Congener profiles of PCBs and PCDD/Fs in Yucheng victims fifteen years after exposure to toxic rice-bran oils and their implications for epidemiologic studies

Transcriptomics provides insights into toxicological effects and molecular mechanisms associated with the exposure of Chinese mitten crab, Eriocheir sinensis, to dioxin

Dioxins are stable, ubiquitous, persistent, and halogenated environmental pollutants that have recently garnered increasing attention. This study constructed a microcosmic system to simulate the real breeding conditions of the Chinese mitten crab (Eriocheir sinensis) to evaluate the impact of environmental dioxins on these aquaculture animals. Histological observation and detection of antioxidant enzyme activities revealed that dioxin exposure for different durations substantially damaged the hepatopancreas of Chinese mitten crabs, increasing the enzymatic activities of total superoxide dismutase (T-SOD) and catalase (CAT) but decreasing that of malondialdehyde (MDA). We also obtained the gene expression profiles of the hepatopancreas corresponding to different periods of dioxin exposure using RNA-seq technology. Compared with the control group, 2999 and 941 differentially expressed genes (DEGs) corresponding to different periods of dioxin exposure were identified in the hepatopancreas. Enrichment analysis indicated that some pathways, such as those governing carbohydrate metabolism, fatty acid metabolism, and immune disease, also responded to dioxin exposure. Subsequently, we selectively analyzed DEGs involved in oxidoreductase activity, carbohydrate metabolic processes, and other processes, identifying that increased expression of Hsp70, Ldh, and Trx1 and decreased expression of Lgbp, Bgal1, and Acsbg2 were potentially caused by sensitivity to environmental dioxin exposure. Therefore, we contend that, although crabs exposed to unfavorable environmental pollutants, such as dioxin, may adapt via antioxidant and immune response modulation. However, continued dioxin exposure would disrupt such homeostatic restorative capabilities. Thus, this study may provide new insights into the toxicological effects exerted by dioxin on aquatic organisms, such as E. sinensis, as well as the mechanisms underlying such toxicity.

Comparison of the PCB serum levels among mother-child pairs in areas of Eastern Japan and Central Taiwan

Polychlorinated biphenyls (PCBs) have been prohibited for two decades in Japan and Taiwan. The aim of this study was to compare the PCB congeners in maternal and cord serum between two countries. Our study subjects were 248 and 100 mother-child pairs in Japan and Taiwan. The measured levels of 23 serum PCB congeners between two countries were analyzed using gas chromatography-electron capture negative ionization quadrupole mass spectrometry (GC-NICI-qMS). The statistical comparisons were conducted by Student's t-test and principal component analysis with further stratification by maternal age and parity. The maternal total PCBs levels in Japan (426 ± 244 pg/g wet wt) were significantly higher than those in Taiwan (254 ± 155 pg/g wet wt), and the similar results were found in cord total PCBs levels (97 ± 76 and 58 ± 87 pg/g wet wt). It showed different distributions of PCB congeners between two countries. Whether in maternal or cord serum, the CB138, CB153 and CB180 were the highest detectable congeners whether in Japan or Taiwan. And, the CB66, CB99, CB206 and CB209 were only detected in maternal serum of Taiwan. The women of advanced maternal age had higher levels of PCB congeners, especially in Taiwan, and the primiparous women had higher levels of PCB congeners in two countries. In summary, the PCB congeners in Japan's mother-child pairs were with higher levels and different distributions when compared to those in Taiwan, and the maternal age and parity were important factors associated with the PCB levels.

Global status of dioxin emission and China's role in reducing the emission

The global status of dioxin emissions across 150 countries/regions were compiled in this study. China, the major emitter of dioxin and the largest developing country, was chosen as an example to illustrate its emission reductions. The global dioxin emissions were about 97.0 kg TEQ/year, Asia and Africa emitted the most dioxins among the continents. Globally, open burning processes were the most important sources of dioxins. Dioxin emissions in developed countries have remained at low and stable level, while those in developing countries have remained at relatively high level or have continued to increase in recent years. It can be speculated that the global dioxin emissions will increase first and then decrease in the future. Chinese dioxin emissions were stable around 9 kg toxic equivalent (TEQ) in recent years, while 17 subcategories are the key sources of dioxin control in the future. Moreover, according to analysis toward China's dioxin emission trend and sources, there is a large space for dioxins reduction in industries such as metal production, waste incineration and disposal. The results indicated that there is at least 30-70% of reduction scope in China based on three scenarios, and this will reduce the world's annual dioxin emissions by 2.7-6.8%.

