Total Polychlorinated Dibenzofurans Research Articles

Effects of low-level prenatal exposure to dioxins on cognitive development in Japanese children at 42 months

BackgroundPrenatal exposure to polychlorinated dibenzo-p-dioxins (PCDDs) or polychlorinated dibenzofurans (PCDFs) and dioxin-like polychlorinated biphenyls (dioxin-like compounds [DLCs]) through environmental chemicals may affect the neurodevelopment of children. In our previous study, an inverse association was observed between prenatal DLCs and neurodevelopment of infants aged 6months in both sexes. However, studies are yet to determine how long these adverse effects last. ObjectiveTo examine whether the effects of DLCs on cognitive development remains at 42months. MethodsIn this prospective cohort study conducted in Sapporo, Japan, pregnant mothers' blood was analyzed for the congener level of DLCs. The Kaufman Assessment of Battery for Children (K-ABC) was used to test their children's cognitive development at 42months. A total of 141 mother-child pairs were included in the final analysis. The multiple linear regression analysis was used to examine the association between the K-ABC scores and DLC levels in the maternal blood. ResultsSeven isomers (1,2,3,6,7,8-HxCDD, 2,3,4,7,8-PeCDF, 33′44′55′-HxCB(#169), 2344′5- PenCB(#114), 233′44′5-HexCB(#156), 233′44′5′-HexCB(#157), 23′44′55′-HexCB(#167), total PCDF, and TEQ-PCDD, PCDF, PCDD/DFs levels were positively associated with the achievement score (AS) of K-ABC. However, total non-ortho PCBs were negatively associated with the Mental Processing Composite Score (MPCS) of K-ABC in males. In females, increased TEQ-dl PCB and TEQ-PCDD/F/dl-PCB were also associated with increasing AS score. ConclusionsThis study suggests that the negative effects of prenatal DLC exposure on children's cognitive development at 6months were not observed in children aged 42months. Regarding the sex-specific effects, AS and DLCs were positively correlated in females, whereas those of MPCS and DLCs were significantly negative in males.

Polychlorinated naphthalene concentrations and profiles in cheese and butter, and comparisons with polychlorinated dibenzo-p-dioxin, polychlorinated dibenzofuran and polychlorinated biphenyl concentrations

Polychlorinated naphthalenes (PCNs) are candidates for inclusion in the Stockholm Convention on persistent organic pollutants. PCNs are structurally and toxicologically similar to 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) and its analogues. Intake in food is considered to be an important human exposure pathway for PCNs. In this preliminary study, cheese and butter samples were analysed for PCNs, polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and polychlorinated biphenyls (PCBs) using an isotope dilution gas chromatography high-resolution mass spectrometry method. The aim of this study was to evaluate the PCN concentrations in the cheese and butter samples and to compare them with the PCDD, PCDF and PCB concentrations. The PCN concentrations were 5.6–103 pg g−1 of wet weight in the seven cheese samples tested and 5.0–199 pg g−1 of wet weight in the seven butter samples tested. The mass concentrations of lower chlorinated congeners were greater than those of the higher chlorinated congeners. Congeners of CN45/36, CN27/30 and CN33/34/37 were much more abundant than other congeners found in tetrachlorinated PCNs. Congeners of CN51, CN66/67 and CN73 were determined to be the predominant congeners in penta-, hexa- and heptachlorinated homologs, respectively. The PCNs contributed around 5% of the total PCN, PCDD, PCDF and PCB toxic equivalence (TEQ) values. CN73 was found to be the dominant PCN congener and contributed more than 40% to the PCN TEQ value. Congeners CN66/67, CN69 and CN63 were also found at relatively high levels. The PCB congener CB118 was the predominant congener (by mass-based concentration) of the 12 dioxin-like PCBs (dl-PCBs). The PCBs contributed 53.8% of the total TEQ, and congener CB126 contributed more than any other compound that was analysed to the total TEQ. The PCDDs and PCDFs contributed 11.6% and 29.7% of the total TEQ values, respectively.

