Total Toxic Equivalents Research Articles

Concentrations of PCDD/PCDFs and PCBs in spent foundry sands

Approximately 10 million tons of spent foundry sand (SFS) are generated in the United States each year, and their beneficial use in agricultural and horticultural applications is being considered. Other studies have demonstrated that trace elements are low enough in sands from iron, steel, and aluminum foundries to allow their beneficial use. Because data were not available on polychlorinated dibenzo- p-dioxins, polychlorinated dibenzofurans, and polychlorinated biphenyls in SFSs, we analyzed representative spent sands from 10 foundries to assess the potential for these compounds to limit their use in soil-related applications. The total TEQ (toxicity equivalent) concentrations ranged from 0.01 to 3.13 ng TEQ kg −1, with an average concentration of 0.58 ng TEQ kg −1. These concentrations are within the range of natural background in soils.

A preliminary investigation on emission of polychlorinated dibenzo-p-dioxins/dibenzofurans and dioxin-like polychlorinated biphenyls from coke plants in China

Thermal related processes are widely recognized as the main sources of formation and emission of polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs) and polychlorinated biphenyls (PCBs). It is well known that, carbonization of coal in coke production involves many thermal reactions at high-temperature. However, there are still no strong evidences to identify coking processes as source of PCDD/Fs and PCBs. In this study, coke production was qualified and quantified for emission of PCDD/Fs and dioxin-like PCBs (dl-PCBs) in some typical coke plants in China. In the preliminary investigation, stack gases from three typical coke plants were collected, and dl-PCBs and 2378-substituted PCDD/Fs were analyzed by isotope dilution HRGC/HRMS technique. The total toxic equivalents of dl-PCBs and PCDD/Fs were in the range of 1.6–1785.4pg WHO-TEQNm−3. For dl-PCBs, the most abundant congener was CB-118, and the most dominant contributor to total WHO-TEQ of dl-PCBs was CB-126. With regard to PCDD/Fs, four congeners comprised of OCDD, 1234678-HpCDD, 1234678-HpCDF and OCDF were the predominant species in stack gases. Further investigation on the emission of dioxins from coking industry is still in process.

An Investigation of Homes with High Concentrations of PCDDs, PCDFs, and/or Dioxin-Like PCBs in House Dust

As part of the University of Michigan Dioxin Exposure Study, the 29 congeners of polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans, and dioxin-like polychlorinated biphenyls that have World Health Organization consensus toxic equivalency factors were measured in house dust from 764 homes using a population-based sampling design over selected regions in five Michigan counties. Twenty homes had a total toxic equivalency in house dust that was more than 2.5 standard deviations above the mean (i.e., defined to be outliers). This follow-up investigation describes the outlier house dust measurements and corresponding soil measurements and explores possible sources of these toxins in house dust. The congener distributions in the house dust outliers varied and were dominated (i.e., >50% of the total toxic equivalency) by either polychlorinated dibenzo-p-dioxins (n = 9), polychlorinated dibenzofurans (n = 1), or dioxin-like polychlorinated biphenyls (n = 9). Likely sources of contamination of house dust were identified in only three cases. In two cases, dust contamination appeared to be related to contaminated soil adjacent to the home; in one case, contamination was related to a source within the home (a carpet pad). In most cases, the source(s) of contamination of house dust could not be identified but appeared likely to be related to uncharacterized sources within the homes. [Supplementary materials are available for this article. Go to the publisher's online edition of the Journal of Occupational and Environmental Hygiene for the following free supplemental resource: a PDF file containing a summary of baseline and dust outlier interview questions and tables containing PCB, PCDD, and PCDF concentrations in various samples of house dust and soil.]

Levels in the U.S. Population of those Persistent Organic Pollutants (2003−2004) Included in the Stockholm Convention or in other Long-Range Transboundary Air Pollution Agreements

