Genotoxicity evaluation and a primary risk assessment of organic pollutants in the drinking water sources of Nanjing, China

An increasing number of industrial, agricultural, and commercial chemicals in the aquatic environment leads to various deleterious effects on organisms, which is becoming an increasingly serious problem in China. In this study, the comet assay was conducted to investigate the genotoxicity to human body caused by organic concentrates in the drinking water sources of Nanjing City from Yangtze River of China, and health and ecology risk due to expose to these organic pollutants were evaluated with the multimedia environmental assessment system （MEAS）. For all the water samples, they were collected from four different locations in the drinking water sourcr samples, es of Nanjing City. The results of the comet assay showed that all the organic concentrates from the water samples could induce different levels DNA damages on human peripheral blood lymphocytes, and a statistically significant difference （p〈0.01） was observed compared with the solvent control, which demonstrated the genotoxicity was in existence. According to the ambient severity （AS） of individual compound, we had sorted out the main organic pollutants in the drinking water source of the four waterworks, and the results showed that there was some potential hazard to human body for all the source water, namely the total ambient severity （TAS） of health for each water source was more than 1. However, the TAS of ecology for each water source was less than 1, which indicated that it was safe to ecology. The results of this investigation demonstrate the application of the comet assay and the MEAS in aquatic environmental monitoring studies, and the comet assay found to be fast, sensitive, and suitable for genotoxicity monitoring programs of drinking water source.

Formation potentials of typical disinfection byproducts and changes of genotoxicity for chlorinated tertiary effluent pretreated by ozone

The effects of ozonation on the formation potential of typical disinfection byproducts （DBPs） and the changes of genotoxicity during post chlorination of tertiary effluent from a sewage treatment plant were investigated. Ozonation enhanced the yields of all detected chlorine DBPs except CHCI3. At a chlorine dose of 5 mg/L, the three brominated THMs and five HAAs increased, while chloroform decreased with the increase of ozone dose from 0 to 10 mg/L （ozone dose in consumption base）. At a chlorine dose of 10 mg/L, the two mixed bromochloro species THMs and two dominant HAAs （DCAA and TCAA） increased firstly and then decreased with the increase of ozone dose, with the turning point approximately occurring at an ozone dose of 5 mg/L. The genotoxicity detected using umu test, on the other hand, was removed from 7 Ixg 4-NQO/L to a negligible level by ozonation under an ozone dose of 5 mg/L. Chlorination could further remove the genotoxicity to some extent. It was found that SUVA （UV absorbance divided by DOC concentration） might be used as an indicative parameter for monitoring the removal of genotoxicity during the oxidation.

Cytotoxicity and genotoxicity assessment of Euphorbia hirta in MCF-7cell line model using comet assay

Objective:To evaluate the cytotoxicity and genotoxicity activity of Euphorbia hirta(E.hirta)in MCF-7 cell line model using comet assay.Methods:The cytotoxicity of E.hirta extract was investigated by employing brine shrimp lethality assay and the genotoxicity of E.hirta was assessed by using Comet assay.Results:Both toxicity tests exhibited significant toxicity result.In the comet assay,the E.hirta extract exhibited genotoxicity effects against MCF-7 DNA in a time-dependent manner by increasing mean percentage of DNA damage.The extract of E.hirta showed significant toxicity against brine shrimp with an LC_(50)value of 620.382μg/mL(24 h).Comparison with positive control potassium dichroniate signifies that cytotoxicity exhibited by the methanol extract might have moderate activity.Conclusion:The present work confirmed the cytotoxicity and genotoxicity of E.hirta.However,the observed toxicity of E.hta extracts needs to be confirmed in additional studies.

