Effect Of Microplastics On The Enrichment Of Bisphenol A In Tissues Of Yellow River Carp And Compound Toxicological Effect

Microplastics(MPs)is a new type of pollutants,because it has small size,large specific surface area and good hydrophobic,easy absorption,environment and other contaminants in the environment of the migration and the MPs in the environment of the pollutants are easy to be at the bottom of the food chain of small biological uptake,finally enters the body through food chain step by step,the threat to the environment and human health.MPs can not only affect the migration,transformation and orientation of organic pollutants in the environment,but also affect the cumulative distribution and toxic effects of pollutants in organisms.As the accumulation of MPs in the environment continues to increase,more and more people pay attention to the environmental risks brought by combined exposure of MPs and other pollutants.However,zebrafish is mostly used as experimental organisms in current studies.However,there are relatively few studies on pollutant enrichment and toxicological effects of MPs and organic pollutants on other fish species under the co-existence of MPs and organic pollutants.Therefore,it is urgent to supplement the gaps in research on local fish species.In this study,polystyrene microplastics(PS-MPS)and BPA,which are widely used in toxicity studies,were selected as representative pollutants.A 21-day subchronic exposure experiment was conducted to investigate the effects of MPs on bisphenol A(BPA)tissue accumulation in Yellow River carp and the associated chronic toxic effects caused by combined exposure of BPA and MPs.The results are as follows:(1)The accumulation of 0.5μm PS-MPS in various tissues of Yellow River Carp follows the following pattern: intestinal > gill > brain > liver,and the bioaccumulation of BPA showed obvious concentration and time dependent effects: The accumulation of PSMPs in tissues of Yellow River carp exposed to BPA and low and high concentrations of PS-MPs was as follows:gill(426±13 μg/g and 660±33 μg/g),liver(7.0±1.6 μg/g and10.2±1.0 μg/g),intestine(725±42 μg/g and 1209±50 μg/g),brain(102±18 μg/g and166±20 μg/g).The tissue content in S4 group was 55.6 %,45.92 %,66.87 % and 62.44 %higher than that in S3 group,respectively.(2)The concentration of BPA in each tissue showed the same trend,with higher concentration in the initial stage and then gradually decreased.After 21 days of exposure,the accumulation pattern of BPA in each tissue of Yellow River Carp basically followed the following pattern: intestinal > liver > brain > gill.The accumulation of BPA in gill(0.188 μg/g),liver(2.424,2.557,3.182 μg/g)and liver(0.373 μg/g,0.271 μg/g,0.373 μg/g,respectively)in single BPA exposure group and combined BPA with low and high concentration PS-MPs exposure group,intestine(7.858,23.295 and 37.228 μg/g),brain(0.303,0.417 and 1.280 μg/g);(3)The distribution of MPs could affect the bioaccumulation of BPA in tissues,but it was not the only condition affecting the bioaccumulation of BPA.The lipophilicity of BPA had a greater effect on the accumulation of BPA than that of PS-MPs.After 21 days of combined exposure to MPs and BPA,20 μg/L and 100 μg/L PS-MPs increased the accumulation of BPA in liver(46 % and 184 %),intestine(10 % and 25 %)and gills(9 %and 46 %)of Yellow River carp.(4)The acute toxicity test results showed that the 96 h LC50 of the Yellow River carp to BPA was 5.01mg/L,and the safe concentration was 0.501mg/L.The harm level of BPA to the Yellow River carp was high toxic substance.The weight of Yellow River carp during subacute exposure showed that single exposure of BPA(1mg/L)and combined exposure of BPA(1mg/L)with low and high doses of PS-MPs(20 μg/L and 100 μg/L)had no significant effects on the body weight of Yellow River carp.At the end of 21 days of exposure,observation of abnormal histopathological sections further revealed that inflammatory cell infiltration,tissue vacuolation,sparse arrangement of liver cells,reduced number of goblet cells in intestinal mucosa layer,loose arrangement of nerve fibers in brain tissue and other pathological changes occurred in gill,liver,intestine and brain tissues.Combined with the detection of PS-MPs and BPA content in each tissue,it was proved that the series of lesions were caused by the infiltration of PS-MPs and BPA in tissues.(5)Oxidative damage results showed that under the experimental concentration conditions,both single and combined exposure of BPA would produce oxidative stress on Yellow River carp.It is speculated that the combined toxic effect of BPA and PS-MPs on the brain and gill of Yellow River carp may be antagonistic,and the combined toxic effect on the liver and intestine of Yellow River carp may be synergistic.