We report human serum levels of selected persistent organic pollutants (POPs) categorized by age, sex, and race/ ethnicity from a statistically representative sampling of the U.S. population during 2003 and 2004. The serum levels are for several chemicals listed in the Stockholm Convention on Persistent Organic Pollutants, in the Geneva Convention on Long-Range Transboundary Air Pollution, or in both. Population data for each chemical are described by geometric means and percentiles and are categorized by age, sex, and race/ ethnicity. At the 90th and 95th percentile, the dioxin total toxic equivalency (TEQ), using the 2005 toxic equivalency factors (TEFs) for all persons 12 years of age and older was 30.9 pg/g lipid (95% confidence interval (CI): 28.2-33.9 pg/g lipid) and 37.8 pg/g lipid (95% CI: 35.3-43.4 pg/g lipid), respectively. At both the 90th and 95th percentiles total TEQ increased significantly with increasing age. The population geometric mean (GM) for the total PCB concentration (sum of 35 congeners) for all persons 12 years of age and older was 0.820 ng/g whole-weight (95% CI: 0.782-0.863 ng/g whole-weight) and 134.4 ng/g lipid (95% CI: 128.9-140.0 ng/g lipid). The population 95th percentile for the total PCB concentration for all persons 12 years of age and older was 3.53 ng/g whole-weight (95% CI: 3.23-3.92 ng/g whole-weight) and 531 ng/g lipid (95% CI: 498-570 ng/g lipid). The concentrations of aldrin, endrin, gamma-HCH, and o,p'-DDT were <limit of detection for all strata in the U.S. population. Hexachlorobenzene was detected in 99.9% of the persons aged 12 years and older (GM: 15.2 ng/g lipid, 95% CI: 14.5-15.9 ng/g lipid). beta-HCH was detected in 69.5% of the persons aged 12 years and older (75th percentile: 14.0 ng/g lipid, 95% CI: 12.1-16.5 ng/g lipid). p,p'-DDT was detected in 73.8% of the persons aged 12 years and older (90th percentile: 11.9 ng/g lipid. 95% CI: 9.9-14.9 ng/g lipid). The DDT metabolite p,p'-DDE was detected in 99.7% of persons aged 12 years and older (GM: 238.4 ng/g lipid, 95% CI: 194.6-292.2 ng/g lipid). Oxychlordane(GM: 9.4 ng/g lipid, 95% CI: 8.7-10.1 ng/g lipid);transnonachlor (GM: 14.6 ng/g lipid, 95% CI: 13.1-16.5 ng/g lipid); and heptachlor epoxide (90th percentile: 13.4 ng/g lipid, 95% CI: 11.1-15.9 ng/g lipid) were detected in 82.9, 92.6, and 60% of persons aged 12 years and older, respectively. Mirexwas detected in 40.7% of persons aged 12 years and older (90th percentile: 8.3 ng/g lipid, 95% CI: <LOD-13.0 ng/g lipid). Dieldrin was detected in 87.2% of persons aged 12 years and older (95th percentile: 18.9 ng/g lipid, 95% CI: 15.8-24.5 ng/g lipid).

Dioxin Concentrations in Commercial Health Tea Materials in Japan

This study determinedthe concentrations ofpolychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and dioxin-like polychlorinated biphenyls (dioxin-like PCBs) in five selected plant materials [dokudami (from houttuynia herb), rose hip (from rosa fruit), ebisugusa (from cassia seed), rooibos, and tochu (from eucommia leaf)] used as health teas in Japan. The toxic equivalent (TEQ) levels for dioxins in the samples ranged from < 0.00 1t o0 .27 pg-TEQ/g weight, when undetectable and trace amounts were taken as zero. The mean of total TEQ level in commercial tea materials was estimated as 0.08 pg-TEQ/g (n = 5). The total TEQ in these samples was mainly dominated by the levels of PCDD/Fs (representing ca. 80% of the total TEQ).

Investigation of PCDD/Fs and dl-PCBs in fish from the southern Baltic Sea during the 2002–2006 period

Concentrations of polychlorinated dibenzo- p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and dioxin-like polychlorinated biphenyls (dl-PCBs) in the southern Baltic herring ( Clupea harengus), sprat ( Sprattus sprattus), and salmon ( Salmo salar) are reported. The significant interspecies and season-specific differences in PCDD/Fs and dl-PCBs concentrations were observed. The contribution of dl-PCBs to the total toxicity equivalents (TEQs) ranged between 50% and 70%, dependently on fish species. In all samples, concentrations of PCDF were higher in comparison with that of PCDD. The permissible limits of the content of PCDD/Fs and dl-PCBs (8 pg g −1 fresh weight for the sum of PCDD/Fs and dl-PCBs, and 4 pg g −1 fresh weight for the PCDD/Fs) were exceeded mainly in salmon samples (in 80% of salmon samples studied). The elevated levels of PCDD/F and dl-PCB were observed only in two of seventy two herring samples, and in ten of 62 sprat samples. The multiple regression analysis revealed that fish lipid content, and concentration of PCB 153, used simultaneously, might be useful in the prediction of TEQ values of fish samples. These two variables explained more than 80% of total variance. For all fish species studied, the correlation coefficients obtained with the multiple regression analysis were higher than that obtained with the regression analysis involving total TEQ values, and only one independent variable: fish lipid content.

