A general model of dioxin contamination in breast milk: results from a study on 94 women from the Caserta and Naples areas in Italy.

BackgroundThe Caserta and Naples areas in Campania Region experience heavy environmental contamination due to illegal waste disposal and burns, thus representing a valuable setting to develop a general model of human contamination with dioxins (PCDDs-PCDFs) and dioxin-like-PCBs (dl-PCBs).Methods94 breastfeeding women (aged 19-32 years; mean age 27.9 ± 3.0) were recruited to determine concentrations of PCDDs-PCDFs and dl-PCBs in their milk. Individual milk samples were collected and analyzed according to standard international procedures. A generalized linear model was used to test potential predictors of pollutant concentration in breast milk: age, exposure to waste fires, cigarette smoking, diet, and residence in high/low risk area (defined at high/low environmental pressure by a specific 2007 WHO report). A Structural Equation Model (SEM) analysis was carried out by taking into account PCDDs-PCDFs and dl-PCBs as endogenous variables and age, waste fires, risk area and smoking as exogenous variables.ResultsAll milk samples were contaminated by PCDDs-PCDFs (8.6 pg WHO-TEQ/98g fat ± 2.7; range 3.8-19) and dl-PCBs (8.0 pg WHO-TEQ/98g fat ± 3.7; range 2.5-24), with their concentrations being associated with age and exposure to waste fires (p < 0.01). Exposure to fires resulted in larger increases of dioxins concentrations in people living in low risk areas than those from high risk areas (p < 0.01).ConclusionsA diffuse human exposure to persistent organic pollutants was observed in the Caserta and Naples areas. Dioxins concentration in women living in areas classified at low environmental pressure in 2007 WHO report was significantly influenced by exposure to burns

Distribution of Polychlorinated Biphenyls in Surface Waters of Various Sources from National Capital Region Delhi India

This paper presents the concentration of twenty eight polychlorinated biphenyls (PCBs) including twelve dioxin-like PCBs (dl-PCBs) congeners in surface water of rivers canals lakes ponds and drains from National Capital Region (NCR) Delhi (India). The total concentrations of 28 PCBs were ranged between 14-1768 ng L-1 with a mean of 332±42 ng L-1. The concentration of dl-PCBs was ranged between <1-146 ng L-1 with the mean of 40±4 ng L-1 and accounted 12% for total 28 PCBs. The toxicity equivalent calculated using WHO toxic equivalency factors (TEFs) was presented and discussed.  In terms of the homolog distribution it was dominated by 3–5 chlorinated biphenyls. The tetra-PCBs (65%) dominate the PCB homolog followed by tri-PCB (47%) and penta-PCB (21%). The concentrations were lower than the guideline values; however levels at some locations were higher. Further in-depth study is proposed to determine PCBs its bioavailability and bioaccumulation through tissues of aquatic biota to assess the risk of these contaminants on the ecosystems and human health more thoroughly. Keywords: polychlorinated biphenyls (PCBs) dioxin-like PCBs surface water Delhi Indi

Estimation of human health risk from polychlorinated biphenyls through consumption of fish from Black Sea, Bulgaria

INTRODUCTION: The present study evaluates the human daily intake of polychlorinated biphenyls (PCBs) through consumption of fish from the Black Sea, Bulgaria. The health risks were assessed using a risk quotient (RQ) of the fish consumption as the ratio of daily fish exposure level in relation to oral reference dose.MATERIALS AND METHODS: PCBs were determined in muscle tissue of four fish species widely consumed by the population of Bulgaria: goby (Neogobius cephalargoides), sprat (Sprattus sprattus), horse mackerel (Trachurus Mediterraneus ponticus) and shad (Alosa pontica pontica). Samples were collected from Bulgarian Black Sea coast during 2007 - 2011. The Indicator and dioxin-like PCBs were determined by capillary gas chromatography system with mass spectrometry detection.RESULTS: The sum of the six Indicator PCBs ranged from 7.2 to 27.3 ng/g ww (in goby and shad, respectively). The EDI of I-PCBs in fish from Black Sea was calculated between 1.36 and 5.14 ng/kg bw day through consumption of goby and shad, respectively. Dioxin - like PCBs were used in order to estimate the toxicity potential (TEQ) of PCB exposure. WHO-TEQs of the 6 `dioxin-like` PCB congeners were calculated from 0.03 pg TEQ/g ww (goby) to 0.28 pg TEQ/g ww (shad) and did not exceed the limit of 3 pg TEQ/g ww, according to European Commission.CONCLUSION: The estimated intake levels of dioxin-like PCBs in this study were several orders lower than their respective TDI for adults. The dietary intake of polychlorinated biphenyls through marine fish for the Bulgarian consumer does not pose a health risk

