Predictors of Serum Dioxins and PCBs among Peripubertal Russian Boys

Background

Although sources and routes of exposure to dioxins and polychlorinated biphenyls (PCBs) have been studied, information regarding exposure among children is limited. Breast-feeding and diet are two important contributors to early life exposure. To further understand other significant contributors to childhood exposure, we studied a cohort of children from a city with high environmental dioxin levels.

Objectives

We investigated predictors of serum concentrations of polychlorinated dibenzo-p-dioxins (PCDDs)/polychlorinated dibenzofurans (PCDFs)/co-planar PCBs (C-PCBs), toxic equivalents (TEQs), and PCBs among 8- to 9-year-old boys in Chapaevsk, Russia.

Methods

We used general linear regression models to explore associations of log₁₀-transformed serum concentrations of PCDDs/PCDFs/C-PCBs, TEQs, and PCBs at study entry with anthropometric, demographic, geographic, and dietary factors in 482 boys in Chapaevsk, Russia.

Results

The median (25th, 75th percentile) concentration for total 2005 TEQs was 21.1 pg/g lipid (14.4, 33.2). Boys who were older, consumed local foods, were breast-fed longer, and whose mothers were employed at the Khimprom chemical plant (where chlorinated chemicals were produced) or gardened locally had significantly higher serum dioxins and PCBs, whereas boys with higher body mass index or more educated parents had significantly lower serum dioxins and PCBs. Boys who lived < 2 km from Khimprom had higher total TEQs (picograms per gram lipid) [adjusted mean = 30.6; 95% confidence interval (CI), 26.8–35.0] than boys who lived > 5 km away (adjusted mean = 18.8; 95% CI, 17.2–20.6).

Conclusions

Our findings suggest that there are specific local sources of dioxin and PCB exposure among children in Chapaevsk including maternal gardening, consumption of locally grown food, and residential proximity to the Khimprom plant.     

Isomer pattern and elimination of dioxins in workers exposed at a municipal waste incineration plant

The aim of this study was to clarify patterns of serum concentrations of dioxins in the employees of a waste incineration plant and to estimate elimination rates and half-lives of serum dioxin isomers, and the maximum serum concentrations of dioxin isomers at the time of plant shutdown. Sixteen subjects participating 3 times or more in annual health examinations during an 8-yr period from 2000 to 2007 were recruited for this study. Serum concentrations of dioxins expressed as TEQ/g lipid decreased gradually after plant shutdown with the highest decrease observed in polychlorinated dibenzofurans (PCDFs) followed by polychlorinated deibenzo-p-dioxins (PCDDs) and then coplanar PCBs. The serum toxic equivalency (TEQ) concentrations of PCDF and PCDD congeners in the employees were higher than those in the general population survey by the Ministry of the Environment, Japan, whereas the serum concentrations of coplanar PCBs were similar to those in the general population. The estimated half-lives and elimination rates of PCDDs and PCDFs in the highly exposed workers increased compared with the moderately exposed workers. The estimated geometric mean serum concentrations of PCDDs, PCDFs and total dioxins at the time of plant shutdown were 35, 53 and 107 pg TEQ/g lipid, respectively.     

PCDDs, PCDFs, and PCBs in human blood in relation to consumption of crabs from a contaminated Fjord area in Norway.

Consumption of fish and shellfish from contaminated areas may be an important source of human exposure to persistent organohalogen compounds such as polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs), and polychlorinated dibenzofurans (PCDFs). We determined concentrations of 2,3,7,8-substituted PCDDs and PCDFs and 19 PCB congeners in whole blood samples from three groups of men, 40-54 years of age, with different consumption levels of crabs from a fjord area in southern Norway polluted with organochlorine compounds from a magnesium production plant. A significant increase of many PCDD/PCDF congeners was found in the blood when comparing the referents, moderate-, and high-intake groups. The greatest difference was observed for several of the PCDFs that are characteristic for the contamination of the marine biota of the fjord. PCBs, in general, play a minor role in the contamination of the fjord by the magnesium production process, except for the highly chlorinated congeners such as PCB-209. Nevertheless, almost all PCBs increased from the referents to the high-intake group. However, the relative concentrations of several highly chlorinated PCBs (particularly PCB-209) in blood are unexpectedly low compared to their abundance in crabs, indicating low uptake of these congeners. The exposure to PCDDs/PCDFs from crab consumption calculated from individual body burdens of these compounds were in good agreement with the intake estimated from previously measured concentrations in crabs, reported fishing sites, and consumption. Almost all subjects in the high-intake group exceeded the tolerable weekly intake of 35 pg TEQ/kg body weight/week proposed by a Nordic Expert Group.     