Levels and Profiles of Polychlorinated Dibenzo-p-Dioxins, Polychlorinated Dibenzofurans, and Polychlorinated Biphenyls in Feedstuffs and Milk From Farms in the Vicinity of Incineration Plants in Tuscany, Italy

Levels of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and polychlorobiphenyls (PCBs) were determined in samples of bovine and ovine milk collected in farms located in the province of Grosseto, Tuscany, in the vicinity of two incineration plants as well as in farms located in areas with presumable background levels of contamination. Samples of feedstuffs of local origin used in the investigated farms were also collected and analysed. The cumulative levels of PCDDs, PCDFs, and dioxin-like PCBs (DL-PCBs) in feedstuffs ranged from 0.25 to 0.61 pg WHO-TE/g fresh weight (fw) in the farms under impact from incinerator emissions and from 0.21 to 0.34 pg WHO-TE/g fw in the control area farms. The sums of the six non-dioxin-like indicator PCB (NDL-PCB) congeners were 0.13 to 9.3 ng/g fw and 1.2 to 1.9 ng/g fw, respectively. In milk samples, the levels detected were 0.71 to 2.9 pg WHO-TE/g fat and 0.52 to 0.59 pg WHO-TE/g fat in farms under impact from the incinerators and in the control area farms, respectively. The corresponding sums of the six indicator PCB congeners were 1.4 to 8.2 ng/g fat and 0.90 to 1.6 ng/g fat. In all samples, contamination levels were below the limits set by the European Community (EC; Commission Directive 2006/13/EC and Commission Regulation 1881/2006/EC.) No relevant differences were found between samples collected in potentially exposed areas and control areas for total toxic equivalents and cumulative analytic levels of PCDDs, PCDFs, DL-PCBs, and NDL-PCBs (p > 0.05, Mann-Whitney U test). Observed levels were in agreement with those found in other countries in areas with background levels of exposure. Congener levels and profiles of PCDDs, PCDFs, and PCBs in feedstuffs and milk samples that were compared describe congener-specific transfer behavior.

Serum dioxins, polychlorinated biphenyls, and endometriosis: A case-control study in Atlanta

Endometriosis among women of reproductive age can result in pain and infertility. The objectives of this study were to test if there is a relation between endometriosis and serum dioxin concentrations as expressed by total toxic equivalence and serum total polychlorinated biphenyl concentrations among women patients at one Atlanta reproductive medicine clinic during 1998–1999; a secondary objective was to provide exposure data for individual congeners of these chemicals and 1,1-dichloro-2,2-bis(4-chlorophenyl)ethane ( p, p′-DDE) in women in Atlanta. Laparoscopy including biopsy and visualization of the peritoneal cavity, ovaries, outside of the fallopian tubes and uterus confirmed all endometriosis cases ( n = 60) and confirmed 30 controls without endometriosis. Other controls had an infertile partner ( n = 27) or ovulation problems ( n = 7) with no signs or symptoms of endometriosis. All serum samples were analyzed at the U.S. Centers for Disease Control and Prevention in 2003. Statistical analyses included Fisher’s exact chi-square tests and logistic regression. Models were presented for the full study sample and for the subset that included all cases ( n = 60) and only controls ( n = 30) with surgical confirmation of disease-free status. Serum concentrations (lipid-adjusted and non lipid-adjusted) of analyzed exposure measures were low and similar for cases and controls and did not explain endometriosis in the study population.

