人体血清二噁英化合物检测方法的建立

目的建立人体血清二噁英(polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans,PCDD/Fs)化合物测定方法,为开展二噁英人体健康风险评估提供检测技术手段。方法基于国际二噁英的测定方法—同位素稀释的高分辨气相色谱/高分辨质谱联用法,血清样品经C18柱固相萃取、酸性硅胶柱和活性炭柱净化的前处理方法,用DB-5MS毛细管柱(60 m×0.25 mm×0.25μm)分离,高分辨质谱检测分析。结果本方法的检出限为0.35~3.26 pg/g脂肪计,采用血清国际标准参考物质(SRM 1958)进行方法验证,与SRM 1958给出的参考质量分数值范围对比,17个PCDD/Fs单体浓度测定值均在参考质量分数值范围内,相对标准偏差为2%~19%(n=3)。该方法进一步应用于实际人体血清分析,同位素标记的17个二噁英单体回收率为61%~135%。结论本方法灵敏度和准确度高、方法性能稳定,满足人体血清二噁英检测方法的要求。     

Temporal trend of polychlorinated dibenzo-p-dioxin/polychlorinated dibenzofuran and dioxin like-polychlorinated biphenyl concentrations in food from Taiwan markets during 2004–2012

The levels of polychlorinated dibenzo-p-dioxin (PCDD) and polychlorinated dibenzofuran (PCDF) or polychlorinated biphenyl (PCB) in foodstuffs have decreased over the past decade in many countries. However, the trend for the levels of these compounds in foodstuffs in Taiwan remains unknown. In this study, we compared the distribution of PCDD/F and PCB in nine foodstuff categories acquired from Taiwan markets from 2004 to 2012. The levels expressed as World Health Organization toxic equivalents (WHO-TEQs) in the different foodstuffs tested were as follows: fish, average 0.463 pg WHO₉₈-TEQ/g sample > seafood, 0.163 pg WHO₉₈-TEQ/g > eggs, 0.150 pg WHO₉₈-TEQ/g > oils, 0.126 pg WHO₉₈-TEQ/g > meats, 0.095 pg WHO₉₈-TEQ/g > dairy products, 0.054 pg WHO₉₈-TEQ/g > cereals, 0.017 pg WHO₉₈-TEQ/g > vegetables, 0.013 pg WHO₉₈-TEQ/g > fruits, 0.009 pg WHO₉₈-TEQ/g. Levels were particularly high in crab (average: 0.6 pg WHO₉₈-TEQ/g sample (1.243 pg WHO₉₈-TEQ/g sample) and large marine fish (0.6). In Taiwan, a decreasing trend of PCDD/Fs or dioxin-like PCBs (dl-PCBs) was observed in meat, dairy, eggs, and vegetables, whereas an elevated trend was observed in cereals or the levels were nearly equal in fruits and oils at alternative time shift. Dl-PCBs contributed to 60–65% toxicity equivalence levels in fish and seafood, but only to 13–40% in meat and cereal samples. The decreasing trend was consistent with the results in other countries; however, the trends in cereals, fruits, and oils were in contrast to previous results reported in other countries. Cereals and fruits are important crops in southern Taiwan, and the local pollution generated by industries or incinerators may seriously affect the distribution of PCDD/Fs and dl-PCBs. To ensure food safety, a risk assessment for residents living in different areas should be adopted for all food categories simultaneously in the future.     

Cryptorchidism and endocrine disrupting chemicals

Prospective clinical studies have suggested that the rate of congenital cryptorchidism has increased since the 1950s. It has been hypothesized that this may be related to environmental factors. Testicular descent occurs in two phases controlled by Leydig cell-derived hormones insulin-like peptide 3 (INSL3) and testosterone. Disorders in fetal androgen production/action or suppression of Insl3 are mechanisms causing cryptorchidism in rodents. In humans, prenatal exposure to potent estrogen diethylstilbestrol (DES) has been associated with increased risk of cryptorchidism. In addition, epidemiological studies have suggested that exposure to pesticides may also be associated with cryptorchidism. Some case-control studies analyzing environmental chemical levels in maternal breast milk samples have reported associations between cryptorchidism and chemical levels. Furthermore, it has been suggested that exposure levels of some chemicals may be associated with infant reproductive hormone levels.     

