The effects of PCB exposure and fish consumption on endogenous hormones

Association between Fish Intake and Serum Testosterone Levels in Older Males: The Hitachi Health Study II

Background

Fish are rich in omega-3 polyunsaturated fatty acids and vitamin D, which can promote testosterone synthesis and secretion. However, some contaminants present in fish may disrupt testosterone production.

Objective

This study aimed to investigate the association between fish intake (total, fatty, and lean fish) and serum testosterone levels in older males.

Methods

This cross-sectional study included 1545 Japanese males aged 60-69 y who participated in the baseline survey of the Hitachi Health Study II. Fish intake was estimated using a validated brief-type self-administered diet history questionnaire. Total testosterone levels were measured by chemiluminescence immunoassay. Multivariable linear regression analysis was used to analyze the association between fish intake and serum testosterone levels.

Results

Higher total fish intake was associated with higher levels of serum testosterone, with an adjusted mean [95% confidence interval (CI) of 5.63 (5.43, 5.83) and 5.99 (5.78, 6.20)] ng/mL for the 1st and 4th quartiles of total fish intake, respectively (P for trend = 0.06). When analyzing fatty and lean fish separately, higher intake of lean fish, but not fatty fish, was associated with higher levels of serum testosterone: adjusted mean (95% CI): 5.63 (5.43, 5.82) and 6.00 (5.79, 6.20) ng/mL for the 1st and 4th quartiles of lean fish intake, respectively (P for trend = 0.01).

Conclusions

Among older males, higher intake of total fish, particularly lean fish, was associated with higher serum testosterone levels. Curr Dev Nutr 20xx;x:xx.

Assessing awareness and compliance with fish consumption advisories on the upper Hudson River: Implications for risk management of the Hudson River Superfund site

Polychlorinated biphenyls (PCBs) are a common environmental contaminant. The NYS Department of Health (DOH) issues fish consumption advisories to limit consumption of PCB-contaminated fish. Fish consumption advisories are utilized as institutional controls within the Hudson River Superfund site to limit exposure to PCBs. There is a "Do Not Eat" advisory for all species caught in the upper Hudson River, from Glens Falls, NY to Troy, NY. The section of the river below Bakers Falls also has a catch-and-release regulation issued by the NYS Department of Environmental Conservation. There is limited research on the effectiveness of these advisories in preventing consumption of contaminated fish in the context of Superfund site risk management. We surveyed individuals actively fishing on the upper Hudson River in the area with a "Do Not Eat" advisory, specifically between Hudson Falls and the Federal Dam in Troy, NY. The goal of the survey was to assess knowledge of the consumption guidelines, and if the guidelines are effectively preventing exposure to PCBs. A subset of individuals continue to consume fish caught from the upper Hudson River Superfund site. Awareness of advisories was inversely related to fish consumption from the Superfund site. Age, race, and possession of a fishing license were associated with overall awareness of fish consumption guidelines; age and possession of a license were associated with awareness of the "Do Not Eat" advisory. While institutional controls appear to have a beneficial impact, there is incomplete awareness and compliance with advisories and regulations aimed at preventing exposure to PCBs from fish consumption. Risk assessment and management strategies for contaminated fisheries should consider imperfect adherence to fish consumption guidelines.

Developmental Exposure to Polychlorinated Biphenyls Prevents Recovery from Noise-Induced Hearing Loss and Disrupts the Functional Organization of the Inferior Colliculus

Exposure to combinations of environmental toxins is growing in prevalence; and therefore, understanding their interactions is of increasing societal importance. Here, we examined the mechanisms by which two environmental toxins, polychlorinated biphenyls (PCBs) and high-amplitude acoustic noise, interact to produce dysfunction in central auditory processing. PCBs are well established to impose negative developmental impacts on hearing. However, it is not known whether developmental exposure to this ototoxin alters the sensitivity to other ototoxic exposures later in life. Here, male mice were exposed to PCBs in utero, and later as adults were exposed to 45 min of high-intensity noise. We then examined the impacts of the two exposures on hearing and the organization of the auditory midbrain using two-photon imaging and analysis of the expression of mediators of oxidative stress. We observed that developmental exposure to PCBs blocked hearing recovery from acoustic trauma. In vivo two-photon imaging of the inferior colliculus (IC) revealed that this lack of recovery was associated with disruption of the tonotopic organization and reduction of inhibition in the auditory midbrain. In addition, expression analysis in the inferior colliculus revealed that reduced GABAergic inhibition was more prominent in animals with a lower capacity to mitigate oxidative stress. These data suggest that combined PCBs and noise exposure act nonlinearly to damage hearing and that this damage is associated with synaptic reorganization, and reduced capacity to limit oxidative stress. In addition, this work provides a new paradigm by which to understand nonlinear interactions between combinations of environmental toxins.SIGNIFICANCE STATEMENT Exposure to common environmental toxins is a large and growing problem in the population. This work provides a new mechanistic understanding of how the prenatal and postnatal developmental changes induced by polychlorinated biphenyls (PCBs) could negatively impact the resilience of the brain to noise-induced hearing loss (NIHL) later in adulthood. The use of state-of-the-art tools, including in vivo multiphoton microscopy of the midbrain helped in identifying the long-term central changes in the auditory system after the peripheral hearing damage induced by such environmental toxins. In addition, the novel combination of methods employed in this study will lead to additional advances in our understanding of mechanisms of central hearing loss in other contexts.

Developmental exposure to polychlorinated biphenyls prevents recovery from noise-induced hearing loss and disrupts the functional organization of the inferior colliculus

Exposure to combinations of environmental toxins is growing in prevalence, and therefore understanding their interactions is of increasing societal importance. Here, we examined the mechanisms by which two environmental toxins - polychlorinated biphenyls (PCBs) and high-amplitude acoustic noise - interact to produce dysfunction in central auditory processing. PCBs are well-established to impose negative developmental impacts on hearing. However, it is not known if developmental exposure to this ototoxin alters the sensitivity to other ototoxic exposures later in life. Here, male mice were exposed to PCBs in utero, and later as adults were exposed to 45 minutes of high-intensity noise. We then examined the impacts of the two exposures on hearing and the organization of the auditory midbrain using two-photon imaging and analysis of the expression of mediators of oxidative stress. We observed that developmental exposure to PCBs blocked hearing recovery from acoustic trauma. In vivo two-photon imaging of the inferior colliculus revealed that this lack of recovery was associated with disruption of the tonotopic organization and reduction of inhibition in the auditory midbrain. In addition, expression analysis in the inferior colliculus revealed that reduced GABAergic inhibition was more prominent in animals with a lower capacity to mitigate oxidative stress. These data suggest that combined PCBs and noise exposure act nonlinearly to damage hearing and that this damage is associated with synaptic reorganization, and reduced capacity to limit oxidative stress. In addition, this work provides a new paradigm by which to understand nonlinear interactions between combinations of environmental toxins.

Significance statement

Exposure to common environmental toxins is a large and growing problem in the population. This work provides a new mechanistic understanding of how the pre-and postnatal developmental changes induced by polychlorinated biphenyls could negatively impact the resilience of the brain to noise-induced hearing loss later in adulthood. The use of state-of-the-art tools, including in vivo multiphoton microscopy of the midbrain helped in identifying the long-term central changes in the auditory system after the peripheral hearing damage induced by such environmental toxins. In addition, the novel combination of methods employed in this study will lead to additional advances in our understanding of mechanisms of central hearing loss in other contexts.

Association between polychlorinated biphenyl exposure and thyroid hormones: a systematic review and meta-analysis

Purpose: To conduct a comprehensive meta-analysis investigating the association between polychlorinated biphenyl (PCB) exposure and serum thyroid hormone levels among adults. Methods: Eleven studies met inclusion criteria for analysis following systematic search of PubMed, Embase, and Scopus databases. Of these, 7 studies measured exposure by the total sum of PCB congeners (∑PCB), 1 study measured individual PCB congener levels, and 3 studies measured both ∑PCB levels and PCB congener levels. Correlation coefficients (r) were extracted from each study. Summary estimates were calculated for ∑PCB levels and PCB congeners reported by 2 or more studies: PCB 28, 52, 101, 105, 118, 138, 153, and 180, using random effects model. Results: Significant negative correlation was found between ∑PCBs and T3 (r: -0.09; 95% CI: -0.17, -0.02) and FT3 (r: -0.24; 95% CI: -0.36, -0.12). Congener-specific analysis found T3 to be negatively correlated with PCB-153 (r: -0.19; 95% CI: -0.34, -0.03) and PCB-180 (r: -0.14; 95% CI: -0.26, -0.01), whereas TSH was positively correlated with PCB-105 (r: 0.15; 95% CI: 0.02, 0.28). Conclusions: The present study is the first meta-analysis to investigate the association between PCB exposure and thyroid hormone dysfunction among adults. Results suggest a significant association between PCB exposure and thyroid hormone dysregulation.