Blood levels of PCDDs, PCDFs, and coplanar PCBs in Yusho mothers and their descendants: Association with fetal Yusho disease

Maternal exposure to polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and polychlorinated biphenyls (PCBs) may result in adverse health effects in their children. In Japan in 1968, an accidental human exposure to rice oil contaminated with PCDDs, PCDFs, and PCBs, led to the development of Yusho disease. Yusho mothers delivered descendants with low birth weights and hyperpigmented skin and mucosa, which are characteristic of fetal Yusho disease (FYD). The Yusho cohort was used to evaluate the effect of maternal exposure to PCDDs, PCDFs, and PCBs on the development of FYD. Blood samples, obtained from 64 Yusho mothers (117 descendants: 10 with FYD and 107 without FYD), were analyzed for congeners of seven PCDDs, 10 PCDFs, and four coplanar PCBs. We investigated the association between the maternal estimated blood levels of dioxins at delivery and the risk of fetal Yusho disease. We also studied the differences in dioxin blood levels in 24 mother–descendant pairs (5 with FYD and 19 without FYD). The estimated levels of total PCDD TEQ, total PCDF TEQ, total coplanar PCB TEQ, and total TEQ in the maternal blood at delivery were associated with significantly increased risk of FYD. The odds ratios, which present the risk of FYD for a 10-fold increase in blood dioxin, were largest for 1,2,3,6,7,8-HexaCDD (odds ratio=28.6, 95% confidence interval=1.67–489.9, p=0.02). The levels of 1,2,3,6,7,8-HexaCDD in both the Yusho mothers and their descendants with FYD were higher than the levels in those without FYD. These findings suggest that 1,2,3,6,7,8-HexaCDD is the most important causative congener for the development of FYD.

Characterization of placental transfer of polychlorinated dibenzo‐p‐dioxins, dibenzofurans and polychlorinated biphenyls in normal pregnancy

Prenatal exposure to dioxins may result in many adverse health effects. However, the mechanisms by which dioxins are transferred from mother to fetus through the placenta are not well understood. The aim of this study was to investigate the differences in dioxin concentrations between maternal blood, the placenta, and cord blood in normal pregnant women, and to identify which individual congeners of these compounds are transferred from mother to fetus through the placenta. Samples were collected from 19 pregnant Japanese women. Specific congeners of seven polychlorinated dibenzo-p-dioxins (PCDDs), 10 polychlorinated dibenzofurans (PCDFs), and four non-ortho polychlorinated biphenyls (PCBs) were analyzed. The TEQ concentrations of PCDDs, PCDFs, and non-ortho PCBs were 8.03, 3.39, and 3.95 pg TEQ/g lipid, respectively, in the maternal blood; 8.78, 3.61, and 0.87 pg TEQ/g lipid in the placenta; and 4.33, 1.25, 1.08 pg TEQ/g lipid in the cord blood. Among specific congeners, 1,2,3,7,8-PentaCDD and 2,3,4,7,8-PentaCDF exhibited a placenta to maternal blood ratio greater than 1.0, while OctaCDD exhibited the greatest cord blood to placenta ratio. The cord blood to maternal blood ratio of total PCDDs was significantly higher than that of total PCDFs and total non-ortho PCBs. The dioxin concentration in cord blood was approximately half of the amount in maternal blood, despite congeners showing a high toxic equivalency factor accumulating in the placenta. PCDDs were transferred more readily than PCDFs and non-ortho PCBs from maternal blood to the fetus through the placenta.

