Associations of organochlorines with endogenous hormones in male Great Lakes fish consumers and nonconsumers

Hormonal Injustice: Environmental Toxicants as Drivers of Endocrine Health Disparities

The toll of multiple endocrine disorders has increased substantially in recent decades, and marginalized populations bear a disproportionate burden of disease. Because of the significant individual and societal impact of these conditions, it is essential to identify and address all modifiable risk factors contributing to these disparities. Abundant evidence now links endocrine dysfunction with exposure to endocrine-disrupting chemicals (EDCs), with greater exposures to multiple EDCs occurring among vulnerable groups, such as racial/ethnic minorities, those with low incomes, and others with high endocrine disease burdens. Identifying and eliminating EDC exposures is an essential step in achieving endocrine health equity.

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.

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 disrupting chemicals: Impacts on human fertility and fecundity during the peri-conception period

It is becoming increasingly difficult to avoid exposure to man-made endocrine disrupting chemicals (EDCs) and environmental toxicants. This escalating yet constant exposure is postulated to partially explain the concurrent decline in human fertility that has occurred over the last 50 years. Controversy however remains as to whether associations exist, with conflicting findings commonly reported for all major EDC classes. The primary aim of this extensive work was to identify and review strong peer-reviewed evidence regarding the effects of environmentally-relevant EDC concentrations on adult male and female fertility during the critical periconception period on reproductive hormone concentrations, gamete and embryo characteristics, as well as the time to pregnancy in the general population. Secondly, to ascertain whether individuals or couples diagnosed as sub-fertile exhibit higher EDC or toxicant concentrations. Lastly, to highlight where little or no data exists that prevents strong associations being identified. From the greater than 1480 known EDCs, substantial evidence supports a negative association between exposure to phthalates, PCBs, PBDEs, pyrethroids, organochloride pesticides and male fertility and fecundity. Only moderate evidence exists for a negative association between BPA, PCBs, organochloride pesticides and female fertility and fecundity. Overall fewer studies were reported in women than men, with knowledge gaps generally evident for both sexes for all the major EDC classes, as well as a paucity of female fertility studies following exposure to parabens, triclosans, dioxins, PFAS, organophosphates and pyrethroids. Generally, sub-fertile individuals or couples exhibit higher EDC concentrations, endorsing a positive association between EDC exposure and sub-fertility. This review also discusses confounding and limiting factors that hamper our understanding of EDC exposures on fertility and fecundity. Finally, it highlights future research areas, as well as government, industry and social awareness strategies required to mitigate the negative effects of EDC and environmental toxicant exposure on human fertility and fecundity.

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.

Human health risks due to airborne polychlorinated biphenyls are highest in New Bedford Harbor communities living closest to the harbor

In response to concerns raised by communities surrounding the New Bedford Harbor Superfund site, we completed a field and modeling study that concluded the harbor is the primary source of polychlorinated biphenyls (PCBs) in air around the harbor. The follow-up question from residents was whether the PCBs measured in air pose a risk to their health. The US Environmental Protection Agency focuses their site-specific, risk-based decisions for site clean-up on cancers. We focused our assessment on the non-cancer effects on the thyroid based on the congener specific patterns and concentrations of PCBs measured in air near and distant to the harbor. Human and animal studies of PCB-induced effects on the thyroid provide evidence to support our analysis. Drawing from the published toxicological data, we used a Margin of Exposure (MOE) approach to derive a human-equivalent concentration in air associated with human health effects on the thyroid. Based on the MOEs calculated herein, evaluation of the MOE indicates that changes in thyroid hormone levels are possible among people living adjacent to the Harbor. Changes in thyroid hormone levels are more likely among people who live near the harbor compared to residents living in areas distant from the harbor. This risk assessment documents potential health risks associated with proximity to a marine Superfund Site using site-specific ambient air PCB congener data.

Association between polychlorinated biphenyl 153 exposure and serum testosterone levels: analysis of the National Health and Nutrition Examination Survey

Background

To examine the effects of environmental polychlorinated biphenyls (PCBs) 153 exposure, an industrial plasticizer, on serum testosterone levels.

Methods

Using data collected from the 1999-2000 and 2001-2002 National Health and Nutrition Examination Survey (NHANES), we analyzed serum total testosterone and PCB153 levels, demographic data and comorbidities for men aged 18 years and older. Univariate and multivariate linear regression analysis was used to evaluate the association between total testosterone and serum PCB153.