Thermal processing reduces PFAS concentrations in blue food - A systematic review and meta-analysis

Per- and polyfluoroalkyl substances (PFAS) are ubiquitous in the environment and often ingested with food. PFAS exposure in people can have detrimental health consequences. Therefore, reducing PFAS burdens in food items is of great importance to public health. Here, we investigated whether cooking reduces PFAS concentrations in animal-derived food products by synthesizing experimental studies. Further, we examined the moderating effects of the following five variables: cooking time, liquid/animal tissue ratio, cooking temperature, carbon chain length of PFAS and the cooking category (oil-based, water-based & no-liquid cooking). In our systematic review searches, we obtained 512 effect sizes (relative differences in PFAS concentration between raw and cooked samples) from 10 relevant studies. These studies exclusively explored changes in PFAS concentrations in cooked seafood and freshwater fish. Our multilevel-meta-analysis has revealed that, on average, cooking reduced PFAS concentrations by 29%, although heterogeneity among effect sizes was very high (I² = 94.65%). Our five moderators cumulatively explained 49% of the observed heterogeneity. Specifically, an increase in cooking time and liquid/animal tissue ratio, as well as shorter carbon chain length of PFAS (when cooked with oil) were associated with significant reductions in PFAS concentrations. The effects of different ways of cooking depended on the other moderators, while the effect of cooking temperature itself was not significant. Overall, cooking can reduce PFAS concentrations in blue food (seafood and freshwater fish). However, it is important to note that complete PFAS elimination requires unrealistically long cooking times and large liquid/animal tissue ratios. Currently, literature on the impact of cooking of terrestrial animal produce on PFAS concentrations is lacking, which limits the inference and generalisation of our meta-analysis. However, our work represents the first step towards developing guidelines to reduce PFAS in food via cooking exclusively with common kitchen items and techniques.

Interactions among thyroid hormones and serum lipid levels in association with PCB exposure in the Mohawk Akwesasne population

Alterations in thyroid function and serum lipid levels were assessed in relation to exposure to polychlorinated biphenyls (PCBs) and three chlorinated pesticides (DDE, hexachorobenzene and mirex) in a sample of Akwesasne Mohawk adults. This population is highly exposed to PCBs because of living in close proximity to three aluminum foundries that used PCBs as hydraulic fluids, which then contaminated local fish, wildlife, water, air and soils. The goal was to assess interactions between thyroid function (TSH, T3, T4 and fT4) and serum lipids (cholesterol, triglycerides and total serum lipids) in relation to concentrations of 101 PCB congeners and three chlorinated pesticides. Previous studies in this population have shown that elevated concentrations of PCBs resulted in suppression of thyroid function in adolescents, and increased risk of clinical hypothyroidism in adults, as well as an elevation in serum lipids. However in adjusted analyses of PCB concentrations of 703 adults we find only small and inconsistent associations between serum PCB levels and thyroid function. The most striking observations were strong significant positive associations between TSH and T3 with serum lipids and a negative association with fT4 in women. Because elevated serum lipids increase risks of other diseases the respective roles of thyroid hormones and PCBs in regulation of serum lipids requires additional study.

Environmental Factors Affecting Thyroid-Stimulating Hormone and Thyroid Hormone Levels

Thyroid hormones are necessary for the normal functioning of physiological systems. Therefore, knowledge of any factor (whether genetic, environmental or intrinsic) that alters the levels of thyroid-stimulating hormone (TSH) and thyroid hormones is crucial. Genetic factors contribute up to 65% of interindividual variations in TSH and thyroid hormone levels, but many environmental factors can also affect thyroid function. This review discusses studies that have analyzed the impact of environmental factors on TSH and thyroid hormone levels in healthy adults. We included lifestyle factors (smoking, alcohol consumption, diet and exercise) and pollutants (chemicals and heavy metals). Many inconsistencies in the results have been observed between studies, making it difficult to draw a general conclusion about how a particular environmental factor influences TSH and thyroid hormone levels. However, lifestyle factors that showed the clearest association with TSH and thyroid hormones were smoking, body mass index (BMI) and iodine (micronutrient taken from the diet). Smoking mainly led to a decrease in TSH levels and an increase in triiodothyronine (T3) and thyroxine (T4) levels, while BMI levels were positively correlated with TSH and free T3 levels. Excess iodine led to an increase in TSH levels and a decrease in thyroid hormone levels. Among the pollutants analyzed, most studies observed a decrease in thyroid hormone levels after exposure to perchlorate. Future studies should continue to analyze the impact of environmental factors on thyroid function as they could contribute to understanding the complex background of gene-environment interactions underlying the pathology of thyroid diseases.

Endocrine, metabolic and apical effects of in utero and lactational exposure to non-dioxin-like 2,2',3,4,4',5,5'-heptachlorobiphenyl (PCB 180): A postnatal follow-up study in rats

PCB 180 is a persistent and abundant non-dioxin-like PCB (NDL-PCB). We determined the developmental toxicity profile of ultrapure PCB 180 in developing offspring following in utero and lactational exposure with the focus on endocrine, metabolic and retinoid system alterations. Pregnant rats were given total doses of 0, 10, 30, 100, 300 or 1000 mg PCB 180/kg bw on gestational days 7-10 by oral gavage, and the offspring were sampled on postnatal days (PND) 7, 35 and 84. Decreased serum testosterone and triiodothyronine concentrations on PND 84, altered liver retinoid levels, increased liver weights and induced 7-pentoxyresorufin O-dealkylase (PROD) activity were the sensitive effects used for margin of exposure (MoE) calculations. Liver weights were increased together with induction of the metabolizing enzymes cytochrome P450 (CYP) 2B1, CYP3A1, and CYP1A1. Less sensitive effects included decreased serum estradiol and increased luteinizing hormone levels in females, decreased prostate and seminal vesicle weight and increased pituitary weight in males, increased cortical bone area and thickness of tibial diaphysis in females and decreased cortical bone mineral density in males. Developmental toxicity profiles were partly different in male and female offspring, males being more sensitive to increased liver weight, PROD induction and decreased thyroxine concentrations. MoE assessment indicated that the 95^th percentile of current maternal PCB 180 concentrations do not exceed the estimated tolerable human lipid-based PCB 180 concentration. Although PCB 180 is much less potent than dioxin-like compounds, it shares several toxicological targets suggesting a potential for interactions.

Associations of PCBS, dioxins and furans with follicle-stimulating hormone and luteinizing hormone in postmenopausal women: National Health and Nutrition Examination Survey 1999-2002

BACKGROUND

The general population is exposed to the group of endocrine disrupting chemicals persistent organic pollutants (POPs), that includes polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs).

OBJECTIVES

The aim of this research was to evaluate the associations of serum levels of PCB, PCDD, and PCDF congeners with follicle stimulating hormone (FSH) and luteinizing hormone (LH) in postmenopausal women not taking exogenous hormones. We hypothesized that associations of POPs with these gonadotropins could be modified by factors affecting endogenous hormones.

METHODS

Cross-sectional analyses were conducted on data from 89 postmenopausal women using data from the National Health and Nutrition Examination Survey (NHANES). POPs were summarized based on classification schemes thought to reflect toxicological properties. Associations of POPs and gonadotropin hormones were modeled with multivariable regression models. When evidence of interaction was found, conditional effects were estimated.

RESULTS

We found inverse associations of LH, but not FSH, with exposure to anti-estrogenic and/or dioxin-like POPs, but not with non dioxin-like PCBs. A doubling of dioxin-like toxic equivalents (TEQs) was associated with a decrease in LH of 11.9% (95% CI = -21.3%, -1.4%, p = 0.03). Inverse associations were enhanced by potential effect modifiers related to both direct and indirect estrogenicity, including obesity and the obesity-related condition inflammation.

CONCLUSIONS

These investigations support a pattern of endocrine-disrupting effects by dioxin-like POPs among postmenopausal women, especially those with conditions related to peripheral estrogenicity.

Multiple organochlorine pesticide exposures and measures of sex steroid hormones in adult males: Cross-sectional findings from the 1999-2004 National Health and Nutrition Examination Survey

BACKGROUND

Organochlorine pesticides are detectable in serum from most adults. Animal studies provide evidence of pesticide effects on sex hormones, suggesting that exposures may impact human reproductive function. Mounting evidence of sex differences in chronic diseases suggest that perturbations in endogenous sex hormones may influence disease risk. However, the association between organochlorine pesticide exposure and sex hormone levels in males across the lifespan is not well understood.