Genotoxicity evaluation of drinking water sources in human peripheral blood lymphocytes using the comet assay

The potential harm of organic pollutants in drinking water to human health is widely focused on in the wodd; more and more pollutants with genotoxic substances are released into the aquatic environment. Water source samples were collected from 7 different localities of Nanjing City. The potential genotoxicity of organic extracts from drinking water sources were investigated by means of the comet assay in human peripheral lymphocytes. The results showed that all the organic extracts from all the water source samples could induce DNA damages of human peripheral blood lymphocytes at different levels. A significant difference （P 〈 0.01） was observed when compared with the solvent control, The DNA damage increased with the increase of the dosage of the original water source. Significant differences of DNA damage were observed in different drinking water sources, as shown by the multiple comparisons analysis at the dosage of 100x; the degree of DNA damage treated by Hushu waterworks （at town level） was the most serious, the arbitrary units （AU） was 141.62±6.96, however, that of Shangyuanmen waterworks （at city level） was only 109.64±2.97. The analysis also revealed that the genotoxicity of town＇s water sources was higher than that of the city. The results demonstrated that the comet assay can be successfully applied to the genotoxicity monitoring programs of drinking water sources.

Genotoxicity of Pesticide Waste Contaminated Soil and Its Leachate

Objective Improper land disposal of hazardous waste can result in leaching of hazardous constituents which may contaminate ground and surface water leading to adverse impact on human health and environment consequences. The present study utilized mammalian cell culture for the genotoxicity assessment of waste and its leachate. Methods Genotoxic potential and chemical analysis of pesticide derived tarry waste contaminated soil extract and its leachate was assessed using in vitro human lymphocyte cultures and GC-MS. Results The investigation revealed that the soil extract could cause significant to highly significant genotoxicity in the form of DNA strand break at 25 mL (P<0.01), 50 mL, 100 mL and 200 mL (P<0.001) and chromosomal aberration at 25 mL (P<0.01) and 50 mL and 100 mL (P<0.001). The leachate could cause significant DNA strand break and chromosomal aberration only at 100 mL and 200 mL (P<0.01) dose levels. Conclusion The genotoxicity observed is attributed to carbaril and tetra methyl naphthyl carbamate, the major ingredients of the extracts, as revealed by GC-MS.

Evaluation of naproxen-induced oxidative stress, hepatotoxicity and in-vivo genotoxicity in male Wistar rats

Naproxen(NP), a nonsteroidal anti-inflammatory drug(NSAID), is used for the treatment of common pain, inflammation and tissue damage. Genotoxicity testing of NP is of prime importance as it represents the largest group of drugs to which humans are exposed. Not many genotoxic studies are reported on NP;therefore, the present study investigated the detailed genotoxic and oxidative stress properties of NP.Male Wistar rats were administered NP orally at the doses of 38.91 and 65.78 mg/kg body weight for 14 days. Reduced glutathione(GSH), superoxide dismutase(SOD), catalase(CAT) and lipid peroxidation(LPO) activities/levels were measured in the liver, kidney and brain tissues. The aspartate aminotransferase(AST), alanine aminotransferase(ALT), alkaline phosphatase(ALP) activities, and total bilirubin(TBIL) levels were measured in the liver tissues. Micronucleus frequency(micronucleus test MNT)and DNA damage(comet assay) were performed in the bone marrow cells and leukocytes, respectively.The results showed that NP treatment decreased the GSH levels and increased the SOD, CAT, LPO, ALT,AST, ALP and TBIL activities/levels compared to the control(p o 0.05). Results of MNT showed an increased micronucleus induction and comet assay showed a significant increase in DNA damage in the NP treated animals(p o 0.05). Treatment of NP resulted in the biochemical imbalance and induced oxidative stress that deteriorated the integrity of the cells, which caused significant damage to the genetic material and affected liver function in male Wistar rats. Therefore, NP is a potential genotoxic agent that induces genotoxicity and oxidative stress.

Effect of Buchanania lanzan Spreng.bark extract on cyclophosphamide induced genotoxicity and oxidative stress in mice

Objective:To elucidate the effect of ethanolic extract of Buchanania lanzan Spreng.(B.lanan) bark against cyclophosphamide induced genotoxicity and oxidative stress in mice.Methods: The prevalence of micronuclei in bone marrow,the extent of lipid peroxidation,reduced glutathione and the status of the antioxidant enzymes,superoxide dismutase and catalase in liver of mice were used as intermediate biomarkers for chemoprolection.Lipid peroxidation and associated compromised antioxidant defenses in cyclophosphamide treated mice were observed in the liver.Results:Pre-treatment with B.lanzan 250,500 and 1 000 mg/ kg,p.o.,daily for 7 days significantly reduced the chromosomal damage and lipid peroxidation with concomitant changes in antioxidants and detoxification systems.Conclusions:These results point out the presence of chemopreventive phytoconstituents in the crude extract offering protection against cyclophosphamide induced genotoxicity and oxidative stress in mice.

