Distribution of persistent organic pollutants in two different fat compartments from obese individuals

Update of the risk assessment of polybrominated diphenyl ethers (PBDEs) in food

The European Commission asked EFSA to update its 2011 risk assessment on polybrominated diphenyl ethers (PBDEs) in food, focusing on 10 congeners: BDE-28, -47, -49, -99, -100, -138, -153, -154, -183 and ‑209. The CONTAM Panel concluded that the neurodevelopmental effects on behaviour and reproductive/developmental effects are the critical effects in rodent studies. For four congeners (BDE-47, -99, -153, -209) the Panel derived Reference Points, i.e. benchmark doses and corresponding lower 95% confidence limits (BMDLs), for endpoint-specific benchmark responses. Since repeated exposure to PBDEs results in accumulation of these chemicals in the body, the Panel estimated the body burden at the BMDL in rodents, and the chronic intake that would lead to the same body burden in humans. For the remaining six congeners no studies were available to identify Reference Points. The Panel concluded that there is scientific basis for inclusion of all 10 congeners in a common assessment group and performed a combined risk assessment. The Panel concluded that the combined margin of exposure (MOET) approach was the most appropriate risk metric and applied a tiered approach to the risk characterisation. Over 84,000 analytical results for the 10 congeners in food were used to estimate the exposure across dietary surveys and age groups of the European population. The most important contributors to the chronic dietary Lower Bound exposure to PBDEs were meat and meat products and fish and seafood. Taking into account the uncertainties affecting the assessment, the Panel concluded that it is likely that current dietary exposure to PBDEs in the European population raises a health concern.

Exposure of children to brominated flame retardants and heavy metals in Morocco: Urine and blood levels in association with global cytosine and adenine methylation

Persistent pollutants, namely brominated flame retardants (BFRs) and heavy metals, are compounds that are added to a wide range of products and materials for preventing ignition, increasing the functionality of materials or improving their performance, e.g. electric conductivity. The exposure of children might consequently be inferred, through indoor dust and hand-to-mouth or toy-chewing behaviors. The current study is aimed at assessing the exposure of Moroccan children to BFRs and heavy metal elements, and evaluating their associations with global DNA methylation. First, parents responded to a questionnaire pertaining to children's lifestyle, then blood and urine samples were collected from (n = 93) children aged between 5 and 11 years for biomonitoring and DNA methylation analysis. BFRs were detected in 54.84% of samples with a median concentration of 0.01 nmol/mL (range: 0.004-0.051 nmol/mL) while metal elements were detected in more than 90% of samples. BFRs showed no variations with global DNA methylation, unlike metal elements, which revealed significant associations with global DNA methylation markers, namely 5-mC, 5-hmC and N⁶-mA levels. Moroccan children may be exposed to flame retardants and heavy metals through several routes. Further research is required to assess the exposure and the health impacts of environmental pollutants and ultimately protect the Moroccan population by the prevention of adverse health effects.

Polychlorinated biphenyls and risk of metabolic syndrome and comparison with the risk of diabetes: A systematic review and meta-analysis

With the increasing incidence of metabolic syndrome (MetS) worldwide and no consistent results on PCBs and MetS. A meta-analysis to explore their relationship was conducted. Given the high correlation and overlap of MetS with diabetes, analysis of diabetes risk, was used as a supplement to compare with MetS. Seven studies included MetS, 15 studies for diabetes, and one study included both outcomes. It was found that PCBs may not be a risk factor for MetS, but their high heterogeneity indicates that they are under-represented. In addition, our results showed that total PCBs might be a protective factor against diabetes. In the whole blood subgroup, which can reflect the accumulation of more than one body load, heterogeneity was reduced, and its OR value suggested that PCBs increased the risk of MetS in the whole blood biomaterial. DL-PCBs were positively associated with MetS and diabetes, while NDL-PCBs were negatively associated with diabetes. In the subgroup analysis of PCBs homologs, DL-PCB-126 and DL-PCB-118 were risk factors for MetS and diabetes, respectively. In addition, PCB-153 and 180 showed a dose-response relationship between them and diabetes mellitus, respectively. The results of total analysis of MetS and diabetes mellitus and subgroup analysis of PCBs were mixed, and this reason might be attributed to the different mechanisms of action and effect sizes of different PCBs, so based on subgroup results and in vivo and in vitro experiments, we considered PCBs to be a risk factor for MetS and diabetes. Due to various reasons, there are still many shortcomings in the evaluation of PCBs impact on human health, and more high-quality research are needed to further explore the role of PCBs of different species and congeners in MetS and diabetes.

Critical Overview on Endocrine Disruptors in Diabetes Mellitus

Diabetes mellitus is a major public health problem in all countries due to its high human and economic burden. Major metabolic alterations are associated with the chronic hyperglycemia that characterizes diabetes and causes devastating complications, including retinopathy, kidney failure, coronary disease and increased cardiovascular mortality. The most common form is type 2 diabetes (T2D) accounting for 90 to 95% of the cases. These chronic metabolic disorders are heterogeneous to which genetic factors contribute, but so do prenatal and postnatal life environmental factors including a sedentary lifestyle, overweight, and obesity. However, these classical risk factors alone cannot explain the rapid evolution of the prevalence of T2D and the high prevalence of type 1 diabetes in particular areas. Among environmental factors, we are in fact exposed to a growing amount of chemical molecules produced by our industries or by our way of life. In this narrative review, we aim to give a critical overview of the role of these pollutants that can interfere with our endocrine system, the so-called endocrine-disrupting chemicals (EDCs), in the pathophysiology of diabetes and metabolic disorders.

Accessibility investigation of semi-volatile organic compounds in indoor dust estimated by multi-ratio equilibrium passive sampling

Many semi-volatile organic compounds (SVOCs) accumulate in indoor dust, which serves as a repository for those compounds. The presence of SVOCs in indoor environments is of concern because many of them are suspected to have toxic effects. Total SVOC concentrations in the dust are generally used for exposure assessment to indoor contaminants, assuming that 100% of the SVOCs is accessible for human uptake. However, such an assumption may potentially lead to an overestimated risk related to dust exposure. We applied a multi-ratio equilibrium passive sampling (MR-EPS) for estimation of SVOC accessibility in indoor settled dust using silicone passive samplers and three particle size dust fractions, <0.25 mm, 0.25-0.5 mm, and 1-2 mm in dry and wet conditions. Equilibrations were performed at various sampler-dust mass ratios to achieve different degrees of SVOC depletion, allowing the construction of a desorption isotherm. The desorption isotherms provided accessible fractions (F_AS), equivalent air concentrations (C_AIR), dust-air partition coefficients (K_DUST-AIR) and organic carbon-air partition coefficients (K_OC-AIR). The highest F_AS were observed in the <0.25 mm dust fraction in wet conditions which is relevant for exposure assessment via oral ingestion. The highest C_AIR were estimated for several organophosphorus flame retardants (OPFRs), polycyclic aromatic hydrocarbons (PAHs) and synthetic musks. The logK_OC-AIR did not differ between dust particle sizes in dry and wet conditions but within compound groups, different relationships with hydrophobicity were observed. Equivalent lipid-based concentrations (C_L⇌DUST) calculated using available lipid-silicone partition coefficients (K_LIP-SIL) were compared with lipid-based concentrations (C_L) measured in human-related samples collected from Europeans. For hexachlorobenzene (HCB), C_L⇌DUST, and C_L were similar, indicating equilibrium attainment between environment and human samples. Lipid-based concentrations for persistent legacy contaminants were also similar but lower for PBDEs in human samples. Overall, accessibility estimation using MR-EPS in dust further contributes to human risk assessment.

Partitioning of Persistent Organic Pollutants between Adipose Tissue and Serum in Human Studies

Blood is the most widely used matrix for biomonitoring of persistent organic pollutants (POPs). It is assumed that POPs are homogenously distributed within body lipids at steady state; however, the variability underlying the partitioning of POPs between fat compartments is poorly understood. Hence, the objective of this study was to review the state of the science about the relationships of POPs between adipose tissue and serum in humans. We conducted a narrative literature review of human observational studies reporting concentrations of POPs in paired samples of adipose tissue with other lipid-based compartments (e.g., serum lipids). The searches were conducted in SCOPUS and PUBMED. A meta-regression was performed to identify factors responsible for variability. All included studies reported high variability in the partition coefficients of POPs, mainly between adipose tissue and serum. The number of halogen atoms was the physicochemical variable most strongly and positively associated with the partition ratios, whereas body mass index was the main biological factor positively and significantly associated. To conclude, although this study provides a better understanding of partitioning of POPs to refine physiologically based pharmacokinetic and epidemiological models, further research is still needed to determine other key factors involved in the partitioning of POPs.