Biomarkers of metabolic disorders and neurobehavioral diseases in a PCB- exposed population: What we learned and the implications for future research

Polychlorinated biphenyls (PCBs) are one of the original twelve classes of toxic chemicals covered by the Stockholm Convention on Persistent Organic Pollutants (POP), an international environmental treaty signed in 2001. PCBs are present in the environment as mixtures of multiple isomers at different degree of chlorination. These compounds are manmade and possess useful industrial properties including extreme longevity under harsh conditions, heat absorbance, and the ability to form an oily liquid at room temperature that is useful for electrical utilities and in other industrial applications. They have been widely used for a wide range of industrial purposes over the decades. Despite a ban in production in 1979 in the US and many other countries, they remain persistent and ubiquitous in environment as contaminants due to their improper disposal. Humans, independent of where they live, are therefore exposed to PCBs, which are routinely found in random surveys of human and animal tissues. The prolonged exposures to PCBs have been associated with the development of different diseases and disorders, and they are classified as endocrine disruptors. Due to its ability to interact with thyroid hormone, metabolism and function, they are thought to be implicated in the global rise of obesity diabetes, and their potential toxicity for neurodevelopment and disorders, an example of gene by environmental interaction (GxE). The current review is primarily intended to summarize the evidence for the association of PCB exposures with increased risks for metabolic dysfunctions and neurobehavioral disorders. In particular, we present evidence of gene expression alterations in PCB-exposed populations to construct the underlying pathways that may lead to those diseases and disorders in course of life. We conclude the review with future perspectives on biomarker-based research to identify susceptible individuals and populations.

Neuroimaging signatures of brain plasticity in adults with prenatal exposure to polychlorinated biphenyls: Altered functional connectivity on functional MRI

Prenatal exposure to polychlorinated biphenyls (PCBs), persistent organic pollutants in food chains and environment, exerts negative effects on children's cognitive function. To study the long-term effects, we examined cognitive functions in the male children of women with substantial PCB exposure in Taiwan during 1978-1979 and investigated neural basis of cognitive function changes through structural magnetic resonance imaging (MRI) and functional MRI (fMRI), which included resting-state and task-activated fMRI with two paradigms: a 2-back task and a picture rotation task. Ten men aged 30.0 ± 3.7 years with prenatal exposure to PCBs and 11 unexposed controls aged 28.1 ± 3.1 years participated. Both groups had similar cognitive phenotypes and behavioral results. Structural MRI analysis results showed that the PCB group had increased cortical thickness over the right inferior parietal lobule. In the resting-state study, the PCB group showed alterations in the default mode network. During the tasks, the PCB group showed decreased task-induced deactivation signals in cognition-associated brain areas during the 2-back task but enhanced deactivations during the picture rotation task. This study demonstrated altered structural MRI as well as resting and task-related fMRI in men with prenatal PCB exposure, suggesting altered brain plasticity and compensatory neuropsychological performance.

Concentrations, spatial distributions, and congener profiles of polychlorinated dibenzo-p-dioxins and dibenzofurans around original plastic solid waste recovery sites in China

The concentrations, profiles, and spatial distributions of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in soil and sediment samples from several typical plastic solid waste (PSW) recovery sites (particularly from areas in which PSW is burned openly) in China were investigated. The results showed that burning PSW directly influenced PCDD/F concentrations immediately around the burning area. All of the samples in which soil contained black burning residue, collected from immediately around burning areas, had PCDD/F concentrations (mean 21708 ng kg^-1) and toxic equivalent (TEQ) concentrations (mean 2140 ng I-TEQ kg^-1 or 1877 ng WHO₂₀₀₆-TEQ kg^-1) more than 100 times higher than the concentrations in samples collected away from burning areas (mean 222 ng kg^-1, 8.75 ng I-TEQ kg^-1, 7.96 ng WHO₂₀₀₆-TEQ kg^-1). Principal component analysis and hierarchical cluster analysis indicated that the PCDD/F concentrations in seven soil samples from near PSW burning areas were influenced by PSW burning but that the PCDD/Fs in these soil samples may have had other or multiple sources. PCDD/F distributions at PSW recovery sites have been investigated in few previous studies. The results presented here indicate that appropriate measures should be taken to decrease the ecological risks posed by PSW recovery and to prevent, control, and remediate PCDD/F and other chemical contamination caused by PSW recovery.