Maternal exposure to high levels of dioxins in relation to birth weight in women affected by Yusho disease

Background Studies on the association of maternal exposure to polychlorinated dibenzo- p-dioxin (PCDDs), polychlorinated dibenzofurans (PCDFs), and polychlorinated biphenyls (PCBs) with decreased birth weight in humans have produced conflicting results. In Japan in 1968, an accidental human exposure to rice oil contaminated with PCDDs, PCDFs, and PCBs, led to the development of Yusho disease. Objective The Yusho cohort was used to evaluate the effect of maternal exposure to PCDDs, PCDFs, and PCBs on birth weight. Methods Blood samples, obtained from 101 Yusho women (190 births) who gave birth after exposure, were analyzed for congeners of seven PCDDs, ten PCDFs, and four non- ortho PCBs. Results Total PCDD TEQ (adjusted beta = − 161.9 g; 95% CI, −265.3 to − 58.6), total PCDF TEQ (adjusted beta = − 105.9 g; 95% CI, −179.5 to − 32.2), and total non- ortho PCBs (adjusted beta = − 178.4 g; 95% CI, −318.3 to − 38.5) levels were inversely associated with birth weight. Significant inverse associations with birth weight were also found for total PCDD TEQ, total PCDF TEQ, and total non- ortho PCB TEQ levels among male, but not female, infants. Significant inverse associations with birth weight were also found for nine congeners among all infants; the adjusted beta coefficients were largest for 1,2,3,6,7,8-HxCDD and smallest for 2,3,4,7,8-PeCDF. Conclusion In the setting of exposure to high levels of dioxins, maternal blood levels of PCDDs, PCDFs and PCBs are associated with lower birth weight in Yusho patients. The association exhibited gender-specific differences, as male infants are more susceptible than females to growth restriction induced by in utero dioxin exposures.

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 beta=-231.5g, 95% CI: -417.4 to -45.6) and total PCDFs TEQ levels (adjusted beta=-258.8g, 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 beta=-24.5g, 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.

Prevention of PCDD/F Formation and Minimization of Their Emission at the Stack of a Secondary Aluminum Casting Plant

Results of an extensive 5 year study on a full-scale plant with the specific aim to investigate polychlorinated dibenzo-p-dioxin (PCDD) and polychlorinated dibenzo furan (PCDF) formation and release in a secondary aluminum casting plant are reported. PCDD and PCDF concentrations were evaluated for all the gaseous and solid streams (no liquid stream was present) as well as for the flue gas upstream and downstream of every single unit of the flue gas cleaning system. The study highlights PCDD and PCDF formation particularly in the narrow 320-360 degrees C range. To prevent formation reactions and/or minimize PCDD and PCDF concentration at the stack, effects of the fabric filter substitution, a quenching chamber and a postcombustor installation together with working conditions are investigated. The flue gas cleaning system results in PCDD and PCDF emission at stack of 0.1-0.2 ng I-TEQ/N m3 and in a mass flow of 250-550 nmol/h. The total PCDD and PCDF release into the environment is 0.06 g I-TEQ/yr and the corresponding emission factor, 0.35 microg I-TEQ/ton. It is shown that the global effects of the technological innovation on the reaction mechanisms are the prevention of PCDD/F formation by de novo synthesis and the minimization of their emission.

Chemical contaminants in fish feeds used in federal salmonid hatcheries in the USA

Recent studies have demonstrated that fish feeds contain significant concentrations of contaminants, many of which can bioaccumulate and bioconcentrate in fish. Organochlorine (OC) contaminants are present in the fish oils and fish meals used in feed manufacture, and some researchers speculate that all fish feeds contain measurable levels of some contaminants. To determine the concentration of contaminants in feeds used in US Fish and Wildlife Service's National Fish Hatcheries, we systematically collected samples of feed from 11 cold-water fish hatcheries. All samples (collected from October 2001 to October 2003) contained at least one polychlorinated dibenzo-p-dioxin (PCDD), polychlorinated dibenzofuran (PCDF), polychlorinated biphenyl (PCB) congener, or dichlorodiphenyltrichloroethane (DDT) metabolite. Of the 55 samples in which they were analyzed 39 contained PCDDs, 24 contained PCDFs and 24 contained DDT or its metabolites. There were 10- to 150-fold differences in concentrations of total PCBs, PCDDs, PCDFs and DDT. Although PCBs were the most commonly detected contaminant in our study, concentrations (range: 0.07-10.46 ng g(-1) wet weight) were low compared to those reported previously. In general, we also found lower levels of OCs than reported previously in fish feed. Perhaps most notable was the near absence of OC pesticides - except for DDT or its metabolites, and two samples containing hexachlorocyclohexane (HCH). While contaminant concentrations were generally low, the ecological impacts can not be determined without a measure of the bioaccumulation of these compounds in the fish and the fate of these compounds after the fish are released.