Dietary exposure to polychlorinated biphenyls and dioxins from infancy until adulthood: A comparison between breast-feeding, toddler, and long-term exposure.

Food is the major source for polychlorinated biphenyl (PCB) and dioxin accumulation in the human body. Therefore, investigating food habits from early ages until reproductive age (25 years) is important in order to assess exposure risk for the next generation. The objective of this study was to assess the PCB/dioxin exposure and the relative contribution of different foods to total exposure during preschool age. Particularly, the importance of lactational PCB/dioxin exposure vs. dietary exposure until adulthood was investigated. A cohort of 207 children was studied from birth until preschool age. Based on 3 planar PCBs and 17 2,3,7,8-substituted dibenzo-para-dioxins (PCDDs) and dibenzofurans (PCDFs) measured in breast milk, a model was developed to calculate the cumulative toxic equivalent (TEQ) intake during breast-feeding (0-1 year). In 3. 5-year-old children, daily dietary intake of planar PCB-TEQ and dioxin-TEQ was measured with a validated food questionnaire. Cumulative TEQ intake from 1 to 5 years was estimated using the PCB- and dioxin-TEQ intake measured with the food questionnaire. Cumulative TEQ intake from 6 to 25 years was estimated using national food consumption and contamination data of PCB- and dioxin-TEQ intake. In toddlers, dairy products contributed 43% to PCB-TEQ and 50% to dioxin-TEQ intake. Meat and meat products contributed 14% and 19%, respectively, and processed foods 23% and 15%, respectively. Breast-feeding for 6 months contributed to the cumulative PCB/dioxin TEQ intake until 25 years of age, 12% in boys and 14% in girls. The daily TEQ intake per kilogram body weight is 50 times higher in breast-fed infants and three times higher in toddlers than in adults. Long-term dietary exposure to PCBs and dioxins in men and women is partly due to breast-feeding (12 and 14%, respectively). After weaning, dairy products, processed foods, and meat are major contributors of PCB and dioxin accumulation until reproductive age. Instead of discouraging breast-feeding, maternal transfer of PCBs and dioxins to the next generation must be avoided by enforcement of strict regulations for PCB and dioxin discharge and by reducing consumption of animal products and processed foods in all ages.     

Dioxins and human toxicity

The term dioxins usually refers to polychlorinated dibenzo-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs). As 2,3,7,8-tetrachloro-dibenzo-p-dioxin (TCDD) has the highest toxic potential, the toxic potentials of other PCDDs and PCDFs are defined in comparison with it. Human exposure to dioxins can be environmental (background), occupational, or accidental pollution. In the human body, dioxins are in part metabolised and eliminated, and the rest is stored in body fat. People vary in their capacity to eliminate TCDD, but it is also dose-dependent; the elimination rate is much faster at higher than lower levels. The liver microsomal P4501A1 enzyme oxygenates lipophilic chemicals such as dioxins. It is encoded by the CYP1A1 gene. Cytosolic aryl hydrocarbon receptor (AhR) mediates their carcinogenic action. It binds to dioxin, translocates to nucleus and together with hydrocarbon nuclear translocator (ARNT) and xenobiotic responsive element (XRE) increases the expression of CYP1A1.Dioxins are classified as known human carcinogens, but they also cause noncancerous effects like atherosclerosis, hypertension, and diabetes. Long-term exposures to dioxins cause disruption of the nervous, immune, reproductive, and endocrine system. Short-term exposure to high levels impairs the liver function and causes chloracne. The most sensitive population to dioxin exposure are the foetuses and infants.A large number of health effects have been documented in the scientific literature, and they all place dioxins among the most toxic chemicals known to man.     