METHODS

We evaluated cross-sectional associations of lipid-adjusted serum concentrations of β-hexachlorocyclohexane, hexachlorobenzene, heptachlor epoxide, oxychlordane, dichlorodiphenyldichloroethylene (DDE), p,p'-dichlorodiphenyltrichloroethane (DDT), trans-nonachlor, and mirex in relation to sex steroid hormone levels [testosterone (ng/dL), sex hormone binding globulin (SHBG; nmol/L), estradiol (pg/mL), and androstanediol glucuronide (ng/dL)] in a sample of 748 males aged 20 years and older from the 1999-2004 cycles of the National Health and Nutrition Examination Survey (NHANES). Survey-weighted linear regression models were performed to estimate geometric means (GM) and their 95% confidence intervals (CIs) for quartiles of lipid-adjusted pesticide concentrations, adjusting for age, race, body mass index, serum lipids, smoking, education, and survey cycle.

RESULTS

Hexachlorobenzene concentration was positively associated with total estradiol (GM Q4 = 43.2 pg/mL (95% CI 36.5-51.1) vs. Q1 GM = 25.6 pg/mL (24.1-27.3), p-trend <0.0001) and free estradiol (GM Q4 = 0.77 pg/mL (95% CI 0.64-0.93) vs. Q1 GM = 0.47 pg/mL (0.44-0.51), p-trend = 0.002). Serum DDT concentration was positively associated with total estradiol (GM Q4 = 31.6 pg/mL (95% CI 25.9-38.5) vs. Q1 GM = 27.3 pg/mL (25.9-28.7), p-trend = 0.05) and free estradiol (GM Q4 = 0.60 pg/mL (95% CI 0.48-0.76) vs. Q1 GM = 0.50 pg/mL (0.47-0.53), p-trend 0.02). There was a suggestive inverse association of DDT and SHBG (GM Q4 = 29.2 nmol/L (95% CI 23.8-35.9) vs. Q1 GM = 33.9 nmol/L (32.3-35.5), p-trend 0.07). A positive association of β-hexachlorocyclohexane with total estradiol (GM Q4 = 30.3 pg/mL (95% CI 26.5-34.6) vs. Q1 GM = 26.7 pg/mL (24.5-29.0), p-trend = 0.09) was also suggestive but did not reach statistical significance. No distinct associations were observed for other hormone levels or other organochlorine pesticides.

CONCLUSIONS

Our findings suggest that select organochlorine pesticides may alter male estradiol levels. The positive associations with estradiol may implicate sex hormones as a possible mechanism for disease risk among those with organochlorine pesticide exposure.

Associations Between Preconception Plasma Fatty Acids and Pregnancy Outcomes

BACKGROUND

Although fatty acids are involved in critical reproductive processes, the relationship between specific fatty acids and fertility is uncertain. We investigated the relationship between preconception plasma fatty acids and pregnancy outcomes.

METHODS

We included 1,228 women attempting pregnancy with one to two previous pregnancy losses from the EAGeR trial (2007-2011). Plasma fatty acids were measured at baseline. We used log-binomial regression to assess associations between fatty acids and pregnancy, pregnancy loss, and live birth, adjusting for age, race, smoking, BMI, physical activity, income, parity, treatment arm, and cholesterol.

RESULTS

Although total saturated fatty acids (SFAs) were not associated with pregnancy outcomes, 14:0 (myristic acid; relative risk [RR] = 1.10, 95% confidence interval [CI] = 1.02, 1.19, per 0.1% increase) and 20:0 (arachidic acid; RR = 1.05, 95% CI = 1.01, 1.08, per 0.1% increase) were positively associated with live birth. Findings suggested a positive association between total monounsaturated fatty acids (MUFAs) and pregnancy and live birth and an inverse association with loss. Total polyunsaturated fatty acids (PUFAs) were associated with lower probability of pregnancy (RR = 0.97, 95% CI = 0.95, 1.00) and live birth (RR = 0.96, 95% CI = 0.94, 0.99), and increased risk of loss (RR = 1.10, 95% CI = 1.00, 1.20), per 1% increase. Trans fatty acids and n-3 fatty acids were not associated with pregnancy outcomes.

CONCLUSIONS

Preconception total plasma MUFAs were positively associated with pregnancy and live birth. PUFAs were inversely associated with pregnancy outcomes. Specific SFAs were associated with a higher probability of live birth. Our results suggest that fatty acids may influence pregnancy outcomes.

Cross-Sectional and Longitudinal Effects of PCB Exposure on Human Stress Hormones in the German HELPcB Surveillance Program

Multiple pathological associations are attributed to PCBs (polychlorinated biphenyls). Research shows a positive association of PCBs with dehydroepiandrosterone sulfate (DHEAS) concentration but the results on the stress hormone cortisol have been inconsistent so far. This study is the first to examine not only the cross-sectional but also the longitudinal effects of PCB exposure on the stress hormones DHEAS and cortisol. Over a period of three years, 112 former employees occupationally exposed to PCBs were tested for their body burden with different types of PCBs (lower and higher chlorinated, dioxin-like and hydroxylated) and for their stress hormone concentration. Highly exposed employees showed a significantly higher risk for higher DHEAS values. Multiple linear regression analysis revealed a positive relationship between the exposure to lower chlorinated PCBs and DHEAS. Mixed models also revealed a significantly positive correlation between lower chlorinated PCBs with DHEAS when controlled for a cross-section. However, an effect for cortisol was not found. These results suggest a causal pathophysiological relationship between PCB exposure and DHEAS concentration, but not with cortisol. The health consequences of high DHEAS concentrations are discussed.

Association between mixture of persistent organic pollutants and thyroid pathologies in a Belgian population

Previous years, the incidence of autoimmune thyroid diseases has increased worldwide. The presence of many pollutants in the environment suspected to be thyroid disruptors may have contributed to the observed increase. Unfortunately, the results from epidemiological studies assessing the association between pollution and thyroid disorders remain inconsistent, maybe due to a nearly complete neglect of the mixture effect. The blood levels of 12 brominated flame retardants, 3 polychlorinated biphenyls, 16 organochlorine pesticides, 7 perfluoroalkyl substances and 16 phenolic organohalogens were measured in 35 hypothyroid and 44 hyperthyroid volunteers and in 160 individuals from the general population designed as controls. Weighted quantile sum (WQS) regressions were performed to compute indexes representing the mixture of POPs, and we assessed the relations with thyroid disorders. Nineteen pollutants were detected in more than 40% of the individuals and were thus included in the WQS indexes. The WQS index was statistically significantly associated with an increased odds of hypothyroidism (odds ratio (OR) = 98.1; 95% CI: 5.51-1747) with the highest weights attributed to PCB 138 (w = 0.210), 3-OH-CB 180 (w = 0.197), 4-OH-CB 146 (w = 0.188), 4',4-DDE (w = 0.156) while there were no evidence of a relation with increased odds of hyperthyroidism. Given the relative low number of individuals included in the present investigation, standard WQS methodology could not be used, this study should thus be considered as a preliminary, hypothesis-generating study. Nevertheless, these results highlighted the importance of considering the potential effect of chemical mixture when studying endocrine disruptors.

Multigenerational metabolic profiling in the Michigan PBB registry

Although polychlorinated biphenyls and polybrominated biphenyls are no longer manufactured the United States, biomonitoring in human populations show that exposure to these pollutants persist in human tissues. The objective of this study was to identify metabolic variations associated with exposure to 2,2'4,4',5,5'-hexabromobiphenyl (PBB-153) and 2,2'4,4',5,5'-hexachlorobiphenyl (PCB-153) in two generations of participants enrolled in the Michigan PBB Registry (http://pbbregistry.emory.edu/). Untargeted, high-resolution metabolomic profiling of plasma collected from 156 individuals was completed using liquid chromatography with high-resolution mass spectrometry. PBB-153 and PCB-153 levels were measured in the same individuals using targeted gas chromatography-tandem mass spectrometry and tested for dose-dependent correlation with the metabolome. Biological response to these exposures were evaluated using identified endogenous metabolites and pathway enrichment. When compared to lipid-adjusted concentrations for adults in the National Health and Nutrition Examination Survey (NHANES) for years 2003-2004, PCB-153 levels were consistent with similarly aged individuals, whereas PBB-153 concentrations were elevated (p<0.0001) in participants enrolled in the Michigan PBB Registry. Metabolic alterations were correlated with PBB-153 and PCB-153 in both generations of participants, and included changes in pathways related to catecholamine metabolism, cellular respiration, essential fatty acids, lipids and polyamine metabolism. These pathways were consistent with pathophysiological changes observed in neurodegenerative disease and included previously identified metabolomic markers of Parkinson's disease. To determine if the metabolic alterations detected in this study are replicated other cohorts, we evaluated correlation of PBB-153 and PCB-153 with plasma fatty acids measured in NHANES. Both pollutants showed similar associations with fatty acids previously linked to PCB exposure. Thus, the results from this study show metabolic alterations correlated with PBB-153 and PCB-153 exposure can be detected in human populations and are consistent with health outcomes previously reported in epidemiological and mechanistic studies.