Polychlorinated Dibenzo-p-Dioxins, Polychlorinated Dibenzofurans, and Coplanar Polychlorinated Biphenyls in Human Milk in Osaka City, Japan

Forty-eight human milk samples were collected from primiparous mothers in Osaka City from June 1999 to January 2000 and analyzed for polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and dioxin-like coplanar polychlorinated biphenyls (CoPCBs). Mean toxic equivalents (TEQs) in the milk were 13.86 pg I-TEQ/g fat or 16.50 pg World Health Organization (WHO)-TEQ/g fat for PCDDs and PCDFs; 9.87 pg WHO-TEQ/g fat for CoPCBs; and 23.74 pg TEQ/g fat using I-TEQ values of PCDDs and PCDFs or 26.36 pg TEQ/g fat using WHO-TEQ values of PCDDs and PCDFs for total PCDDs, PCDFs, and CoPCBs. The TEQ levels of these chemicals in human milk in Osaka City were in the range of levels in human milk surveyed in Japan, but the TEQ levels of PCDDs and PCDFs and total PCDDs, PCDFs, and CoPCBs from our study were slightly higher than average TEQ levels in human milk in Japan. When comparing our data with the latest data from the United States and some European countries, the TEQ levels of PCDDs and PCDFs in human milk from Osaka City were relatively high, whereas those of CoPCBs were ranked as being of intermediate level. Only TEQ values of CoPCBs in human milk were found to correlate with the increasing age of mothers and their estimated intake of seafood during the year before pregnancy. Concentrations of PCBs 105 and 118 contributed to TEQ values of CoPCBs associated with seafood intake, whereas those of PCBs 156, 157, 114, 189, 167, and 169 contributed to TEQ values of CoPCBs associated with increasing maternal age.

Predictors of serum dioxin levels among adolescent boys in Chapaevsk, Russia: A cross-sectional pilot study

BackgroundToxicological studies and limited human studies have demonstrated associations between exposure to polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and polychlorinated biphenyls (PCBs) and adverse developmental and reproductive health effects. Given that children may be particularly susceptible to reproductive and developmental effects of organochlorines, and the paucity of information available regarding childhood exposures to dioxins in particular, we undertook a pilot study to describe the distribution of, and identify potential predictors of exposure to, dioxin-like compounds and dioxins among adolescent boys in Chapaevsk, Russia. The pilot study was also designed to guide the development of a large prospective cohort study on the relationship of exposure to PCDDs, PCDFs, and PCBs with growth and pubertal development in peri-pubertal Chapaevsk boys.Methods221 boys age 14 to 17 participated in the pilot study. Each of the boys, with his mother, was asked to complete a nurse-administered detailed questionnaire on medical history, diet, and lifestyle. The diet questions were used to measure the current and lifetime consumption of locally grown or raised foods. Blood samples from 30 of these boys were sent to the Centers for Disease Control and Prevention (CDC) for analysis of dioxins, furans and PCBs.ResultsThe median (25th, 75th percentile) concentrations for total PCDDs, PCDFs and coplanar PCBs were 95.8 pg/g lipids (40.9, 144), 33.9 pg/g lipids (20.4, 61.8), and 120 pg/g lipids (77.6, 157), respectively. For WHO-TEQs, the median (25th, 75th percentile) for total PCDDs, PCDFs, and coplanar PCBs were 0.29 (0.1, 9.14), 7.98 (5.27, 12.3), and 7.39 (4.51, 11.9), respectively. Although TCDD was largely non-detectable, two boys had high TCDD levels (17.9 and 21.7 pg/g lipid). Higher serum levels of sum of dioxin-like compounds and sum of dioxin TEQs were positively associated with increased age, consumption of fish, local meats other than chicken, PCB 118, and inversely with weeks of gestation.ConclusionThe total TEQs among Chapaevsk adolescents were higher than most values previously reported in non-occupationally exposed populations of comparable or even older ages. Dietary consumption of local foods, as well as age and weeks of gestation, predicted dioxin exposure in this population.