Body burden and influencing factors of polychlorinated dibenzodioxins and dibenzofurans (PCDD/Fs) in male workers from a municipal waste incineration plant in China

Emissions of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) from municipal solid waste incinerators (MSWIs) have aroused public concern around the world. However, biomonitoring evidence regarding the influence of MSWIs on the human body burden of PCDD/Fs is scarce. The aim of this study is to investigate the human body burden levels of PCDD/Fs in MSWI workers and to further explore the potential influencing factors, including duration of occupation and dietary habits, on the PCDD/F levels. A total of 98 paired serum samples from MSWI workers and non-MSWI workers were collected. Seventeen 2,3,7,8-chlorine substituted PCDD/Fs in the serums were analyzed using an isotope dilution high-resolution gas chromatograph/high-resolution mass spectrometer (HRGC/HRMS). The results showed that the mean levels of toxic equivalent (TEQ)-PCDD/Fs for the MSWI workers and the control group were 18.28 pg TEQ g^-1 lipid and 5.81 pg TEQ g^-1 lipid, respectively. Significantly higher concentrations of PCDD/Fs existed in the incinerator workers compared with the control subjects after adjustment of the confounding factors. OCDD was the most abundant congener in both the MSWI workers and the control subjects, accounting for 82.2% and 89.4% of the ∑₁₇PCDD/Fs, respectively. The serum levels of PCDFs in the MSWI workers increased with the duration of occupation (β = 0.498, P = 0.031), and a higher total concentration of PCDD/Fs were present in senior workers classified as production supervisors than routine operation staff (β = 8.809, P = 0.008). No significant relationship was found between the PCDD/F concentrations and dietary habits. This study was the first to explore the associations between the body burden of PCDD/Fs and occupational exposure as well as dietary intake of MSWI workers in China. The findings provide scientific information for health risk assessments of human exposure to PCDD/Fs.

Insights into disruption of lipid metabolism in digestive gland of female scallop Chlamys farreri under B[a]P exposure

Lipids are the main energy support during gametogenesis. Digestive gland is the key organ of aquatic animal metabolism for storing nutrition and supplying energy. It participates in a variety of life activities (such as growth, digestion, immunity, and reproduction). Nutrients stored in digestive glands, especially lipids, provide energy for reproductive behaviors such as gametogenesis and ovulation. A large number of studies have confirmed the accumulation of lipids from digestive gland to gonad during gametogenesis. At present, the research on the interference mechanism of persistent organic pollutants (POPs) on lipid metabolism of aquatic animals and the adaptive response of aquatic animals to POPs stress focus on biochemical levels or a few genes. The potential molecular mechanism of lipid metabolism interference needs to be further studied. In addition, as an important stage of aquatic animals, the reproductive period is a vigorous period of lipid metabolism. However, at present, there is no report on the molecular mechanism of POPs interfering with the lipid metabolism of the digestive gland in the reproductive process of aquatic animals. In this study, female scallop C. farreri was cultured in natural seawater and exposed to 4 μg/L B[a]P in seawater. Transcriptome analysis of digestive glands at multiple stages (proliferative stage, growth stage, mature stage and spawn stage) was performed, and iPath pathway analysis was used to analyze lipid metabolism pathways and differential genes. The interference mechanism of lipid metabolism in bivalves during reproductive period was revealed. This study will provide valuable genomic information on the role of digestive glands in lipid metabolism and reproduction of C. farreri, and will contribute to further functional genomics of bivalves and other closely related species.

Differential Bioaccumulation Patterns of α, β-Hexachlorobenzene and Dicofol in Adipose Tissue from the GraMo Cohort (Southern Spain)

To identify bioaccumulation patterns of α-, β- hexachlorocyclohexane (HCH) and dicofol in relation to sociodemographic, dietary, and lifestyle factors, adipose tissue samples of 387 subjects from GraMo cohort in Southern Spain were analyzed. Potential predictors of these organochlorine pesticides (OCP) levels were collected by face-to-face interviews and assessed by multivariable linear and logistic regression. OCPs were detected in 84.2% (β-HCH), 21.7% (α-HCH), and 19.6% (dicofol) of the population. β-HCH levels were positively related to age, body mass index (BMI), mother's occupation in agriculture during pregnancy, living in Poniente and Alpujarras, white fish, milk and water consumption, and negatively related to being male, living near to an agricultural area, working ≥10 years in agriculture, and beer consumption. Detectable α-HCH levels were positively related to age, BMI, milk consumption, mother's occupation in agriculture during pregnancy, and negatively with residence in Poniente and Alpujarras, Granada city, and Granada Metropolitan Area. Residence near to an agricultural area, smoking habit, white fish and water consumption, and living in Poniente and Alpujarras, Granada city and Granada Metropolitan Area were negatively associated with detectable dicofol levels. Our study revealed different bioaccumulation patterns of α, β-HCH and dicofol, probably due to their dissimilar period of use, and emphasize the need for assessing the exposure to frequently overlooked pollutants.

A PBPK model describing the pharmacokinetics of γ-HBCD exposure in mice

The brominated flame retardant, hexabromocyclododecane (HBCD), is added-but not bound-to consumer products and is eventually found in the environment and human tissues. Commercial-grade HBCD mixtures contain three major stereoisomers, alpha (α), beta (β), and gamma (γ), that are typically at a ratio of 12%:6%:82%, respectively. Although HBCD is widely used, the toxicological effects from its exposure in humans are not clearly understood. Using a physiologically based pharmacokinetic (PBPK) model could help improve our understanding of the toxicity of HBCD. The aim of this work was to develop a PBPK model, consisting of five permeability limited compartments (i.e., brain, liver, adipose tissue, blood, and rest of the body), to evaluate the pharmacokinetics of γ-HBCD in C57BL/6 mice. Physiological parameters related to body size, organ weights, and blood flow were taken from the literature. All partition coefficients were calculated based on the log Kow. The elimination in urine and feces was optimized to reflect the percent dose eliminated, as published in the literature. Compared with data from the literature for brain, liver, blood, and adipose tissue, the model simulations accurately described the mouse data set within 1.5-fold of the data points. Also, two examples showing the utility of the PBPK model supplement the information regarding the internal dose that caused the health effects observed during these studies. Although this version of the PBPK model expressly describes γ-HBCD, more efforts are needed to clarify and improve the model to discriminate between the α, β, and γ stereoisomers.

Health toxicity effects of brominated flame retardants: From environmental to human exposure

Hexabromocyclododecane (HBCD) and Tetrabromobisphenol A (TBBP-A) are brominated flame retardants widely used in variety of industrial and consumer products (e.g., automobiles, electronics, furniture, textiles and plastics) to reduce flammability. HBCD and TBBPA can also contaminate the environment, mainly water, dust, air and soil, from which human exposure occurs. This constant exposure has raised some concerns against human health. These compounds can act as endocrine disruptors, a property that gives them the ability to interfere with hormonal function and quantity, when HBCD and TBBPA bind target tissues in the body. Studies in human and animals suggest a correlation between HBCD and TBBPA exposure and adverse health outcomes, namely thyroid disorders, neurobehavior and development disorders, reproductive health, immunological, oncological and cardiovascular diseases. However, in humans these effects are still poorly understood, once only a few data evaluated the human health effects. Thus, the purpose of this review is to present the toxicity effects of HBCD and TBBPA and how these compounds affect the environment and health, resorting to data and knowledge of 255 published papers from 1979 to 2020.

Polychlorinated biphenyl congener 180 (PCB 180) regulates mitotic clonal expansion and enhances adipogenesis through modulation of C/EBPβ SUMOylation in preadipocytes

PCB 180 is a typical non-dioxin-like polychlorinated biphenyl (NDL-PCB). It is one of the most prevalent PCB-congeners found in human adipose tissue. However, the role of PCB 180 in obesity remains poorly understood. The aim of this study was to explore the adipogenic effect and mechanism of PCB 180. Significant enhancement in adipogenesis was observed when differentiating murine 3T3-L1 preadipocytes or human preadipocytes-visceral (HPA-v) that were exposed to PCB 180. Furthermore, exposure to PCB 180 during the first two days was critical to the adipogenic effect. According to results from sequential cell cycle analyses, cell counting, BrdU incorporation, and cyclin D1, cyclin B1, and p27 protein quantification, PCB 180 was found to enhance mitotic clonal expansion (MCE) during early adipogenic differentiation. Molecular mechanistic investigation revealed that PCB 180 promoted accumulation of the C/EBPβ protein, a key regulator that controls MCE. Finally, it was found that PCB 180 mitigated degradation of the C/EBPβ protein by repressing the SUMOylation and subsequent ubiquitination of C/EBPβ by the upregulation of SENP2. In summary, it was shown for the first time that PCB 180 facilitated adipogenesis by alleviating C/EBPβ protein SUMOylation. This result provides novel evidence regarding obesogenic effect of PCB 180.

Antioxidative Molecules in Human Milk and Environmental Contaminants

Breastfeeding provides overall beneficial health to the mother-child dyad and is universally recognized as the preferred feeding mode for infants up to 6-months and beyond. Human milk provides immuno-protection and supplies nutrients and bioactive compounds whose concentrations vary with lactation stage. Environmental and dietary factors potentially lead to excessive chemical exposure in critical windows of development such as neonatal life, including lactation. This review discusses current knowledge on these environmental and dietary contaminants and summarizes the known effects of these chemicals in human milk, taking into account the protective presence of antioxidative molecules. Particular attention is given to short- and long-term effects of these contaminants, considering their role as endocrine disruptors and potential epigenetic modulators. Finally, we identify knowledge gaps and indicate potential future research directions.