Harbor seals (Phoca vitulina) in British Columbia, Canada, and Washington State, USA, reveal a combination of local and global polychlorinated biphenyl, dioxin, and furan signals

The harbor seal (Phoca vitulina) can serve as a useful indicator of food web contamination by persistent organic pollutants (POPs) because of its high trophic level, wide distribution in temperate coastal waters of the Northern Hemisphere, and relative ease of capture. In 1996 through 1997, we live-captured 60 harbor seal pups from three regions, spanning remote (Queen Charlotte Strait, BC, Canada), moderately industrialized (Strait of Georgia, BC, Canada), and heavily industrialized (Puget Sound, WA, USA) marine basins straddling the Canada-United States border. Biopsy samples of blubber were taken and analyzed for congener-specific polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs), and polychlorinated dibenzofurans (PCDFs) by using high-resolution gas chromatography-high-resolution mass spectrometry. Harbor seals in Puget Sound were heavily contaminated with PCBs, whereas seals from the Strait of Georgia had relatively high concentrations of PCDDs and PCDFs. Pattern evaluation and principal components analysis suggested that proximity to sources influenced the mixture to which seals were exposed, with those inhabiting more remote areas being exposed to lighter PCB congeners (those with lower Henry's law constant and K(ow)) that disperse more readily through atmospheric and other processes. Total toxic equivalents to 2,3,7,8-tetrachlorodibenzo-p-dioxin for the PCBs, PCDDs, and PCDFs suggest that Puget Sound seals are at greatest risk for adverse health effects, and that PCBs represent the class of dioxinlike contaminants of greatest concern at all sites.     

Regional variations in human toxics exposure in the USA: An analysis based on the National Human Adipose Tissue Survey

Regional human exposure was evaluated by examining human tissue chemical concentrations. National Human Adipose Tissue Survey data for 54 toxic substances [pesticides, polychlorinated biphenyls (PCBs), semi-volatiles, volatiles, and polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs)], were sorted by United States census divisions.Regional differences in human toxics exposure were found. Based on the data analyzed, it appears that individuals residing in the South Atlantic, East South Central, West South Central, and East North Central regions may be exposed to greater amounts of toxic substances than those of other regions of the country. Higher concentrations of organochlorine pesticides, PCBs, and PCDDs in older individuals indicate that these toxics bioaccumulate in human adipose tissue.     

Associations of environmental exposure to dioxins with prevalent diabetes among general inhabitants in Japan

The aim of this study was to evaluate the associations of environmental exposure to dioxins with diabetes among general inhabitants in Japan. A cross-sectional study was performed on 1374 participants, who were not occupationally exposed to dioxins, aged 15-73 years, living widely in 75 different residential areas of 25 prefectures in Japan through 2002-2006. Seven polychlorinated dibenzo-p-dioxins (PCDDs), 10 polychlorinated dibenzofurans (PCDFs), 12 dioxin-like polychlorinated biphenyls (PCBs), which are assigned a toxic equivalency factor, and biochemical factors were determined in fasting blood. A questionnaire survey on life-style including past history of diseases and treatments was also performed. We examined the associations of the accumulated toxic equivalents (TEQs) of PCDDs+PCDFs, dioxin-like PCBs and total dioxins with prevalent diabetes. Simple and partial correlation analyses revealed that HbA1c correlated with the accumulated TEQs of PCDDs+PCDFs, dioxin-like PCBs and total dioxins. In logistic regression analyses, the third and the highest quartiles of dioxin-like PCBs had adjusted odds ratios (ORs) of 3.07 (95% CI 1.16-8.81) and 6.82 (95% CI 2.59-20.1) compared to the reference (first plus second quartiles). On the other hand, the highest but not the third quartiles of PCDDs+PCDFs and total dioxins had significantly higher adjusted ORs compared to the respective references. These associations persisted when the subjects with poor liver or poor renal function were removed from the analysis. This recent representative data from general inhabitants in Japan showed associations of environmental exposure to dioxins, especially dioxin-like PCBs, with diabetes.     

