Concentrations And Profiles Of Chlorinated Aromatic Hydrocarbons In Typical Dairy Products And Beef

Polychlorinated dibenzo-p-dioxins and dibenzofurans(PCDD/Fs), polychlorinated biphenyls(PCBs) and polychlorinated naphthalenes(PCNs) are typical chlorinated aromati c hydrocarbons. Dietary intake is the primary pathway of human exposure to these compounds. The main source of chlorinated aromatic hydrocarbons in the diet is food of animal origin such as meat, dairy products, etc. To improve the understanding of human exposure to PCDD/Fs, PCBs and PCNs through food consumption, not only the concentrations and profiles in raw materials should be investigated, but also the influence of cooking on concentrations and profiles should be paid much attention. Cheese, butter and beef were selected as the typical foods and collected from Beijing market in this study. PCDD/F, PCB and PCN concentrations and profiles in cheese and butter were investigated. The effect s of cooking temperature and addition of oil on PCB concentrations and profiles in meat were also discussed. The main results were:(1) Pretreatment method was developed for the trace analysis of PCDD/Fs and PCBs in cheese and butter. The concentrations and profiles of PCDD/Fs and PCBs in cheese and butter were investigated. The concentrations of 2,3,7,8-PCDFs, 2,3,7,8-PCDDs, and dl-PCBs in cheese samples were 0.76–20 pg g-1, 0.59–4.5 pg g-1, and 0.62–72 pg g-1 ww, respectively. The concentrations of 2,3,7,8-PCDFs, 2,3,7,8-PCDDs, and dl-PCBs were 3.0–44 pg g-1, 0.31–18 pg g-1, and 12–331 pg g-1 ww in butter samples. In general, the concentrations of each of the three groups of pollutants were higher in the butter samples than in the cheese samples. The dl-PCB concentrations in the cheese and butter samples were much higher than the 2,3,7,8-PCDD/F concentrations. The 2,3,7,8-PCDD/F patterns were dominated by the high-chlorinated congeners. For dl-PCBs, the most abundant congener was PCB-118, and the most dominant contributor to total WHO-TEQ of dl-PCBs was PCB-126.(2) The levels and profiles of PCNs were investigated and compared with PCDD, PCDF and PCB concentrations. The results show that PCN concentrations were 5.6–103 pg g-1 in the seven cheese samples and 5.0–199 pg g-1 in the butter samples. CN5/7 and CN24/14 were the dominant congeners, accounting for 31.5% and 20.0% of the total PCN concentrations, respectively. CN73 made the largest contribution(44.2%) to the total PCN TEQ. The contribution of PCNs to the total TEQ was 4.9%, which was smaller than that of PCDDs, PCDFs and PCBs.(3) Beef and bean oil were used to study the effects of cooking temperature and addition of oil on the levels and distribution patterns of PCBs in meat. The results show that a higher reduction of dl-PCBs in beef was achieved at higher cooking temperature, while the addition of soybean oil into the cooking matrices decreased the effect of cooking temperature on dl-PCB levels. The percentage of the predominant congener, PCB-118, declined with the increase of cooking temperature. The proportion of PCB-118 in beef samples with oil did not significantly change compared to that in raw beef.