Adipose to serum ratio and mixtures of persistent organic pollutants in relation to endometriosis: Findings from the ENDO Study

BACKGROUND

Endometriosis is an estrogen-dependent disease. Endocrine disrupting chemicals (EDCs) and their mixtures may play an etiologic role.

OBJECTIVES

We evaluated an adipose-to-serum ratio (ASR) of lipophilic EDCs and their mixtures associated with incident endometriosis.

METHODS

We quantified 13 polychlorinated biphenyl (PCB) congeners, 6 polybrominated diphenyl ether (PBDE) congeners, and 11 organochlorine pesticides (OCPs) in serum and omental fat among women from the ENDO Study (2007-2009) aged 18-44 years diagnosed with (n=190) or without (n=283) surgically-visualized incident endometriosis. Odds ratios (OR) and 95% confidence intervals (CI) between ASR and endometriosis were estimated using logistic regression models adjusted for age (years), body mass index (kg/m²), serum cotinine (ng/ml), and breastfeeding conditional on parity. Bayesian hierarchical models (BHM) compared estimated associations for adipose and ASR to serum. Bayesian kernel machine regression (BKMR) estimated change in latent health and 95% posterior intervals (PI) between chemical mixtures and endometriosis.

RESULTS

Select ASR for estrogenic PCBs and OCPs were associated with an increased odds of an endometriosis diagnosis, but not for anti-estrogenic PCBs or PBDEs. Across all chemicals, BHMs generated ORs that were on average 14% (95% PI: 6%, 22%) higher for adipose and 20% (95% PI: 12%, 29%) higher for ASR in comparison to serum. ORs from BHMs were greater for estrogenic PCBs and OCPs, with no differences for PBDEs. BKMR models comparing the 75th to 25th percentile were moderately associated with endometriosis for estrogenic PCBs [adipose 0.27 (95% PI: 0.18, 0.72) and ASR 0.37 (95% PI: 0.06, 0.80)] and OCPs [adipose 0.17 (95% PI: 0.21, 0.56) and ASR 0.26 (95% PI: 0.05, 0.57)], but not for antiestrogenic PCBs and PBDEs.

DISCUSSION

ASR added little insight beyond adipose for lipophilic chemicals. BKMR results supported associations between ASR and adipose estrogenic PCB and OCP mixtures and incident endometriosis. These findings underscore the importance of choice of biospecimen and considering mixtures when assessing exposure-disease relationships.

Update of the risk assessment of hexabromocyclododecanes (HBCDDs) in food

The European Commission asked EFSA to update its 2011 risk assessment on hexabromocyclododecanes (HBCDDs) in food. HBCDDs, predominantly mixtures of the stereoisomers α-, β- and γ-HBCDD, were widely used additive flame retardants. Concern has been raised because of the occurrence of HBCDDs in the environment, food and in humans. Main targets for toxicity are neurodevelopment, the liver, thyroid hormone homeostasis and the reproductive and immune systems. The CONTAM Panel concluded that the neurodevelopmental effects on behaviour in mice can be considered the critical effects. Based on effects on spontaneous behaviour in mice, the Panel identified a lowest observed adverse effect level (LOAEL) of 0.9 mg/kg body weight (bw) as the Reference Point, corresponding to a body burden of 0.75 mg/kg bw. The chronic intake that would lead to the same body burden in humans was calculated to be 2.35 μg/kg bw per day. The derivation of a health-based guidance value (HBGV) was not considered appropriate. Instead, the margin of exposure (MOE) approach was applied to assess possible health concerns. Over 6,000 analytical results for HBCDDs in food were used to estimate the exposure across dietary surveys and age groups of the European population. The most important contributors to the chronic dietary LB exposure to HBCDDs were fish meat, eggs, livestock meat and poultry. The CONTAM Panel concluded that the resulting MOE values support the conclusion that current dietary exposure to HBCDDs across European countries does not raise a health concern. An exception is breastfed infants with high milk consumption, for which the lowest MOE values may raise a health concern.

Adipose Tissue and Endocrine-Disrupting Chemicals: Does Sex Matter?

Obesity and metabolic-related diseases, among which diabetes, are prominent public health challenges of the 21st century. It is now well acknowledged that pollutants are a part of the equation, especially endocrine-disrupting chemicals (EDCs) that interfere with the hormonal aspect. The aim of the review is to focus on adipose tissue, a central regulator of energy balance and metabolic homeostasis, and to highlight the significant differences in the endocrine and metabolic aspects of adipose tissue between males and females which likely underlie the differences of the response to exposure to EDCs between the sexes. Moreover, the study also presents an overview of several mechanisms of action by which pollutants could cause adipose tissue dysfunction. Indeed, a better understanding of the mechanism by which environmental chemicals target adipose tissue and cause metabolic disturbances, and how these mechanisms interact and sex specificities are essential for developing mitigating and sex-specific strategies against metabolic diseases of chemical origin. In particular, considering that a scenario without pollutant exposure is not a realistic option in our current societies, attenuating the deleterious effects of exposure to pollutants by acting on the gut-adipose tissue axis may constitute a new direction of research.

Temporal transcriptome analysis in female scallop Chlamys farreri: First molecular insights into the disturbing mechanism on lipid metabolism of reproductive-stage dependence under benzo[a]pyrene exposure

Polycyclic aromatic hydrocarbons (PAHs) are one of the most widespread persistent organic pollutants (POPs) in marine environment. Benzo[a]pyrene (B[a]P), the most toxic carcinogen of PAHs, is widely studied as a representative that interferes with lipid metabolism. However, the underlying molecular mechanisms of lipid metabolism by B[a]P interference towards bivalve, one of the marine-pollution bio-indicators have not been elucidated yet, especially during gonadal development which is closely associated with lipids. In this study, female scallops Chlamys farreri were cultured with natural and 4 μg/L B[a]P exposed seawater, respectively, and a multi-stage (proliferative, growth, mature, and spawn stage) ovarian transcriptome profiling was performed to decipher the reproductive stage-dependence disturbing mechanisms on lipid metabolism caused by B[a]P in bivalves. The results revealed the potential molecular mechanism of B[a]P-induced triglycerides (TGs) accumulation, which probably resulted from the collaboration of promoting synthesis and inhibiting metabolization of TGs, notably, this mechanism also occurred at spawn stage. Correspondingly, B[a]P and TGs contents measured in ovary offered direct biochemical evidences for the interference effects and stage-dependent accumulation patterns of B[a]P. Moreover, the gene expressions of fatty acids synthesis related enzymes were down-regulated cooperatively, illustrating the molecular compensatory mechanism that reduced susceptibility from oxidative damage. And these results further emphasized the important role of prostaglandins (PGs) in immune response mediated by arachidonic acid metabolism. In addition, this study explored the underlying molecular mechanism affected by B[a]P on sterol metabolism, which possibly posed a threat to normal reproductive functions in bivalves. Taken together, our findings filled the gap of the stage-dependent interference molecular mechanisms on lipid metabolism behind bivalves, and provided a new perspective for investigating the adaptive mechanisms of bivalves under POPs stress.

Association of endocrine active environmental compounds with body mass index and weight loss following bariatric surgery

INTRODUCTION

The objective of this study was to study associations of a wide range of halogenated biphenyls, dibenzo-p-dioxins, dibenzofurans and diphenylethers with body mass index (BMI) and evaluate changes in their concentration following bariatric surgery.

METHODS

Subcutaneous fat, visceral fat and liver tissue samples were collected from 106 patients undergoing Roux-en-Y gastric bypass surgery for weight loss or patients who were undergoing abdominal surgery for nonbariatric reasons. We measured concentrations of an extensive panel of chlorinated and brominated biphenyls, dioxins, and furans, and brominated diphenylethers in the samples. We conducted linear regression to examine associations with BMI, adjusting for age and gender. Changes in concentration for indicator chemicals were evaluated in samples collected following bariatric surgery in a small subpopulation.

RESULTS

After adjustments for age and gender and correction for multiple testing, seven ortho-chlorinated biphenyls, one nonortho-chlorinated biphenyl, four PCDD/Fs and one ortho-brominated biphenyl were associated with BMI. The strongest associations between BMI and lipid-adjusted concentrations were seen with PCB-105 in subcutaneous fat (beta = 16.838 P-val = 1.45E-06) PCB-126 in visceral fat (beta = 15.067 P-val = 7.72E-06) and PCB-118 (beta = 14.101 P-val = 2.66E-05) in liver. The concentrations of sum PCBs, chlorinated toxic equivalent quantity (TEQ's) and brominated compounds increased significantly with weight loss in subcutaneous fat in a group of ten individuals resampled up to five years after bariatric surgery and substantial weight loss.

CONCLUSION

We show that selected polychlorinated biphenyls PCBs and structurally related polychlorinated dibenzo-p-dioxins dibenzofurans (PCDD/Fs) were associated with BMI. Concentrations of these lipophilic compounds in subcutaneous fat increased following bariatric surgery.