The Ah receptor: adaptive metabolism, ligand diversity, and the xenokine model

Author Posting. © American Chemical Society, 2020. This is an open access article published under an ACS AuthorChoice License. The definitive version was published in Chemical Research in Toxicology, 33(4), (2020): 860-879, doi:10.1021/acs.chemrestox.9b00476.The Ah receptor (AHR) has been studied for almost five decades. Yet, we still have many important questions about its role in normal physiology and development. Moreover, we still do not fully understand how this protein mediates the adverse effects of a variety of environmental pollutants, such as the polycyclic aromatic hydrocarbons (PAHs), the chlorinated dibenzo-p-dioxins (“dioxins”), and many polyhalogenated biphenyls. To provide a platform for future research, we provide the historical underpinnings of our current state of knowledge about AHR signal transduction, identify a few areas of needed research, and then develop concepts such as adaptive metabolism, ligand structural diversity, and the importance of proligands in receptor activation. We finish with a discussion of the cognate physiological role of the AHR, our perspective on why this receptor is so highly conserved, and how we might think about its cognate ligands in the future.This review is dedicated in memory of the career of Alan Poland, one of the truly great minds in pharmacology and toxicology. This work was supported by the National Institutes of Health Grants R35-ES028377, T32-ES007015, P30-CA014520, P42-ES007381, and U01-ES1026127, The UW SciMed GRS Program, and The Morgridge Foundation. The authors would like to thank Catherine Stanley of UW Media Solutions for her artwork

New WHO TEFs for dioxins and dioxin-like PCBs: Assessment of consequence of altered TEF values for dioxins and dioxin-like PCBs on current exposure in the Norwegian population

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Toxic equivalency factors (TEFs) for PCBs, PCDDs, PCDFs for humans and wildlife.

An expert meeting was organized by the World Health Organization (WHO) and held in Stockholm on 15-18 June 1997. The objective of this meeting was to derive consensus toxic equivalency factors (TEFs) for polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) and dioxinlike polychlorinated biphenyls (PCBs) for both human, fish, and wildlife risk assessment. Based on existing literature data, TEFs were (re)evaluated and either revised (mammals) or established (fish and birds). A few mammalian WHO-TEFs were revised, including 1,2,3,7,8-pentachlorinated DD, octachlorinated DD, octachlorinated DF, and PCB 77. These mammalian TEFs are also considered applicable for humans and wild mammalian species. Furthermore, it was concluded that there was insufficient in vivo evidence to continue the use of TEFs for some di-ortho PCBs, as suggested earlier by Ahlborg et al. [Chemosphere 28:1049-1067 (1994)]. In addition, TEFs for fish and birds were determined. The WHO working group attempted to harmonize TEFs across different taxa to the extent possible. However, total synchronization of TEFs was not feasible, as there were orders of a magnitude difference in TEFs between taxa for some compounds. In this respect, the absent or very low response of fish to mono-ortho PCBs is most noticeable compared to mammals and birds. Uncertainties that could compromise the TEF concept were also reviewed, including nonadditive interactions, differences in shape of the dose-response curve, and species responsiveness. In spite of these uncertainties, it was concluded that the TEF concept is still the most plausible and feasible approach for risk assessment of halogenated aromatic hydrocarbons with dioxinlike properties

Scientific Opinion on the presence of dioxins (PCDD/Fs) and dioxin-like PCBs (DL-PCBs) in commercially available foods for infants and young children

