the increased micronuclei frequencies observed in human lymphocytes showed the presence of human-derived hazardous substances, which were hardly determinable with the use of conventional chemical methods. Given that the presence of priority pollutants in river surface waters, heavily burdened by anthropogenic activities, could give no clear evidence for their biological risk, the results of the present study showed that chemical and biological assays should be applied in parallel, thus serving as a reliable tool for the assessment of river water quality.

Differential micronuclei induction in human lymphocyte cultures by imidacloprid in the presence of potassium nitrate.

Humans are exposed to pesticides as a consequence of their application in farming or their persistence in a variety of media, including food, water, air, soil, plants, animals, and smoke. The interaction of pesticides with environmental factors may result in the alteration of their physicochemical properties. Square wave cathodic stripping voltammetry (SW-CSV), a technique that simulates electrodynamically the cellular membrane, is used to investigate whether the presence of potassium nitrate (KNO3) in the culture medium interferes with the genotoxic behavior of imidacloprid. The cytokinesis block micronuclei (CBMN) method is used to evaluate imidacloprids genotoxicity in the absence or presence of KNO3 in the culture medium and, as a consequence, its adsorption by lymphocytes. Comparing micronuclei (MN) frequencies in control and imidacloprid-treated blood cell cultures, statistically significant differences were not detected. KNO3 did not induce MN frequencies compared to control. Statistically significant differences in MN frequencies were observed when blood cell cultures were treated with imidacloprid in the presence of increasing concentrations of KNO3. SW-CSV revealed that by increasing KNO3 molarity, imidacloprids concentration in the culture medium decreased in parallel. This finding indicates that imidacloprid is adsorbed by cellular membranes. The present study suggests a novel role of a harmless environmental factor, such as KNO3, on the genotoxic behavior of a pesticide, such as imidacloprid. KNO3 rendered imidacloprid permeable to lymphocytes, resulting in elevated MN frequencies.

Evaluation of the genotoxic and antigenotoxic effects of Chios mastic water by the in vitro micronucleus test on human lymphocytes and the in vivo wing somatic test on Drosophila.

Chios mastic gum, a plant-derived product obtained by the Mediterranean bush Pistacia lentiscus (L.) var. chia (Duham), has generated considerable interest because of its antimicrobial, anticancer, antioxidant and other beneficial properties. Its aqueous extract, called Chios mastic water (CMW), contains the authentic mastic scent and all the water soluble components of mastic. In the present study, the potential genotoxic activity of CMW, as well as its antigenotoxic properties against the mutagenic agent mitomycin-C (MMC), was evaluated by employing the in vitro Cytokinesis Block MicroNucleus (CBMN) assay and the in vivo Somatic Mutation And Recombination Test (SMART). In the former assay, lymphocytes were treated with 1, 2 and 5% (v/v) of CMW with or without MMC at concentrations 0.05 and 0.50 µg/ml. No significant micronucleus induction was observed by CMW, while co-treatment with MMC led to a decrease of the MMC-induced micronuclei, which ranged between 22.8 and 44.7%. For SMART, larvae were treated with 50 and 100% (v/v) CMW with or without MMC at concentrations 1.00, 2.50 and 5.00 µg/ml. It was shown that CMW alone did not modify the spontaneous frequencies of spots indicating lack of genotoxic activity. Τhe simultaneous administration of MMC with 100% CMW led to considerable alterations of the frequencies of MMC-induced wing spots with the total mutant clones showing reduction between 53.5 and 74.4%. Our data clearly show a protective role of CMW against the MMC-induced genotoxicity and further research on the beneficial properties of this product is suggested.

Evaluation of genetic damage in tobacco-growing farmers occupationally exposed to a mixture of metalaxyl and imidacloprid

The use of pesticides, to which humans are exposed, will possibly be increased in the near future. Exposure occurs via inhalation or skin contact during the preparation of the solutions to be sprayed or during spraying. The aim of this study was to evaluate the potent genetic damage in tobacco-growing farmers occupationally exposed to a mixture of metalaxyl and imidacloprid before and after spraying. This evaluation was performed by the micronucleus assay. The results obtained show that there are no statistically significant differences in the micronuclei frequencies of our studied groups before and after spraying. Analysis on the basis of smokers versus non-smokers did not show statistically significant differences. Analysis between control and exposed farmers revealed a significant difference in the smoking group after exposure to these pesticides. Further studies are required in order to estimate the potential effects of pesticides.

Genotoxic and Antigenotoxic Assessment of Chios Mastic Oil by the In Vitro Micronucleus Test on Human Lymphocytes and the In Vivo Wing Somatic Test on Drosophila.

Chios mastic oil (CMO), the essential oil derived from Pistacia lentiscus (L.) var. chia (Duham), has generated considerable interest because of its antimicrobial, anticancer, antioxidant and other beneficial properties. In the present study, the potential genotoxic activity of CMO as well as its antigenotoxic properties against the mutagenic agent mitomycin-C (MMC) were evaluated by employing the in vitro Cytokinesis Block MicroNucleus (CBMN) assay and the in vivo Somatic Mutation And Recombination Test (SMART). In the in vitro experiments, lymphocytes were treated with 0.01, 0.05 and 0.10% (v/v) of CMO with or without 0.05 μg/ml MMC, while in the in vivo assay Drosophila larvae were fed with 0.05, 0.10, 0.50 and 1.00% (v/v) of CMO with or without 2.50 μg/ml MMC. CMO did not significantly increase the frequency of micronuclei (MN) or total wing spots, indicating lack of mutagenic or recombinogenic activity. However, the in vitro analysis suggested cytotoxic activity of CMO. The simultaneous administration of MMC with CMO did not alter considerably the frequencies of MMC-induced MN and wing spots showing that CMO doesn’t exert antigenotoxic or antirecombinogenic action. Therefore, CMO could be considered as a safe product in terms of genotoxic potential. Even though it could not afford any protection against DNA damage, at least under our experimental conditions, its cytotoxic potential could be of interest.