Thyroid effects of endocrine disrupting chemicals

In recent years, many studies of thyroid-disrupting effects of environmental chemicals have been published. Of special concern is the exposure of pregnant women and infants, as thyroid disruption of the developing organism may have deleterious effects on neurological outcome. Chemicals may exert thyroid effects through a variety of mechanisms of action, and some animal experiments and in vitro studies have focused on elucidating the mode of action of specific chemical compounds. Long-term human studies on effects of environmental chemicals on thyroid related outcomes such as growth and development are still lacking. The human exposure scenario with life long exposure to a vast mixture of chemicals in low doses and the large physiological variation in thyroid hormone levels between individuals render human studies very difficult. However, there is now reasonably firm evidence that PCBs have thyroid-disrupting effects, and there is emerging evidence that also phthalates, bisphenol A, brominated flame retardants and perfluorinated chemicals may have thyroid disrupting properties.     

The Belgian PCB/dioxin incident: analysis of the food chain contamination and health risk evaluation

The Belgian PCB incident occurred at the end of January 1999 when a mixture of polychlorinated biphenyls (PCBs) contaminated with dioxins was accidentally added to a stock of recycled fat used in the production of animal feeds. Although signs of poultry poisoning were noticed by February, 1999, the source and the extent of the contamination were discovered only in May 1999, when it appeared that more than 2500 farms could have been supplied with contaminated feeds. This resulted in a major food crisis, which rapidly extended to the whole country and could be resolved only by the implementation of a large PCB/dioxin food monitoring program. Screening for PCB contamination was based on the determination of the seven PCB markers. When PCB concentrations exceeded the tolerance levels of 0.1 (milk), 0.2 (poultry, bovine, and pig meat), or 1 (animal feed) microg/g fat, dioxins (17 PCDD/Fs congeners) were also determined. At the end of December 1999, the database contained the results of more than 55,000 PCB and 500 dioxin analyses. The study of PCB levels and profiles in contaminated feeds delivered to poultry or pig farms confirmed that the Belgian PCB incident was due to a single source of PCB oil introduced into the food chain at the end of January 1999. This PCB oil had a congeners pattern closely matched to a mixture of Aroclor 1260/1254 in the proportion 75/25. The total amount of PCBs added to recycled fats was estimated at 50 kg (sum of the seven markers) or approximately 150 kg total PCBs, which corresponds to about 100 liters of PCB oil. This PCB mixture contained about 1g TEQ dioxins (more than 90- contributed by PCDFs) and about 2g TEQ dioxin-like PCBs. The proportions of PCB 52 and 101 congeners were fairly constant in animal feeds, excluding the possibility of secondary contamination due to fat recycling from contaminated animals. The highest concentrations of PCBs and dioxins were found in poultry and especially in the reproduction animals (hens and chicks), which showed the classical manifestations of chick edema disease. The pigs were also affected but to a lesser extent and no sign of intoxication was observed. The study of PCB/dioxin patterns and of the PCB:dioxin ratios revealed major differences in the metabolism of these compounds by farm animals. Whereas the PCBs:dioxins ratio was fairly constant in all poultry products with a mean value similar to that found in contaminated feeds (50,000), in pigs this ratio was both much higher and more variable (values up to 10,000,000), reflecting a faster elimination of dioxins than PCBs in these animals. These metabolic differences also emerged from the PCB and dioxin patterns which were altered much more in pigs than in poultry. Although the most contaminated food products (chicken meat) had PCB and dioxin levels more than 100 times above maximal recommended values, it is unlikely that this incident could have caused adverse effects in the general population of Belgium. A doubling of the PCB and dioxin burden of the young adult population would require the consumption of, respectively, 10 and 20 highly contaminated meals. In view of the very limited proportion of the poultry chain effectively contaminated during the incident (around 2%), such an extreme scenario was quite improbable for the general population except perhaps for farmers consuming their own products. But even in that case, it would have meant going back to the levels in the 1980s or attaining the body burden of subjects regularly eating contaminated seafood.     

中国某水域海水养殖鱼和淡水养殖鱼中二噁英污染特征的比较研究

目的对中国某水域的海鱼和淡水鱼样品开展二英污染水平与同系物轮廓表征研究,并评估该典型地区人群通过鱼类暴露二英的膳食摄入量。方法通过布点抽样采集8个养殖点(海水与淡水各半)31份样品,以同位素稀释的HRGCHRMS-多离子检测方式测定样品中的PCDDsFs。结果海水养殖鱼和淡水养殖鱼中PCDDFs平均浓度以湿重计分别为1.43和3.34pgg,以WHOTEQ计分别为0.28pgg和0.43pgg。OCDD、2,3,7,8TCDF为最主要的优势污染同系物;如以毒性的主要贡献者计,则以1,2,3,7,8PeCDD、2,3,4,7,8PeCDF、2,3,7,8TCDD为主。该地区人群摄入鱼的二英PCDDFs的平均膳食暴露量的估算是0.63pgWHOTEQkgbw·day。结论该水域中的鱼已受到了一定程度的PCDDFs污染,淡水养殖鱼高于海水养殖鱼(约为1倍)。鱼体中所检测到的二英污染的平均水平低于欧盟制定的限量标准(3.0pgWHOTEQg)。     