The spatial distribution of congener-specific human PCB concentrations in a PCB-polluted region

Serum PCB congener concentrations were measured in 602 adults living near a PCB pollution source in eastern Slovakia. We created isoconcentration maps for 21 PCB congeners by geocoding each participant's place of residence and kriging. Concentrations of PCB congeners were inversely associated with the distance of the participants' residence from the source of pollution. Congener-specific risk factors were derived, particularly for PCBs 52 and 153. We observed that the spatial distribution of serum concentrations was influenced by micro-climatic parameters and physicochemical properties of the congeners. PCB congener profiles strongly correlated with that of the PCB commercial product Delor 106, which was manufactured in the region. The isoconcentration maps indicate that the zones with the highest predicted congener concentration have a mean area of approximately 235.75±188.56km² and the mean enrichment of concentration of congeners in serum in these zones is about 5.12±1.36. We estimate that depending on congener approximately 23,457±18,762 individuals with PCB concentrations exceeding health-based guidance values live in these zones.

Approaches for incorporating environmental mixtures as mediators in mediation analysis

Mediation analysis offers an essential and rapidly expanding tool in environmental health studies to investigate the contribution of environmental factors towards observed associations between risk factors and health outcomes. When evaluating environmental factors, there may be particular interest in quantifying the impact of exposure to environmental mixtures on human health. In this context, evaluating the joint effect of multiple chemicals or pollutants, rather than individual examination, allows accurate identification of risk factors, assessment of interactions, and ultimately development of more targeted public health interventions. While mediation analysis has been extended to incorporate several methodological complexities specific to environmental factors, little attention has been given to integrating the analysis of environmental mixtures. The aim of this review is to present some of the available methods for environmental mixtures, and discuss how these methods can be integrated within a mediation analysis framework. By incorporating these methods into a mediation framework, investigators will be able to evaluate the contribution of environmental mixtures as mediators of exposure-outcome associations, based on methodologies that are currently available. While standard regression-based methods for multiple mediators can be used, these can easily become unstable as the number of mixture components increases. Summary and classification methods, or hierarchical modeling, can reduce the number of mediators by creating scores or possibly uncorrelated subgroups. This approach allows retrieving indirect effects due to the mixture or to a specific subgroup, but makes identification of component-specific effects and interactions complicated. Finally, one can use various approaches for analyzing mixtures in a two-stage fashion, selecting relevant mediators to be included in the final model. We focused this review on techniques that have been presented to the environmental health community and that can be conducted with major statistical software. We encourage researchers to move beyond the evaluation of one environmental factor at a time to the assessment of the joint effects of environmental mixtures when a mediation model is of interest. Available methods target different aspects related to environmental mixtures and the choice of the suitable approach will depend on data structures and the research question of interest.

Biomonitoring programs in Michigan, Minnesota and New York to assess human exposure to Great Lakes contaminants

Over the past century, industrialization and urban practices have resulted in the contamination of the Great Lakes ecosystem-the world's largest surface freshwater system-that provides drinking water and recreation to more than 40 million residents. In 2010, the Great Lakes Restoration Initiative was launched to accelerate efforts to protect and restore the Great Lakes and surrounding areas. Funded by GLRI, the Agency for Toxic Substances and Disease Registry initiated the Biomonitoring of Great Lakes Populations (BGLP) program. The objective of the program is to assess human exposure to legacy and emerging contaminants in the Great Lakes by measuring the body burden of contaminants in potentially susceptible populations. The BGLP program consists of a series of cross-sectional studies carried out collaboratively with states that are funded through ATSDR. The first BGLP Program (BGLP-I) began in 2010 and was completed in September 2015 through cooperative agreements with state health departments in Michigan, Minnesota, and New York. The three state programs targeted susceptible adult populations living in designated areas of contamination. Contaminants measured in all populations include mercury, lead, mirex, hexachlorobenzene, dichlorodiphenyltrichloroethane, and selected polychlorinated biphenyl congeners. In addition, some chemicals of emerging concern, such as per- and polyfluoroalkyl substances, were measured in several populations. The biomonitoring results helped guide public health actions to mitigate chemical exposures in these vulnerable Great Lakes populations. We provide an overview of the BGLP-I program's study populations, designs, and general methods. This overview provides a lead-in for subsequent manuscripts that present human biomonitoring data for legacy and emerging contaminants in culturally diverse susceptible populations-i.e., shoreline anglers, sport anglers, American Indians, and Burmese immigrants-residing in seven areas of concern.

Human Sex Hormone Disrupting Effects of New Flame Retardants and Their Interactions with Polychlorinated Biphenyls, Polybrominated Diphenyl Ethers, a Case Study in South China

Even though sex hormone disrupting effects of polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) are widely understood, similar effects associated with new flame retardants (NFRs) have not been so well studied. This study aimed to explore the sex hormone disruption of NFRs and their interactions with PCBs and PBDEs through the conduct of an ecological study in an e-waste dismantling and control region in South China. Questionnaires and blood samples were collected from local adult residents. Results of generalized additive model and linear regression analyses indicate that several species of NFRs showed similar disrupting effects with PBDE congeners on female follicle-stimulating hormone (FSH) and male testosterone. Judged by the curved shape and statistical significance, ΣNFR (sum of 8 species of NFRs) showed stronger disrupting effects on male testosterone and female FSH compared to ΣPBDE (sum of 13 congeners of PBDEs). The interactions induced by NFRs complicated the original sex hormone disruption led by PCBs and PBDEs. The disrupting effects and interactions induced by NFRs decreased female FSH levels in the exposed group. Comprehensive evaluation is needed to provide the evidence base for judging the health risks arising from the increased usage of NFRs.

Polychlorinated biphenyls, indicators of thyroid function and thyroid autoantibodies in the Anniston Community Health Survey I (ACHS-I)

In this study, we examined associations between serum concentrations of 35 polychlorinated biphenyl (PCB) congeners, pesticides, and indicators of thyroid function in participants of the Anniston Community Health Survey (ACHS). Study subjects lived in the vicinity of a former PCB production facility and had PCB concentrations 2 to 3 times higher than similar age and race groups from the general population. We investigated associations among serum levels of thyroid hormones (thyroxin [T4], free thyroxin [fT4], triiodothyronine [T3], thyroid stimulation hormone [TSH]) and auto-antibodies (thyroglobulin antibody [TgAb] or thyroperoxidase antibody [TPOAb]) and combined indicators of thyroid function with the sum of PCBs, varying PCB groups, individual PCB congeners, and 8 pesticides. Logistic and linear regression models were adjusted for log10 transformed total lipids, age, sex, ethnicity, BMI, smoking, and family history of thyroid disease. We also performed analyses stratified by ethnicity and sex. Linear regression showed inverse associations between TT3 and thyroid-like PCBs (sum of PCBs 28, 52, 74, 101, 105, and 118; p = .0004), two pesticides (hexachlorobenzene, and pp'-DDE), and individual congeners (PCBs 74, 105). Null associations were observed between PCBs, pesticides, TSH, TT4, and fT4. Logistic regression analyses did not provide support for TT3 findings and found no association with other thyroid hormones, antibodies, or combined indicator of thyroid function. These results suggest there is little evidence that these chemicals have any major clinical effect on thyroid function in this highly PCB exposed population.

Polychlorinated biphenyls (PCBs) in recreational marina sediments of San Diego Bay, southern California

Polychlorinated biphenyl (PCB) concentrations were determined in surface sediments from three recreational marinas in San Diego Bay, California. Total PCB concentrations ranged from 23 to 153, 31-294, and 151-1387ngg^-1 for Shelter Island Yacht Basin (SIYB), Harbor Island West (HW) and Harbor Island East (HE), respectively. PCB concentrations were significantly higher in HE and PCB group composition differed relative to HW and SIYB, which were not significantly different from each other in concentration or group composition. In marina sediments there was a predominance (82-85%) of heavier molecular weight PCBs with homologous groups (6CL-7CL) comprising 59% of the total. In HE 75% of the sites exceeded the effect range median (ERM), and toxicity equivalence (TEQ dioxin-like PCBs) values were higher relative to those of HW and SIYB, suggesting a potential ecotoxicological risk.