Genotoxicity of substituted nitrobenzenes and the quantitative structure－activity relationship

The genotoxicity of 22 substituted nitrobenzenes were evaluated by the chromosome aberrations test in in vitro human peripheral lymphocytes.18 of 22 compounds exhibit genotoxic activities.Quantitative structure-activity relationship model was established to correlate the genotoxicity of substituted nitrobenzenes with the characteristics of the substituents on benzene ring.

Hexabromocyclododecane-induced Genotoxicity in Cultured Human Breast Cells through DNA Damage

To investigate the genotoxicity and reveal the potential toxicological mechanisms of Hexabromocyclododecane （HBCD）, human breast cells HBL-100 were exposed to a sequence of HBCD concentrations （0, 5, 10, and 50 mg/L） for 24 h. With a series of zymology and molecular biology methods, we found that HBCD induced dose-dependent oxidative stress on HBL-100 DNA. As revealed in q RT-PCR, activated prognostic factor ATM down-regulated tumor suppressor gene BRCA1 and prompted DNA repair genes h OGG1 and h MTH1 expression in lower concentrations of HBCD （〈 10 mg/L）. However, DNA repair were inhibited as well as cell proliferation rate by higher concentrations of HBCD （50 mg/L）. The results inferred that the genotoxicity of HBCD was dose-dependent and related to DNA repair pathway.

Synthesis,Characterizations and in Vitro Assessment of the Cytotoxicity and Genotoxicity of Novel Silicon Nitride-Based Porous Ceramics

Porous Si3N4-SiO2-based ceramics with different porosity were prepared via free sintering of Si3N4 on air with an addition of semolina (5, 10 and 20 wt%) as a pore-forming agent. The semolina content in the starting powder controlled the volume fraction of pores in the sintered body. Small pores (5 μm) formed a continuous network in the whole volume of the ceramic material, while the large pores (~100 μm), formed from the added semolina were mostly isolated in the ceramic matrix. Mercury porosimetry and strength measurements have shown that specific surface area, volume density and compressive strength decreased with the amount of semolina in the samples. Mechanical properties similar to bone were obtained for the sample with 20 wt% semolina pore forming agent (compressive strength 350 MPa, density 2.17 g.cm-3). The prepared Si3N4-SiO2-based ceramics were evaluated for cytotoxic and genotoxic potential on human fibroblast VH10 and B-HNF-1 cells. Biological tests have shown that both these human fibroblast cell lines were sensitive to the samples with lower porosity and cell growth inhibition was observed in the range 14.9% - 21.3%. The cytotoxicity of the sample with the highest porosity (~40%) was not significant (10%). The microscopic observations have shown that VH10 and B-HNF-1 cells growing around the silicon nitride ceramic discs were homogeneously distributed on the cultivation surface. No significant morphologic changes were found in treated cells, their morphology was very similar to that of the control cells. None of the tested Si3N4-based ceramic samples induced necrotic/apoptotic death of human fibroblasts. Sample S-20 had similar properties to bones and was characterized by very good biocompatibility, slight cytotoxicity and none genotoxicity. Therefore, Si3N4-SiO2-based ceramics prepared by free sintering on air are potential biomaterials for medical applications.

Assessment of genotoxicity and cytotoxicity of standardized aqueous extract from leaves of Erythroxylum cuneatum in human HepG2 and WRL68 cells line

Objective:To investigate the cytotoxicity and the genotoxicity of standardized aqueous of dry leaves of Erythroxylum cuneatum(E.cuneatum)in human HepG2 and WRL68 cells.Methods:The cytoloxicity of E.cuneatum extract was evaluated by both MTS and LDH assays.Genotoxicity study on E.cuneatum extract was assessed by the single cell gel electrophoresis(comet assay).The protective effect of E.cuneatum against menadione-induced cytotoxicity was also investigated.Results:Results from this study showed that E.cuneatum extract exhibited cytotoxic activities towards the cells with IC_(50)value of(125±12)and(125±14)μg/mL for HepG2and WRL68 cells respectively,after 72 h incubation period as determined by MTS assay.LDH leakage was detected at(251±19)and(199.5±12.0)μg/mL for HepG2 and WRL68 respectively.Genotoxicity study results showed that treatment with E.cuneatum up to 1 mg/mL did not cause obvious DNA damage in WRL68 and HepG2 cells.Addition of E.cunaetum did not show significant protection towards menadione in WRL68 and HepG2 Cells.Conclusions:E.cuneatum standardized aqueous extract might be developed in onler to establish new pharmacological possibilities for its application.