Ethoxyresorufin O-deethylase induction by TCDD,PeCDF and TCDF in ring-necked pheasant and Japanese quail hepatocytes: Time-dependent effects on concentration–response curves

Ethoxyresorufin O-deethylase (EROD) activity was measured in primary cultures of ring-necked pheasant (Phasianus colchicus) and Japanese quail (Coturnix japonica) embryonic hepatocytes exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), 2,3,4,7,8-pentachlorodibenzofuran (PeCDF) and 2,3,7,8-tetrachlorodibenzofuran (TCDF) for 12, 24, 36 and 48 h. In ring-necked pheasant hepatocytes there was a significant time-dependent increase in the EROD-inducing potency of TCDD, PeCDF and TCDF (i.e. decrease of the EC50). In Japanese quail hepatocytes there was no time-dependent change in the EROD-inducing potency of TCDD, PeCDF and TCDF. There was no time-dependent change in the relative potency of PeCDF and TCDF (i.e. compared to the potency of TCDD) in ring-necked pheasant hepatocytes and of PeCDF in Japanese quail hepatocytes. The results indicate that the relative potencies of these compounds at 24 h are representative of their relative potencies between 12 and 48 h. However, in Japanese quail hepatocytes, the relative potency of TCDF decreased in a time-dependent manner (up to 3.6-fold difference). These results suggest that the effect of time on the EROD-inducing potency of TCDD, PeCDF and TCDF in ring-necked pheasant and Japanese quail hepatocytes is compound- and species-specific, but experimental conditions could also be involved in the differences observed.     

Human uptake of persistent chemicals from contaminated soil: PCDD/Fs and PCBs

Trace amounts of polychlorinated dibenzo-p-dioxins/furans (PCDD/Fs) and polychlorinated biphenyls (PCBs) are ubiquitous in the environment. Because of industrial activity, other human activities, and accidents, higher concentrations of these chemicals may be present in soil, in residential and recreational areas. Human uptake of these chemicals from such soils has been assumed by regulators, and people contacting such soils may be concerned about potential adverse health effects. Accordingly, clean up levels have been set by state and federal agencies. Whether and to what extent humans actually take up these chemicals from soil is the focus of this review. Since humans are also exposed to PCDD/Fs and PCBs in food and air, their concentrations in these media are presented. We find that their presence in soils is unlikely to increase human body burdens.     

Significant decreasing trend in human dietary exposure to PCDD/PCDFs and PCBs in Catalonia, Spain

The concentrations of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/PCDFs), and 18 polychlorinated biphenyls (PCBs) were determined in samples of foodstuffs widely consumed by the population of Catalonia, Spain. The dietary intake of PCDD/PCDFs and dioxin-like (DL)-PCBs was subsequently estimated for the population of this Spanish region. These results were compared with those of a previous survey performed during 2000. For PCDD/PCDFs, the highest WHO-TEQ values corresponded to oils and fats (0.223 ng/kg), followed by fish and seafood (0.131 ng/kg) and dairy products (0.057 ng/kg), while the lowest levels were found in fruits (0.003 ng/kg), as well as in vegetables and milk (0.009 ng/kg). For DL-PCBs the highest WHO-TEQ values corresponded to the groups of fish and seafood (0.761 ng/kg) followed by oils and fats (0.169 ng/kg), and dairy products (0.039 ng/kg), while the lowest values were observed in fruits (0.004 ng/kg), and vegetables (0.005 ng/kg) and tubers (0.006 ng/kg). The current dietary intakes of PCDD/PCDFs, DL-PCBs, and PCDD/PCDFs plus DL-PCBs were estimated to be 25.7, 52.4, and 78.1 pg WHO-TEQ/day vs. 95.4, 150.1, and 245.5 pg WHO-TEQ/day found in our previous survey. It means reductions of 73%, 65%, and 68%, for PCDD/PCDFs, DL-PCBs, and PCDD/PCDFs plus DL-PCBs, respectively. The current estimated intake for an adult male, 1.12 pg WHO-TEQ/kg body weight per day, is lower than most intakes recently reported in a number of countries over the world.