Risk for animal and human health related to the presence of dioxins and dioxin-like PCBs in feed and food

The European Commission asked EFSA for a scientific opinion on the risks for animal and human health related to the presence of dioxins (PCDD/Fs) and DL-PCBs in feed and food. The data from experimental animal and epidemiological studies were reviewed and it was decided to base the human risk assessment on effects observed in humans and to use animal data as supportive evidence. The critical effect was on semen quality, following pre- and postnatal exposure. The critical study showed a NOAEL of 7.0 pg WHO2005-TEQ/g fat in blood sampled at age 9 years based on PCDD/F-TEQs. No association was observed when including DL-PCB-TEQs. Using toxicokinetic modelling and taking into account the exposure from breastfeeding and a twofold higher intake during childhood, it was estimated that daily exposure in adolescents and adults should be below 0.25 pg TEQ/kg bw/day. The CONTAM Panel established a TWI of 2 pg TEQ/kg bw/week. With occurrence and consumption data from European countries, the mean and P95 intake of total TEQ by Adolescents, Adults, Elderly and Very Elderly varied between, respectively, 2.1 to 10.5, and 5.3 to 30.4 pg TEQ/kg bw/week, implying a considerable exceedance of the TWI. Toddlers and Other Children showed a higher exposure than older age groups, but this was accounted for when deriving the TWI. Exposure to PCDD/F-TEQ only was on average 2.4- and 2.7-fold lower for mean and P95 exposure than for total TEQ. PCDD/Fs and DL-PCBs are transferred to milk and eggs, and accumulate in fatty tissues and liver. Transfer rates and bioconcentration factors were identified for various species. The CONTAM Panel was not able to identify reference values in most farm and companion animals with the exception of NOAELs for mink, chicken and some fish species. The estimated exposure from feed for these species does not imply a risk.

Fetal exposure markers of dioxins and dioxin-like PCBs

Fetal exposure to polychlorinated biphenyls (PCBs), polychlorinated-p-dibenzodioxins (PCDDs), and polychlorinated dibenzofurans (PCDFs) have been associated with a number of adverse health outcomes. Although the placenta acts as a barrier between the mother and the fetus, these contaminants transfer through the placenta exposing the fetus. Several studies have investigated placental transfer, but few have assessed the co-variation among these contaminants. Maternal blood, cord blood, and cord tissue were collected from 41 Japanese mother-infant pairs and analyzed for dioxin-like PCBs and PCDD/Fs. Hierarchical cluster analysis followed by principal component analysis were used to assess the co-variation. Two stable clusters of dioxin-like PCBs were found in maternal and cord blood. One cluster of low/medium chlorinated dioxin-like PCBs was present in all three matrices with 2,3',4,4',5-PeCB(#118) and 3,3',4,4',5-PeCB(#126) explaining the majority of the clusters' variances. Medium/high chlorinated dioxin-like PCBs clustered in maternal blood and cord blood but not in cord tissue. 2,3,4,4',5-PeCB(#114) and 2,3,3',4,4',5,5'-HpCB(#189) explained the majority of the clusters' variances. There was a substantial correlation between the sum of dioxin-like PCBs and total PCDD/F in all three matrices. The sum of the four suggested PCBs plus 3,3',4,4'-TeCB(#77) correlated well with total PCDD/F in all three matrices. Apart from the dioxin-like PCBs, little co-variation existed among the studied contaminants. The five PCBs can be used as fetal exposure markers for dioxin and dioxin-like PCBs in maternal and cord blood respectively. In cord tissue, more higher chlorinated dioxin-like PCBs need to be measured as well.

Do polychlorinated biphenyls cause cancer? A systematic review and meta-analysis of epidemiological studies on risk of cutaneous melanoma and non-Hodgkin lymphoma

In 2015 a IARC Working Group upgraded the classification of PCBs to Group 1 "Carcinogenic to humans", also on the basis of evidence from epidemiological studies showing an excess risk for melanoma. Increased risks for non-Hodgkin lymphoma (NHL) and breast cancer were also reported though the evidence was limited. However, some recent reviews of studies on PCB exposure and risk of cancer provided discrepant findings. Therefore, we re-evaluated the association between exposure to PCBs and risk of melanoma and NHL by a systematic review and meta-analysis. We retrieved 11 independent cohort studies on occupationally exposed workers. About half of them showed increased standardized mortality or incidence ratios (SMRs or SIRs) for melanoma and none for NHL. The pooled SMRs were 1.32 (95% CI: 1.05-1.64) for melanoma and 0.94 (0.73-1.23) for NHL. Among population-based cohort and case-control studies with individual measures of PCB exposure, one only study was carried out on PCB exposure and melanoma, showing an odds ratio (OR) of 6.0 (2.0-18.2) for the highest compared to lowest quartile of PCB distribution. 13 cohort and case-control studies evaluated the association between NHL and PCB concentration in blood or subcutaneous fat, with summary OR = 1.5 (1.1-1.7) for the highest vs lowest quantile of PCB distribution. However, two cohort studies on people intoxicated by rice oil containing PCBs found no excess of deaths for skin cancer and inconsistent results for NHL. In conclusion, these findings do not provide a strong evidence that PCB exposure can increase the risk of melanoma and NHL in humans.