Serum Levels of Persistent Organic Pollutants and Insulin Secretion among Children Age 7-9 Years: A Prospective Cohort Study

BACKGROUND

Persistent organic pollutants (POPs) are endocrine disruptors and have been suggested as possible risk factors for diabetes. Few studies have been performed to investigate this association among children.

OBJECTIVES

In this study, we prospectively examined the relationship between the serum concentration of POPs and glucose metabolism in children.

METHODS

Data were collected from the Ewha Birth & Growth Cohort Study, an ongoing birth cohort study initially constructed between 2001 and 2006. In 2010-2012, the POP concentration was measured in serum from a total of 214 children, 7-9 years of age. Using fasting glucose and insulin measurements at both baseline and the second year of follow-up, the homeostatic model assessment of beta-cell function (HOMA-β) and homeostatic model assessment of insulin resistance (HOMA-IR) were calculated. Multiple linear regression analysis and a linear mixed-effects model were used to determine the relationship between POP tertiles and metabolic biomarkers.

RESULTS

Compared with the lowest tertile of total marker PCBs, participants in the third tertile had decreased HOMA-β values, after adjustment for age, sex, body mass index z-score, mother's education, ponderal index, and history of breastfeeding (-18.94%; 95% CI: -32.97%, -1.98%). In a linear mixed model, the HOMA-β values were still lower in subjects in the highest compared with the lowest tertile of total PCBs at the 2-year follow-up period (108.3 vs. 135.0, respectively).

CONCLUSION

The results of the study suggested that exposure to POPs among children might affect insulin secretory function, which could lead to an increased risk of developing diabetes. Citation: Park SH, Ha EH, Hong YS, Park H. 2016. Serum levels of persistent organic pollutants and insulin secretion among children age 7-9 years: a prospective cohort study. Environ Health Perspect 124:1924-1930; http://dx.doi.org/10.1289/EHP147.

Association between organochlorine pesticide exposure and thyroid hormones in floriculture workers

Several studies have suggested that exposure to DDT may be related to changes in thyroid hormone levels in animals and humans, even though results across studies are inconsistent. The aim of this study was to assess the association between exposure to p,p'-DDE (a stable metabolite of DDT) and serum levels of thyroid hormones in floriculture workers. A longitudinal study was conducted on 136 male subjects from the States of Mexico and Morelos, Mexico, who were occupationally exposed to pesticides, during agricultural periods of high (rainy season) and low (dry season) levels of pesticide application. Using a structured questionnaire, a survey was carried out on socio-demographic characteristics, anthropometry, clinical history, alcohol and tobacco consumption, residential chemical exposure, and occupational history. Blood and urine samples were collected to determine serum levels of TSH, total T3, total T4, and p,p'-DDE, and metabolites of organophosphate pesticides (OP), respectively. The analysis of the associations between p,p'-DDE levels and thyroid hormone profile adjusting by potential confounding variables including urinary OP metabolites was carried out using multivariate generalized estimating equation (GEE) models. Our results showed that the geometric means of p,p'-DDE levels were 6.17 ng/ml and 4.71 ng/ml in the rainy and dry seasons, respectively. We observed positive associations between the serum levels of p,p'-DDE and those of total T3 (β=0.01, 95% CI: -0.009, 0.03), and total T4 (β=0.08, 95% CI:0.03, 0.14) and negative but no significant changes in TSH in male floricultural workers, supporting the hypothesis that acts as thyroid disruptor in humans.

Deterministic modeling of the exposure of individual participants in the National Health and Nutrition Examination Survey (NHANES) to polychlorinated biphenyls

A population's exposure to persistent organic pollutants, e.g., polychlorinated biphenyls (PCBs), is typically assessed through national biomonitoring programs, such as the United States National Health and Nutrition Examination Survey (NHANES). To complement statistical methods, we use a deterministic modeling approach to establish mechanistic links between human contaminant concentrations and factors (e.g. age, diet, lipid mass) deemed responsible for the often considerable variability in these concentrations. Lifetime exposures to four PCB congeners in 6128 participants from NHANES 1999-2004 are simulated using the ACC-Human model supplied with individualized input parameters obtained from NHANES questionnaires (e.g., birth year, sex, body mass index, dietary composition, reproductive behavior). Modeled and measured geometric mean PCB-153 concentrations in NHANES participants of 13.3 and 22.0 ng g^-1 lipid, respectively, agree remarkably well, although lower model-measurement agreement for air, water, and food suggests that this is partially due to fortuitous error cancellation. The model also reproduces trends in the measured data with key factors such as age, parity and sex. On an individual level, 62% of all modeled concentrations are within a factor of three of their corresponding measured values (Spearman r_s = 0.44). However, the model attributes more of the inter-individual variability to differences in dietary lipid intake than is indicated by the measured data. While the model succeeds in predicting levels and trends on the population level, the accuracy of individual-specific predictions would need to be improved for refined exposure characterization in epidemiological studies.

Exposure to polychlorinated biphenyls and the thyroid gland - examining and discussing possible longitudinal health effects in humans

BACKGROUND

Many previous studies have dealt with the effect of polychlorinated biphenyls (PCBs) on the thyroid gland, but their findings are inconsistent. One problem of these studies has been their use of cross-sectional designs.

OBJECTIVES

The aim of the current study is to investigate longitudinal effects of PCBs on the thyroid gland, focusing on: morphological changes in thyroid tissue (i.e. thyroid volume), changes in thyroid hormones and in thyroid antibodies.

METHODS

A total of 122 individuals (Mage=44.7) were examined over a period of four years (t(1) until t(4)). Medical history was collected via interviews, an ultrasound examination was performed and blood samples were taken to determine plasma PCB levels, thyroid stimulating hormone (TSH), free triiodthyronine (fT3), free thyroxine (fT4), thyroid peroxidase antibodies (TPOab), thyreoglobulin antibodies (TGab) and thyroid-stimulating hormone receptor antibodies (TSHRab). Rank correlation coefficients and mixed effect models were performed controlling for age and total lipids.

RESULTS

There were negative correlations between higher chlorinated biphenyls and fT3, cross-sectionally as well as longitudinally. We also found an interaction effect of higher-chlorinated PCBs over time for fT4 as well as TSHRab. In case of high exposure, a decrease in fT4 and an increase in TSHRab level were found over time. In regards to the other variables, our findings yielded no clear results in the examined time period.

CONCLUSION

This is the first study to shows a PCB-related effect on fT3, fT4 and TSHRab over a four year period. The data also suggest that morphological and antibody findings remain inconsistent and do not allow for unambiguous interpretation.

Relationship between e-waste recycling and human health risk in India: a critical review

Informal recycling of waste (including e-waste) is an emerging source of environmental pollution in India. Polychlorinated biphenyls (PCBs), polychlorinated diphenyl ethers (PBDEs), and heavy metals, among other substances, are a major health concern for workers engaged in waste disposal and processing, and for residents living near these facilities, and are also a detriment to the natural environment. The main objective of this review article was to evaluate the status of these impacts. The review found that, huge quantity of e-waste/waste generated, only a small amount is treated formally; the remainder is processed through the informal sector. We also evaluated the exposure pathways, both direct and indirect, and the human body load markers (e.g., serum, blood, breast milk, urine, and hair), and assessed the evidence for the association between these markers and e-waste exposure. Our results indicated that the open dumping and informal e-waste recycling systems should be replaced by the best available technology and environmental practices, with proper monitoring and regular awareness programs for workers and residents. Further and more detailed investigation in this area is also recommended.

A Preliminary Link between Hydroxylated Metabolites of Polychlorinated Biphenyls and Free Thyroxin in Humans

BACKGROUND

Polychlorinated biphenyls (PCBs) and their hydroxylated metabolites (HO-PCBs) interfere with thyroid hormone action both in vitro and in vivo. However, epidemiologic studies on the link between PCB exposure and thyroid function have yielded discordant results, while very few data are available for HO-PCBs.

OBJECTIVES

Our study aimed at investigating the relationship between clinically available markers of thyroid metabolism and serum levels of both PCBs and HO-PCBs.