Blood chemistry, alpha-fetoprotein and hepatitis B surface antigen in Yusho

Summary Background and Objective: An incident of accidental human exposure to polychlorinated biphenyls (PCBs) occurred in the western part of Japan in 1968. The disease is known as Yusho, because its cause was the ingestion of rice bran oil that was contaminated with PCBs. The various symptoms such as acneform skin eruptions were observed in the early stage in Yusho patients. An important fact is that polychlorinated dibenzofurans (PCDFs) were detected in the contaminated rice oil. PCDFs have a much higher toxicity than do PCBs. Analysis of blood concentration of PCDFs was performed throughout Japan in 2002. There have been no reports on the relationship between blood concentration of PCDFs and blood chemistry, alpha-fetoprotein or hepatitis B surface antigen (HBsAg) in Yusho. This is the first study to report on the relationship between blood concentration of PCDFs and blood chemistry, alpha-fetoprotein or HBsAg in Yusho. Methods: We analyzed blood chemistry by measuring the following 20 items—total protein, serum albumin, alanine and aspartate aminotransferase, lactate dehydrogenase, alkaline phosphatase, leucine aminopeptidase, gamma-glutamyl transferase (GGT), total bilirubin, conjugated bilirubin, cholinesterase, total cholesterol, high-density lipoprotein (HDL) cholesterol, triglyceride, glucose, amylase, creatine kinase, urea nitrogen, creatinine and uric acid. Alpha-fetoprotein and HBsAg were also measured. We studied the relationship between blood concentrations of total PCDFs and the items of the blood chemistry analysis, alpha-fetoprotein and HBsAg. Results: Of the 20 items of blood chemistry, alpha-fetoprotein and HBsAg, we found three items (GGT, HDL cholesterol and creatinine) were significantly related to the total PCDF level using three-way analysis of variance (ANOVA). Conclusion: A significant relationship between three items of the blood chemistry analysis (GGTP, HDL cholesterol and creatinine) and total PCDF levels in the blood was observed in 2002. The blood concentrations of total PCBs and PCDFs have now decreased; however, the PCDFs in patients with Yusho still affect blood chemistry.

Dermatological manifestations in Yusho: correlation between skin symptoms and blood levels of dioxins, such as polychlorinated dibenzofurans (PCDFs) and polychlorinated biphenyls (PCBs)

Summary Background and objective: Yusho occurred in western Japan in 1968 and was caused by ingestion of rice bran oil that was contaminated with polychlorinated biphenyls (PCBs) and dioxins such as polychlorinated dibenzofurans (PCDFs). At that time, the skin symptoms presented by patients with Yusho were at their most prominent and worst severity. Analysis of blood to determine the concentration of dioxins started in 2001 in Fukuoka prefecture, and in 2002 the examination was performed throughout Japan. There have been no reports on the relationship between blood concentration of dioxins and skin symptoms in Yusho. This is the first report to examine the relationship between blood concentration of dioxins and skin symptoms in Yusho, using statistical analyses. Methods: Using the global skin severity grade, we analyzed the change in skin symptoms, which were examined at the annual medical check-up of patients with Yusho. We also investigated the relationship between the items of the annual dermatological examination and blood concentrations of total PCDFs and total PCBs. Results: The severity of skin symptoms improved significantly in the first 20 years; nowadays, however, further improvement can hardly be observed. Using three-way analysis of variance (ANOVA), we found that of the 21 items of the dermatological examination, nine were significantly related to total PCDFs, and five were related to total PCBs. Only one item was significantly related both to total PCDFs and total PCBs. Conclusion: More than 36 years have passed since the Yusho incident, and about 60% of the patients currently present with no skin symptoms. In contrast, in about 40% of the patients, characteristic skin symptoms of Yusho, such as pigmentation of skin, black comedones and acneform eruptions, could still be observed. Our analysis of the relationship between skin symptoms and blood concentrations of total PCDFs and total PCBs proves that not only PCBs but also PCDFs have an important role in the skin symptoms of Yusho.