Endocrine disrupting chemicals and ovulation: Is there a relationship?

Although the potential for endocrine disrupting chemicals (EDCs) to disrupt female fecundity is great, few studies have assessed the threat to human reproduction. This study investigates levels of organochlorines in relation to their impact on women's menstrual cycles and ovulatory status. To address concerns of the Akwesasne Mohawk community in upstate New York regarding well-established exposure to EDCs, women's fertility and reproductive health endpoints, we recruited 215 women between the ages of 21 and 38 years to measure menstrual cycle characteristics and levels of local pollutants. Of these, 155 women collected saliva over the course of their menstrual cycle allowing for analysis of estradiol and progesterone levels and the determination of ovulatory status in relationship to their serum pollutant levels. A subset of participants (15) who did not commence cycling within a month of their enrollment were not included in the analysis, hence reducing the sample size to 140 participants. Additionally, a lipid panel, estradiol and progesterone were assessed in serum on Day 3 of the menstrual cycle. Median cycle length for women in the sample was 29 days. After aligning the cycles, 110 women were considered ovulatory and 45 (29%) anovulatory. Concentrations of groups of more persistent PCBs congeners, HCB, and p,p'-DDE did not differ significantly with ovulatory status. However, a sub-group of low-chlorinated PCB congeners, considered to be estrogenic were significantly higher among anovulatory women. These findings suggest that certain EDC's, ubiquitous in our environment, may adversely affect menstrual cycles and thus have the capacity to impair reproductive function, including likelihood of conception.

Toxicological effects of polychlorinated biphenyls (PCBs) on freshwater turtles in the United States

Prediction of vertebrate health effects originating from persistent organic pollutants (POPs) such as polychlorinated biphenyls (PCBs) has remained a challenge for decades thus making the identification of bioindicators difficult. POPs are predominantly present in soil and sediment, where they adhere to particles due to their hydrophobic characteristics. Animals inhabiting soil and sediment can be exposed to PCBs via dermal exposure while others may obtain PCBs through contaminated trophic interaction. Freshwater turtles can serve as bioindicators due to their strong site fidelity, longevity and varied diet. Previous research observed the health effects of PCBs on turtles such as decreased bone mass, changed sexual development and decreased immune responses through studying both contaminated sites along with laboratory experimentation. Higher deformity rates in juveniles, increased mortality and slower growth have also been observed. Toxicological effects of PCBs vary between species of freshwater turtles and depend on the concertation and configuration of PCB congeners. Evaluation of ecotoxicological effects of PCBs in non-endangered turtles could provide important knowledge about the health effects of endangered turtle species thus inform the design of remediation strategies. In this review, the PCB presence in freshwater turtle habitats and the ecotoxicological effects were investigated with the aim of utilizing the health status to identify areas of focus for freshwater turtle conservation.

Interconversion between Methoxylated and Hydroxylated Polychlorinated Biphenyls in Rice Plants: An Important but Overlooked Metabolic Pathway

To date, there is limited knowledge on the methoxylation of polychlorinated biphenyls (PCBs) and the relationship between hydroxylated polychlorinated biphenyls (OH-PCBs) and methoxylated polychlorinated biphenyls (MeO-PCBs) in organisms. In this study, rice (Oryza sativa L.) was chosen as the model organism to determine the metabolism of PCBs in plants. Limited para-substituted 4'-OH-CB-61 (major metabolite) and 4'-MeO-CB-61 (minor metabolite) were found after a 5-day exposure to CB-61, while ortho- and meta-substituted products were not detected. Interconversion between OH-PCBs and MeO-PCBs in organisms was observed for the first time. The demethylation ratio of 4'-MeO-CB-61 was 18 times higher than the methylation ratio of 4'-OH-CB-61, indicating that formation of OH-PCBs was easier than formation of MeO-PCBs. The transformation products were generated in the roots after 24 h of exposure. The results of in vivo and in vitro exposure studies show that the rice itself played a key role in the whole transformation processes, while endophytes were jointly responsible for hydroxylation of PCBs and demethylation of MeO-PCBs. Metabolic pathways of PCBs, OH-PCBs, and MeO-PCBs in intact rice plants are proposed. The findings are important in understanding the fate of PCBs and the source of OH-PCBs in the environment.

