| DDTs and HCHs were generally used in agricultural production,which were hard to break down once they entered into environment.What's more,DDTs and HCHs can enter human body through breathing,diet,and skin and researchers found that they have the characteristics of carcinogenic,teratogenic and mutagenic.Hence,the environment-behavior and ecotoxicity of DDTs and HCHs have become hot research topics.It is significant to conduct studies on their residual and associated health risks.However,current researches on DDTs and HCHs pollution in food and atmosphere in Nanjing city were quite limited.In this study,Xianlin district of Nanjing city was chosen as the study area,and DDTs and HCHs in food as well as in atmosphere were taken as research subjects.Eight categories of foods including vegetable,fruit,meat,fish,egg,milk,oil and cereal,which were daily consumed by local residents,were collected.Gas and particle phase air were sampled in both summer and winter in this region.DDTs and HCHs concentrations were determined by gas chromatography mass spectrometry(GC-MS),and the pollution sources,ingestion and inhalation exposure,and the induced health risk of DDTs and HCHs were further analyzed in this study.The order of ?-10OCPs concentrations in different food categories in Xianlin district of Nanjing was fish>meat>egg>milk>oil>vegetable>fruit>cereal.The concentrations of DDTs and HCHs in fish were 3.53±0.01 and 1.18±0.01ng·g-1,respectively,whereas those of them in cereal were 0.97±0.13 and 0.37±0.02 ng g-1,respectively,being very low.The concentration of DDTs(2.24 ng·g-1)in foods was generally higher than that of HCHs(1.03ng·g-1),and they were both below the standard of GB2673-2014 and the maximum residue limits(MRLs)specified by UN.Compared with data in similar studies worldwide,the concentrations of DDTs and HCHs in foods in Xianlin district of Nanjing were at a middle level.The concentration of DDTs(0.91 ng·m-3)in atmosphere in Xianlin district of Nanjing was much higher than that of HCHs(0.54 ng·m-3).Concentrations of DDTs and HCHs in winter were largerthan those in summer,and those in gas phase were higher than in particle phase.Compared with other cities at home and abroad,the pollution level of DDTs and HCHs in atmosphere in Xianlin district of Nanjing was at a medium level.Through the source analysis,the ratios of WDDD/WDDT in all categories of foods except vegetable were lower than 1,indicating that DDTs in vegetable in Xianlin district of Nanjing were from historical residual,whereas in other categories of foods there was new input of DDTs.The ratios of W?/(?+?)-HCH in all foods except milk were higher than 0.5,implying that the main source of HCHs in foods was historical residual.In addition,the ratios of WDDD/WDDT in gas and particle phase in summer in Xianlin district of Nanjing were less than 1,suggesting that the atmosphere in the studying area was contaminated by fresh DDTs emission.On the contrary,the ratios of WDDD/WDDT in atmosphere in winter were greater than 1,implying that the main source of DDTs in winter was from historical residual.The ratios of W?/(?+?)-HCH in atmosphere in both summer and winter were higher than 0.5,implied that the pollution of HCHs in atmosphere in both summer and winter was caused mainly by historical accumulation.The dietary exposure dose of DDTs and HCHs for eight population groups in Xianlin district of Nanjing in decreasing order was:girls>boys>female adolescents>male adolescents>female seniors>female adults>male seniors>male adults.The dietary exposure of DDTs and HCHs for children was the largest among all population groups.Besides,females showed higher exposure dose than males in all age groups.Dietary DDTs exposure was larger than HCHs for the same population group.Contributions of diverse food categories to the dietary DDTs exposure were different,and the top contributor was vegetable(26.69%)while the lowest was other livestock meat(beef and mutton)(2.30%).Similarly,vegetable(17.72%)made the biggest contribution to the dietary exposure of HCHs,whereas other livestock meat(beef and mutton)(2.76%)made the lowest contribution.The inhalation exposure dose of DDTs and HCHs for eight population groups in decreasing order was:male adults>female adults>girls>boys>female adolescents>female seniors>male seniors>male adolescents.The inhalation exposure of DDTs and HCHs for adults was the largest among all population groups.In addition,males showed higher exposure dose than females in all age groups.HCHs inhalation exposure was larger than DDTs for the same population group.According to the season,the inhalation exposure of?10OCPs in winter was littler larger than in summer.According to the phase,the inhalation exposure of ?10OCPs in gas phase was little higher than in particle phase.The non-cancer risk of DDTs and HCHs in food and atmosphere for different age and gender groups in Xianlin district of Nanjing were all less than 1,indicating there was no non-cancer risk for local residents.Cancer risk induced by dietary exposure:The major contributors of foods for DDTs induced cancer risk were vegetable(24.99%)and milk(11.64%),whereas the major contributors of foods for HCHs induced cancer risk were vegetable(21.12%)and pork(13.39%).Cancer risk induced by dietary DDTs and HCHs exposure for different age and gender groups was between 10-6 and 10-4,indicating a potential risk for local residents owing to the residual DDTs and HCHs in food.The cancer risk of HCHs was higher than DDTs,and the cancer risk of children was higher than other age groups,and females showed higher risk than males in all age groups.Cancer risk induced by inhalation exposure:Cancer risks induced by DDTs and HCHs inhalation exposure for different age and gender groups were all lower than 10-6,indicating a low risk level.The cancer risk of HCHs was higher than DDTs,and the cancer risk of adults was higher than other age groups,and males showed higher risk than females.The cancer risk of ?10OCPs in winter was a little higher than in summer,and the cancer risk in gas phase atmosphere was a little larger than in particle phase.The total cancer risk induced by both dietary and inhalation exposure:The cancer risks of DDTs,HCHs and ?10OCPs in both food and air for the eight population groups in were all higher than 10-6,but lower than 10-4,indicating a potential cancer risk.What's more,the total cancer risk of HCHs were higher than DDTs,and dietary exposure was the main route to total cancer risk. |
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