Interspecies comparison of the residue levels and profiles of persistent organic pollutants in terrestrial top predators

Serum samples from three species of living terrestrial top predators were analysed for six groups of persistent organic pollutants (POPs), such as polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethane and its metabolites (DDTs), chlordane compounds (CHLs), hexachlorocyclohexane isomers (HCHs), hexachlorobenzene (HCB) and polybrominated diphenyl ethers (PBDEs). The study included three carnivore species: lion (Panthera leo), hyena (Hyena brunnea) and cheetah (Acinonyx jubatus). All samples were collected from healthy living animals between 2004 and 2005. Most of the samples (wild lions (n = 50) and hyenas (n = 11)) were collected from various locations within the Kruger National Park and Addo National Park (South Africa), while captive lions (n = 6) and cheetahs (n = 3) were collected from the Antwerp Zoo (Belgium). In general, relatively low levels of POPs were found in the studied species, varying widely within species and locations. Median concentrations of POPs were higher in captive lions (PCBs: 505 pg/mL; DDTs: 270 pg/mL; HCHs: 72 pg/mL; HCB: 34 pg/mL; CHLs: 24 pg/mL; PBDEs: 8 pg/mL) compared to wild lions (DDTs: 274 pg/mL; HCHs: 44 pg/mL; CHLs: 7.9 pg/mL; PCBs: 2.1 pg/mL; HCB: < LOQ; PBDEs: < LOQ). In the wild animals, POPs accumulated in the following order: DDTs > HCHs > CHLs > HCB > PCBs > PBDEs, while in the captive animals, the order was: PCBs > DDTs > CHLs > HCHs > HCB > PBDEs, suggesting differences in the diet of these animals. Furthermore, wild hyena contained significantly higher (p < 0.05) median levels of POPs compared to wild lions, possibly reflecting differences in metabolic capacity and/or feeding habits, together with an uneven distribution of POPs in the area where the animals lived. No previous data are available to compare for similar terrestrial top predators, such as lion, hyena and cheetah. To our knowledge, this is first study on POPs in these three species. The low POP levels found in this study were several orders of magnitude lower than those for other carnivore species, such as polar bears, grizzly bears, brown bears and wolves worldwide. The present study has revealed the need for expanding research and monitoring on occurrence, levels and disposition of POPs in the top predators of the terrestrial environment.

Molecular response mechanism in Escherichia coli under hexabromocyclododecane stress

The effects of hexabromocyclododecane (HBCD) on the relationship between physiological responses and metabolic networks remains unclear. To this end, cellular growth, apoptosis, reactive oxygen species, exometabolites and the proteome of Escherichia coli were investigated following exposure to 0.1 and 1 μM HBCD. The results showed that although there were no significant changes in the pH value, apoptosis and reactive oxygen species under HBCD stress, cell growth was inhibited. The metabolic network formed by glycolysis, oxidative phosphorylation, amino acids biosynthesis, membrane proteins biosynthesis, ABC transporters, glycogen storage, cell recognition, compound transport and nucleotide excision repair was disrupted. Cell chemotaxis and DNA damage repair were the effective approaches to alleviate HBCD stress. This work improves our understanding of HBCD toxicity and provides insight into the toxicological mechanism of HBCD at the molecular and network levels.

How polluted is your fat? What the study of adipose tissue can contribute to environmental epidemiology

The study of the potential contribution of low-dose exposure to environmental chemicals on the development of chronic conditions in human populations is often hampered by methodological issues, including exposure misclassification and the inability to assess biological effects in target organs. White adipose tissue (WAT) presents the unique feature of being both an advantageous matrix for assessing long-term exposure to mixtures of persistent organic pollutants and an interesting tissue to investigate early preclinical effects. Moreover, other lipophilic non-persistent chemicals and heavy metals have been recently quantified in fat, suggesting that human WAT contains chemical mixtures more complex than initially thought. However, WAT has been scarcely used in environmental epidemiology due to collection difficulties. In this essay we discuss the potential of using human WAT as a source of both exposure and effect biomarkers, with the aim of advancing the epidemiological research of obesity-related diseases, including metabolic syndrome and cancer. Overall, we discuss the implications of investigating WAT in a multidisciplinary framework combining toxicological and epidemiological knowledge in order to improve the inference of causal relationships in observational settings. We finalise by suggesting feasible designs and scenarios in which WAT samples may be reasonably collected.

Determination of the Polychlorinated Biphenyls Distribution in Different Fat Tissues of Cattle by Age and Gender

Polychlorinated biphenyls (PCBs), which cause environmental pollution, are found in animal-based fatty foods. Due to their long half-life and lipophilic properties, they can accumulate in the fat tissues of cattle. The study was conducted to compare the PCB levels (PCB28, 52, 101, 118, 138, 153, and 180) in the different fat tissues (muscle, liver, kidney, spinal cord, lung, back fat, perihepatic fat, and perirenal fat) of cattle by age and gender. This information is also useful to evaluate the exposure risks for different bovine edible tissues. Therefore, 15 female and 15 male cattle under 24 months of age and 15 female and 15 male cattle over 24 months of age were used, and 480 samples were analyzed for target PCBs using gas chromatography-mass spectrometry. Of all the samples, two (50.2 µg/kg in perihepatic fat and 51.1 µg/kg in kidney) were found above the maximum residue limit; these samples were taken from the animals in the elderly female group (over 24 months). There were more PCBs in cattle older than 2 years. Muscle, kidney, and perihepatic fat presented higher PCB concentrations than other tissues, and perirenal fat presented lower PCB concentrations than other tissues. PCB101, PCB153, and PCB138 were found to have the highest contribution to the PCB concentration. Thus, it is concluded that perihepatic fat, muscle, or kidney should be sampled, particularly in routine residue monitoring, and specifically analyzed for PCB101, PCB153, and PCB138.

Legacy and emerging persistent organic pollutants in the freshwater system: Relative distribution, contamination trends, and bioaccumulation

In this study, a comprehensive investigation was performed to understand the overall occurrence, relative distribution, and bioaccumulation of seven different groups of POPs, comprising 27 polybrominated diphenyl ethers (PBDEs), 76 polychlorinated biphenyls (PCBs), 23 organochlorine pesticides (OCPs), three hexabromocyclododecanes (HBCDs), and 13 perfluoroalkyl substances (PFASs) as legacy POPs, and 41 polychlorinated naphthalenes (PCNs) and 24 short-chain chlorinated paraffins (SCCPs) as emerging POPs, by monitoring crucian carp, sediment, and river water in the freshwater system. Among the targeted POPs, SCCPs were predominant in sediment and crucian carp (more than 95%), while a dominance of PFASs was observed in river water (92%). Principal component analysis revealed four different groups/patterns of POPs in all media: one for PBDEs, PCBs, and OCPs, another for HBCDs and PFASs, and the two others for PCNs and SCCPs. Also, sexually dimorphic growth-dependent accumulation of legacy POPs was observed in crucian carp such that POPs concentration increased with increasing fish size and males recorded significantly higher levels of POPs compared to females.

The challenging use and interpretation of blood biomarkers of exposure related to lipophilic endocrine disrupting chemicals in environmental health studies

The use of exposure biomarkers has been growing during the last decades, being considered the 'gold-standard' approach for individual exposure assessment to environmental chemicals. However, lipophilic endocrine disrupting chemicals (LEDC) have specific physicochemical and biological properties implying particular analytical challenges and interpretative caveats. The epidemiological literature is therefore afflicted by methodological inconsistencies and results divergences, in part due to recognised sources of exposure measurement error and misinterpretation of results. The aim of the present review is to identify external and endogenous sources of variability and uncertainty associated with the LEDC blood biomarkers in epidemiological studies. The dynamic nature of blood and an overview of the known mechanisms of transport, storage and partition of LEDCs in the organism are first described. The external sources of variability and uncertainty introduced at pre-analytical and analytical level are subsequently presented. Subsequently, we present some specific cases where the dynamics of lipids and LEDCs may be substantially modified and thus, the interpretation of biomarkers can be particularly challenging. The environmental obesogens as source of biomarkers variability is also discussed in the light of the most recent findings. Finally, different modelling approaches (statistical and pharmacokinetic models) proposed to improve the use and interpretation of biomarkers are appraised.

Mobilization of Environmental Toxicants Following Bariatric Surgery

OBJECTIVE

Persistent organic pollutants (POPs) are lipophilic environmental toxicants that accumulate in adipose tissue. Weight loss leads to mobilization and increased redistribution of these toxicants. Many are obesogens and endocrine disruptors. Increased exposure could pose long-term health risks. The study objective was to measure the changes in serum concentrations of lipophilic POPs during significant weight loss.

METHODS

This study enrolled 27 patients at a university hospital in a longitudinal, 6-month, observational study examining changes in POP blood levels after bariatric surgery. The primary outcome was the changes in the concentrations of 24 polychlorinated biphenyls (PCBs), 9 organochlorine pesticides (OCPs), 11 polybrominated diphenyl ethers, 2,2',4,4',5,5'-hexabromobiphenyl, and 4 perfluorochemicals (PFCs).

RESULTS

Older adults (those born before 1976) had baseline levels of PCBs, OCPs, and PFCs that were two- to fivefold higher than younger adults (those born after 1976). Older adults had greater increases in PCBs, OCPs, and polybrominated diphenyl ethers associated with weight loss. Conversely, younger adults had greater increases in PFCs associated with weight loss. On average, blood POP levels increased as weight loss occurred.