Current skin symptoms of Yusho patients exposed to high levels of 2,3,4,7,8-pentachlorinated dibenzofuran and polychlorinated biphenyls in 1968

Yusho was a mass food poisoning event due to the ingestion of rice oil contaminated with polychlorinated biphenyls (PCBs) and various dioxins and dioxin-like compounds. At its outbreak in 1968, Yusho patients suffered severe skin symptoms. Although the blood concentrations of PCBs and dioxins, especially highly toxic 2,3,4,7,8-pentachlorinated dibenzofuran (2,3,4,7,8-PeCDF) remain high in these patients, extensive analysis has not been performed on their current skin symptoms. We categorized and evaluated the specific skin symptoms in Yusho in 2012 by grading their severity using an arbitrary scoring system, and analyzed their correlations with the blood concentrations of 2,3,4,7,8-PeCDF and PCBs. A total of 352 Yusho patients underwent annual dermatological check-ups, in which five skin symptoms: black comedones, acneiform eruptions, scar formation, pigmentation and nail deformity, were evaluated for their distribution and severity. Approximately one-third of Yusho patients still presented with black comedones, acneiform eruptions and scar formation; the distributions of these symptoms were similar to those at the time of the Yusho outbreak. The mean blood concentrations of 2,3,4,7,8-PeCDF and total PCBs in Yusho patients were still higher than those in controls. The prevalence and severity of black comedones were correlated with age. Severity scores of black comedones and scar formation were positively correlated with 2,3,4,7,8-PeCDF blood level, and those of black comedones, scar formation, and pigmentation were positively correlated with total PCBs blood level. This study suggests that 2,3,4,7,8-PeCDF and PCBs remaining in Yusho patients still play crucial roles in the development of skin symptoms in Yusho.

Developmental and reproductive effects of chemicals associated with unconventional oil and natural gas operations

Unconventional oil and gas (UOG) operations have the potential to increase air and water pollution in communities located near UOG operations. Every stage of UOG operation from well construction to extraction, operations, transportation, and distribution can lead to air and water contamination. Hundreds of chemicals are associated with the process of unconventional oil and natural gas production. In this work, we review the scientific literature providing evidence that adult and early life exposure to chemicals associated with UOG operations can result in adverse reproductive health and developmental effects in humans. Volatile organic compounds (VOCs) [including benzene, toluene, ethyl benzene, and xylene (BTEX) and formaldehyde] and heavy metals (including arsenic, cadmium and lead) are just a few of the known contributors to reduced air and water quality that pose a threat to human developmental and reproductive health. The developing fetus is particularly sensitive to environmental factors, which include air and water pollution. Research shows that there are critical windows of vulnerability during prenatal and early postnatal development, during which chemical exposures can cause potentially permanent damage to the growing embryo and fetus. Many of the air and water pollutants found near UOG operation sites are recognized as being developmental and reproductive toxicants; therefore there is a compelling need to increase our knowledge of the potential health consequences for adults, infants, and children from these chemicals through rapid and thorough health research investigation.

Polychlorinated biphenyls and cancer: an epidemiological assessment

Polychlorinated biphenyls (PCBs) are toxic and persistent chemicals produced between 1930s and 1980s primarily for insulating fluids in heavy-duty electrical equipment in power plants, industries, and large buildings. They persist in the environment and accumulate in plants and animals, and have been classified as probable carcinogens to humans. We performed a systematic review and meta-analysis of scientific literature on the relationship between PCB exposure and human cancer. Two cohorts of people highly exposed to PCBs through ingestion of contaminated rice oil and some cohorts of occupationally exposed workers failed to show a definite increase in total cancer mortality and provided inconsistent results regarding single cancers. Several cohort and case-control studies investigated the association between PCBs and specific cancers, showing an association between PCB serum levels and non-Hodgkin lymphomas (NHL), with a summary odds ratio of 1.5 (95% confidence interval: 1.1-1.7), but no consistent results for the other cancer sites and types. In conclusion, this review provides some evidence for the role of PCBs in the development of NHL, although the inconsistent results of studies performed on highly polluted people and occupationally exposed workers do not allow a firm conclusion to be drawn.