Results

Five hundred and fifty-seven men met inclusion criteria. Median age was 45.7 [33.4-60.4] years old while median serum total testosterone and PCB153 levels were 479 [352.5-607] ng/dL and 0.20 [0.11-0.39] ng/g, respectively. Increasing age, higher body mass index (BMI), higher levels of serum PCB153, lower levels of activity and a history of diabetes mellitus and coronary heart disease were associated with decreasing serum testosterone levels on univariate linear regression. On multivariate linear regression, increasing age (estimate -6.29 ng/dL per year of life, P<0.001) and BMI (estimate -7.08 ng/dL per unit BMI, P<0.001) were associated with declining serum testosterone levels. While serum PCB153 levels were found to be negatively correlated with serum testosterone levels on univariate analysis (estimate -179.67, P<0.001), this association was not significant on the multivariable model (estimate -12.83, P=0.673).

Conclusions

In this population-based analysis, we report an association between a decrease in serum testosterone with increasing serum levels of PCB153. Identifying environmental factors for etiology of low testosterone and mechanisms for causation will be important to aid in strategies to increase testosterone naturally in men.

Environmental exposure to pesticides and risk of thyroid diseases

Occupational and environmental exposure to pesticides has been associated with thyroid dysfunction, particularly changes in circulating thyroid hormone levels (T3, T4) and thyroid stimulating hormone (TSH). This study assessed the association between environmental exposure to pesticides and the risk of developing thyroid diseases. A population-based case-control study was carried out among Spanish populations living in areas categorized as of high or low pesticide use according to agronomic criteria, which were used as surrogates for environmental exposure to pesticides. The study population consisted of 79.431 individuals diagnosed with goiter, thyrotoxicosis, hypothyroidism, and thyroiditis (according to the International Classification of Diseases, Ninth Revision) and 1.484.257 controls matched for age, sex and area of residence. Data were collected from computerized hospital records for the period 1998 to 2015. Prevalence rates and risk of having thyroid diseases were significantly higher in areas with higher pesticide use, with a 49% greater risk for hypothyroidism, 45% for thyrotoxicosis, 20% for thyroiditis and 5% for goiter. Overall, this study indicates an association between increased environmental exposure to pesticides as a result of a greater agricultural use and diseases of the thyroid gland, thus supporting and extending previous evidence. This study also provides support to the methodology proposed for real-life risk simulation, thus contributing to a better understanding of the real life threat posed by exposure to multiple pesticides from different sources.

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

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

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.

Aroclor1254 disrupts the blood-testis barrier by promoting endocytosis and degradation of junction proteins via p38 MAPK pathway

The blood–testis barrier (BTB) constituted by coexisting junction apparatus between Sertoli cells (SCs) plays an important role in spermatogenesis, which is a known target of various environmental toxicants. The commercial polychlorinated biphenyls mixture, Aroclor1254, has been shown to impair male reproduction by decreasing sperm count and affecting SC metabolism. This study was designed to investigate the effects of Aroclor1254 on the BTB integrity and elucidate the underlying mechanisms. We found that Aroclor1254 treatment in rats (1 or 3 mg/kg per day for 21 consecutive days) and in primary cultured SCs (5 or 10 μg/ml for 48 h) could induce BTB disruption via p38 MAPK pathway, concurrently with increments in junction proteins (JAM-A, N-cadherin, and β-catenin) endocytosis, and occludin ubiquitination. Either inhibition of caveolin-dependent membrane protein internalization by cholesterol oxidase or silencing E3 ubiquitine ligase Itch by small interfering RNA could partially counteract the effects of Aroclor1254 on the barrier function of cultured SCs. These results demonstrate that Aroclor1254 disrupts the BTB function by promoting the caveolin-dependent endocytosis and ubiquitine–proteasome degradation of junction proteins through the p38 MAPK pathway, which might be the potential reasons for its negative effects on spermatogenesis and male reproduction.

Organochlorine pesticides, their toxic effects on living organisms and their fate in the environment

Organochlorine (OC) pesticides are synthetic pesticides widely used all over the world. They belong to the group of chlorinated hydrocarbon derivatives, which have vast application in the chemical industry and in agriculture. These compounds are known for their high toxicity, slow degradation and bioaccumulation. Even though many of the compounds which belong to OC were banned in developed countries, the use of these agents has been rising. This concerns particularly abuse of these chemicals which is in practice across the continents. Though pesticides have been developed with the concept of target organism toxicity, often non-target species are affected badly by their application. The purpose of this review is to list the major classes of pesticides, to understand organochlorine pesticides based on their activity and persistence, and also to understand their biochemical toxicity.

Type of sweet flavour carrier affects thyroid axis activity in male rats

PURPOSE

Non-nutritive sweeteners are the most widely used food additives worldwide. However, their metabolic outcomes are still a matter of controversy and their effect on the thyroid activity, a key regulator of metabolism, has not been previously studied. Therefore, we aim to determine the influence of the sweet type flavour carrier on selected parameters of thyroid axis activity.