SUBJECTS AND METHODS

In a group of 180 subjects, thyroid-stimulating hormone (TSH) and free thyroxin (fT4), 29 PCBs (expressed both in lipid weight and in wet weight) and 18 HO-PCBs were measured in serum.

RESULTS

In regression models, adjusted for gender, age, current smoking behavior, BMI and total lipid levels, serum levels of 3HO-PCB118 and 3HO-PCB180, and PCB95(lw), PCB99(lw) and PCB149(lw) were independent, significant predictors of fT4. A stepwise, multiple regression with gender, age, current smoking behavior, BMI and total lipid levels and all five previously identified significant compounds retained age, BMI, PCB95(lw), PCB99(lw) and 3HO-PCB180 as significant predictors of fT4. TSH levels were not predicted by serum levels of any of the PCBs or HO-PCBs.

CONCLUSIONS

Our study indicates that in vivo, circulating fT4 levels can be linked to serum levels of several PCBs and hydroxylated PCB metabolites.

Associations of bisphenol A and polychlorinated biphenyls with spermatogenesis and steroidogenesis in two biological fluids from men attending an infertility clinic

BACKGROUND

In the testis, steroid hormones play an important role in spermatogenesis, the production of semen, and the maintenance of secondary sex characteristics and libido. They may also play a role as a target for substances called endocrine disruptors (EDs). As yet, however, no complex study has been conducted evaluating the relationships between EDs and the steroid spectrum in the plasma and seminal plasma.

OBJECTIVES

To shed more light into mechanisms of EDs and the effects of bisphenol A (BPA) and polychlorinated biphenyls (PCBs) on human spermatogenesis and steroidogenesis.

METHODS

We determined BPA and 11 steroids in the plasma and seminal plasma of 191 men with different degrees of fertility, using a newly developed liquid-chromatography mass spectrometry method. Concurrently, plasma levels of 6 congeners of PCBs, gonadotropins, selenium, zinc and homocysteine were measured. Partial correlations adjusted for age, BMI and abstinence time were performed to evaluate relationships between these analytes.

RESULTS

Seminal BPA, but not plasma BPA, was negatively associated with sperm concentration (r=-0.198; p=0.009), sperm count (r=-0.178; p=0.018) and morphology (r=-0.160; p=0.044). Divergent and sometimes opposing associations of steroids and BPA were found in both body fluids. The sum of PCB congeners was negatively associated with testosterone, free testosterone, the free androgen index and dihydrotestosterone in plasma.

CONCLUSION

BPA may negatively contribute to the final state of sperm quality. Moreover, our data indicate that BPA influences human gonadal and adrenal steroidogenesis at various steps. Environmental levels of PCBs negatively correlated with androgen levels, but surprisingly without negative effects on sperm quality.

Persistent organic pollutants and biomarkers of diabetes risk in a cohort of Great Lakes sport caught fish consumers

BACKGROUND

Exposure to persistent organic pollutants (POPs) is associated with increased diabetes risk, although the mechanism of action is not well delineated.

METHODS

We investigated established diabetes biomarkers that could implicate potential mechanistic pathways, including C-reactive protein (CRP), a marker of systemic inflammation; gamma glutamyl transferase (GGT), a liver enzyme associated with oxidative stress; and adiponectin, an adipokine modulating glucose regulation and fatty acid oxidation. These biomarkers as well as hemoglobin A1c (HA1c), and POPs [polychlorinated biphenyls (PCBs), p,p-dichlorodiphenyldichloroethylene (DDE) and polybrominated diphenyl ethers (PBDEs)] were measured in a cohort of Great Lakes sport caught fish (GLSCF) consumers. We examined associations of POPs and fish consumption with HA1c and incident diabetes, and evaluated mediation and moderation by the diabetes biomarkers.

RESULTS

Odds of incident diabetes were elevated with exposure to DDE and PCBs. DDE and PCB 118 were positively, and fish meals were inversely, associated with HA1c. CRP was inversely associated with saltwater and total fish meals, particularly in persons with higher adiposity, but did not mediate the associations of fish meals with HA1c. There were few associations of POPs with adiponectin, CRP and GGT, with the exception of positive associations of PCB 118 with GGT, PBDEs with GGT in older persons, and PBDEs with adiponectin. Adiponectin, CRP and GGT did not mediate associations of DDE and PCBs with HA1c or incident diabetes. However, the association of DDE with HA1c was stronger in persons with higher CRP, GGT and BMI, and lower adiponectin, while the association of PCB 118 with HA1c was stronger in persons with higher GGT.

CONCLUSIONS

These findings suggest that adiponectin, CRP and GGT did not mediate effects of POPs on diabetes or HA1c. However, POPs may have stronger effects on blood glucose in persons at higher risk for diabetes.

Residue profiles of organohalogen compounds in human serum from e-waste recycling sites in North Vietnam: Association with thyroid hormone levels

This study demonstrated the contamination levels of polychlorinated biphenyls (PCBs), hydroxylated PCBs (OH-PCBs), polybrominated diphenyl ethers (PBDEs), methoxylated PBDEs (MeO-PBDEs), hydroxylated PBDEs (OH-PBDEs), and bromophenols (BPhs), and their relationships with thyroid hormones (THs), in the serum of human donors from an e-waste recycling site and a rural site in Hung Yen province, Vietnam. Occupationally related exposure was indicated by significantly higher residue levels of PCBs, OH-PCBs, PBDEs, and BPhs in the serum of donors from the e-waste recycling site (median: 420, 160, 290, and 300pgg(-1) wet wt, respectively) than those in the serum of donors from the rural site (median: 290, 82, 230, and 200pgg(-)(1) wet wt, respectively). On the other hand, levels of OH-/MeO-PBDEs were significantly higher in serum of donors from the reference site (median: 160 and 20pgg(-1) wet wt, respectively) than in those from the e-waste recycling site (median: 43 and 0.52pgg(-1) wet wt, respectively). In addition, we implemented stepwise generalized linear models to assess the association between the levels of TH and PCBs, PBDEs, and their related compounds. In females, we found positive associations of PCBs and OH-PCB concentrations with total thyroxine, free thyroxine, total triiodothyronine, and free triiodothyronine, and a negative association with thyroid-stimulating hormone concentrations.

Monitoring chlorinated persistent organic pollutants in adolescents in Flanders (Belgium): concentrations, trends and dose-effect relationships (FLEHS II)

BACKGROUND

In 2007, the second cycle of the Flemish human biomonitoring survey started, with a main focus on 14-15 year-old adolescents.

OBJECTIVES

The main objectives were generating reference values for exposure markers, determining the pollution pressure in industrial hotspots and establishing dose-effect relationships between exposure to pollutants and hormone levels, sexual development, asthma and allergy, genotoxic and hematological markers.

METHODS

Geometric means with 95% confidence intervals (CI) were calculated for a reference population of 200 14-15 year-old adolescents. Stepwise multiple regression analyses with correction for confounders and covariates were performed to establish dose-effect relationships.

RESULTS

Geometric mean concentrations (with 95% CI) of 49.6 (45.7, 53.8), 70.8 (63.6, 78.8) and 8.34 (7.76, 8.97) n gg(-1) lipid for the sum of PCB 138, 153 and 180, p,p'-DDE and HCB were respectively 23%, 26% and 60% lower than those obtained five years earlier. Geometric mean concentrations of 108 (101, 114) and 32.1 (30.1, 34.2) pgCALUX-BEQg(-1) lipid were observed for the PCDD/Fs and dioxin-like PCBs, respectively. Multiple dose-effect relationships were observed between POPs and several effect markers, including positive (boys) and negative (girls) associations with data on sexual development and positive associations with asthma, animal allergy and free thyroxine (boys and girls).

CONCLUSIONS

Our findings suggest that chlorinated POP concentrations are decreasing over time and that even relatively low concentrations are associated with biological effects.

Persistent organic pollutants and male reproductive health

Environmental contaminants such as persistent organic pollutants (POPs) are man-made bioaccumulative compounds with long half-lives that are found throughout the world as a result of heavy use in a variety of consumer products during the twentieth century. Wildlife and animal studies have long suggested adverse effects of exposure to these compounds on human reproductive health, which, according to the endocrine disrupter hypothesis, are ascribed to the compounds’ potential to interfere with endocrine signaling, especially when exposure occurs during certain phases of fetal and childhood development. An extensive number of epidemiological studies have addressed the possible effects of exposure to POPs on male reproductive health, but the results are conflicting. Thus far, most studies have focused on investigating exposure and the different reproductive health outcomes during adulthood. Some studies have addressed the potential harmful effects of fetal exposure with respect to malformations at birth and/or reproductive development, whereas only a few studies have been able to evaluate whether intrauterine exposure to POPs has long-term consequences for male reproductive health with measurable effects on semen quality markers and reproductive hormone levels in adulthood. Humans are not exposed to a single compound at a time, but rather, to a variety of different substances with potential divergent hormonal effects. Hence, how to best analyze epidemiological data on combined exposures remains a significant challenge. This review on POPs will focus on current knowledge regarding the potential effects of exposure to POPs during fetal and childhood life and during adulthood on male reproductive health, including a critical revision of the endocrine disruption hypothesis, a comment on pubertal development as part of reproductive development and a comment on how to account for combined exposures in epidemiological research.