Coexposure of dioxin-like polychlorinated biphenyls and polychlorinated dibenzo-p-dioxins and dibenzofurans in free-range hens and implications derived from congener profile analysis

The consumption of free-range eggs is becoming more popular worldwide. We analyzed the levels of 12 dioxin-like polychlorinated biphenyls (dl-PCBs) and their congener profiles from 6 free-range and 12 caged egg samples. The mean levels of dl-PCBs in the free-range samples were 5.4 times higher than those in caged eggs. All egg samples exhibited at least two characteristic dl-PCB congener patterns, which reflected distinctive contamination sources. Additionally, for the first time, we demonstrated that the dl-PCB levels in the free-range eggs were highly correlated with elevated levels of 17 polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) (r = 0.986; p < 0.001), indicating a coexposure scenario in free-range hens. Cluster analysis of congener patterns implied that this coexposure scenario could be attributed to distinct dl-PCB and PCDD/F sources. This congener profile information provides insights from a different perspective for further identifying potential dl-PCB and PCDD/F sources in the polluted free-range eggs.

Relative importance of wastewater treatment plants and non-point sources of perfluorinated compounds to Washington State rivers

Perfluorinated compounds (PFCs) were measured in 10 Washington State rivers and 4 wastewater treatment plants (WWTPs) under periods of low and high flows to investigate the relative importance of point and non-point sources to rivers. PFCs were detected in all samples with summed values ranging from 1.11 to 74.9 ng/L in surface waters and 62.3-418 ng/L in WWTP effluent. Concentrations in 6 of the 10 rivers exhibited a positive relationship with flow, indicating runoff as a contributing source, with PFC loads greatest at all 10 waterbodies during high flows. Perfluoroheptanoic acid:perfluorooctanoic acid homologue ratios suggest atmospheric contributions to the waterbodies are important throughout the year. Principal component analysis (PCA) indicated distinct homologue profiles for high flow, low flow, and effluent samples. The PCA demonstrates that during the spring when flows and loads are at their greatest; WWTP discharges are not the primary sources of PFCs to the river systems. Taken together, the evidence provided signifies non-point inputs are a major pathway for PFCs to surface waters in Washington State.

An occupational exposure assessment of polychlorinated dibenzo-p-dioxin and dibenzofurans in firefighters

Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) are unintentional byproducts of combustion and industrial processes. Firefighters face the risk of occupational exposure to PCDD/Fs. Congener-specific analyses of 17 PCDD/Fs were performed on 20 serum samples collected from firefighters and fire scene investigators, and four soot samples that had deposited on the surfaces of the fire helmets and were collected after the firefighters had fought fires. The PCDD/F concentrations on the helmets that were contaminated by being worn at the fire scenes were 63-285 times higher than those on a clean helmet. The median serum PCDD/F concentration of the 16 firefighters (12 pg WHO(2005)-TEQ g(-1)lipid) was not different from those of the males from the general Taiwanese population (9.4 pg WHO(2005)-TEQ g(-1) lipid). However, the median PCDD/F level in the four fire scene investigators (15 pg WHO(2005)-TEQ g(-1) lipid) was higher than those in the male from the general Taiwanese population (Mann-Whitney U test, p<0.01). Furthermore, the serum samples from the firefighters and fire scene investigators, and the soot samples from the fire scenes presented similarly distinctive PCDD/F profiles that had elevated proportions for 10 PCDF congeners. Limited data indicated that the fire scene investigators were occupationally exposed to PCDD/Fs at the fire scenes. We suggested that the firefighters were not occupationally exposed to PCDD/Fs at the fire scenes due to appropriate protection. However, the fire scene investigators may have had more occupational exposure to PCDD/Fs due to poor protection, and further research must be performed to confirm this.

Age-dependent congener profiles of polychlorinated dibenzo-p-dioxins and dibenzofurans in the general population of Taiwan

A congener profile of polychlorinated dibenzo-p-dioxin and dibenzofurans (PCDD/Fs) could provide valuable information for identifying possible sources of exposure to these compounds. The purpose of this study is to identify factors associated with PCDD/F congener profiles in the general population of Taiwan. Serum samples from 251 subjects of the general population in Taiwan were collected, and the levels of 17 2,3,7,8-chlorinated substituted PCDD/Fs were measured. The relationships between PCDD/F congener profiles and demographic parameters were evaluated using a multivariate analysis of variance method (MANOVA). Of the five demographic factors investigated, age was found to have the greatest impact on PCDD/F congener profiles. The PCDD/F congener pattern for the group I subjects (aged 18-29) was significantly different from those for the other three older age groups (p<0.001), and 12 congeners contributed to the effects (difference index: 71%). In addition, the group I subjects did not exhibit trends parallel to those of the other groups in the relationship between age and PCDD/F levels. Age was associated with PCDD/F levels and congener profiles in the general population of Taiwan and the young subjects (aged 18-29) was quite different from the other older subjects that could be influenced by the individual differences in pharmacokinetics and/or background exposure from dietary sources. We conclude that investigators must consider subjects' age and other underlying factors that could influence PCDD/F congener profiles in humans when identifying exposure sources.