METHODS

Male Sprague-Dawley rats (n = 105) were divided into 3 groups fed ad libitum for three weeks isocaloric diets (3.76 ± 0.5 kcal/g): two with the same sweet flavour intensity responded to 10% of sucrose (with sucrose-SC-and sucralose-SU) and one non-sweet diet (NS). To evaluate the post-ingested effects, animals were euthanised at fast and 30, 60, 120, 180 min after meal.

RESULTS

The results obtained indicate that both the presence and the type of sweet taste flavour carrier affect thyroid axis activity both at fasting and postprandial state. Compared to diet with sucrose which stimulates thyroid axis activity, sucralose addition diminishes thyroid hormone synthesis as thyroid peroxidase (TPO) activity, plasma thyroxine (T4), and triiodothyronine (T3) concentration was lower than in SC and NS while in non-sweet diet the lowest level of hepatic deiodinase type 1 (DIO1) and the highest reverse T3 (rT3) level indicate on altered thyroid hormone peripheral metabolism.

CONCLUSION

Both the presence and the type of sweet flavour carrier have a significant impact on thyroid axis activity. Our findings suggest that this organochlorine sweetener is metabolically active and might exacerbate metabolic disorders via an adverse effect on thyroid hormone metabolism.

Pesticide exposure and thyroid function in an agricultural population in Brazil

Although numerous pesticides may interfere with thyroid function, however, epidemiological evidence supporting this relationship is limited, particularly regarding modern non-persistent pesticides. We sought to evaluate the association of agricultural work practices, use of contemporary-use pesticides, and OC pesticides residue levels in serum with circulating thyroid hormone levels in an agricultural population. A cross-sectional study was conducted with a random sample of 275 male and female farm residents in Farroupilha, South of Brazil. Information on sociodemographics, lifestyle and agricultural work was obtained through questionnaire. Blood samples were collected on all participants and analyzed for cholinesterase activity, serum residues of OC pesticides, and levels of free T4 (FT4), total T3 (TT3) and TSH. Non-persistent pesticides exposure assessment was based on questionnaire information on current use of pesticides, and frequency and duration of use, among others. Associations were explored using multivariate linear regression models. Total lifetime years of use of fungicides, herbicides and dithiocarbamates in men was associated with increased TSH accompanied by decrease in FT4, with evidence of a linear trend. In addition, there was an association between being sampled in the high pesticide-use season and increased TSH levels. Conversely, farm work and lifetime use of all pesticides were related with slight decrease in TSH and increased TT3 and FT4, respectively. In general, pesticide use was not associated with thyroid hormones in women. Subjects with detected serum concentrations of β-hexachlorocyclohexane, endrin, dieldrin, heptachlor epoxide B, γ-chlordane, transnonachlor, heptachlor, p,p'-dichlorodiphenylethane and endosulfan II experienced slight changes in TT3; however, associations were weak and inconsistent. These findings suggest that both cumulative and recent occupational exposure to agricultural pesticides may affect the thyroid function causing hypothyroid-like effects, particularly in men.

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.

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.

Influence of Occupational and Environmental Exposure to Low Concentrations of Polychlorobiphenyls and a Smoking Habit on the Urinary Excretion of Corticosteroid Hormones

The effects of occupational exposure to low concentrations of polychlorobiphenyls (PCBs) on the urinary excretion of corticosteroid hormones were evaluated, taking into account the influence of cigarette smoking. The study included 26 males working as electrical maintenance staff in a steel factory, previously exposed to a mixture of PCBs (exposed workers), and 30 male workers with no occupational exposure to PCBs (controls). Serum PCBs (33 congeners), urinary 17-hydroxycorticosteroids, 17-ketosteroids (KS) and pregnanes, and their respective glucuronidated and sulfonated compounds, were determined for each subject. PCBs were significantly higher in the exposed workers than controls, and were correlated with age. Both the urinary concentrations of the total 17-KS and pregnanes, and those of some single steroids and their glucuronidated compounds, were significantly lower in the exposed workers than controls, but higher in smokers than the non-smokers + ex-smokers. Two-way analysis of variance showed a negative association between serum PCBs and both total glucuronidated 17-KS and total and glucuronidated pregnanes, and a positive association between cigarette smoking and both total and glucuronidated 17-KS. PCBs seem to act as endocrine disruptors by reducing the urinary excretion of corticosteroid hormones, particularly of the glucuronidated fraction. Cigarette smoking could boost these effects of PCBs in smokers.

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.