Evaluation of the in vitro and in vivo Genotoxicity of Almond Skins

Objective It aims to study potential genotoxicity of almond skins.Methods A bacterial reverse mutation assay was performed on S.typhimurium strains TA97,TA98,TA100,TA102,and TA1535 in the absence or presence of S-9 mixture at a dose range of 312.5 to 5 000 μg/plate.A micronucleus test and a mammalian bone marrow chromosome aberration tests were performed in Swiss Albino （CD-1） mice at doses of 625,1 250,and 2 500 mg/kg bw used.Results Almond skins exerted no mutagenic activity in various bacterial strains of Salmonella typhimurium in either the absence or the presence of metabolic activation at all doses tested.Various doses of almond skins did not affect the proportions of immature to total erythrocytes,the number of micronuclei in the immature erythrocytes,or the number of structural and numerical chromosomal aberrations of Swiss albino mice.Conclusion Almond skins are not genotoxic under the conditions of the in vitro bacterial reverse mutation assay and two in vivo tests-micronucleus test and mammalian bone marrow chromosome aberration test,which supports the safety of almond skins for dietary consumption.

Genotoxicity and Safety Pharmacology Studies of Indole Alkaloids Extract from Leaves of Alstonia scholaris (L.) R. Br.

Indole alkaloids extract(IAAS)was prepared from leaves of Alstonia scholaris(L.)R.Br.,an evergreen tropical plant widely distributed throughout the world.This plant has been used historically by the Dai ethnic people of China to treat respiratory diseases.This study evaluated the genotoxicity and safety pharmacology of IAAS to support clinical use.The bacterial reverse mutation(Ames)test,in vitro mammalian chromosomal aberration test,and in vivo mammalian erythrocyte micronucleus(MN)test were performed to evaluate genotoxicity.Mice were administered IAAS(240,480,or 960 mg/kg bw)once orally to observe adverse central nervous system effects.Furthermore,beagle dogs were administered IAAS(10,30,60 mg/kg bw)once via the duodenum to evaluate its effects on the cardiovascular and respiratory systems.IAAS with or without S9-induced metabolic activation showed no genotoxicity in the Ames test up to 500μg/plate,in the mammalian chromosomal aberration test up to 710μg/mL,or in the MN test up to 800 mg/kg bw.No abnormal neurobehavioral effects were observed in mice following treatment with up to 960 mg/kg bw of IAAS.Moreover,blood pressure,heart rate,electrocardiogram parameters,and depth and rate of breathing in anesthetized beagle dogs did not differ among the IAAS doses or from the vehicle group.These data indicated that IAAS did not induce mutagenicity,clastogenicity,or genotoxicity,and no pharmaco-toxicological effects were observed in the respiratory,cardiovascular,or central nervous systems.Our results increased understanding of safety considerations associated with IAAS,and may indicate that IAAS is a possible drug candidate.

Double-endpoint Genotoxicity Quantification and PAHs Characterization of Drinking Water Source alongside Polluted Yinghe River with High Tumor Mortality