深圳市市售食品中二恶英、多氯联苯污染现状研究

目的了解深圳市市售食品中二恶英、多氯联苯本底水平和污染情况,为开展食品中二恶英类化合物污染状况的风险评估和预警监测提供科学依据。方法于2004年10月至2008年10月期间,采集深圳市市售鱼、猪肉、牛肉、羊肉、鸡肉、鸭肉、禽蛋、奶粉、植物油、豆制品、米面、蔬菜12种食品共123份样品,参照美国国家环保局EPA1613、1668A方法,采用索式抽提装置和FMS自动纯化系统分别对样品进行提取和净化,采用同位素稀释技术,用已建立的高分辨气相色谱/高分辨双聚焦磁式质谱联用(HRGC/HRMS)超痕量有机分析技术平台,对样品中的7个多氯二苯并-对-二恶英(PCDD s)、10个多氯二苯并-对-呋喃(PCDFs)、4个共平面的多氯联苯(PCBs)化合物、8个单邻位取代的PCBs化合物以及6个指示性的PCBs化合物共计35个单体进行定量分析检测和毒性当量浓度汇总分析和评价。结果共检测123份市售食品样品,总二恶英(包括PCDD/Fs和PCBs)污染毒性当量浓度水平,动物性食品由大至小依次是:鱼类>禽蛋>牛肉>奶粉>羊肉>鸡肉>鸭肉>猪肉,植物性食品以植物油>豆制品>粮谷类>蔬菜依次降低。其中动物性食品以鱼类二恶英含量最高,...     

Accumulation profiles of persistent organochlorines in waterbirds from an estuary in Korea

Persistent organochlorine pollutants (POPs), such as polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), polychlorinated biphenyls (PCBs), and organochlorine (OC) pesticides such as DDTs (dichlorodiphenyltrichloroethane), HCHs (hexachlorocyclohexane isomers), CHLs (chlordane compounds) and HCB (hexachlorobenzene), were measured in subcutaneous fat of resident and migratory birds collected from the Nakdong River estuary (NRE) in Korea. Black-tailed gull, a resident bird from the NRE, contained greater concentrations of PCDD/Fs and PCBs than the migratory birds collected in the estuary. For example, mean concentrations of PCDD/Fs in black-tailed gull (395.5 pg/g fat weight) were higher than those in migratory birds, such as greenshank (198.3 pg/g fat weight), common gull (90.9 pg/g fat weight) black-headed gull (84.2 pg/g fat weight), and common tern (47.1 pg/g fat weight). However, concentrations of DDTs and/or HCHs were great in some migratory species, such as little tern (mean DDT 6,200 ng/g fat weight) and black-necked grebe (HCHs 475 ng/g fat weight). This suggested that contamination of PCDD/Fs and PCBs in resident gulls are due to intake of locally contaminated fish near the NRE. Elevated OC pesticide levels in migratory birds indicated that these birds have been exposed to DDTs and HCHs during their migration in Southeast Asian countries where chlorinated pesticides are still used. 2,3,7,8-Tetrachloro dibenzo-p-dioxin equivalents (TEQs) were calculated using the toxic equivalency factors (TEFs) reported by World Health Organization in 1998. Four of the 2,3,7,8-substituted congeners of PCDD/Fs contributed over 90% of the TEQs. Received: 27 October 2000/Accepted: 15 April 2001     