Elevated PCDD/F levels and distinctive PCDD/F congener profiles in free range eggs

Chicken eggs are one of the most important foods in the human diet all over the world, and the demand for eggs from free range hens has steadily increased. Congener-specific analyses of 17 polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) were performed on 6 free range and 12 caged chicken egg samples collected in Taiwan. The mean level of PCDD/Fs in the free range egg samples was 5.7 (1.79/0.314) times higher than those in the caged egg samples. Principle component analysis revealed that at least three characteristic patterns of PCDD/F congener were observed among the 18 egg samples. The different PCDD/F congener patterns between free range and caged egg samples may reflect distinctive exposure scenarios among the free range and caged hens. We suggest that the differences of PCDD/F levels and congener patterns between free range and caged egg samples give rise to the issues related to the safety of eating free range chicken eggs. The present data may provide useful information for further investigation of the possible PCDD/F sources in the contaminated free range eggs.

Concentrations of polychlorinated biphenyls in blood of Yusho patients over 35 years after the incident

We conducted a congener-specific analysis of polychlorinated biphenyls (PCBs) in blood collected from 242 Yusho patients (mean: 65.5 years, median: 67.0 years) and 74 Yusho-suspected persons (mean: 54.7 years, median: 55.0 years) in 2004, and compared each congener concentrations of PCBs among the groups of Yusho patients, Yusho-suspected persons, and normal controls (mean: 68.1 years, median: 67.0 years) with the concentrations previously reported. Among the 209 PCB congeners, 8 congeners of mono-ortho PCBs and 56 congeners of non-dioxin-like PCBs were identified in the blood of Yusho patients and Yusho-suspected persons. Among the PCB congeners measured in the present study, hexaCB-153, hexaCB-138, heptaCB-180, and heptaCB-182/heptaCB-187 showed high ratios to total concentrations of 64 PCB congeners detected in the blood of Yusho patients and Yusho-suspected persons, and the congener profiles were the same as those obtained in normal controls. The sums of the concentrations of 64 PCB congeners in the blood of Yusho patients and Yusho-suspected persons were 40-3032 (mean: 645, median: 536) and 20-1418 (mean: 355, median: 317) ng g(-1) lipid, respectively, and the concentrations were 50% higher and 20% lower than those of normal controls, respectively. The relative contribution ratios of the concentrations of the triCBs, tetraCBs, and pentaCBs to the total concentrations of 64 PCB congeners in the blood of Yusho patients were slightly lower than those of Yusho-suspected persons and normal controls, and the ratios of nonaCBs and decaCB-209 concentrations were nearly the same among the Yusho patients, Yusho-suspected persons, and normal controls. However, the ratios of the concentrations of hexaCBs, heptaCBs, and octaCBs to the total concentrations of 64 PCB congeners in the blood of Yusho patients tended to be slightly higher compared to those of the Yusho-suspected persons and normal controls. From the results comparing the concentrations of 64 PCB congeners in the blood between Yusho patients and normal controls, the concentrations of hexaCB-156, hexaCB-157, heptaCB-181, and heptaCB-189 of the Yusho patients were 3.4, 3.8, 3.9, and 3.8 times higher than those of the normal controls, respectively, indicating that even now, 35 years after exposure, Yusho patients still have a higher concentration of hexaCB-156, hexaCB-157, heptaCB-181, and heptaCB-189 in their blood than do unaffected people. These four congeners may be considered the most important congeners for evaluating the PCBs toxicity of Yusho patients.

