Horizontal Exposure Assessment Of Dioxin And Its Analogs In Typical Areas And Development Of Reference Materials

Dioxins and their analogs are typical persistent organic pollutants with high toxicity,lipophilicity,bioaccumulation,etc.,and can enter the human body through the food chain.Dietary intake are the main route of intake of dioxin analogs,such as fish,meat,eggs,dairy products,etc.,and long-term exposure can lead to serious health threats especially for animal-drived foods.The pollution status of dioxin-like compounds in foods and human exposure are the focus of the world.The thesis focuses on the following work in dioxin-like compounds in animal-derived foods:?1?Assessment of dioxin levels and dietary exposure in lard in typical areas;?2?Assessment of indicator PCBs and dietary exposure in animal-derived foods in Hubei Province;?3?Development of reference materials for dioxins and polychlorinated biphenyls in fish.The main contents and results of the study are as follows:1.30 lard samples were collected in 5 regions of a certain province?GXGPN,GXYLBB,GXHCJCJ,GXGLYS,GXWECW?.After pretreatment,the samples were analyzed by isotope dilution-high resolution gas chromatography/high-resolution magnetic mass spectrometry.The results showed that the concentration of PCDD/Fs in lard in the GXGGPN region was the highest,1.65 pg?g^-1 fat.The total content of PCDD/Fs in lard samples ranged from 0.24 to 5.5 pg?g^-1 fat with an average of 1.4pg?g^-1 fat;the total content of DL-PCBs ranged from 2.4 to 26 pg?g^-1 fat with an average of 9.9 pg?g^-1 fat.The content of TEQ PCDD/Fs+DL-PCBs in lard ranged from0.028 to 0.26 pg?g^-1 fat with an average of 0.073 pg?g^-1 fat.Amongst them,OCDD has the highest contribution rate to the total content of PCDD/Fs,accounting for 72.3%,with an average of 1.0 pg?g^-1 fat.PCB118 has the highest contribution rate to the total content of DL-PCBs,accounting for 61.6%,with an average of 6.1 pg?g^-1 fat.This suggests that the dioxins and their compounds in lard are mainly derived from the emission of waste gas and waste residue from waste incineration plants,chemical plants,and paint factories.The average dietary exposure level of lard in the province was 0.47 pg TEQ^-1kg bw^-1month,which was at a lower health risk level.2.300 samples of animal-derived foods?aquatic,meat,milk,and eggs?were collected in nine areas of Hubei Province.After pretreatment,six kinds of indicative PCBs were detected by isotope dilution-high resolution gas chromatography/high-resolution magnetic mass spectrometry.The results showed that the average content of NDL-PCBs in fish in Hubei province was the highest,being 266.255 pg?g^-1 ww;followed by meat,48.712 pg?g^-1 ww;milk and eggs were 26.535 pg?g^-1 ww,18.543pg?g^-1 ww,respectively.PCB28 and PCB153 have the highest contribution rate to the total content,which is 31.43%and 30.49%respectively.This infers that the indicative PCBs are mainly derived from the impregnating agent of the power capacitor and the additives of materials such as paints,resins,and binders.The dietary intake of aquatic products in Hubei Province is 0.256 ng?kg^-1bw?day^-1,dietary intake of meat is 0.054ng?kg^-1bw?day^-1,and dietary intake of milk is 0.01 ng?kg^-1bw?day^-1,and the dietary intake of eggs is 0.01 ng?kg^-1bw?day^-1.Aquatic products account for 79.56%of the total dietary intake of the four types of food,the main PCBs source for the population of the province.3.In this study,fish samples satisfying the screening principle and requirements of the candidates were selected as standard substance candidates,which were mixed,divided,lyophilized and pulverized to make fishmeal.The fishmeal samples were pretreated,and the dioxins and polychlorinated biphenyls in the fishmeal were determined by isotope dilution-high resolution gas chromatography/high-resolution magnetic mass spectrometry.After uniformity and stability tests,the values of dioxin and polychlorinated biphenyls in fish were determined and analyzed by a number of laboratory collaborative methods.Following single factor analysis and F test,the test value F of the uniformity test between bottles is less than the critical value F_0.01?9,20?.The stability test results show that the fixed value compound satisfies the slope|b1|<t_?0.95,2??s?b₁?in the linear exponential equation,an indication that the trend of eigenvalues is not statistically significant.The development of this reference material provides an allegation reference and capability evaluation for dioxin and PCB testing.