Prevalence and incidence rates of mental syndromes after occupational exposure to polychlorinated biphenyls

Mental disorders were often reported following hazardous substance exposure. The present study analyses this association in relation to a work-related exposure to PCBs (polychlorinated biphenyls). Specifically, the aim was to investigate (a) the relationship of inner PCB burden and the severity of mental symptoms and (b) the prevalence and incidence of mental syndromes. This study was initiated as part of the occupational medical surveillance program HELPcB (Health Effects in high level exposure to PCB). A total of 136 individuals were included in the analysis. The plasma PCBs were collected via biomonitoring and the psychological syndromes (i.e., somatoform, depressive, anxiety, panic) with a standardized screening instrument. The relationship of PCB and the severity of mental syndromes were analyzed via linear regression. Prevalence rates, the respective odds ratios (OR) and the incidence rates were calculated with logistic regressions. We thereby compared the higher-PCB burdened individuals with those individuals showing PCB levels comparable to the general population. We found especially a significant relationship between PCB burden and depressivity. Within the higher-PCB-exposed group prevalence rates were descriptively higher than for normal-exposed participants, except for anxiety syndrome. Similarly, the higher exposed group had a higher risk for developing a depressive syndrome. The incidence rates were always descriptively higher in higher-exposed group. To summarize, this study supports a relationship between PCB exposure and mental illness.

Thyroid hormones are associated with exposure to persistent organic pollutants in aging residents of upper Hudson River communities

The aim of this study was to evaluate the association between persistent organic pollutants (POPs) and thyroid hormones in an aging population. Forty-eight women and 66 men, aged 55-74 years and living in upper Hudson River communities completed a questionnaire and provided blood specimens. Serum was analyzed for thyrotropin (thyroid stimulating hormone, TSH), free (fT4) and total thyroxine (T4), total triiodothyronine (T3), and for POPs. POPs included 39 polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethane (DDT) and dichlorodiphenyldichloroethylene (DDE) determined by gas chromatography with electron capture detection (GC-ECD), and nine polybrominated diphenyl ethers (PBDEs) determined by high-resolution gas chromatography with high-resolution mass spectrometry detection (HRGC-HRMS). Multivariable linear regression analysis was used to evaluate associations between thyroid hormones and sums of POPs, adjusted for covariates and stratified by sex. Effects were expressed as differences in thyroid hormone levels associated with a doubling in the level of exposure. Among women, DDT+DDE increased T4 by 0.34μg/dL (P=0.04) and T3 by 2.78ng/dL (P=0.05). Also in women, sums of PCBs in conjunction with PBDEs elicited increases of 24.39-80.85ng/dL T3 (P<0.05), and sums of PCBs in conjunction with DDT+DDE elicited increases of 0.18-0.31μg/dL T4 (P<0.05). For men estrogenic PCBs were associated with a 19.82ng/dL T3 decrease (P=0.003), and the sum of estrogenic PCBs in conjunction with DDT+DDE elicited an 18.02ng/dL T3 decrease (P=0.04). Given age-related declines in physiologic reserve, the influence of POPs on thyroid hormones in aging populations may have clinical implications and merits further investigation.

Serum concentrations of polychlorinated biphenyls (PCBs) in participants of the Anniston Community Health Survey

Serum concentrations of 35 ortho-substituted polychlorinated biphenyl congeners (PCBs) were measured in 765 adults from Anniston, Alabama, where PCBs were manufactured between 1929 and 1971. As part of the Anniston Community Health Survey (ACHS), demographic data, questionnaire information, and blood samples were collected from participants in 2005-2007. Forty-six percent of study participants were African-American, 70% were female, and the median age was 56 years. The median concentration of the sum of 35 PCB congeners (ΣPCBs) was 528 ng/g lipid, with a 90th percentile of 2,600 ng/g lipid, minimum of 17.0 ng/g lipid, and maximum of 27,337 ng/g lipid. The least square geometric mean ΣPCBs was more than 2.5 times higher for African-American participants than for White participants (866 ng/g lipid vs. 331 ng/g lipid); this difference did not change materially after adjustment for age, sex, body mass index (BMI) and current smoking. In spite of large differences in absolute PCB levels, relative contributions of individual congeners to ΣPCBs were quite similar between race groups. Nevertheless, while percent contributions to ΣPCBs for most of the most abundant penta- to heptachlorobiphenyls were higher among African-Americans, the percentages were higher in Whites for the lower-chlorinated PCBs 28 and 74 and for octa- to decachlorinated PCBs. No major differences were observed in geometric mean ΣPCBs between women and men when adjusted for age, race, BMI and current smoking (516 ng/g lipid vs. 526 ng/g lipid). Principal component analysis revealed groups of co-varying congeners that appear to be determined by chlorine substitution patterns. These congener groupings were similar between ACHS participants and the National Health and Nutrition Examination Survey (NHANES) 2003-04 sample of the general United States population, despite ACHS participants having serum concentrations of ΣPCBs two to three times higher than those in comparable age and race groups from NHANES.

Relationships of polychlorinated biphenyls and dichlorodiphenyldichloroethylene (p,p'-DDE) with testosterone levels in adolescent males

BACKGROUND

Concern persists over endocrine-disrupting effects of persistent organic pollutants (POPs) on human growth and sexual maturation. Potential effects of toxicant exposures on testosterone levels during puberty are not well characterized.

OBJECTIVES

In this study we evaluated the relationship between toxicants [polychlorinated biphenyls (PCBs), dichlorodiphenyldichloroethylene (p,p´-DDE), hexachlorobenzene (HCB), and lead] and testosterone levels among 127 Akwesasne Mohawk males 10 to < 17 years of age with documented toxicant exposures.

METHODS

Data were collected between February 1996 and January 2000. Fasting blood specimens were collected before breakfast by trained Akwesasne Mohawk staff. Multivariable regression models were used to estimates associations between toxicants and serum testosterone, adjusted for other toxicants, Tanner stage, and potential confounders.

RESULTS

The sum of 16 PCB congeners (Σ16PCBs) that were detected in ≥ 50% of the population was significantly and negatively associated with serum testosterone levels, such that a 10% change in exposure was associated with a 5.6% decrease in testosterone (95% CI: -10.8, -0.5%). Of the 16 congeners, the more persistent ones (Σ8PerPCBs) were related to testosterone, whereas the less persistent ones, possibly reflecting more recent exposure, were not. When PCB congeners were subgrouped, the association was significant for the sum of eight more persistent PCBs (5.7% decrease; 95% CI: -11, -0.4%), and stronger than the sum of six less persistent congeners (3.1% decrease; 95% CI: -7.2, 0.9%). p,p´-DDE was positively but not significantly associated with serum testosterone (5.2% increase with a 10% increase in exposure; 95% CI: -0.5, 10.9%). Neither lead nor HCB was significantly associated with testosterone levels.

CONCLUSIONS

Exposure to PCBs, particularly the more highly persistent congeners, may negatively influence testosterone levels among adolescent males. The positive relationship between p,p´-DDE and testosterone indicates that not all POPs act similarly.

CITATION

Schell LM, Gallo MV, Deane GD, Nelder KR, DeCaprio AP, Jacobs A; Akwesasne Task Force on the Environment. 2014. Relationships of polychlorinated biphenyls and dichlorodiphenyldichloroethylene (p,p´-DDE) with testosterone levels in adolescent males. Environ Health Perspect 122:304-309; http://dx.doi.org/10.1289/ehp.1205984.