The etiology for the high tumor mortality in heavy polluted Yinghe river basin is still unclear and polycyclic aromatic hydrocarbons(PAHs)belong to the priority pollutants in water based on the former surveillance data.In order to explore the potential genotoxicants contributing to the double-endpoint genotoxicity of polluted drinking water source,12 groundwater and 3 surface water samples were collected from 3 villages and the nearby rivers alongside Yinghe river basin,respectively and their comprehensive genotoxicity was estimated with a bioassay group of sOS/umu test and micronucleus(MN)test(MNT).Some groundwater samples showed positive genotoxicity and all surface water samples were highly genotoxic.Eight groundwater samples showed DNA genotoxic effct with the average 4-NQO equivalent concentration(TEQ_(4-NQO))of 0.067μg/L and 0.089μg/L in wet and dry season,respectively.The average MN ratios of groundwater samples were 14.19‰ and 17.52‰ in wet and dry season,respectively.Groundwater samples showed different genotoxic effect among 3 villages.The total PAHs concentrations in all water samples ranged from 8.98 to 25.17 ng/L with an average of 14.97±4.85 ng/L.BaA,CHR,BkF,BaP and DBA were the main carcinogenic PAHs contributing to the genotoxicity of water samples.In conclusion,carcinogenic PAHs are possibly related to the high tumor mortality in the target area.Characterization of carcinogenic PAHs to genotoxicity of drinking water source may shed light on the etiology study for high tumor mortality in Yinghe river basin.Key words:genotoxicity test;drinking water source;high tumor mortality;Yinghe river basin;polycyclic aromatic hydrocarbons(PAHs)

Acute andchronic cytotoxicity and genotoxicity induced by 2,6-dichloro-1,4-benzoquinone in NIH3T3 cells

Objective:This study aimed to evaluate the acute and chronic cytotoxicity and genotoxicity of 2,6-dichloro-1,4-benzoquinone(2,6-DCBQ).Methods:NIH3T3 cells were exposed to 2,6-DCBQ for 3 and 72 h,and relative cell viability was calculated.NIH3T3 cells were treated with different concentrations of 2,6-DCBQ for 24 h.The solvent and positive controls were dimethyl sulfoxide(DMSO)and 0.5μmol/L ethylmethylsulfone,respectively.The values of Olive tail moment were measured by comet assay.NIH3T3 cells were then simultaneously treated with 5μg/mL cytochalasin B and different concentrations of 2,6-DCBQ.The solvent and positive controls were DMSO and 1μmol/L mitomycin C,respectively.Micronucleus rates were calculated after 48 h.Results:The half lethal doses of 2,6-DCBQ in NIH3T3 cells were 64.93μmol/L for 3 hand 13.46μmol/L for 72 h.The values of Olive tail moment in the 7.5 and 10μmol/L groups were significantly higher than those in the solvent control(P<0.05).Moreover,the micronucleus rates in the 10 and 15μmol/L groups were significantly higher than those in the solvent control(P <0.05).The results of comet assay and micronucleus test showed a dose-response relationship.Conclusion:2,6-DCBQ exhibited strong cytotoxicity and induced DNA and chromosomal damage in NIH3T3 cells.

Genotoxicity Clues to Predict Intervertebral Disc Degeneration: A Systematic Review

Objective: To characterize the association between DNA damage and Intervertebral disc degeneration (IDD). Summary of Background Data: IDD is the main disorder causing low back pain and is the most promising target for intervention. Many factors can contribute to the etiology, such as genetics, environment and lifestyle, but it is not yet fully understood. DNA damage can influence this process and needs to be studied, as well as the agents that can determine these damages. Methods: A systematic literature search of PubMed, Web of Science and Scopus was performed to identify studies related to DNA damage to the intervertebral disc. Results: After screening 61 records, 7 articles were included according to the selection criteria. All studies showed some relation between DNA damage and IDD. However, DNA damage was always considered a secondary issue to be investigated. Conclusions: Many factors can influence DNA damage induced by different genotoxic agents on the degenerative cascade of IVD. However, the correlation between IDD severity and DNA damage, as well as the factual role of DNA damage in disc degeneration could not be defined.

Genotoxicity Tests and Their Contributions in Aquatic Environmental Research

As many chemicals with genotoxic potential are emitted to surface water, genotoxicity tests are gaining importance which led to the development of several techniques to detect directly DNA damage. The relevance of detecting the genotoxic risks associated with water pollution was firstly perceived in the late 1970s. Since that time several tests have been developed for evaluating DNA alterations in aquatic animals. These tests rely on the premise that any changes to DNA may have long-lasting and profound consequences. Sister chromatid test, chromosome aberrations, comet assay, and micronucleus test are currently the most widely employed methods to detect DNA lesions in ecotoxicology. Chromosomal aberration and sister chromatid exchanges are time consuming, resource intensive and require proliferating cell population. Hence, Comet assay and Micronucleus test as cost effective and more sensitive test systems have now been introduced for assessing the genotoxicity of chemicals. This review presents a synthesis of the state of the art in the methodologies of comet assay and micronucleus test and their contributions in aquatic environmental research. The text explores the latest knowledge and thinking on these very important approaches for the assessment of environmental health, management, and conservation. The primary concern of the present review is the measurement of genotoxic potential in aquatic organisms under field and laboratory conditions, where effects of chemicals at different levels of biological organization can be examined.