Prevalence of Metabolic Syndrome Associated with Body Burden Levels of Dioxin and Related Compounds among Japan’s General Population

BackgroundEnvironmental exposure to some persistent organic pollutants has been reported to be associated with a metabolic syndrome in the U.S. population.ObjectivesWe evaluated the associations of body burden levels of dioxins and related compounds with the prevalence of metabolic syndrome among the general population in Japan.MethodsWe conducted a cross-sectional study with 1,374 participants not occupationally exposed to these pollutants, living throughout Japan during 2002–2006. In fasting blood samples, we measured biochemical factors and determined lipid-adjusted concentrations of 10 polychlorinated dibenzo-p-dioxins (PCDDs), 7 polychlorinated dibenzofurans (PCDFs), and 12 dioxin-like poly-chlorinated biphenyls (DL-PCBs) all of which have toxic equivalency factors. We also performed a questionnaire survey.ResultsThe toxic equivalents (TEQs) of PCDDs, PCDFs, and DL-PCBs and total TEQs had significant adjusted associations with metabolic syndrome, whether or not we excluded diabetic subjects. By analyzing each component of metabolic syndrome separately, the DL-PCB TEQs and total TEQs were associated with all components, and the odds ratios (ORs) in the highest quartile of DL-PCB TEQs in four of the five components were higher than those for PCDDs or PCDFs. We also found congener-specific associations with metabolic syndrome; in particular, the highest quartiles of PCB-126 and PCB-105 had adjusted ORs of 9.1 and 7.3, respectively.ConclusionsThese results suggest that body burden levels of dioxins and related compounds, particularly those of DL-PCBs, are associated with metabolic syndrome. Of the components, high blood pressure, elevated triglycerides, and glucose intolerance were most closely associated with these pollutants.

Exposure to dioxin-like pollutants via different food commodities in Swedish children and young adults

The dietary intake of polychlorinated dibenzo- p-dioxins (PCDDs), dibenzofurans (PCDFs) and biphenyls (PCBs) in terms of toxic equivalents (TEQs) was investigated in Swedish children and young adults. Exposure was estimated from concentration data of six groups of individual food commodities (meat, fish, dairy products, egg, edible fats and other foodstuff) combined with food intake data from a 7-day record book obtained from 670 individuals aged 1–24 years. The results showed that Swedish boys and girls, up to the age of ten, had a median TEQ intake that exceeded the tolerable daily intake (TDI) of 2 pg TEQ/kg body weight. Children exceeding the TDI varied from almost all individuals among the youngest children to about 20% among young men and women. Dairy and fish products were the main sources of exposure for the average child, accounting for 59% of the total TEQ intake. The individuals most highly exposed were, on the other hand, characterized by a high consumption of fish. Since children constitute a vulnerable group, results obtained from the present study show that it is essential to perform age specific dietary intake assessments of pollutants and more carefully consider sensitive and/or highly exposed groups in the population in the risk management processes.

Human exposure to PCDDs, PCDFs and dioxin-like PCBs associated with seafood consumption in Korea from 2005 to 2007

Concentrations of polychlorinated dibenzo- p-dioxins and dibenzofurans (PCDD/Fs) and dioxin-like polychlorinated biphenyls (DLPCBs) were measured in 26 seafoods commonly consumed by the Korean population. The total toxic equivalent (TEQ) concentrations in seafood samples ranged from 0.01 to 6.76 pg TEQ/g wet wt, which were comparable with those found in other countries. The predominant congeners found in seafood samples were 2, 3, 4, 7, 8-PeCDF and 2, 3, 7, 8-TCDF for PCDD/Fs and PCB 118 for DLPCBs. Dietary intakes of PCDD/Fs and DLPCBs from seafood consumption were estimated for various age groups and gender in Korea. The dietary intake of PCDD/Fs and DLPCBs from seafood consumption for the general population was estimated to be 1.23 pg TEQ/kg bw/day, values that are in the range of those reported for other countries. Mackerel, tuna and hairtail contributed to the highest TEQ intakes, which collectively accounted for 66% of the total intake. Among the eight age groups investigated, 3–6 year old children had the highest TEQ exposure, followed by 50–64 years, 30–39 years and < 2 years. Considering contributions of seafood consumption to the total dietary intake studies, the dietary TEQ intakes to the general population appear to be below the threshold values by international organizations. The present study may be useful for risk management for dioxins and dioxin-like contaminants in Korean seafood.