Case report: human exposure to dioxins from clay

CONTEXT: For the general population, the dominant source of exposure to dioxin-like compounds is food. As part of the University of Michigan Dioxin Exposure Study (UMDES), we measured selected polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and dioxin-like polychlorinated biphenyls (PCBs) in serum of 946 subjects who were a representative sample of the general population in five Michigan counties. CASE PRESENTATION: The total toxic equivalency (TEQ; based on 2005 World Health Organization toxic equivalency factors) of serum from the index case was 211 ppt on a lipid-adjusted basis, which was the highest value observed in the UMDES study population. This subject had no apparent opportunity for exposure to dioxins, except that she had lived on property with soil contaminated with dioxins for almost 30 years, and had been a ceramics hobbyist for > 30 years. Soil from her property and clay that she used for ceramics were both contaminated with dioxins, but the congener patterns differed. DISCUSSION: The congener patterns in this subject's serum, soil, and ceramic clay suggest strongly that the dioxin contamination in clay and not soil was the dominant source of dioxin contamination in her serum. RELEVANCE TO PUBLIC HEALTH PRACTICE: It appears that ceramic clay, in particular the process of firing clay with unvented kilns, can be a significant nonfood and nonindustrial source of human exposure to dioxins among ceramics hobbyists. The extent of human exposure from ceramic clay is unclear, but it may be widespread. Further work is needed to more precisely characterize the routes of exposure.     

Relationships between environmental organochlorine contaminant residues, plasma corticosterone concentrations, and intermediary metabolic enzyme activities in Great Lakes herring gull embryos

Experiments were conducted to survey and detect differences in plasma corticosterone concentrations and intermediary metabolic enzyme activities in herring gull (Larus argentatus) embryos environmentally exposed to organochlorine contaminants in ovo. Unincubated fertile herring gull eggs were collected from an Atlantic coast control site and various Great Lakes sites in 1997 and artificially incubated in the laboratory. Liver and/or kidney tissues from approximately half of the late-stage embryos were analyzed for the activities of various intermediary metabolic enzymes known to be regulated, at least in part, by corticosteroids. Basal plasma corticosterone concentrations were determined for the remaining embryos. Yolk sacs were collected from each embryo and a subset was analyzed for organochlorine contaminants. Regression analysis of individual yolk sac organochlorine residue concentrations, or 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (TEQs), with individual basal plasma corticosterone concentrations indicated statistically significant inverse relationships for polychlorinated dibenzo-p-dioxins/polychlorinated dibenzofurans (PCDDs/PCDFs), total polychlorinated biphenyls (PCBs), non-ortho PCBs, and TEQs. Similarly, inverse relationships were observed for the activities of two intermediary metabolic enzymes (phosphoenolpyruvate carboxykinase and malic enzyme) when regressed against PCDDs/PCDFs. Overall, these data suggest that current levels of organochlorine contamination may be affecting the hypothalamo-pituitary-adrenal axis and associated intermediary metabolic pathways in environmentally exposed herring gull embryos in the Great Lakes.     

Body burdens of polychlorinated dibenzo-p-dioxins, dibenzofurans, and biphenyls and their relations to estrogen metabolism in pregnant women

Polychlorinated dibenzo-p-dioxins (PCDDs, dioxins), polychlorinated dibenzofurans (PCDFs), and polychlorinated biphenyls (PCBs) are environmental endocrine disruptors that have half-lives of 7-10 years in the human body and have toxicities that probably include carcinogenesis. A high ratio of 4-hydroxyl estradiol (4-OH-E2) to 2-hydroxyl estradiol (2-OH-E2) has been suggested as a potential biomarker for estrogen-dependent neoplasms. In this cohort study of maternal-fetal pairs, we examined the relationship of PCDD/PCDF and PCB exposure to levels of estrogen metabolites in the sera of 50 pregnant women 25-34 years of age from central Taiwan. Maternal blood was collected during the third trimester, and the placenta was collected at delivery. We measured 17 dioxin congeners, 12 dioxin-like PCBs, and 6 indicator PCBs in placenta using gas chromatography coupled with high-resolution mass spectrometry. Estrogen metabolites in maternal serum were analyzed by liquid chromatography tandem mass spectrometry. The ratio of 4-OH-E2:2-OH-E2 decreased with increasing exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (beta=-0.124, p=0.004 by the general linear regression model, R=0.4). Meanwhile, serum levels of 4-OH-E2 increased with increasing concentrations of high-chlorinated PCDFs (i.e., 1,2,3,4,6,7,8-hepta-CDF: beta=0.454, p=0.03, R=0.30). Altered estrogen catabolism might be associated with body burdens of PCDDs/PCDFs. Our study suggests that exposure to PCDDs/PCDFs significantly affects estrogen metabolism. Therefore, PCDD/PCDF exposure must be considered when using the OH-E2 ratio as a breast cancer marker.     