CONCLUSIONS

Although weight loss is considered beneficial, the release and redistribution of POPs to other lipid-rich organs such as the brain, kidneys, and liver warrant further investigation. Interventions should be considered to limit organ exposure to POPs when weight loss interventions are planned.

Distribution of Organohalogen and Synthetic Musk Compounds in Breast Adipose Tissue of Breast Cancer Patients in Ulster County, New York, USA

We determined the concentrations of 98 halogenated organic compounds and synthetic musks in breast fat tissues of 50 breast cancer patients (age range: 34-77 years) collected during 1996-1998 in Ulster County, New York, USA. Polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), polybrominated biphenyl 153 (PBB-153), polybrominated diphenyl ethers (PBDEs), and synthetic musk compounds (SMCs) were analyzed in breast fat tissues, and 46 analytes were found at a detection frequency of ≥ 65% and at concentrations in the decreasing order of OCPs > PCBs > SMCs > PBDEs > PBB-153. PCBs (median: 323 ng/g wet wt) and dichlorodiphenyltrichloroethanes (DDTs, median: 293 ng/g wet wt) were the major compounds found in breast fat tissues. Among PCB congeners, hexa- and hepta-chlorobiphenyls (60% of total PCBs) were the abundant ones. p,p'-DDE accounted for more than 99% of the total DDT concentrations. The concentrations of SMCs and PBDEs were 1-2 orders of magnitude lower than those of PCBs and DDTs. 1,3,4,6,7,8-Hexahydro-4,6,6,7,8,8-hexamethylcyclopenta-r-2-benzopyran (median: 33 ng/g wet wt) was the most abundant SMC, whereas BDE-47 (median: 4.5 ng/g wet wt) was the most dominant PBDE congener present in breast tissues. A significant correlation (p < 0.05) between women's age and concentrations of DDTs, chlordanes, hexachlorobenzene and PCBs in breast tissues was found. Concentrations of PCBs, PBDEs, OCPs, and SMCs were not significantly different between malignant and benign tumor cases. This study adds baseline information on target tissue burdens of persistent organic contaminants in breast cancer patients.

Quantitative bias analysis of the association of type 2 diabetes mellitus with 2,2',4,4',5,5'-hexachlorobiphenyl (PCB-153)

An association between serum concentrations of persistent organic pollutants (POPs), such as 2,2',4,4',5,5'-hexachlorobiphenyl (PCB-153), and risk of type 2 diabetes mellitus (T2DM) has been reported. Conditional on body mass index (BMI) and waist circumference (WC), a higher serum PCB-153 concentration may be a marker of T2DM risk because it reflects other aspects of obesity that are related to T2DM risk and to PCB-153 clearance. To estimate the amount of residual confounding by other aspects of obesity, we performed a quantitative bias analysis on the results of a specific study. A physiologically-based pharmacokinetic (PBPK) model was developed to predict serum levels of PCB-153 for a simulated population. T2DM status was assigned to simulated subjects based on age, sex, BMI, WC, and visceral adipose tissue mass. The distributions of age, BMI, WC, and T2DM prevalence of the simulated population were tailored to closely match the target population. Analysis of the simulated data showed that a small part of the observed association appeared to be due to residual confounding. For example, the predicted odds ratio of T2DM that would have been obtained had the results been adjusted for visceral adipose tissue mass, for the ≥90th percentile of PCB-153 serum concentration, was 6.60 (95% CI 2.46-17.74), compared with an observed odds ratio of 7.13 (95% CI 2.65-19.13). Our results predict that the association between PCB-153 and risk of type 2 diabetes mellitus would not be substantially changed by additional adjustment for visceral adipose tissue mass in epidemiologic analyses. Confirmation of these predictions with longitudinal data would be reassuring.

The brominated flame retardant BDE 47 upregulates purine metabolism and mitochondrial respiration to promote adipocyte differentiation

Adipocyte differentiation is closely associated with obesity and obesity-induced metabolic disorders. Epidemiological studies have demonstrated the association of obesity with environmental pollutants, such as polybrominated diphenyl ethers (PBDEs), common flame retardants in various consumer products. However, their obesogenic effects and mechanism are underexplored. We employed non-targeted metabolomics studies based on liquid chromatography-high resolution mass spectrometry to determine how 2,2',4,4'-tetra-brominated biphenyl ether (BDE 47), one of the main congeners of PBDEs detected in human tissue, promotes adipocyte differentiation of mouse preadipocyte 3 T3-L1 cells. The promoting effects of BDE 47 exposure (5 or 10 μM) on adipocyte differentiation were confirmed by enhancing lipid accumulation and expression levels of biomarkers of adipogenesis. For the first time, we demonstrated that BDE 47 upregulated purine metabolism and altered glutathione metabolism to promote oxidative stress and uric acid production in adipocytes. BDE 47 also elevated mitochondrial respiration and glycolysis in adipocytes to induce more ATP to combat oxidative stress. Antioxidant treatments, including the suppression of xanthine oxidase, inhibited the effects of BDE 47 on inducing oxidative stress and lipid accumulation. BDE 47 may be a potential environmental obesogen by providing a permissive oxidative environment to induce adipocyte differentiation.

Association of polybrominated diphenyl ethers in two fat compartments with increased risk of insulin resistance in obese individuals

BACKGROUND

Polybrominated diphenyl ethers (PBDEs), a widely utilized class of flame retardants in various commercial products, represent a prominent source of environmental contaminants. PBDEs tend to accumulate in adipose tissue, potentially altering the function of this endocrine organ and increasing risk of insulin resistance. The aim of this study was to compare levels of PBDEs in adipose tissues from two metabolically distinct obese groups; the insulin sensitive (IS) and the insulin resistant (IR).

METHODS

Levels of 28 PBDE congeners were assessed in subcutaneous and omental adipose tissues from 34 obese Qatari individuals (11 IS and 23 IR) using gas chromatography (Trace GC Ultra) coupled to a TSQ Quantum triple Quadrupole mass spectrometer. Correlations of identified PBDEs and mediators of metabolic disease were established and effects of PBDEs treatment on insulin signaling in primary omental preadipocytes were determined.

RESULTS

Out of 22 detectable PBDEs in subcutaneous and omental adipose tissues, PBDEs 28, 47, 99 and 153 were predominant in omental adipose tissues from obese Qatari subjects. PBDEs 99, 28, and 47 were significantly higher in IR individuals compared to their IS counterparts. Significant positive correlations were identified between PBDEs 28 and 99 in the omental tissues and with fasting insulin levels. When considering PBDEs congeners, penta congeners were also higher in IR compared to IS individuals, while no significant differences were detected in mono, tri, tertra, hexa, hepta and octa congeners between the two studied groups. Treatment of human omental preadipocytes from insulin sensitive individuals with PBDE28 caused inhibition of phosphorylation of GSK3 α/β (Ser²¹/Ser⁹), mTOR (Ser²⁴⁴⁸), p70 S6 kinase (Thr³⁸⁹) and S6 ribosomal protein (Ser²³⁵/Ser²³⁶) and activation of PTEN (Ser³⁸⁰) phosphorylation, suggesting inhibition of insulin signaling.

CONCLUSION

This pilot data suggests that accumulation of specific PBDEs in human adipose tissues is associated with insulin resistance in obese individuals. Further investigation of the functional role of PBDEs in the pathology of insulin resistance should help developing therapeutic strategies targeting obese individuals at higher risk.

Dynamics of persistent organic pollutants in obese adolescents during weight loss

We have investigated the dynamics of various persistent organic pollutants (POPs) in the serum of 94 obese adolescents (34 boys and 60 girls: age range 11-19years) before (0M) and after 5months (5M) of undergoing weight loss treatment. Six groups of POPs, such as polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethane and its metabolites (DDTs), chlordane compounds (CHLs), hexachlorocyclohexane isomers (HCHs), hexachlorobenzene (HCB) and polybrominated diphenyl ethers (PBDEs), were detected in all samples in the decreasing order of median levels: DDTs>PCBs>HCB>HCHs>CHLs>PBDEs. Levels and patterns of POPs between boys and girls at two time-points were similar. DDTs (0M/5M; median: 31/42ng/g lw) and PCBs (0M/5M; median: 17/28ng/g lw) were the major POPs. PCB 153 (0M/5M; 33/34% of the sum PCBs) was the most dominant PCB congener, followed by PCB 138 (0M/5M; 31/31%) and PCB 180 (0M/5M; 13/12%), respectively. The most important PBDE congeners were BDE 47 and 153, although total PBDE levels were low and ranged between 0.63 and 0.88ng/g lw. In general, levels of POPs in the obese adolescents were lower than previously reported in Belgian adolescents and adults. Due to weight loss, serum levels (except PBDEs) increased significantly thereafter combined with a body weight decrease (from 4 to 42kg). Serum concentrations increased by 1-3.5% per kilogram weight loss and 1-2.5% per BMI z-score loss for most POPs. To our knowledge, this is the first report on the dynamics of POPs in obese adolescents during weight loss. Lipid-soluble contaminants were released from adipose tissue into the blood leading to redistribution into the body. Whether the increase in the internal exposure to POPs may adversely influence health remains to be determined.

