Polycyclic Aromatic Hydrocarbons And Organochlorine Pesticides In Fish From Taihu Lake: Their Levels, Distribution And Human Health Risk Assessment

Polycyclic aromatic hydrocarbons (PAHs) and organochlorine pesticides(OCPs), are a class of persistent organic pollutants (POPs), which are generallycharacterized by properties of persistence, bioconcentration, toxicity and along-range global transport. Because of their high lipophilicity, PAHs and OCPs arecapable of bioconcentration and biomagnification through food chains. Fish oftencontain high contaminant concentrations due to their relatively high position in thefood chain and consequent elevated exposure levels in the aquatic environment.Many investigations have reported high concentrations of environmentalcontaminants including a suit of organochlorine compounds, polycyclic aromatichydrocarbons and metals in fish all over the world, and suggested that they may posea health risk to human body. Diets are one of the major sources of PAHs and OCPsexposed to human.Taihu Lake is the second largest lake in China, and also is an important fisherybase. However, reports on PAHs and OCPs in fish from the lake were limited. In thisstudy, the concentrations of15PAHs and20OCPs were determined in193samplesof24fish species collected from Taihu Lake in2009. The biomagnification of PAHsand OCPs in these fish species were investigated. The results showed that PAHs andOCPs could be detected in all samples, with an average total concentration of PAHsand OCPs in each species ranging from289to9500ng/g lw and from121to904ng/g lw, respectively. The lowest concentrations of PAHs and OCPs were observedin S. dabryi, and the highest were observed in S. asotus and P.pekinensis,respectively. Compared with those in wild freshwater fish from other water bodies inChina and some other countries, fish in Taihu Lake are moderately contaminated byPAHs and OCPs.Among the15PAHs, phenanthrene was the predominant congeners, accountingfor45.8%of the total PAH, followed by fluoranthene, pyrene, and fluorine. The PAH fingerprints were dominated by the lower molecular weight hydrocarbons withtricyclic PAHs being the most abundant, which accounted for63.0%of the totalPAHs. Among the OCPs analyzed, DDTs and HCHs were predominant in all thesamples, which contributed to82.8%and7.4%of the total OCPs, respectively.Among DDT and HCH isomers, p,p’-DDE and β-HCH was respectively the mostaboundant congener of DDTs and HCHs, which accounted for88.1%and90.8%ofthe total DDTs and HCHs, respectively. According to molecular ratios of individualPAHs and OCPs, it indicated that PAHs were mainly originated from both unburnedpetroleum and combustion of fossil fuels, while DDTs and HCHs were mainly agedresidues. The trophic magnification factor (TMFs) of individual PAHs and OCPscongeners ranged from0.91to1.90and from0.83to2.49, respectively. Comparedwith fish at lower trophic position, fish at higher trophic position had relative highercontaminant concentrations. On the basis of trophic levels, the potential humanhealth risks posed via fish consumption were assessed. The daily intake and hazardquotient increased with the trophic levels increasing. Compared with fish at lowertrophic position, fish at higher trophic position had relative higher health risks.In2010, we sampled9species fish from the lake. The whole-muscles (mixedmuscle including dorsal, ventral, and tail muscles) of the nine species (includingWuchang bream, white amur bream, crucian carp, common carp, silver carp, bigheadcarp, yellow catfish, spotted steed, and topmouth culter), and the portion-musclesfrom three portions (i.e., dorsal, ventral, and tail muscles) of4fish species (includingsilver carp, bighead carp, common carp, and topmouth culter) were used to measurethe concentrations of DDTs and HCHs. A total of123samples including55whole-muscle samples and68portion-muscle samples were analyzed. Theconcentrations of DDTs and OCPs in mixed muscle of nine species fish ranged fromranged from786to3389pg g-1ww, and from67.3to300pg g-1ww, respectively.Compared with samples collected in2009, the total concentrations of DDTs andHCHs in the present study were slightly lower. The significant differences of theconcentrations of DDTs and HCHs in three portions (i.e., dorsal, ventral, and tailmuscle) of four species were caused by the lipid contents and hydrophobic property of contaminants. The concentrations of DDTs and HCHs were lowest in dorsalmuscle among three portions. The concentrations of DDTs were highest in tailmuscle, and the concentrations of HCHs were highest in ventral muscle.The potential human health risks posed via fish consumption were assessed.The results showed that consumption most of the portion-muscles of the fish couldnot cause cancer and non-cancer risks except for the ventral and tail muscles oftopmouth culter. The benefit-risk of co-ingestion of eicosapentaenoic acid (EPA) anddocosahexaenoic acid (DHA), and contaminants (DDTs, HCHs, polychlorinatedbiphenyls(PCBs) and polybrominated diphenyl ethers (PBDEs)) was evaluated viaconsumption of fish from Taihu Lake. The benefit-risk quotient (BRQ) wascalculated. The results suggested that to achieve the recommended EPA+DHAintake of250mg d–1for a healthy adult, the consumption of most fish species fromthe lake can cause cancer and non-cancer risks. The results also suggested that therisk of consuming silver carp was generally lower than other fish species, and thoseof dorsal muscles were lower than ventral and tail muscles.