| Persistent organic pollutants (POPs) is a hotspot issue to chemists in recent decades. POPs can be classified into two types according to its source, by-products of dioxin and chemical products which contain polychlorinated biphenyl, organochlorine pesticide and brominated flame retardants. POPs have increasingly become a significant concern worldwide for its severe toxicity, stable chemical property, strong bioaccumulation, long-distance migration and hazardous to environment and human health. Human breast milk is considered the main source of POPs to infants since breast milk are dominant source of food to infants and POPs are liposoluble, therefore monitoring of POPs in breast milk potential offered reliable information of health risk of the infants and maternal body burden of POPs.The main research contents are as follows:Chapter one has introduced accidents, human health risk, main exposure pathway and situation of POPs (PCDD/DFs, PCBs and PBDEs) contamination. The progress of several POPs testing methods worldwide has also been presented. Finally, the significance and thought of our study was briefly illustrated.Chapter two:Method development and validation. A method was developed to determine 17 PCDD/DFs,12 DL-PCBs,6 M-PCBs and 8 PBDEs in breast milk, using ASE extraction and sequential cleanup (including D-SPE and tandem SPE cartridges) and determination of isotopic dilution GC-HRMS. Tandem Solid Phrase Extraction (SPE) purification was developed to achieve high-throughput test and low solvent consumption. Limits of quantitation were 0.01pg/g-0.1pg/g,0.02pg/g and 0.2pg/g for PCDD/DFs, PCBs (PCB118:0.12pg/g) and PBDEs (BDE 209:2pg/g), respectively. The recoveries of spiking test ranged from 70% to 120%, and the recoveries of isotopic internal standard ranged from 42% to 80%, which accords with requirement of methods from EPA (U.S.), depending on the different target congeners. The developed method has been applied in two certificated reference materials (CRM) with satisfactory results. The whole method validation meets the requirement of the international standard methods, such as U.S. EPA method 1613b/1668a/1614b, EN-1948 and GB/T 5009.205-2007. Compared with traditional methods, the method exhibits the following advantages:rapidness and simplicity and automation, saving in organic solvent consumption and labor, robustness, and high throughput for the routine monitoring of large numbers of samples.Chapter three:Sample monitoring and data analysis.150 samples were collected from the immigrants in Shanghai. Optimized method is applied for sample detection, and breast-fed infants’daily intake of human breast milk is estimated through data analysis and statistic. The Toxic Equivalent Quantity (TEQ) value of PCDD/DFs and dioxin like PCBs ranged from 0.98～30pg/g lipid, whose mean and median level is 6.0 pg/g lipid 5.0 pg/g lipid respectively. The TEQ level is comparatively low in foreign country but high in domestic. The exposure level of Marker-PCBs ranged from 1718-35450 pg/g lipids, whose mean and median level is 7519 pg/g lipid and 13488 pg/g lipid respectively. The exposure level of PBDEs (including BDE 209) ranged from 1391～235461 pg/g lipids, whose mean and median level is 6625 pg/g lipid and 7067 pg/g lipid. The exposure level of Marker-PCBs is ranked middle in domestic, which was obviously below the exposure level of local population in Shanghai. However, PBDEs exposure level is ranked forefront in domestic. The data is analyzed by Mann-Whitney U test and Spearman correlation test, and result shows no obvious relationship between POPs exposure level and Body Mass Index (BMI) but great relationship with age. The mean level of newborns’ EDI of ∑PCDD/DFs-DL-PCBs is 33.0 pgTEQ/kg·bw/day (ranged from 7.6～98 pgTEQ/kg·bw/day), in which the EDI of PCDD/DFs and DL-PCBs is 21.5 pgTEQ/kg·bw/day and 11.5 pgTEQ/kg·bw/day respectively. The EDI level of our study is middle-ranked among all the levels reported by literature worldwide. |
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