Associations between serum levels of selected organochlorine compounds and endometriosis in infertile Japanese women

Endocrine-disrupting chemicals (EDCs) have been proposed as risk factors for endometriosis. Persistent organochlorine compounds, a group of suspected EDCs, are present to some extent in almost all human adipose tissue and blood via the food chain. A few animal studies have confirmed that exposure to these compounds can increase the incidence of endometriosis. In this study, we examined the associations between endometriosis and exposure to selected organochlorine compounds, including 8 polychlorinated dibenzo-p-dioxins (PCDDs), 10 polychlorinated dibenzofurans (PCDFs), 4 coplanar polychlorinated biphenyls (cPCBs), 36 ortho-substituted polychlorinated biphenyls (PCBs), and 13 chlorinated pesticides or their metabolites. The participants were 139 infertile Japanese women who were examined by laparoscopy and diagnosed as either endometriosis cases (Stages II-IV) or controls (Stages 0-I). The serum levels (lipid adjusted) of the targeted organochlorine compounds were in both 58 cases and 81 controls. There were very few differences in the various levels between endometriosis cases and controls. The total serum toxic equivalency (TEQ) value of PCDDs was significantly higher in the controls than in the cases (P=0.02). No other total TEQ values differed between cases and controls. For PCDDs, PCDFs, cPCBs, and PCBs, the multivariate odds ratio was 0.38 [95% confidence interval (CI), 0.12-1.17] and 0.41 (95% CI, 0.14-1.27) for the third and highest quartiles, respectively, compared to the lowest quartile of total TEQ values. A weak, negative dose-response relationship was evident for total TEQs (P for trend of 0.06). The results of this study provide some evidence that serum levels of these organochlorine compounds are not associated with an increased risk of endometriosis in infertile Japanese women.     

Investigation of a wood treatment facility: Impact on an aquatic ecosystem in the San Joaquin River, Stockton, California

Polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), polychlorinated biphenyls (PCBs), and metals were monitored in the river sediments near the McCormick and Baxter (MCB) wood treatment facility, Stockton, CA. Transplanted clams and resident fish species were used to assess bioavailability. The highest PCDD and PCDF contamination in sediments were confined to an area next to the facility and an area in the nearby Stockton harbor (DK location). Pentachlorophenol (PCP) wood treatment at MCB was the most probable source of the contamination. PCBs contaminated a wider area of the Stockton Ship Channel and harbor. Metal concentrations were uniformly low except for the metalloid arsenic in the Old Mormon Slough and lead and zinc near boat docks in the Stockton harbor. Despite high mortality rates, clams (Corbicula fluminea) bioaccumulated PCBs, PCDDs, and PCDFs. In clams, PCBs and 2,3,7,8 TCDD were much closer to equilibrium with the sediments than were higher chlorinated PCDDs and PCDFs. All fish were at background levels for 2,3,7,8 TCDD. All fish had lower lipid adjusted PCDD/F and PCB concentrations in the skinned muscle than in the whole fish. PCBs in fish were above background levels for United States river systems. Although high contamination exists in the river near this superfund site, adverse effects on the aquatic community could not be demonstrated.     

A Survey of Dietary Intake of Polychlorinated Dibenzo-<Emphasis Type="Italic">p</Emphasis>-dioxins,Polychlorinated Dibenzofurans,and Dioxin-like Coplanar Polychlorinated Biphenyls from Food During 2000–2002 in Osaka City,Japan

