| Organochlorine pesticides(OCPs)and polychorinated biphenyls(PCBs)are important environmental persistent organic pollutants.The most common OCPs include DDT and its degradation products(DDTs),four configurations of(HCHs)and hexachlorobenzene(HCB);PCBs consist of 209 congeners with different chlorine substitutions.OCPs and PCBs have adverse effects on humans and living things and are currently banned by countries around the world.However,due to the persistence characteristics of these pollutants,they are still ubiquitous in various environmental media,and there are also different levels of OCPs and PCBs in freshwater fish.The population's dietary exposure to OCPs and PCBs,and dietary intake may have carcinogenic and non-carcinogenic health risks to humans.Taihu Lake is the third largest freshwater lake in China and an important fishing base in the Yangtze River Delta region.From 2011 to 2017,a total of 173 samples of five fish species from Taihu Lake were collected and analyzed for the contamination levels of OCPs and PCBs in these samples.The results showed that the concentrations of OCPs(DDTs,HCHs,HCB)and PCBs in Taihu Lake were 77.8–654 and 16.7–84.4 ng/g lipid weight,and the pollution level was at the middle level in the world.The compositional distribution characteristics show that DDTs are the most important organochlorine pesticides,accounting for97.9% of the total concentration of OCPs;tetra-hexachloro-substituted PCBs are the most important PCB pollutants,especially pentachlorobiphenyl,average concentration percentage It was 26.5%,followed by tetrachlorobiphenyl(23.7%)and hexachlorobiphenyl(19.9%).Source analysis shows that the pollution of OCPs and PCBs in Taihu fish is mainly derived from historical residues.Through statistical analysis between the changes of OCPs and PCBs pollution concentration in Taihu Lake fish and the related indicators of regionalsocial development,it is found that there is a significant correlation between the concentration changes of pollutants in fish and the relevant indicators of regional social development.The concentration changes of DDTs and PCBs decreased by7.1% and 4.9%,respectively,with the proportion of the secondary industry in the region,while the concentration of HCB increased by 19.7% per year.No similar trend was found in HCHs;however,the increase in HCB concentration may be related to industrial production.The combustion emissions from industrial manufacturing are related to waste disposal and require further analysis.The health risk assessment data of fish from Taihu Lake showed that the average total daily intake(EDI)of the target pollutants(DDTs,HCHs and PCBs)under the additive effect was 3.01 ng/kg bw d–5.41 ng/kg bw d(child),and 2.65ng/kg bw d–4.76 ng/kg bw d(adult)using the average concentration in the five fish samples from Taihu Lake,far below the World Health Organization and Food Agriculture Organization.Children's intake is generally higher than that of adults and needs more attention.The risk factor values of DDTs,HCHs and PCBs by fish in Taihu Lake(except for crucian carp and topmouth culter of DDTs)are less than 1,indicating that eating Taihu fish does not cause potential carcinogenic and non-carcinogenic effects on human body.Health risks.When OCPs and PCBs coexist in Taihu Lake,the contribution rate of relative risk values for carcinogenicity and non-carcinogenicity is different.The relative risk value of DDTs in carcinogenic risk accounted for 63%,and in non-carcinogenic risk,PCBs were the main ones,accounting for up to 80%. |
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