Long-term exposure to organochlorine pesticides and thyroid status in adults in a heavily contaminated area in Brazil

Organochlorine (OC) pesticides are endocrine disruptors altering the thyroid hormonal system. The aim of this study is to investigate the relationship between exposure to OC pesticides and thyroid status in adults from a rural area in Rio de Janeiro, Brazil, heavily contaminated with OC pesticides. A cross-sectional study was carried out in 303 men and 305 women >14 years old. Concentrations of 19 OC pesticides and levels of free thyroxine (T4), total triiodothyronine (T3), thyroid-stimulating hormone (TSH), anti-thyroperoxidase (TPOAb) and anti-thyroglobulin (TgAg) antibodies were analyzed in serum samples. Associations between OC pesticides concentrations and values of biochemical thyroid parameters were determined using multivariate regression models stratified by gender. Prevalence of subclinical hyperthyroidism and the presence of TPOAb antibodies were higher than those described for euthyroid populations elsewhere. After adjusting for confounders, total T3 levels were associated with lower concentrations of endosulphan 2 in men and with higher alpha-chlordane, p,p'-dichlorodiphenyltrichloroethane (DDT), endosulphan 2, and methoxychlor in women. Levels of free T4 showed inverse association with beta-hexachlorocyclohexane (HCH) and p,p'-DDT in men, and were positively associated with hexachlorobenzene (HCB), heptachlor, o,p'-DDT, and p,p'-DDT in women. TSH levels were associated with higher beta-HCH in men. A positive association was observed between exposure methoxychlor in males and presence of TPOAb, but no association with TPOAb was found in women. These results suggest that OC pesticides can affect the thyroid system through gender-specific mechanisms that may differ among compounds. Further detailed investigations and health monitoring should be warranted for this population.

Association between perfluoroalkyl substances and thyroid stimulating hormone among pregnant women: a cross-sectional study

BACKGROUND

Perfluoroalkyl substances (PFASs) are a group of highly persistent chemicals that are widespread contaminants in wildlife and humans. Exposure to PFAS affects thyroid homeostasis in experimental animals and possibly in humans. The objective of this study was to examine the association between plasma concentrations of PFASs and thyroid stimulating hormone (TSH) among pregnant women.

METHODS

A total of 903 pregnant women who enrolled in the Norwegian Mother and Child Cohort Study from 2003 to 2004 were studied. Concentrations of thirteen PFASs and TSH were measured in plasma samples collected around the 18th week of gestation. Linear regression models were used to evaluate associations between PFASs and TSH.

RESULTS

Among the thirteen PFASs, seven were detected in more than 60% of samples and perfluorooctane sulfonate (PFOS) had the highest concentrations (median, 12.8 ng/mL; inter-quartile range [IQR], 10.1 -16.5 ng/mL). The median TSH concentration was 3.5 (IQR, 2.4 - 4.8) μIU/mL. Pregnant women with higher PFOS had higher TSH levels. After adjustment, with each 1 ng/mL increase in PFOS concentration, there was a 0.8% (95% confidence interval: 0.1%, 1.6%) rise in TSH. The odds ratio of having an abnormally high TSH, however, was not increased, and other PFASs were unrelated to TSH.

CONCLUSIONS

Our results suggest an association between PFOS and TSH in pregnant women that is small and may be of no clinical significance.

Association between several persistent organic pollutants and thyroid hormone levels in serum among the pregnant women of Korea

Persistent organic pollutants such as polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and organochlorine pesticides (OCPs) are of global concern because of their widespread contamination and adverse health effects. Potential endocrine disruption, especially of thyroid status by PCBs has been repeatedly suggested in both experimental and epidemiological studies. However the associations with PBDEs or OCPs have been arguable especially in human populations. We investigated the associations between major groups of POPs and thyroid hormone balances among pregnant women. One hundred five pregnant women at delivery were recruited from four cities of Korea in 2011 and were investigated. Blood samples were collected within a day before delivery. Serum was then analyzed for 19 PCBs, 19 PBDEs, and 19 OCPs, along with five thyroid hormones (free and total T3 and T4, and TSH). Several PCBs such as PCB28, 52, and 118 showed negative associations with T3 or T4. BDE47 and total PBDEs showed significant associations with T3 or T4. For OCPs, dichlorodiphenyltrichloroethanes (DDTs) and hexachlorobenzene (HCB) were generally associated with reduction of T3 or T4. The thyroid hormone levels of all subjects were within the reference range, however exposure to several target POPs were clearly related with potential for disrupting thyroid hormone balance among pregnant women, at the current level of exposure. Although subtle, the changes in thyroid hormones should be seen with caution because even minor changes within pregnant women may have significant consequences especially on sensitive population like fetus.

Persistent organochlorine pollutants with endocrine activity and blood steroid hormone levels in middle-aged men

BACKGROUND

Studies relating long-term exposure to persistent organochlorine pollutants (POPs) with endocrine activities (endocrine disrupting chemicals) on circulating levels of steroid hormones have been limited to a small number of hormones and reported conflicting results.

OBJECTIVE

We examined the relationship between serum concentrations of dehydroepiandrosterone, dehydroepiandrosterone sulphate, androstenedione, androstenediol, testosterone, free and bioavailable testosterone, dihydrotestosterone, estrone, estrone sulphate, estradiol, sex-hormone binding globulin, follicle-stimulating hormone, and luteinizing hormone as a function of level of exposure to three POPs known to interfere with hormone-regulated processes in different way: dichlorodiphenyl dichloroethene (DDE), polychlorinated biphenyl (PCB) congener 153, and chlordecone.

METHODS

We collected fasting, morning serum samples from 277 healthy, non obese, middle-aged men from the French West Indies. Steroid hormones were determined by gas chromatography-mass spectrometry, except for dehydroepiandrosterone sulphate, which was determined by immunological assay, as were the concentrations of sex-hormone binding globulin, follicle-stimulating hormone and luteinizing hormone. Associations were assessed by multiple linear regression analysis, controlling for confounding factors, in a backward elimination procedure, in multiple bootstrap samples.

RESULTS

DDE exposure was negatively associated to dihydrotestosterone level and positively associated to luteinizing hormone level. PCB 153 was positively associated to androstenedione and estrone levels. No association was found for chlordecone.

CONCLUSIONS

These results suggested that the endocrine response pattern, estimated by determining blood levels of steroid hormones, varies depending on the POPs studied, possibly reflecting differences in the modes of action generally attributed to these compounds. It remains to be investigated whether this response pattern is predictive of the subsequent occurrence of disease.

Different profiles of anthropogenic and naturally produced organohalogen compounds in serum from residents living near a coastal area and e-waste recycling workers in India

We determined the contamination status and accumulation profiles of polychlorinated biphenyls (PCBs), hydroxylated PCB congeners (OH-PCBs), polybrominated diphenyl ethers (PBDEs), hydroxylated PBDEs (OH-PBDEs), methoxylated PBDEs (MeO-PBDEs), and bromophenols (BPhs) in serum from e-waste recycling workers and residents near a coastal area in India. Residue levels of penta- to octa-chlorinated PCBs, penta- to octa-chlorinated OH-PCBs, 6MeO-BDE47, 6OH-BDE47, and 2,4,6-tri-BPh in serum from residents living near the coastal area were significantly higher than those in serum from e-waste recycling workers. Residue levels of tri- to tetra-chlorinated PCBs, tri- to tetra-chlorinated OH-PCBs, PBDEs, octa-brominated OH-PBDEs, and tetra-BPhs in serum from e-waste recycling workers were higher than those in serum from residents living near the coastal area. Principal component analysis revealed that residents living near the coastal area and e-waste recycling workers had different serum profiles of chlorinated and brominated compounds.

Polychlorinated biphenyl exposure, diabetes and endogenous hormones: a cross-sectional study in men previously employed at a capacitor manufacturing plant

BACKGROUND

Studies have shown associations of diabetes and endogenous hormones with exposure to a wide variety of organochlorines. We have previously reported positive associations of polychlorinated biphenyls (PCBs) and inverse associations of selected steroid hormones with diabetes in postmenopausal women previously employed in a capacitor manufacturing plant.

METHODS

This paper examines associations of PCBs with diabetes and endogenous hormones in 63 men previously employed at the same plant who in 1996 underwent surveys of their exposure and medical history and collection of bloods and urine for measurements of PCBs, lipids, liver function, hematologic markers and endogenous hormones.

RESULTS

PCB exposure was positively associated with diabetes and age and inversely associated with thyroid stimulating hormone and triiodothyronine-uptake. History of diabetes was significantly related to total PCBs and all PCB functional groupings, but not to quarters worked and job score, after control for potential confounders. None of the exposures were related to insulin resistance (HOMA-IR) in non-diabetic men.

CONCLUSIONS

Associations of PCBs with specific endogenous hormones differ in some respects from previous findings in postmenopausal women employed at the capacitor plant. Results from this study, however, do confirm previous reports relating PCB exposure to diabetes and suggest that these associations are not mediated by measured endogenous hormones.