EFSA was asked by the Federal Institute for Risk Assessment (BfR) to deliver a scientific opinion on the presence of dioxins and dioxin-like polychlorinated biphenyls (DL-PCBs) in commercially available foods for infants and young children. It was requested to describe the relation of important parameters of the distribution of the occurrence data to the new EU maximum levels (MLs), and to assess whether these MLs are sufficient to aim to decrease the dietary exposure of infants and young children to dioxins and DL-PCBs. The CONTAM Panel did not perform an exposure or risk assessment, but evaluated whether the enforcement of the new EU MLs will result in a decrease in the concentration of dioxins and DL-PCBs in foods for infants and young children, and thus in a potential decrease in exposure of this population group. A total of 516 samples was included in the evaluation, reported by 13 European countries and covering the period 2003 to 2011. All accepted data (upper-bound) were below the current MLs for foods for infants and young children of 0.1 pg WHO2005-TEQ/g w.w. for dioxins and 0.2 pg WHO2005-TEQ/g w.w. for the sum of dioxins and DL-PCBs. Therefore, the CONTAM Panel concluded that, based on the available data, the current MLs are not an incentive to decrease the concentrations of dioxins and DL-PCBs in the relevant foods. From the reported data, it is not possible to conclude on any time trend concerning the dioxin and DL-PCB levels in foods for infants and young children. The Panel recommended that more occurrence data on representative samples are needed, particularly for those foods for infants and young children where only a few results are available so far. Moreover, the sensitivity of the analytical methods should be improved, if lower MLs were to be considered in the future

The 2005 World Health Organization Reevaluation of Human and Mammalian Toxic Equivalency Factors for Dioxins and Dioxin-Like Compounds

In June 2005, a World Health Organization (WHO)-International Programme on Chemical Safety expert meeting was held in Geneva during which the toxic equivalency factors (TEFs) for dioxin-like compounds, including some polychlorinated biphenyls (PCBs), were reevaluated. For this reevaluation process, the refined TEF database recently published by Haws et al. (2006, Toxicol. Sci. 89, 4-30) was used as a starting point. Decisions about a TEF value were made based on a combination of unweighted relative effect potency (REP) distributions from this database, expert judgment, and point estimates. Previous TEFs were assigned in increments of 0.01, 0.05, 0.1, etc., but for this reevaluation, it was decided to use half order of magnitude increments on a logarithmic scale of 0.03, 0.1, 0.3, etc. Changes were decided by the expert panel for 2,3,4,7,8-pentachlorodibenzofuran (PeCDF) (TEF = 0.3), 1,2,3,7,8-pentachlorodibenzofuran (PeCDF) (TEF = 0.03), octachlorodibenzo-p-dioxin and octachlorodibenzofuran (TEFs = 0.0003), 3,4,4′,5-tetrachlorbiphenyl (PCB 81) (TEF = 0.0003), 3,3′,4,4′,5,5′-hexachlorobiphenyl (PCB 169) (TEF = 0.03), and a single TEF value (0.00003) for all relevant mono-ortho-substituted PCBs. Additivity, an important prerequisite of the TEF concept was again confirmed by results from recent in vivo mixture studies. Some experimental evidence shows that non-dioxin-like aryl hydrocarbon receptor agonists/antagonists are able to impact the overall toxic potency of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and related compounds, and this needs to be investigated further. Certain individual and groups of compounds were identified for possible future inclusion in the TEF concept, including 3,4,4′-TCB (PCB 37), polybrominated dibenzo-p-dioxins and dibenzofurans, mixed polyhalogenated dibenzo-p-dioxins and dibenzofurans, polyhalogenated naphthalenes, and polybrominated biphenyls. Concern was expressed about direct application of the TEF/total toxic equivalency (TEQ) approach to abiotic matrices, such as soil, sediment, etc., for direct application in human risk assessment. This is problematic as the present TEF scheme and TEQ methodology are primarily intended for estimating exposure and risks via oral ingestion (e.g., by dietary intake). A number of future approaches to determine alternative or additional TEFs were also identified. These included the use of a probabilistic methodology to determine TEFs that better describe the associated levels of uncertainty and "systemic” TEFs for blood and adipose tissue and TEQ for body burde