Genotoxicity Assessment of Contaminated Drinking Water Sources in a Rural Community in Edo State of Nigeria

In most rural settlements in Nigeria, provision of potable water for drinking and domestic purposes is a big challenge;therefore analysis of drinking water is of great importance as contaminated water jeopardizes both the physical and social health of all people. Water samples were obtained during the dry and wet seasons from a borehole and a man-made lake constructed through self-help effort in Obazuwa community in Ovia North East Local Government Area of Edo State, Nigeria. They were analyzed for physicochemical parameters and subjected to cyto-genotoxic evaluation using the Allium cepa assay. Results of the physicochemical analysis showed that most of the parameters (pH, chromium, copper, chlorides, nickel, iron, zinc, cadmium, lead and manganese) of the lake water in both seasons exceeded World Health Organisation (WHO) permissible limits. Total heterotrophic bacteria and E. coli were present with dry season water samples having higher amounts. Compared to the control, the mitotic index decreased significantly (p < 0.05) in the water samples and were characterized by a number of chromosomal aberrations notably bridges, fragments, sticky chromosomes, disoriented chromosomes, and micronuclei in significant amounts and these were more pronounced in water samples obtained during the dry season. The findings in this study are of public health relevance as access to safe water is a fundamental human need and therefore, a basic human right.

An Evaluation of Genotoxicity and Cytotoxicity of Melamine in Combination with Cyanuric Acid at Three Mass Ratios

Melamine in combination with cyanuric acid has been considered to be more toxic than either melamine or cyanuric acid alone. The objective of this study was designed to evaluate the combined genotoxicity and cytotoxicity of melamine （M） and cyanuric acid （C） at three mass ratios （1：1, 1：2, 2：1）. MC （1：1）, MC （1：2）, and MC （2：1） were evaluated for their potential genotoxic risk, at gene level by Ames test, and at chromosomal level by micronucleus test. In order to evaluate cytotoxicity in HEK-293 cells, the MTT assay was included. Western blot was also employed to investigate the renal injury molecule-1 （Kim-1） expression in HEK-293 cells exposed to MC. Neither genotoxicity at gene level nor at chromosomal level was observed for MC （1：1）, MC （1：2）, and MC （2：1）. Based on MTT assay, three ratios of MC at 82.5 and 165 μg/mL slightly inhibited viability of HEK-293 cells （P〈0.05）. MC （1：1） at 41.25 and 82.50 IJg/mL could elevate the Kim-1 expression in HEK-293 cells.

Evaluation of Genotoxicity of Abrus mollis Hance with Single-cell Gel Electrophoresis Assay

[ Objective] This study aimed to evaluate the genotoxicity ofAbrus mollis Hance by using single cell gel electrophoresis. [Method] Forty mice were di- vided into five groups randomly, including positive control group （ cyclophosphamide group ）, negative control group （ physiological saline group）, high-dose A. moles Hance group （30 g/kg）, moderate-dose A. mollis Hance group （20 g/kg） and low-dose A. mollis Hance group （10 g/kg）. Tail DNA% and Tail Moment of mouse liver, kidney, lung and testicular cells were analyzed by using single cell gel electrophoresis assay, to investigate the effect of A. mollis Hance on DNA in mouse cells. [Result] Compared with positive control group, Tail DNA% and Tail Moment of moose liver, kidney, lung and testicular cells in A. moles Hance groups were significantly lower （ P 〈 0.01 ）. Compared with negative control group, Tail DNA% and Tail Moment of mouse liver, kidney, lung and testicular ceils in high-dose A. mollis Hance group were significantly lower （ P 〈 0.01 ）, while the other A. mollis Hance groups showed no statistically significant difference （ P 〉0.05 ）. [ Conclusion] A. mollis Hance has no damage effect on DNA in mouse cells within this experimental dose range.