PCDDs/PCDFs and dioxin-like PCBs: Recent body burden levels and their determinants among general inhabitants in Japan

Objective The objective was to grasp the recent body burden levels of polychlorinated dibenzo- p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and dioxin-like polychlorinated biphenyls (DL-PCBs) and to investigate their determinants among general inhabitants in Japan. Methods This study was performed on 1374 participants aged 15–73 years, who were not occupational exposure to PCDDs/PCDFs and DL-PCBs, living widely in 75 different residential areas of 25 prefectures in Japan. Seven PCDDs, ten PCDFs, twelve DL-PCBs, which are assigned a toxicity equivalent factor, and biochemical factors were determined in fasting blood. A questionnaire survey on life-style was also performed. Results The median of total toxicity equivalent (TEQ) was 20 pg TEQ/g lipid. The TEQs of PCDDs/PCDFs, DL-PCBs and total TEQ increased with age. The intake frequency of fish-and-shellfish was positively associated with the TEQ of DL-PCBs in both sexes. Current smoking was negatively related to the TEQ of DL-PCBs in male subjects but not in female subjects. Feeding status was significantly related to the TEQs of PCDDs/PCDFs, DL-PCBs and total TEQ, being lowest in breast feeding and highest in never and bottle feeding. According to the results of subgroup analysis, parity was not associated with the TEQs. Conclusions The fish-and-shellfish consumption may contribute to the accumulation of DL-PCBs, and smoking may induce some biological action for the elimination of DL-PCBs from the human body. Breast feeding is considered to be one of the major excretory pathways of PCDDs/PCDFs and DL-PCBs in women, while parity may not largely contribute to the elimination of these pollutants.

TEQ S and body burden for PCDDs, PCDFs, and dioxin-like PCBs in human adipose tissue

Polychlorinated dibenzo- p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), mono- ortho and non- ortho polychlorinated biphenyls (dioxin-like PCBs) were determined in samples of human fat tissue from nine Italian obese patients. The toxicity equivalent (TEQ) values ranged from 9 to 25 pg TEQ g −1 lipid (WHO-TEF values, 2005 [Van den Berg, M., Birnbaum, L.S., Denison, M., De Vito, M., Farland, W., Feeley, M., Fiedler, H., Hakansson, H., Hanberg, A., Haws, L., Rose, M., Safe, S., Schrenk, D., Tohyama, C., Tritscher, A., Tuomisto, J., Tysklind, M., Walker, N., Peterson, R.E., 2006. The 2005 World Health Organization reevaluation of human and mammalian Toxic Equivalency Factors for dioxins and dioxin-like compounds. Toxicol. Sci. 93, 223–241]), the contribution of dioxin-like PCBs was more than 30% of the total TEQ values. The obese body burdens varied from 6 to 11 ng TEQ kg −1 body weight (BW), exceeding the estimated steady-state body burden 5 ng TEQ kg −1 BW, based on lipid adjusted serum concentrations from several populations in the mid-1990s, calculated in the risk assessment US EPA document.

Detection and quantitative analysis of polychlorinated biphenyls in tilapia from Hawaiian waters

The purpose of this study was to investigate polychlorinated biphenyls (PCBs) contamination in tilapia ( Oreochromis mossambicus) collected from the Manoa stream and Ala Wai Canal of O’ahu, an island of the geographically isolated Hawaiian archipelago. Our results show that the average concentrations of PCBs varied from 51.90 to 89.42 ng g −1 lipid weight for the sampling sites. Relative toxic potencies (RTPs) and toxic equivalencies (TEQs) were determined to be 20.38–40.60 ng TCDD g −1 lipid weight and 2.89–4.17 ng TEQ g −1 lipid weight by 7-ethoxy-resorufin- O-deethylase (EROD) activity analysis and calculation of PCB concentrations based on toxic equivalency factors (TEFs), respectively. Penta-chlorinated congeners were found to be predominant, which revealed that Aroclor 1254 was a possible major source of PCBs in our fish samples. PCB 118, an indicator PCBs, constituted more than 55% and 30% of the total PCBs and TEQs, respectively. In addition, PCB 118 was found to have a linear correlation to the total PCBs ( R = 0.975) and TEQs ( R = 0.782). Detection of concentrated PCBs in Hawaiian waters suggests a potentially adverse impact of this pollutant on human health, as well as ecological systems, and suggests the necessity of environmental monitoring and hazard assessment of PCBs within the Hawaiian Islands.