Concentrations of polychlorinated dibenzo-p-dioxins, dibenzofurans, non-ortho polychlorinated biphenyls, and mono-ortho polychlorinated biphenyls in Japanese flounder, with reference to the relationship between body length and concentration

The concentrations of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), non-ortho polychlorinated biphenyls (non-ortho PCBs), and mono-ortho polychlorinated biphenyls (mono-ortho PCBs) in Japanese flounder (Paralichthys olivaceus, body length 10.4-36.6 cm) collected from Sendai Bay, Japan, were determined using high-resolution gas chromatography-mass spectrometry. The relationship between the concentrations of these compounds (dioxins) and the body length of the Japanese flounder was examined. The total PCDD and total PCDF concentrations did not correlate with body length (both r(2) < 0.1, both p > 0.05), whereas the total non-ortho PCB and total mono-ortho PCB (coplanar polychlorinated biphenyls, Co-PCBs) concentrations were significantly correlated (r(2)= 0.8, p < 0.05 and r(2)= 0.63, p < 0.05, respectively). The bioaccumulation properties of PCDD/Fs in Japanese flounder differed from those of Co-PCBs. Toxicity equivalency quotient (TEQ) values derived from the Co-PCBs made up 46.3%-63.7% of the total TEQ value for all the dioxins. Although the concentrations of non-ortho PCBs were lower than those of mono-ortho PCBs, the TEQ value for non-ortho PCBs was higher than that for mono-ortho PCBs. The TEQ value for non-ortho PCBs increased more with increasing body length than did the values for PCDDs, PCDFs, and mono-ortho PCBs. These results show that from the standpoint of risk management, non-ortho Co-PCBs are the most important of the dioxins in Japanese flounder.

Health of Tree Swallow ( Tachycineta bicolor ) Nestlings Exposed to Chlorinated Hydrocarbons in the St. Lawrence River Basin. Part II. Basal and Stress Plasma Corticosterone Concentrations

Sixteen-day-old tree swallows (Tachycineta bicolor) were collected in 1999 and 2000 from nine sites within the vicinity of the St. Lawrence River in Canada and the United States to determine if organochlorine contaminant concentrations correlated with corticosterone levels. Basal plasma corticosterone levels were determined in chicks reared in nest boxes, and stress plasma corticosterone levels were determined in chicks after exposure to a 10-min standardized stress test. Mean basal plasma corticosterone concentrations ranged from 4 to 37 ng/ml in 1999, and from 5 to 20 ng/ml in 2000. Mean poststress plasma corticosterone levels ranged from 26 to 67 ng/ml in 1999, and from 26 to 109 ng/ml in 2000. In 1999 and 2000, basal corticosterone was negatively correlated with polychlorinated dibenzofuran (PCDF). Total PCDFs ranged from 4.8 to 120.5 ng/kg wet weight in chicks in 1999 and 2000 among sites. These results indicate that current levels of organochlorine contaminants in the St. Lawrence River and surrounding tributaries may be interfering with the glucocorticoid endocrine axis of tree swallows.