Prenatal and Postnatal PCB-153 and p,p'-DDE Exposures and Behavior Scores at 5–9 Years of Age among Children in Greenland and Ukraine

BACKGROUND

Studies have reported some evidence of adverse effects of organochlorine exposures on child development, but the results have been inconsistent, and few studies have evaluated associations with child behavior.

OBJECTIVE

We investigated the association between prenatal and early-life exposures to 2,2',4,4',5,5'-hexachlorobiphenyl (PCB-153) and 1,1-dichloro-2,2-bis(p-chlorophenyl)-ethylene (p,p'-DDE) and behaviors in children between 5 and 9 y of age.

METHODS

In the Biopersistent organochlorines in diet and human fertility: Epidemiologic studies of time to pregnancy and semen quality in Inuit and European populations (INUENDO) cohort, consisting of mother-child pairs from Greenland and Ukraine (n=1,018), maternal serum PCB-153 and p,p'-DDE concentrations were measured during pregnancy, and cumulative postnatal exposures during the first 12 months after delivery were estimated using a pharmacokinetic model. Parents completed the Strengths and Difficulties Questionnaire (SDQ), and children's behaviors were dichotomized as abnormal (high) versus normal/borderline for five SDQ subscales and the total difficulties score.

RESULTS

The total difficulties score, an overall measure of abnormal behavior, was not clearly associated with pre- or postnatal exposures to PCB-153 or to p,p'-DDE. However, pooled adjusted odds ratios (ORs) for high conduct problem scores with a doubling of exposure were 1.19 (95% CI: 0.99, 1.42) and 1.16 (95% CI: 0.96, 1.41) for pre- and postnatal PCB-153, respectively, and 1.25 (95% CI: 1.04, 1.51) and 1.24 (95% CI: 1.01, 1.51) for pre- and postnatal p,p'-DDE, respectively. Corresponding ORs for high hyperactivity scores were 1.24 (95% CI: 0.94, 1.62) and 1.08 (95% CI: 0.81, 1.45) for pre- and postnatal PCB-153, respectively, and 1.43 (95% CI: 1.06, 1.92) and 1.27 (95% CI: 0.93, 1.73) for pre- and postnatal p,p'-DDE, respectively.

CONCLUSION

Prenatal and early postnatal exposures to p,p'-DDE and PCB-153 were associated with a higher prevalence of abnormal scores for conduct and hyperactivity at 5–9 y of age in our study population. These findings provide further support for the importance of minimizing organochlorine exposures to young children and to women of childbearing age. https://doi.org/10.1289/EHP553.

Adipose Tissue as a Site of Toxin Accumulation

We examine the role of adipose tissue, typically considered an energy storage site, as a potential site of toxicant accumulation. Although the production of most persistent organic pollutants (POPs) was banned years ago, these toxicants persist in the environment due to their resistance to biodegradation and widespread distribution in various environmental forms (e.g., vapor, sediment, and water). As a result, human exposure to these toxicants is inevitable. Largely due to their lipophilicity, POPs bioaccumulate in adipose tissue, resulting in greater body burdens of these environmental toxicants with obesity. POPs of major concern include polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins and furans (PCDDs/PCDFs), and polybrominated biphenyls and diphenyl ethers (PBBs/PBDEs), among other organic compounds. In this review, we (i) highlight the physical characteristics of toxicants that enable them to partition into and remain stored in adipose tissue, (ii) discuss the specific mechanisms of action by which these toxicants act to influence adipocyte function, and (iii) review associations between POP exposures and the development of obesity and diabetes. An area of controversy relates to the relative potential beneficial versus hazardous health effects of toxicant sequestration in adipose tissue. © 2017 American Physiological Society. Compr Physiol 7:1085-1135, 2017.

Organochlorine compounds in the adipose tissue of urban and rural women who gave birth by cesarean delivery in northern Turkey

In this study, the levels of a group of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) in the adipose tissue of women living in northern Turkey who gave birth by cesarean delivery were investigated. Sixty subcutaneous samples were collected in 2013 from women in urban (30) and rural (30) areas. The levels of nine OCPs, namely α-hexachlorocyclohexane (HCH), β-HCH (lindane), γ-HCH, hexachlorobenzene (HCB), aldrin, and dichlorodiphenyltrichloroethane (DDT) and its metabolites, 2,4'-dichlorodiphenyldichloroethylene (DDE), 4,4'-DDE, 2,4'-DDT, 4,4'-DDT, and 16 PCBs, PCB-28, -52, -70, -74, -81, -99, -101, -118, -138, -153, -156, -170, -180, -183, -187 and -208, were investigated with a gas chromatograph equipped with an electron capture detector (GC-ECD). β-HCH was detected in nine samples (mean 23.70 ± 4.24 ng g-1 of fat) and γ-HCH was detected in six samples (mean 41.88 ± 12.41 ng g-1 of fat). HCB was detected in five samples (mean 30.97 ± 14.31 ng g-1 of fat), 2,4'-DDT in one sample (5 ng g-1 of fat), 4,4-DDT in two samples (mean 6.70 ± 0.42 ng g-1 of fat), 2,4'-dichlorodiphenyldichloroethylene in three samples (mean 6.27 ± 0.42 ng g-1 of fat), PCB-28 in six samples (mean 10.03 ± 7.79 ng g-1 of fat), PCB-81 in one sample (7.60 ng g-1 of fat) and PCB-118 in one sample (10.20 ng g-1 of fat). In total, organochlorine compounds were detected in 12 (40%) of rural and 12 (40%) of urban women. These results are an indication of the level of organochlorine compounds in the environment where the subjects of the study lived.

Human adipose tissue levels of persistent organic pollutants and metabolic syndrome components: Combining a cross-sectional with a 10-year longitudinal study using a multi-pollutant approach

We aimed to assess the influence of long-term exposure to POPs on the risk of metabolic syndrome, combining a cross-sectional with a 10-year longitudinal follow-up design. Residues of eight POPs were quantified in adipose tissue samples from 387 participants recruited between 2003 and 2004 in Granada province (Spain). The outcome ("metabolically compromised") was defined as having ≥1 diagnosis of type 2 diabetes, hypertension, hypertriglyceridemia, and/or low HDL cholesterol. The cross-sectional analysis was conducted in the initial cohort, while the 10-year longitudinal analysis was conducted in those 154 participants free of any of the so-mentioned metabolic diseases and classified as "metabolically healthy" at recruitment. Statistical analyses were performed using single and multi-pollutant approaches through logistic and Cox regression analyses with elastic net penalty. After adjusting for confounders, β-hexachlorocyclohexane (β-HCH) and hexachlorobenzene (HCB) were independently associated with an increased risk of being metabolically compromised (unpenalized ORs=1.17, 95% CI=1.01-1.36 and 1.17, 95% CI=0.99-1.38, respectively). Very similar results were found in the 10-year longitudinal analysis [HRs=1.28, 95% CI=1.01-1.61 (β-HCH); 1.26, 95% CI=1.00-1.59 (HCB)] and were in line with those obtained using elastic net regression. Finally, when the arithmetic sum of both compounds was used as independent variable, risk estimates increased to OR=1.25, 95% CI=1.03-1.52 and HR=1.32, 95% CI=1.02-1.70. Our results suggest that historical exposure to HCB and β-HCH is consistently associated with the risk of metabolic disorders, and that these POPs might be partly responsible for the morbidity risk traditionally attributed to age and obesity.

Mechanistic Pharmacokinetic Modeling of the Bioamplification of Persistent Lipophilic Organic Pollutants in Humans during Weight Loss

Bioamplification means the liberation of persistent lipophilic organic pollutants (PLOPs) into blood from their storage in inert adipose tissue during rapid weight loss. Here, using a modified mechanistic pharmacokinetic model, we investigated how chemical properties and anthropometric parameters interact to influence the bioamplification of various PLOPs in humans. The model succeeds in reproducing literature documented weight loss-induced increments in human blood PLOP concentrations. We simulated the degree of bioamplification, as characterized by the bioamplification factor (BAmF), of hypothetical PLOPs with different combinations of partitioning and biotransformation properties at various rates of lipid loss. We also investigated how BAmF evolves with the duration of weight loss. Results show that bioamplification is expected to occur for any chemical with even moderate lipophilicity (log K_OW > 2 and log K_OA > 6) as long as the half-life for metabolic elimination is long relative to the time scale of relative lipid loss (e.g., exceeding 10⁴ h in the case of lipid loss of 3 kg month^-1 with an initial lipid mass of 40 kg). While BAmF of a chemical is time-variant, whether bioamplification occurs for a chemical or not is independent of the duration of weight loss. The successful application of such a simple model demonstrates that it is the lipid dynamics that predominantly govern the dynamics of PLOPs rather than vice versa.