Total TEQ reference range (PCDDs, PCDFs, cPCBs, mono-PCBs) for the US population 2001–2002

We report reference ranges for the total toxic equivalency (TEQ) and TEQ sub-fractions of polychlorinated dibenzo- p-dioxins (PCDDs), dibenzofurans (PCDFs), coplanar biphenyls (cPCBs), and mono-ortho-substituted biphenyls (mPCBs) in a statistically designed sampling of the US population in 2001–2002. The TEQ and TEQ sub-fractions have been stratified by age, sex, and race/ethnicity. The TEQ levels are lower using the 2005 toxic equivalency factors (TEFs) compared to using the 1998 TEF values, principally due to the much lower 2005 TEF values assigned to the mPCBs. Mexican Americans (MA) have significantly lower TEQ levels than both non-Hispanic whites (NHW) and non-Hispanic blacks (NHB). Using the 1998 or 2005 TEF values, males and females have nearly the same distribution of TEQ sub-fractions. We found a significant increase in TEQ levels with age for males, females, and NHW. About 80–90% of the total TEQ can be estimated by using seven congeners, namely 2,3,7,8-TCDD, 1,2,3,7,8-PeCDD, 1,2,3,6,7,8-HxCDD, 2,3,4,7,8-PeCDF, PCB-126, PCB-118, and PCB-156. We also measured geometric mean TEQ levels in pooled samples from the US population. The geometric mean TEQ levels also increase with age. In the youngest age group (12–19 years), the TEQ levels were higher in males than in females while females had higher TEQ levels than males in all older age groups. In the pools, as age increases the percent contribution of the PCDD TEQ levels increases while the percent contribution of the PCDF TEQ levels decreases for all race/ethnicity and sex strata.

Development of human dermal epithelial cell-based bioassay for the dioxins

None of bioassays is complete for assessing biological impact in humans upon the xenobiotic exposure due to species and organ-specific responsiveness. Thus, it is speculated that the human cell-based bioassay may be more appropriate system because of its direct relevance to humans. Here, we have developed a human epidermal cell-based bioassay for the dioxins and related compounds. The AD12-SV40-immortalized human keratinocyte cell line was stably transfected with a recombinant expression vector which contains the luciferase gene under dioxin-inducible control of four DREs. The tansfectants showed a consistent dose–response of luciferase activity upon dioxin exposure even after 120 passages. The maximal half effective dose (EC 50) was 200 pM with a maximum of 32-fold induction of luciferase activity at 5 nM. The minimum detection limit was 10 pM. Optimal exposure time for the assay was 24 h. When cells were treated with aryl hydrocarbon receptor agonists of different toxic equivalent factor (TEF) values, the shape of the dose–response curve for each compound was parallel to that of TCDD and the maximum response was similar, indicating that this bioassay system can be applied to generate the total toxic equivalency (TEQ) estimate from the samples. When relative induction potency of luciferase activities for each compound was calculated, it was similar to WHO-TEF values within an order of magnitude. This human cell system can be used as an efficient screening tool to quantify the TEQ values of dioxin-like chemicals in the samples and may help understand the interspecies difference between humans and animals.

Uncertainty analysis of dioxin‐like polychlorinated biphenyls–related toxic equivalents in fish

The toxic equivalent (TEQ) concept is widely used to assess toxicity potential of a dioxin-like chemical mixture. The TEQ approach converts concentrations of various dioxin-like compounds into a single concentration that is toxicologically equivalent to the most toxic dioxin compound, 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD), using toxic equivalency factors (TEFs). It has been shown that in the absence of costly measurements of dioxin-like polychlorinated biphenyls (dl-PCBs) in fish, relatively inexpensive measurements of total PCB can be utilized to estimate dl-PCB-related TEQ (i.e., TEQ(dl-PCB)). The present study assesses the impacts of uncertainties in dl-PCB measurements and estimates, and mammalian TEFs on TEQ(dl-PCB) using the Monte Carlo technique. The analysis suggests that measurement errors for dl-PCBs translate into up to 1.3-fold uncertainty in TEQ(dl-PCB), while uncertainties in estimates of dl-PCBs generally produce up to a threefold uncertainty in TEQ(dl-PCB). In contrast, the uncertainty due to TEFs normally ranges 10- to 13-fold and spans over 30- to 40-fold under extreme cases. For 2005 TEFs, PCB-126 is the dominating contributor to uncertainty in TEQ(dl-PCB). When we considered uncertainties in the TEFs and estimated dl-PCB concentrations simultaneously, there was little increase in uncertainty in TEQ(dl-PCB) that was already produced by the TEFs only. These results indicate that the dl-PCB composition in fish and/or the relationship between total PCB and TEQ(dl-PCB) can be utilized to estimate TEQ(dl-PCB) with reasonable confidence.