Studies of the dietary intake of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and dioxin-like coplanar polychlorinated biphenyls (dioxin-like PCBs), collectively referred as dioxins, were conducted using the total diet study (TDS) method with food purchased in Osaka City, Japan during 2000–2002. The daily intake of dioxin-TEQ (toxic equivalent) from food per adult person was estimated respectively as 104.24 pg TEQ/person/day in 2000, 72.73 pg TEQ/person/day in 2001, and 87.28 pg TEQ/person/day in 2002, corresponding to 2.08, 1.45, and 1.74 pg TEQ/kg body weight (bw)/day for an adult weighing 50 kg. The highest contribution ratio to the total intake of dioxin-TEQ was from fish and shellfish (group 10) in each year, accounting for 77–92%. The next highest contributor was meat and eggs (groups 11-A and 11-B). An annual decrease of the intake of dioxin-TEQ was not observed clearly. Otherwise, the dietary intake of non-2,3,7,8-substituted PCDDs/PCDFs were estimated together. The intake of 1,3,6,8-TeCDD came mostly from intake of fish and shellfish (group 10), green vegetable (group 7), and the other vegetables, including mushrooms and seaweed (group 8). In addition, the intake of 1,3,6,8-TeCDF, which reportedly antagonizes 2,3,7,8-TeCDD-mediated aryl hydrocarbon hydroxylase (AHH) and ethoxyresorufin O-deethylase (EROD) induction activities, was an insufficient amount to suppress 2,3,7,8-TeCDD-mediated activities. Furthermore, we discussed different TEQ compositions of PCDDs/PCDFs to dioxin-like PCBs from food intake and in human samples and inferred that the difference was caused by low bioaccumulation properties of 3,3′,4,4′,5-PeCB (PCB 126).     

Prenatal exposure to PCDDs/PCDFs and dioxin-like PCBs in relation to birth weight

Several human studies have shown that low-level exposure to environmental contaminants, such as polychlorinated biphenyls (PCBs) and organochlorine pesticides, negatively influences birth outcomes. However, the effects of low-level exposure to polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and dioxin-like PCBs (DL-PCBs) on birth outcomes have not been clarified in human studies.A prospective cohort study was established to investigate the possible adverse effects of PCDDs/PCDFs and DL-PCBs on fetal growth and neurodevelopment. We recruited 514 pregnant women between July 2002 and October 2005 in Sapporo, Japan. We measured 29 congener levels of PCDDs/PCDFs and DL-PCBs in maternal blood.Using multiple liner regression analysis of the association between birth weight and the levels of PCDDs/PCDFs and DL-PCBs with full adjustments for potential confounders, a significant adverse effect was observed regarding total PCDDs toxic equivalents (TEQ) levels (adjusted β=−231.5 g, 95% CI: −417.4 to −45.6) and total PCDFs TEQ levels (adjusted β=−258.8 g, 95% CI: −445.7 to −71.8). Among male infants, significant adverse associations with birth weight were found for total PCDDs TEQ level, total PCDDs/PCDFs TEQ level, and total TEQ level. However, among female infants, these significant adverse associations were not found. With regard to individual congeners of PCDDs/PCDFs and DL-PCBs, we found significantly negative association with the levels of 2,3,4,7,8-PeCDF (adjusted β=−24.5 g, 95% CI: −387.4 to −61.5).Our findings suggest that prenatal low-level exposure to PCDDs and PCDFs, especially 2,3,4,7,8-PeCDF, may accumulate in the placenta and retard important placental functions, which result in lower birth weight.     

Fish intake,plasma ω-3 polyunsaturated fatty acids,and polychlorinated dibenzo-<Emphasis Type="Italic">p</Emphasis>-dioxins/polychlorinated dibenzo-furans and co-planar polychlorinated biphenyls in the blood of the Japanese population

