The Distribution,bioaccumulation And Depuration Of 3,3',4,4',5-Pentachlorobiphenyl In Tilapia Oreochromis Nilotica Through Fish Feed

Polychlorinated biphenyls?PCBs?are ubiquitous in our environment.And dioxin-like PCBs?dl-PCBs?are similar to dioxin,they can do harm to humans through food chains,due to their high lipophilicity and biomagnification.Fish is easy to accumulate PCBs,what's more,3,3',4,4',5-pentachlorobiphenyl?PCB126?has the highest toxic equivalency factor?TEF?in dl-PCBs.Therefore,there exists a risk that people might expose to high concentration of PCB126 in foods.Feed is the main source for farmed fish to intake PCBs,however,the distribution,bioaccumulation and depuration of PCB126 in farmed fish is fragmentary,especially in China.In order to investigate the transfer of PCB126 to fish through feed,tilapias?Oreochromis nilotica?were fed with different concentrations of PCB126 in feed.In this study,two series of experiments?bioaccumulation and depuration?were conducted on the tilapias under real conditions.In experiment bioaccumulation,the tilapias were fed with three kinds of fish feed contaminated with different PCB126 levels for 50days,and the levels PCB126 in these feeds were 0,50,500 ng·kg^-1 wet weight,respectively.And then,all tilapias were fed with 0 ng PCB126·kg^-1 feed in experiment depuration for 34 days.The contents of PCB126 in 0,500 ng·kg^-1 feed group?liver,muscle,blood and kidney?and 50 ng·kg^-1 feed group?only liver?were analyzed by High Resolution Gas Chromatography-High Resolution Mass Spectrometry?HRGC-HRMS?,the regularity of distribution,bioaccumulation,depuration and simple dietary exposure estimation of PCB126 in fish tissues were investigated.The results showed that PCB126 was easy to be accumulated in fish,and the levels of PCB126 in tilapia's liver,muscle,kidney and blood of 500 ng·kg^-1 feed group were significantly increased more than 8 times on the first day in bioaccumulation,then the rapid and smooth increase of PCB126 in liver and blood were appeared,the peak levels of PCB126 in muscle and kidney appeared later than liver and blood;and the contents of PCB126?calculated by lipid?in tilapia's liver of 50 ng·kg^-1 feed group were also significantly increased on the second day in bioaccumulation.Moreover,the PCB126 in livers of 500 ng·kg^-1 feed group was 2¹4 times as high as that of 50 ng·kg^-1 feed group,the more PCB126 content in fish feed,the higher PCB126 concentration was found in liver.During depuration period,the levels of PCB126 in tissues except muscle were significantly decreased,PCB126 contents in muscle decreased slowly.