Developing risk-based screening guidelines for dioxin management at a Melbourne sewage treatment plant

Dioxin is a generic term used to refer to the congeners of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs). The principal source of dioxin production is generally thought to be from unintended by-products of waste incineration, but dioxins are also naturally formed from volcanic activity and forest fires (WHO, 1998). Estimates of dioxin emissions in Australia suggest that approximately 75% of the total PCDD and PCDF emissions derive from prescribed burning and wild bushfires. Currently, no screening guidelines for dioxins within soils are available in Australia. This paper presents the general approach and results of a human health risk-based assessment performed by URS Australia in 2001 to develop site specific reference criteria for remediation of a former sewage plant in Melbourne. Risk-based soil remediation concentrations for dioxins at the sewage treatment plant site were developed using tolerable daily intake values of 4, 2 and 1 pg/kg/day. The potentially significant exposure pathways and processes for exposure to dioxins were identified and risk-based soil concentrations derived in accordance with the general method framework presented in the National Environmental Protection Measure (Assessment of Site Contamination). The derived dioxin reference criteria were used to develop an effective risk management program focussed on those conditions that present the greatest contribution to overall risk to human health.

Sources of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and coplanar polychlorinated biphenyls (Co-PCBs), and their bioaccumulation through the marine food web in Sendai Bay, Japan.

The concentrations of PCDD/F and Co-PCB congeners in seawater, sediment, Pacific oyster, Japanese anchovy, marbled sole, and Japanese flounder samples from Sendai Bay, Japan, were analyzed. The compositions of total PCDD/F and total Co-PCB concentrations in sediment and Pacific oyster reflected that in seawater--the compositions of total PCDD, PCDF, and Co-PCB concentrations were approximately 60, 10, and 30%, respectively. The compositions in Japanese anchovy, marbled sole, and Japanese flounder were different from those in seawater and sediment-the ratio of total Co-PCB concentration to total PCDD/F plus Co-PCB concentrations in Japanese anchovy, marbled sole, and Japanese flounder was above 90%. Tetrachlorinated PCDDs (T4CDDs), such as 1,3,6,8- and 1,3,7,9-T4CDD, were the predominant congeners in seawater and sediment; the total T4CDD concentrations in seawater and sediment were approximately 46 and 48% of the total PCDD concentration. Furthermore, shipments of the herbicide 1,3,5-trichloro-2-(4-nitrophenoxy)benzene to Miyagi Prefecture, the so-called granary of Japan, were the highest in Japan over the last 12 years. The major sources of PCDD/Fs and Co-PCBs in Sendai Bay, which is in Miyagi Prefecture, are impurities in chlorinated herbicides. The order of concentration of PCDD/Fs was Pacific oyster > Japanese anchovy = marbled sole > Japanese flounder; the concentration in Japanese flounder, which is a higher-trophic-level consumer in the marine food web, was lower than that in shellfish (Pacific oyster) and Japanese anchovy, which are lower-trophic-level consumers. The order of concentration of Co-PCBs was Pacific oyster < Japanese anchovy = marbled sole < Japanese flounder; the concentrations in the higher-trophic-level consumers were higher than the concentrations in the lower-trophic-level consumers. Different PCDD/F congeners tended to bioaccumulate in different organisms. On the other hand, all species of Co-PCB congener tended to bioaccumulate in all organisms.

Fish intake, plasma ω-3 polyunsaturated fatty acids, and polychlorinated dibenzo-p-dioxins/polychlorinated dibenzo-furans and co-planar polychlorinated biphenyls in the blood of the Japanese population

To evaluate background exposure levels and determinants of the individual variations in the exposure to dioxins in Japan. 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. 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). 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.

Assessment of health effects in New York City firefighters after exposure to polychlorinated biphenyls (PCBs) and polychlorinated dibenzofurans (PCDFs): the Staten Island Transformer Fire Health Surveillance Project.