Evaluation of background persistent organic pollutant levels in human from Taiwan: polychlorinated dibenzo-p-dioxins, dibenzofurans, and biphenyls

This study was intended to determine the background levels of PCDD/PCDFs and PCBs in the Taiwanese population and to investigate factors potentially related to PCDD/PCDF and PCB levels. The levels of seventeen PCDD/PCDFs in the 251 serum samples collected from the general population in Taiwan ranged from 4.92 to 26.7 pg WHO(1998)-TEQ/g lipid (median: 11.5) and those of the twelve dioxin-like PCBs ranged between 1.74 and 21.6 pg WHO(1998)-TEQ/g lipid (median: 6.14). Five factors, age, gender, region of residence, dietary status, and smoking status, showed statistically significant association with the TEQ level of PCDD/PCDFs. The TEQ level of PCBs was statistically associated with age only, but not with the other four factors. The trends observed between age and the levels of PCDD/PCDFs and PCBs were not parallel in young subjects (<30 years old) and old subjects (>30 years old). The levels of PCDD/PCDFs and PCBs increased by 0.16 and 0.03 WHO(1998)-TEQ/g lipid per year for subjects above the age of 30, but there was no evidence of any association between age and the levels for subjects below the age of 30 years. These factors should be considered when investigating relationships between background serum levels of persistent organic pollutants and parameters associated with exposure sources or health outcomes.

Increased risk of diabetes and polychlorinated biphenyls and dioxins: a 24-year follow-up study of the Yucheng cohort

OBJECTIVE

Polychlorinated biphenyls (PCBs) and polychlorinated dibenzofurans (PCDFs) are important and persistent organic pollutants (POPs) in humans. Recent cross-sectional studies have detected increased concentrations of serum POPs in diabetic patients. We aimed to examine the association between previous high exposures to PCBs and PCDFs and the cumulative incidence of type 2 diabetes and hypertension.

RESEARCH DESIGN AND METHODS

During the late 1970s, the consumption of rice-bran oil laced with PCBs poisoned thousands of Taiwanese. Between 1993 and 2003, we examined 1,054 Yucheng ("oil disease") victims against neighborhood reference subjects using a protocol blinded for POP exposure. Here, we report the results derived from 378 Yucheng subjects and 370 matched references.

RESULTS

The diabetes risk to members of the Yucheng cohort relative to their reference subjects was significantly increased for women (odds ratio [OR] 2.1 [95% CI 1.1-4.5]) but not for men after considering age, BMI, cigarette smoking, and alcohol intake. Yucheng women diagnosed with chloracne had adjusted ORs of 5.5 (95% CI 2.3-13.4) for diabetes and 3.5 (1.7-7.2) for hypertension compared with those who were chloracne free.

CONCLUSIONS

Yucheng women, who had endured previous exposure to PCBs and PCDFs, suffered from increased incidences of diabetes, particularly those who had retained significant levels of pollutant as evident from chloracne. When planning treatments against diabetes, the body burden of PCBs and dioxins should be carefully considered, especially for women.

Congener profiles of occupational PCB exposure versus PCB exposure from fish consumption

The composition of polychlorinated biphenyl (PCB) congeners in serum samples is compared between a cohort previously exposed to PCBs from working at a capacitor plant (n=180) and a cohort of Great Lakes sport-caught fish eaters (n=217). Fourteen congeners were measured in both samples. A multiple logistic regression model differentiating the two groups as a function of relative proportions amongst congeners 74, 138, 153, 180, and 201 correctly classifies more than 99% of the people (395/397); higher proportions of congeners 74, 153, and 201 characterize capacitor plant workers, while higher proportions of congeners 138 and 180 characterize fish eaters. The pattern is driven by the relative amounts of 74+153+201 compared to 138+180; all of the fish eaters, but only 5% of the capacitor plant workers, have a greater percent of 138+180 than 74+153+201. Consideration of combinations of congener levels and their relative proportions is relevant to tracking route of exposure and may also be relevant to modeling effects on health outcomes.

Dioxin and polychlorinated biphenyl analysis: Automation and improvement of clean-up established by example of spices

To analyze polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDDs/PCDFs) and polychlorinated biphenyls (PCBs) in spices by gas chromatography-mass spectrometry, a new clean-up method had to be developed owing to the high content of essential oils in the samples. A solid-phase extraction (SPE) column with activated silica endowed with sulfuric acid and sodium hydroxide was used. Under these conditions, clean-up was achieved using at least 5-7 g of pepper and even higher amounts of other spices. The automatized clean-up comprised three additional chromatographic steps after accelerated solvent extraction (ASE) followed by gel permeation: chromatography on a florisil SPE column, extract cleaning with the above-mentioned silica SPE column and chromatography with an activated charcoal column. On the basis of this automatized clean-up, a method that is more effective, rapid, simplified and economical than the available methods for PCDD/PCDF and PCB analysis is proposed. In model studies, the average recoveries for PCDDs/PCDFs ranged between 82.6% and 105.6% and for the PCBs between 71.3% and 113.3%.