| Persistent organic pollutants(POPs)can be enriched in food through food chains,and thus affect food safety and expose potential risks to human health.Diet have been proved to be the major exposure pathway of POPs to human.However,previous risk assessments merely focused on the concentration levels of POPs in foods.The impacts of the bioaccessibility of POPs on risk assessment were ignored.Furthermore,the distribution,transformation,and elimination process of POPs in human tissue may have some affects the internal exposure levels of POPs in human.As a result,two dependent researches were conducted in the present study.Firstly,we selected the typical POPs,such as DDTs and PBDEs,as target compounds and examined whether there was significant difference in the bioaccessibility values derived from DDTs in native and spiked fish,then compared the bioaccessibility of DDTs and PBDEs in raw and cooked fish,finally assessed the potential human health risk based on the bioaccessibility of DDTs and PBDEs in raw and cooked fish.Secondly,Sprague-Dawley rat was selected as the model animal to simulate the toxicokinetics of BDE-209 in humans.Rats were continuously exposed to BDE-209 through a low oral dose for 7 d and depurated for 22 d.We are intend to characterize the tissue distributions of BDE-209 in dosed rats during the uptake and depuration periods and identify the metabolites of BDE-209 in dosed rats.The half-lives of BDE-209 and its metabolites were estimated in different tissues of rats after multi-dose exposure.One fish species(yellow grouper)from Hailing bay contained substantially higher concentration of DDTs(110 ng/g)were used as the digestion material.The bioaccessibility of p,p'-DDE-d8,p,p'-DDD-d8,and p,p'-DDT-d8 were 48 ± 2.1%,56 ± 11%,and 47 ± 11%,consistent with those of p,p'-DDE,p,p'-DDD,and p,p'-DDT(50 ± 9.1%,46 ± 15%,and 47 ± 16%)in native fish.Apparently bioaccessibility were not significantly different between native and spiked fish based on either individual DDT components or total DDTs.Addition of plant oil to fish substantially increased the bioaccessibility of DDTs and PBDEs from 60 ± 8.0% to 83 ± 8.7% and from 26 ± 3.3% to 63 ± 12%,respectively,demonstrating the significance of plant oil in increasing the bioaccessibility of DDTs and PBDEs in fish.The bioaccessibility of DDTs and PBDEs decreased from 83 ± 8.7% to 66% ± 9.3 and from 63 ± 12% to 40 ± 6.3%,respectively,in fish subjecting to heating after oil was added,demonstrating heating process decreased the bioaccessibility of DDTs and PBDEs in fish.The measured bioaccessibility values were used to correct concentrations of DDTs and PBDEs in fish,so as to better examine fish consumption limits.Human health risk assessment based on bioaccessible concentrations of DDTs and PBDEs in fish showed that the non-carcinogenic HQs based on the bioaccessible concentrations for different age groups were all substantially smaller than one,suggesting that consumption of the fish species does not pose non-cancer risk.In addition,the non-carcinogenic HQs were not significantly different among different age groups.However,enhanced carcinogenic HQs(0.85(95% CI of 0.39-1.57))for different age groups were obtained when cooking oil was incorporated into the risk assessment,suggesting high cancer risk associated with the consumption of cooked fish.Human health risk assessment based on bioaccessible concentrations of DDTs and PBDEs in fish also showed that the maximum allowable daily fish consumption rates decreased from 25,59,and 86 g d-1 to 22,53,and 77 g d-1 for children,youths,and adults,respectively,after the fish has been cooked with oil.To minimize carcinogenic risk,the number of days per month for consuming cooked fish by local residents should be fewer than 19 days based on a worst-case scenario.During a 7-day exposure period,the concentrations of BDE-209 in all tissues tended towards exponential growth.After exposure,the mean BDE-209 concentration in liver,small intestine,adipose,and serum were 13000 ± 1000 ng/g 1800 ± 77,910 ± 100,and 630 ± 26 ng/g wet weight,respectively.After the cessation of a 22-day elimination period,the mean BDE-209 concentration were 130 ± 7.5,130 ± 7.7,900 ± 89,and 11 ± 1.5 ng/g wet weight,respectively.It was worth noting that the tissue distributions of BDE-209 on a wet weight basis were different in the exposure and depuration periods.The nona-BDEs and octa-BDEs appeared to form via meta-debromination(s)of BDE-209 were detected in all tissues.BDE-197 and 207 were the major isomers in the octa and nona homologue groups,respectively.The half-lives of BDE-209,207,and 197 in serum and liver were 1.1,2.7,and 11 and 0.9,2.2,and 12 days,respectively.In addition,the half-live of BDE-207 was 2.7,2.2,and 22 days in serum,liver,and small intestine,respectively.These results suggested that the half-lives of BDE congeners in the serum and liver increased with the decreasing degree of bromination from deca-to octa-BDEs the half-life of BDE-207 was longer in the small intestine than liver. |
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