OBJECTIVES: To evaluate background exposure levels and determinants of the individual variations in the exposure to dioxins in Japan. METHODS: A cross-sectional study was performed on 131 men and 122 women (aged 20-76 years), who resided in five prefectures of Japan and had no occupational exposure to dioxins. Seven polychlorinated dibenzo-p-dioxins (PCDDs), ten polychlorinated dibenzo-furans (PCDFs) and 12 polychlorinated biphenyls (PCBs), which are assigned a toxicity equivalent factor, were determined in fasting blood. Biochemical analysis of plasma and a questionnaire survey on life-style, including dietary habit, were also performed. Factors associated with the levels of dioxin-related compounds in blood were evaluated by multiple linear regression. RESULTS: The median of total toxicity equivalents (TEQs) in men and women was 17 and 16 pg TEQ/g lipid, respectively, with no gender difference. After adjustment for age and other covariates, plasma concentrations of eicosapentaenoic acid, a biomarker of fish intake, were found to be positively associated with blood levels of total dioxin, PCDDs, PCDFs and PCBs, all of which were expressed on a TEQ basis (P<0.01). The frequency of intake of coastal fish, such as horse mackerel, mackerel and sardine, was also associated with TEQ-based concentrations of PCDFs (P=0.03) and PCBs (P=0.08). The intake of raw fish was positively related to total dioxins (P=0.06) and PCBs (P=0.03). CONCLUSIONS: The level of intake of marine fish, especially raw fish and coastal varieties, may be associated with increased blood levels of dioxin-related compounds among the population. Despite high fish consumption in Japan, the body burden of dioxins in the population was not found to be higher than that in western countries.     

Associations of exposure to dioxins and polychlorinated biphenyls with diabetes: based on epidemiological findings

Persistent organic pollutants (POPs) are a group of chemical substances that have the common properties of resistance to biodegradation, wide-range transportation, high lipophilicity, bioaccumulation in fat, and biomagnification in the food chain. POPs are persistent in the environment worldwide and have potential adverse impacts on human health and the environment. Polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and polychlorinated biphenyls (PCBs) are well known chemicals that are considered as POPs. The association between high-level exposure to dioxins and type 2 diabetes among U.S. Air Force veterans who had been exposed to Agent Orange contaminated with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) during the Vietnam War was reported in the late 1990s. This association has been supported by similar epidemiologic studies, whose subjects were exposed to high doses of dioxins in their places of work involving phenoxyacid herbicide production and spraying, and in the industrial accident in Seveso, Italy. Recently, low-level exposure to dioxins and PCBs has been reported to be linked to type 2 diabetes. Cross-sectional studies in the U.S. general population and Japanese general population showed that body burden levels of some dioxins and PCBs were strongly associated with the prevalence of type 2 diabetes. Very recently, following these cross-sectional studies, several prospective studies have suggested that low-level exposure to some PCBs predicted the future risk of type 2 diabetes in the general population. Environmental exposure to some dioxins and PCBs, which mainly accumulate in adipose tissue, may play a role in the development of type 2 diabetes.     

Association between blood levels of PCDDs/PCDFs/dioxin-like PCBs and history of allergic and other diseases in the Japanese population

Background

Previous studies reported that exposure to dioxins was associated with an increased risk of various diseases in general populations.

Objectives

The aim of this study was to examine the association between levels of dioxins in blood and allergic and other diseases.

Methods

We conducted a cross-sectional study on 1,063 men and 1,201 women (aged 15–76 years), who were living throughout Japan and not occupationally exposed to dioxins, during 2002–2010. In fasting blood samples, polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and dioxin-like PCBs (DL-PCBs) were analyzed by isotope dilution high-resolution gas chromatography/mass spectrometry. We obtained information on life style and self-reported history of diseases using a questionnaire. Blood pressure, blood levels of hemoglobin A1c, and serum lipids were also measured. Multiple logistic regression models were used to analyze the association between dioxin levels in blood and various diseases.

Results

Toxic equivalents of PCDDs/PCDFs and total dioxins showed significant inverse dose–response relationships with atopic dermatitis, after adjustments for potential confounders. The highest quartile for total dioxins had an adjusted odds ratio of 0.26 (95 % confidence interval 0.08–0.70) compared to the reference group (first quartile). The odds ratios for hypertension, diabetes mellitus, hyperlipidemia, gout in men, and gynecologic diseases in women significantly increased with increasing toxic equivalents of PCDDs/PCDFs, DL-PCBs, and total dioxins in blood.

Conclusions

The present findings suggest that background exposure to dioxins was associated with reduced risk of atopic dermatitis. The results also support the idea that low-level exposure to dioxins is associated with an increased risk of diabetes, hypertension, and hyperlipidemia.