Studies On The Combined Effect Of DNA Damage Induced By Microcystins And Organic Compounds Extracted From Drinking Water

Since the 1970s, the research on Synthetic toxic organic compounds has become a hot topic around the world. The monitoring and controlling of toxic organic compounds in the drinking water has become a hotspot of research field of environmental health in the developed countries. In the present, the quantity of Synthetic organic compounds has amounted to 250 million ton. The amount of variety of organic compounds has been increasing to 7 million, and its amount keeps on increasing by the velocity of thousands per year. It was estimated that ten thousands organic compounds especially the industrial pollutants has released to the environment through waters. and some of these organic compounds are toxic, which can induce cancer,mutation and teratogenicity. These organic compounds are difficult to degradation by the microorganism in nature, but they are easy to cumulate and spread in the environment. Some of these can even get into human body directly through drinking water. Because of the varieties of organic compounds and its low concentration (μg/L, ng/L) in drinking water, it is difficult to be detected and monitored by using ordinary detecting devices and equipments. In order to detect these organic compounds, besides some high sensitivity and accuracy equipments, we also need the high efficient enriching technique. Macroporous adsorption Resin is a kind of Resins which developed from 1970s. This Resin is a new type of Polymer Absorbent which contains three-dimensional porous structure. Its has stable Physical and chemical properties and Resin is allowed to use in acid,Alkali and Organic Solvent. This Resin can concentrate and separate specific kinds of organic compounds but do not be interfered by the mineral salt and Low-molecular-weight compounds. Macroporous adsorption Resin has strong adsorption competence and high Enrichment multiples. It can be Regenerated and less pollution. It is widely used in enriching organic compounds from waters for its well performance.With the increasing eutrophication of lakes, the hazard caused by algal bloom has been concerned by many environmental scientists around the world. The most part of these hazards is cyanobacterial Toxin pollution caused by the toxic algal. In all kinds of algal Toxins, microcystins toxin that induced by microcystis aeruginosa is the most widely spread in the world and bring about huge damage to the health of human body. microcystins is one kind of Daejeon soft sponge acid which can induce cancer. It has been reported as liver specific toxins and it might also be tumor initiators. According to some epidemiological reports, microcystins are one of the risk factors for the high incidence of primary liver cancer in certain areas of China, where people have consumed pond-ditch water contaminated with blue-green algae. These people have 8 time primary liver cancer incidence rate as high as the people who drink deep well water. Shi Wei found that microcystins can induce dose dependent DNA strand breaks in cell line HL-7702 by using comet assay under the dose which do not induce cytotoxicity. This may suggest that microcystins have genetoxicity and might cause DNA damage.Mixed organic compounds extracted from drinking water have been prove that it can cause DNA damage and Oxidative damage even DNA strand breaks. It also can induce the abnormal expression of oncogene and anti-oncogene. Some research made by domestic specialists has show that regular water treatment technique can not eliminate microcystins completely. In addition, by using the Chlorination to disinfection, it might lead to the death of microcystis aeruginosa and result in releasing more and more microcystins. Therefore, it is possible that microcystis and organic compounds would bring about combined effect. And this can increased the potential risk of incidence of tumor. So, the research on safety of drinking water should consider the possible combined effect of variable toxins rather than focus on the hazard of single toxin.This study aim to measure and compare the static adsorption rate and dynamic adsorption curve among XAD-2,XAD-8 and mixed-Resin of two for researching the property of Resin to absorb and concentrate organic pollutants from drinking water. Using solid extraction technique and GC-MS to detect and analyze the variety of organic compounds extracted from HanJiang River. In addition, using single cell gel electrophoresis to explore the effect of DNA strand breaks induced by microcystins and organic compounds in cell line HepG2, and this study also apply the factorial analysis to explore the possible type of combined effect in this experiment.This paper is consisted of three parts:Part I: the research on the property of macroporous adsorption Resin to absorb and concentrate organic pollutants from drinking waterThis study aim to measure and compare the static adsorption rate and dynamic adsorption curve among XAD-2,XAD-8 and mixed-Resin of two for researching the property of Resin to absorb and concentrate organic pollutants from drinking water. To measure the optic density (OD) of water sample by using ultraviolet spectrophotometer at the wave length of 254nm.The measurement of OD is used to indicate the concentration of organic pollutants in drinking water, and to demonstrate the adsorption competence of Resin by analyzing the difference of measurement between absorbed and pre-absorbed. The result show that: The static adsorption rate of XAD-2,XAD-8 and mixed-Resin of two is 75.77%,58.76% and 32.61% respectively. And the dynamic adsorption curve of XAD-2 Resin is superior to other Resins; the amount of organic compounds enriched by XAD-2 Resin is larger than other two kinds of Resin, and this may associated with the high concentration of nonpolarity organic compounds in drinking water. The amount of kinds of organic compounds detected in XAD-2,mixed resin and XAD-8 absorbed sample is 77,155 and 107 respectively, this result may show that the property of mixed-Resin is superior to XAD-8 and XAD-2 Resin at the aspect of competence to enrich more varieties of organic compounds. Part II: Detection and analyze of organic compounds in Hanjiang drinking water by using GC-MSUsing XAD series macroporous adsorption Resin and applying solid extraction technique and GC-MS to detect and analyze the variety of organic compounds extracted from HanJiang River. The result show that: The amount of kinds of organic compounds detected in XAD-2,mixed resin and XAD-8 absorbed sample is 77,155 and 107 respectively. Under the same conditions, the amount of organic compounds enriched by XAD-2 Resin is larger than other two kinds of Resin, but the competence of XAD-8 Resin to enrich varieties of organic compounds is superior to the single XAD-2 Resin. XAD-2 Resin suit to enrich nonpolarity organic compounds, and XAD-8 Resin suit to enrich polarity organic compounds. if want to consider either the amount or varieties of organic compounds, it is better to use the mixed Resin and increase the Volume of water sample so as to obtain the best adsorptive efficient. In this study, applying GC-MS to detect and analyze the variety of organic compounds extracted from Han jiang water. The result show that the amount of varieties of organic compounds detected in water sample is 155, and the major kinds of toxic organic compounds are benzendicarboxylic acid,Phthalate and fatty acid.Part III: Research on DNA damage induced by mixed organic compounds combined with microcystinsUsing single cell gel electrophoresis to explore the effect of DNA strand breaks induced by microcystins and organic compounds in cell line HepG2.the result show that: (1) exposed to dose 30ml/ml of mixed organic compounds, Olive tail measurement of cell HepG2 have no statistic significant with compare to the control group(P 0.1426).when we increase the dose of microcystins, Olive tail measurement of cell HepG2 is also increasing accordingly and have dose-dependent effect.(2) with the increasing dose of microcystins, Olive tail measurement of joint exposed group increase gradually. Comparing to the single mixed organic group, the joint exposed group with low dose microcystins have no statistic significant (P 0.9299), but the joint exposed groups with medium dose and high dose microcystins both have statistic significant (P<0.0001). as the same, Comparing to the control group, the joint exposed group have statistic significant with increasing dose of microcystins. This result suggests that here is a possible combined effect on DNA damage induced by microcystins with organic compounds. (3) Comparing to the high dose microcystins group, the joint exposed groups with microcystins have statistic significant but the joint exposed groups with low and medium dose microcystins have not.(4) applying the factorial analysis to explore the possible type of combined effect in this experiment. We found that there is a synergistic effect between microcystins and mixed organic compounds. Microcystins can enhance the DNA damage effect caused by mixed organic compounds.