Organochlorine pesticides in tree bark and human hair in Yunnan Province, China: Concentrations, distributions and exposure pathway

The concentrations and distributions of organochlorine pesticides (OCPs) in West China were investigated and internal and external exposure of humans to OCPs were assessed by analyzing samples of human hair and tree bark collected in Kaiyuan, in Yunnan Province, China. Dichlorodiphenyltrichloroethane and its metabolites (collectively called DDTs), hexachlorocyclohexanes (HCHs), and hexachlorobenzene (HCB) were the dominant OCPs in the human hair and tree bark samples. The mean total DDT, total HCH, and HCB concentrations in the tree bark samples were 298pg/g dry weight (dw), 100pg/g dw, and 183pg/g dw, respectively, and the mean total DDT, total HCH, and HCB concentrations in the hair samples were 2850pg/g dw, 348pg/g dw, and 1026pg/g dw, respectively. The results indicated that relatively new DDT and lindane inputs have occurred in the study area. DDT and lindane may have been released in products that are used locally. The HCB in the environment in the study area is mainly supplied by long-range atmospheric transport. External exposure was found to be the main factor controlling the p,p'-DDT, γ-HCH, and HCB concentrations in human hair, whereas p,p'-DDE and β-HCH were found to be mainly controlled by internal exposure.

Persistent organic pollutants in adipose tissue should be considered in obesity research

Although low doses of persistent organic pollutants (POPs), strong lipophilic chemicals with long half-lives, have been linked to various endocrine, immune, nervous and reproductive system diseases, few obesity studies have considered adipose tissue as an important POPs exposure source. Because the toxicodynamics of POPs relate directly to the dynamics of adiposity, POPs might explain puzzling findings in obesity research. In two people exposed to the same amounts of environmental POPs, the one having more adipose tissue may be advantaged because POPs storage in adipose tissue can reduce burden on other critical organs. Therefore, adipose tissue can play a protective role against the POPs effects. However, two situations increase the POPs release from adipose tissue into the circulation, thereby increasing the risk that they will reach critical organs: (i) weight loss and (ii) insulin resistance. In contrast, weight gain reduces this possibility. Therefore, avoiding harmful health effects of POPs may mostly contradict conventional judgments about obesity and weight change. These contradictory situations can explain the obesity paradox, the adverse effects of intensive intentional weight loss and the protective effects of obesity against dementia. Future studies should consider that adipose tissue is widely contaminated with POPs in modern society.

Demographic and temporal trends of hexabromocyclododecanes (HBCDD) in an Australian population

Hexabromocyclododecanes (HBCDD) were measured in 67 pooled serum samples collected between 2002 and 2015 in South East Queensland, Australia. These data are the first report of HBCDD in Australian human serum. Temporal and demographic (age and gender) trends were investigated. HBCDD were detected in measurable concentrations in 69% of samples. The average ∑HBCDD concentration was 3.1ng/g lipid, whilst the range was <0.5 to 36ng/g lipid. α-HBCDD was the dominant stereoisomer making up an average of 60% of ∑HBCDD. The remainder was made up by γ-HBCDD. In contrast to another group of brominated flame retardants (BFRs, (polybrominated diphenyl ethers (PBDEs)), HBCDD were found in the lowest concentrations in pools from children aged 0-4 years. This could be attributed to differences in exposure, usage, and/ or the much lower half-life of HBCDD in the human body compared to PBDEs. HBCDD concentrations appear to be significantly higher in females than in males, however the reasons for this are unclear.

Distribution of persistent organic pollutants in serum, omental, and parietal adipose tissue of French women with deep infiltrating endometriosis and circulating versus stored ratio as new marker of exposure

Several studies have assessed the potential role of environmental chemicals in the onset, growth, and/or physiopathology of endometriosis. However, their contour in terms of considered exposure markers remains limited. The present study aimed to characterize the internal exposure levels of 78 persistent organic pollutants (POPs, including dioxins, polychlorobiphenyls, brominated flame retardants and organochlorine pesticides) in a set of 113 adult French women (45 controls, 68 cases), and to characterize the distribution of these POPs within three biological compartments (omental adipose tissue, parietal adipose tissue, and serum). For all targeted substances, the correlation between the concentrations measured in omental versus parietal adipose tissue was found strongly significant (p<0.0001). An equivalence of the measures performed in parietal and omental adipose tissue was moreover observed with median levels of 6.4 vs. 7.4pg/gl.w. for WHO-TEQ₂₀₀₅ PCDD/F, 4.5 vs. 4.7pg/gl.w. for WHO-TEQ₂₀₀₅ dl-PCB, 137.1 vs. 147.9ng/gl.w. for sum of 6 ndl-PCB, and 2.1 vs. 2.0ng/gl.w. for sum of 7 i-PBDE, respectively. The same observation was made for individual targeted OCs compounds. Significant correlations were also observed between these concentrations determined in adipose tissue and those measured in serum for dioxins (WHO-TEQ₂₀₀₅ PCDD/F=6.1pg/gl.w), PCBs (WHO-TEQ₂₀₀₅ dl-PCB=3.6pg/gl.w., sum of 6 ndl-PCB=81.1ng/gl.w.), and brominated flame-retardants (sum of 7 i-PBDE=0.9ng/gl.w.). The circulating versus stored ratio of some exposure markers (Sum PCDDs, 1,2,3,6,7,8-HxCDF, slightly versus highly chlorinated PCBs ratio, PBDE 99 and PBB 153) was found statistically different for control and case individuals. These extended exposure data from deep infiltrating endometriosis patients are the first ones available for France and give a new insight about the equilibrium of chemicals between storage and circulating compartments that should be further considered as new marker of exposure in the context of exposure-health relationship studies.

Brominated flame retardants and organochlorine compounds in duplicate diet samples from a Portuguese academic community

Concentrations of persistent organic pollutants (POPs), including polybrominated diphenyl ethers (PBDEs), hexabromocyclododecanes (HBCDDs), polychlorinated biphenyls (PCBs), hexachlorocyclohexane isomers (HCHs), hexachlorobenzene (HCB), chlordane compounds (CHLs) and dichlorodiphenyltrichloroethane and its metabolites (DDTs), were measured in duplicate diet samples from 21 volunteers at a Portuguese academic community (University of Aveiro). Overall, the levels of the target compounds were low, with detection frequencies varying widely depending on the compounds and with brominated flame retardants (BFRs) registering the lowest detection frequencies. Among PCB congeners, nondioxin-like PCBs were predominant and detected in the majority of the samples. Organochlorine pesticides were also detected in the majority of the samples, with 100% detection for DDTs and HCHs. Estimated daily intakes (EDIs) were calculated using lower and upper bound estimations, and in both cases values were far below the currently established tolerable daily intakes for PCBs and OCs and the reference doses for PBDEs and HBCDDs.

Levels and profiles of brominated and chlorinated contaminants in human breast milk from Thessaloniki, Greece

Human breast milk samples (n=87) collected between July 2004 and July 2005 from primipara and multipara mothers from Thessaloniki, Greece were analysed for six groups of persistent organic pollutants (POPs): polybrominated diphenyl ethers (PBDEs), polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethane and its metabolites (DDTs), chlordane compounds (CHLs), hexachlorocyclohexane isomers (HCHs) and hexachlorobenzene (HCB). DDTs [median: 410ng/g lipid weight (lw)], PCBs (median: 90ng/g lw) and HCHs (median: 40ng/g lw) were the predominantly identified compounds in all the breast milk samples. Levels of PBDEs (median: 1.5ng/g lw) in human breast milk samples from Thessaloniki, Greece were lower compared to other countries. Maternal age had a positive correlation with most compounds, but not with PBDEs. Women with a higher occupational exposure to PBDEs (i.e., working in office environments) had higher PBDE concentrations than all others and showed strong correlations, especially for BDE 47 and BDE 153. None of the analysed compounds showed any correlation with parity. Based on these levels, the daily intake of each group of POPs via human milk was calculated and compared with the tolerable daily intakes (TDI) or the reference doses (RfD). For the majority of samples (85 out of 87) a higher daily intake of PCBs than the TDI was calculated, while 11 out of 87 samples had a higher HCB intake than the TDI. The TDI and the RfD were not exceeded for DDTs and PBDEs, respectively. This is the first report of brominated flame retardants in human breast milk from Greece.

Pivotal Role for the Visceral Fat Compartment in the Release of Persistent Organic Pollutants During Weight Loss

CONTEXT

Polychlorinated biphenyls (PCBs), are implicated as potential endocrine disruptors and obesogens. These lipophilic substances are preferentially stored in the fat compartment and released into the circulation during weight loss.

OBJECTIVE

The aim of this study was to examine the contribution of abdominal adiposity, and visceral adiposity in particular, to the increase of serum PCB levels during weight loss.

MATERIALS AND METHODS

Fourty-five obese women were prospectively recruited. Twenty individuals received dietary counseling and 25 underwent bariatric surgery. Anthropometric data were collected and intra-abdominal adiposity was assessed by measurement computed tomography scanning of the abdominal fat compartment, delineating the visceral and subcutaneous compartment. Serum levels of 27 PCBs were determined and the sum of all PCBs (ΣPCBs) calculated. Follow-up measurements of anthropometric data, computed tomography scanning, and PCB levels were performed after 6 months in all patients.

RESULTS

In patients who lost weight, serum ΣPCB levels displayed an increase after 6 months of approximately 50%. Both correlation and regression analysis, focusing on the relative contribution of the visceral vs the subcutaneous fat compartment, suggested that the increase in ΣPCB serum levels after 6 months of weight loss was more pronounced in patients losing relatively more visceral adipose tissue. This trend could be established in the diet-treated, but not the surgery-treated subgroup.