Relationship between insulin sensitivity and exposure to dioxins and polychlorinated biphenyls in pregnant women

The aim of this study was to examine the relationship between insulin sensitivity and polychlorinated biphenyls (PCBs) exposure in non-diabetic pregnant women. Forty gravidas, 21–39 years of age and residing within the study area, were recruited. Seventeen 2,3,7,8-substituted dichloro- p-dioxin, dibenzofurans and 12 PCBs were measured using high-resolution gas chromatography/high-resolution mass spectrometry (HRGC/HRMS). Serum insulin and glucose were also measured. Insulin sensitivity and the quantitative insulin sensitivity check index (QUICKI) were calculated based on fasting glucose and insulin levels. Three specific congeners of PCBs (123, 126, and 169) were significantly associated with insulin activity ( r=−0.34∼−0.36, p<0.05). Statistical analyses revealed that insulin sensitivity was significantly associated with age- and pre-pregnancy body mass indices (BMI)-adjusted for decreasing toxic equivalents (TEQ) of PCBs ( p=0.02 for age- and BMI-adjusted). We also performed an insulin correlation for total TEQ and the TEQ of PCBs, and determined that insulin sensitivity was predicted by the TEQ of PCBs by a regression coefficient of −0.189 after adjustment for age and pre-pregnancy BMI. These findings suggest that PCBs may be associated with decreasing insulin sensitivity in non-diabetic pregnant women; however, the mechanism remains to be ascertained.

Improved accuracy in the determination of polycyclic aromatic hydrocarbons in air using 24 h sampling on a mixed bed followed by thermal desorption capillary gas chromatography–mass spectrometry

A new sampling method for the determination of polycyclic aromatic hydrocarbons (PAHs) in ambient air is described. The method is based on active sampling on sorption tubes consisting of polydimethylsiloxane (PDMS) foam, PDMS particles and a TENAX TA bed. After sampling, the solutes are quantitatively recovered by thermal desorption and analysed by capillary GC–MS. The new sampling method has been compared to the classical method using high-volume sampling on a glass fiber filter followed by polyurethane foam for 24 h sampling of ambient air. Volumes enriched were 144 l on the mixed bed and 1296 m 3 with the classical method. The concentrations measured using the new method were significantly higher that the values obtained using the classical method, i.e. a factor 1.2–3 for the high molecular weight PAHs and up to 35 times for naphthalene and 23 times for acenaphthene. The total toxicity equivalence value (TEQ) for PAHs was ca. two times higher compared to the conventional method, illustrating that the concentrations of PAHs in ambient air have been underestimated until now. Some figures of merit (mean value for 17 PAHs) of the method are repeatability 7.4%, detection limit 13 pg/m 3, accuracy 105.6% and linearity 0.996. The method also opens interesting perspectives for the determination of other semi-volatile persistent organic pollutants (POPs) in air as illustrated with the analysis of polychlorinated biphenyls (PCBs) at a workplace during removal of transformer oil.

Tissue‐dependent distribution and bioaccumulation of polychlorinated dibenzo‐p‐dioxins and dibenzofurans in vegetation samples collected from Dongting Lake, China

The concentration of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) were determined in soils and different species of vegetation collected from the Dongting Lake region, China. Use of sodium pentachlorophenate (Na-PCP) was the main contamination source of PCDD/Fs for soil/sediment and vegetation in the Dongting Lake region. Reed (Phragmitas communis Trin), Polygonum orientale L., and Artemisia selengensis Turcz ex Bess were selected as model plants to explore the pathway of PCDD/Fs transfer from contaminated soil to vegetation. In the vegetation tissue samples, the total international toxic equivalency values ranged from 0.14 to 1.64 pg international toxic equivalency/g dry weight with a mean value of 0.67 pg international toxic equivalency/g dry weight. Polychlorinated dibenzo-p-dioxins and dibenzofurans congener distribution and bioaccumulation varied among vegetation species. Polychlorinated dibenzo-p-dioxins and dibenzofuran levels in the leaves were found to be higher than those in the root and stem, which were affected considerably by volatilization from contaminated soil. Volatilization from polluted soil and subsequent sorption to leaves may be a significant pathway for contamination of vegetation in Dongting Lake region.