Study On The Complex Toxicity Of Polystyrene Microplastics And Tetrabromobisphenol-A To Zebrafish

In recent years,the pollution of microplastics(MPs)in the world’s waters has increased year by year.Polystyrene(PS)is a kind of plastic used in daily life,and it has been accepted as a new type of environmental pollutant and the public’s attention.Tetrabromobisphenol-A(TBBPA)is the most widely used brominated flame retardant,and its potential harm to human health has attracted people’s attention.A variety of environmental contaminants often interact with each other,causing a complex biotoxic effect.Since TBBPA is used as a flame retardant for making polystyrene foam,both of them often appear in the environment at the same time.However,the research report on the combined pollution of micro-plastics has not been found at home and abroad.In this study,zebrafish was used as a model organism for static water exposure,and then zebrafish were exposed individually and in combination with exposure levels of TBBPA(300μg/L)and PS(0.5mg/L,5mg/L).The experiment was carried out for 10 days after exposure for 14 days.The research results are expected to improve the existing research foundation and reveal the mode of action of the combined pollution of the two,in order to provide a theoretical basis for comprehensive evaluation of its ecological risks.The main conclusions of this study are as follows:(1)PS microplastics have certain adsorption capacity to TBBPA in water environment.When the initial concentrations of TBBPA and PS are 100μg/L and 10mg/L,respectively,the adsorption amount of PS to TBBPA at equilibrium is 9.03mg/g.Moreover,the concentration of PS has a significant effect on the adsorption rate of adsorbed TBBPA.(2)After exposure to TBBPA,it is mainly enriched in zebrafish liver tissue,while PS increases the enrichment of TBBPA in zebrafish liver.In the exposure test,the levels of TBBPA detected in the liver and muscle tissues of the composite exposure group(low concentration PS,high concentration PS)were 5.94,4.66,4.09,3.15ng/g dw,respectively,which were significantly greater than the TBBPA exposure group alone(2.03,1.10ng/g dw).During the purification period,the results indicate that PS will prolong the residence time of TBBPA in zebrafish and have a long-term effect on tissues.(3)Both TBBPA and PS have oxidative stress on zebrafish.However,these two substances did not cause irreversible oxidative damage to the zebrafish liver tissue under the experimental concentration conditions set this time.The combined exposure has a greater effect on various enzymes,and it can not be effectively recovered during the purification period.Compared with the blank control group,the inhibition rate is up to 53.5% and the induction rate is up to 94.5%.This indicates that the combined exposure of PS and TBBPA can cause irreversible oxidative damage to the liver tissue of zebrafish.(4)At the end of the exposure period,the levels of T3 and T4 detected in the liver tissue of zebrafish decreased,and the inhibition rate ranged from 14.1% to 68.0%.The effect of combined exposure on zebrafish was significantly different from exposure alone.(5)The combined toxic effects of TBBPA and PS on zebrafish are mainly synergistic,and the combined pollution of the two will produce more intense oxidative stress and endocrine disrupting effects on zebrafish.It is necessary to pay attention to the micro-plastics in the environment as well as TBBPA to avoid its potential impact on human health.