CONCLUSION

Our study suggests that the contribution of PCBs released from the visceral fat compartment might be more pronounced compared with the subcutaneous fat compartment during weight loss. These findings are present in the entire study group whereas subanalysis of the diet vs surgery groups suggested the same effect in the diet group but failed to reach statistical significance in the surgery group. This suggests a possible weight-loss method-specific effect.

In vivo contaminant partitioning to silicone implants: Implications for use in biomonitoring and body burden

Silicone polymers are used for a wide array of applications from passive samplers in environmental studies, to implants used in human augmentation and reconstruction. If silicone sequesters toxicants throughout implantation, it may represent a history of exposure and potentially reduce the body burden of toxicants influencing the risk of adverse health outcomes such as breast cancer. Objectives of this research included identifying a wide variety of toxicants in human silicone implants, and measuring the in vivo absorption of contaminants into silicone and surrounding tissue in an animal model. In the first study, eight human breast implants were analyzed for over 1400 organic contaminants including consumer products, chemicals in commerce, and pesticides. A total of 14 compounds including pesticides such as trans-nonachlor (1.2-5.9ng/g) and p,p'-DDE (1.2-34ng/g) were identified in human implants, 13 of which have not been previously reported in silicone prostheses. In the second project, female ICR mice were implanted with silicone and dosed with p,p'-DDE and PCB118 by intraperitoneal injection. After nine days, silicone and adipose samples were collected, and all implants in dosed mice had p,p'-DDE and PCB118 present. Distribution ratios from silicone and surrounding tissue in mice compare well with similar studies, and were used to predict adipose concentrations in human tissue. Similarities between predicted and measured chemical concentrations in mice and humans suggest that silicone may be a reliable surrogate measure of persistent toxicants. More research is needed to identify the potential of silicone implants to refine the predictive quality of chemicals found in silicone implants.

Macronutrient composition determines accumulation of persistent organic pollutants from dietary exposure in adipose tissue of mice

Accumulation of persistent organic pollutants (POPs) has been linked to adipose tissue expansion. As different nutrients modulate adipose tissue development, we investigated the influence of dietary composition on POP accumulation, obesity development and related disorders. Lifespan was determined in mice fed fish-oil-based high fat diets during a long-term feeding trial and accumulation of POPs was measured after 3, 6 and 18months of feeding. Further, we performed dose-response experiments using four abundant POPs found in marine sources, PCB-153, PCB-138, PCB-118 and pp'-DDE as single congeners or as mixtures in combination with different diets: one low fat diet and two high fat diets with different protein:sucrose ratios. We measured accumulation of POPs in adipose tissue and liver and determined obesity development, glucose tolerance, insulin sensitivity and hepatic expression of genes involved in metabolism of xenobiotics. Compared with mice fed diets with a low protein:sucrose ratio, mice fed diets with a high protein:sucrose ratio had significantly lower total burden of POPs in adipose tissue, were protected from obesity development and exhibited enhanced hepatic expression of genes involved in metabolism and elimination of xenobiotics. Exposure to POPs, either as single compounds or mixtures, had no effect on obesity development, glucose tolerance or insulin sensitivity. In conclusion, this study demonstrates that the dietary composition of macronutrients profoundly modulates POP accumulation in adipose tissues adding an additional parameter to be included in future studies. Our results indicate that alterations in macronutrient composition might be an additional route for reducing total body burden of POPs.

Circulating persistent organic pollutants and body fat distribution: Evidence from NHANES 1999-2004

OBJECTIVE

To evaluate and compare the correlations of various circulating persistent organic pollutants (POPs) with fat mass percentages (FM%) of trunk, leg, and whole body measured by dual-energy X-ray absorptiometry.

METHODS

This study included 2358 adults (≥20 years) in the National Health and Nutrition Examination Survey 1999-2004. Partial Pearson correlation coefficients were calculated, after adjusting for major confounders, including age, smoking status, and history of lactation and parity. Wolfe's method was used to compare correlation coefficients derived from the same participants.

RESULTS

Twelve POPs showed significantly different correlations with fat depots in trunk and leg regions. β-hexachlorocyclohexane, heptachlorodibenzo-p-dioxin, octachlorodibenzo-p-dioxin, and polychlorinated biphenyl (PCB)-126 showed stronger positive correlations with trunk FM% than with leg FM%, whereas PCBs with ≥6 chlorines were more inversely correlated with trunk FM% than leg FM%. Age-stratified analysis showed stronger inverse correlations between POPs and trunk FM% mainly in participants <40 years, whereas stronger positive correlations between POPs and trunk FM% were observed in older participants.

CONCLUSIONS

Stronger associations between POPs and trunk fat as compared to leg fat possibly indicated a more important role of trunk fat in the pharmacokinetics of POPs, or a stronger effect of POPs, as endocrine disruptors, on trunk fat metabolism.

Considerable exposure to the endocrine disrupting chemicals phthalates and bisphenol-A in intensive care unit (ICU) patients

Critical care medicine has largely benefited from plastic-containing medical devices. However, bisphenol-A (BPA) and phthalates present in the plastics can leach from such devices. We hypothesized that intensive care unit (ICU) patients are exposed to BPA and phthalates through (plastic) medical devices. Serum (n = 118) and urine (n= 102) samples of adult ICU patients (n = 35) were analyzed for total BPA and phthalate metabolites (PMs). Our results showed that adult ICU patients are continuously exposed to phthalates, such as di(2-ethylhexyl)phthalate (DEHP), as well as to BPA, albeit to a lesser extent. This exposure resulted in detectable high serum and urinary levels in almost every patient and at every studied time point. Moreover, these levels were significantly higher than in controls or compared to referenced literature. The chronology of exposure was demonstrated: pre-operative urinary and serum levels of the DEHP metabolites were often below the detection limit. Plastic-containing medical devices were the main source of DEHP exposure: post-operative patients on hemofiltration, extracorporeal membrane oxygenation or both showed serum levels 100-or 1000-fold higher than the levels in the general population reported in the literature. The serum and some of the urinary levels of the DEHP metabolites are the highest ever reported in humans; some at biologically highly relevant concentrations of ≥ 10-50 μM. Despite the continuously tightening regulations, BPA and DEHP appear to be still present in (some) medical devices. Because patient safety is a concern in the ICU, further research into the (possibly toxic and clinical) effects of these chemicals released from medical devices is imperiously necessary.

Polychlorinated Biphenyls (PCB 101, 153, and 180) Impair Murine Macrophage Responsiveness to Lipopolysaccharide: Involvement of NF-κB Pathway

Non-dioxin-like (NDL) polychlorinated biphenyls (PCBs) are persistent organic pollutants, associated with a range of adverse health effects, including interference with the immune system. In this study, we investigate the capability of NDL-PCBs 101, 153, and 180, 3 of the 6 NDL-PCBs defined as indicators, to impair the immune response in lipopolysaccharide (LPS)-activated J774A.1 and primary murine macrophages. Our results clearly demonstrate that the exposure of J774A.1 and primary macrophages to NDL-PCB 153 or 180 or all NDL-PCBs mixtures causes a significant reduction in LPS-induced cytokine/chemokine synthesis, such as tumor necrosis factor-α and interleukin-6, together with monocyte chemoattractant protein-1, involved in cell recruitment. Moreover, PCBs were found to suppress LPS-stimulated NO production, and to reduce cyclooxygenase-2 and inducible nitric oxide synthase expression in J774A.1 and primary macrophages. At mechanistic level, PCBs significantly counteract the LPS-driven toll-like receptor (TLR) 4 and CD14 upregulation, therefore inhibiting downstream nuclear factor-κB (NF-κB) activation in J774A.1. Furthermore, PCBs determine a significant loss of macrophage endocytic capacity, a prerequisite for efficient antigen presentation. Taken together, these data indicate that NDL-PCBs reduce macrophage responsiveness, particularly when they are combined at concentrations per se inactive, impairing the capability to orchestrate a proper immune response to an infectious stimulus, disrupting TLR4/NF-κB pathway.

Inverse correlation among organochlorine pesticide levels to total lipid serum contents: a preliminary study in Veracruz, México

Organochlorine pesticides, due to their hydrophobic nature and persistence, accumulate in tissues rich in lipids, which had been used as a biomarker for environmental pollution. In humans, organochlorine pesticides are continuously circulating and equilibrating among body compartments. The objective of the study was to evaluate the concentrations of organochlorine pesticides in blood serum and compare their levels to the total lipid contents in Veracruz, México inhabitants. Our hypothesis is that concentrations of organochlorine pesticides will increase just as lipid concentrations. Levels of organochlorine pesticides were divided in ascending tertils according to their total lipid content. The linear trend model applied surprisingly reveals that the average level of all organochlorine pesticides decreases as the lipid concentration increases. From one tertil to the next β-HCH, it shows a decrease of -3.19 mg kg(-1) on lipid basis, pp.'DDE levels decrease by -3.70 mg kg(-1) on lipid basis and pp.'DDT levels decrease -1.13 mg kg(-1) on lipid basis. We conclude that the levels and the orderly sequence of organochlorine pesticide distributions in the blood serum maintain an inverse relationship to total lipid blood serum concentrations.