Following an electrical transformer fire in Staten Island, New York, a health surveillance program was established for 60 New York City firefighters and emergency medical technicians exposed to polychlorinated biphenyls (PCBs) and polychlorinated dibenzofurans (PCDFs). Exposure potential was documented after high levels of PCBs and PCDFs were found on transformer and firefighters' uniforms. Personnel received comprehensive medical examinations, and the results were compared with preexposure values. Serum was analyzed for PCBs, PCDFs, and polychlorinated dibenzo-p-dioxins (PCDDs). Follow-up was conducted 9 mo later. Thirty-two of 58 (55%) firefighters reported initial symptoms, and 3 firefighters required brief medical leave. Pulmonary functions, exercise performance, serum liver functions, and serum lipid profiles were normal or unchanged from preexposure baselines. Serum PCBs averaged 2.92 +/- 1.96 ppb (range = 1.9-11.0 ppb). Five (8%) had serum PCBs that were greater than or equal to 6 ppb. Eight (73%) had a significant decrease (p = .05) in serum PCB level at the time of follow-up. Serum toxic equivalency (TEQ [1998 World Health Organization]) for total PCDDs and PCDFs averaged 39.0 +/- 21.5 (n = 48). Eighteen (38%) had elevated TEQs (i.e., > 40). All firefighters had no short-term heath effects. Modern firefighting uniforms are not meant to replace HAZMAT suits, but these uniforms provide protection from this chemical exposure for most firefighters.

Differential Effects of Two Lots of Aroclor 1254: Congener-Specific Analysis and Neurochemical End Points

Aroclor 1254 is a widely studied commercial polychlorinated biphenyl (PCB) mixture which, by definition, contains 54% chlorine by weight. Recent reports indicate substantial differences in the congener composition among Aroclor lots and hence their biologic effects. We designed the current study to compare the effects of two lots of Aroclor 1254 (lots 6024 and 124-191). We analyzed these two lots for PCB congeners, polychlorinated dibenzofurans (PCDFs), polychlorinated naphthalenes (PCNs), and polychlorinated dibenzodioxins (PCDDs). We used previously established techniques for analyzing intracellular Ca(2+) buffering and protein kinase C (PKC) translocation to test their biologic activity in neuronal preparations. PCB congener-specific analysis indicated that ortho and non-ortho congeners in these two lots varied in their percent contribution. Among all congeners, the percentages of non-ortho congeners (PCBs 77, 81, 126, and 169) were higher in lot 6024 (2.9% of total) than in lot 124-191 (0.02% of total). We detected no dioxins in these two lots (< 2 ppb). Although there are some differences in the congener composition, total PCNs were similar in both lots: 171 ppm in lot 6024 and 155 ppm in lot 124-191. However, total PCDFs were higher in lot 6024 (38.7 ppm) than in lot 124-191 (11.3 ppm). When we tested these two Aroclors on Ca(2+) buffering and PKC translocation in brain preparations, the effects were significantly different. Although lot 124-191 was more potent on PKC translocation than lot 6024, lot 6024 was slightly more active on Ca(2+) buffering than lot 124-191. These effects could not be attributed to the differences in the percentage of non-ortho congeners or PCDFs because they were inactive on these two parameters. The effects could not be attributed to PCNs because the levels were almost similar. The effects seen with two lots of Aroclor 1254 in neuronal cells were also not predicted based on the TCDD toxic equivalents (TEQs), although TEQs predicted the effects on ethoxyresorufin-O-deethylase (EROD) or methoxyresorufin-O-deethylase (MROD) activities. It is possible that the differential effects seen in neuronal cells could be caused by differences in the composition of ortho-congeners in these two mixtures, because PCBs with ortho-lateral substitutions can exhibit different activities on the selected neurochemical end points. Because of these differential effects with different lot numbers, the composition of Aroclor mixtures used in investigations should be disclosed.

Effects of dioxins and furans on liver enzymes, lipid parameters, and thyroid hormones in former thermal metal recycling workers.

A cross-sectional study was performed to examine the internal exposure of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDF) in former workers in a nonferrous metal recycling facility. Liver enzymes, lipid parameters, and thyroid hormones were measured to check possible biologic effects. Compared to background levels, the international toxicity equivalent levels of exposed workers were slightly elevated (median 42 ppt, range 13-281 ppt). The workers also had higher total PCDF concentrations (median 128 ppt, range 30-1138 ppt). Correlation analyses demonstrate significant associations with only one liver enzyme, alanine aminotransferase. There were no such associations with serum cholesterol levels or with serum thyroid hormones. Because of the cross-sectional design of the study, firm conclusions cannot be drawn. For further evaluation, a follow-up examination appears necessary.