Mercury-nutrient signatures in seafood and in the blood of avid seafood consumers

Dietary recommendations for seafood are confusing due to the desire to balance both benefits from nutrients and risks from contaminants. The overall health value of different fish and shellfish items depends on concentrations of multiple nutrients (e.g., selenium (Se), omega-3 fatty acids) and contaminants (e.g., mercury (Hg)). However, few studies have examined the connections between human exposure to multiple nutrients and contaminants and the consumption of specific types of seafood. Our goals were to compare 1) Hg, Se and omega-3 fatty acid concentrations (Hg-nutrient signatures) among common fish and shellfish items and 2) Hg-nutrient signatures in the blood of avid seafood consumers, based on seafood consumption habits. We compiled nutrient and Hg concentration data for common fish and shellfish items from the literature. We also measured blood concentrations of Hg and seafood nutrients collected from adult, avid seafood consumers on Long Island, NY. Canonical discriminant analyses revealed distinct Hg-nutrient signatures among seafood items, and these signatures were reflected in the blood of consumers based on different consumption habits. For example, consumers with a salmon-dominated seafood diet had relatively high percentage of omega-3 fatty acids in blood, and consumers who tend to eat top predator seafood have higher Hg, but similar blood nutrient concentrations compared to consumers who tend to eat low trophic level seafood. These results provide direct evidence of links between the ecological characteristics of the type of seafood consumed and Hg-nutrient exposure. This approach helps assess the overall human health value of specific seafood types, leads to specific diet recommendations, and can be used to characterize risk:benefit status among seafood consumers.

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.

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.

Controlled Cohort Study of Serum Gonadal and Adrenocortical Steroid Levels in Males Prior to Onset of Rheumatoid Arthritis (pre-RA): A Comparison to pre-RA Females and Sex Differences among the Study Groups

Serum testosterone levels are generally reported to be lower in male rheumatoid arthritis (RA) patients, but it is not determined if a deficiency may occur before clinical onset of disease (pre-RA). Lower testosterone levels were recently reported in males many years before RA onset but were predictive only of rheumatoid factor (RF)—negative disease. A preceding prospective study did not reveal androgenic-anabolic hormone association with risk of RA in men or women. This cohort study of males analyzed baseline serum levels of gonadal and adrenocortical steroids, luteinizing hormone, and prolactin in 18 pre-RA versus 72 matched non-RA control (CN) subjects. Findings in males were compared to those in female pre-RA and CN subjects in the same cohort, and sex differences were analyzed. Steroidal and hormonal levels, including total testosterone, were similar between male study groups. In females, mean (±SE) serum androstenedione (nmol/L) was slightly (P = 0.048) lower in 36 pre-RA (6.7 ± 0.36) than 144 CN (7.6 ± 0.22). With the exception of 3 partial correlations of hormonal variables observed to differ between pre-RA versus CN subjects, the patterns were similar overall. However, partial correlations of hormonal variables differed frequently by sex, both within and between study groups.

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.

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.

Prenatal exposure to a polychlorinated biphenyl (PCB) congener influences fixation duration on biological motion at 4-months-old: a preliminary study

Adverse effects of prenatal exposure to polychlorinated biphenyl (PCB) congeners on postnatal brain development have been reported in a number of previous studies. However, few studies have examined the effects of prenatal PCB exposure on early social development. The present study sought to increase understanding of the neurotoxicity of PCBs by examining the relationship between PCB congener concentrations in umbilical cord blood and fixation patterns when observing upright and inverted biological motion (BM) at four-months after birth. The development of the ability to recognize BM stimuli is considered a hallmark of socio-cognitive development. The results revealed a link between dioxin-like PCB #118 concentration and fixation pattern. Specifically, four-month-olds with a low-level of prenatal exposure to PCB #118 exhibited a preference for the upright BM over inverted BM, whereas those with a relatively high-level of exposure did not. This finding supports the proposal that prenatal PCB exposure impairs the development of social functioning, and indicates the importance of congener-specific analysis in the risk analysis of the adverse effects of PCB exposure on the brain development.

Reproductive hormone profile and pubertal development in 14-year-old boys prenatally exposed to polychlorinated biphenyls

Because polychlorinated biphenyls (PCBs) are thought to cause endocrine disruption, we examined 438 adolescent boys from a birth cohort in the Faroe Islands, where PCB exposures are elevated. We measured PCBs and p,p'-dichlorodiphenyldichloroethylene (DDE) in cord blood and in serum from clinical examination at age 14. Higher prenatal PCB exposure was associated with lower serum concentrations of both luteinizing hormone (LH) and testosterone. In addition, sex hormone binding globulin (SHBG) was positively associated with both prenatal and concurrent PCB exposures. The PCB-SHBG association was robust to covariate adjustment. In a structural equation model, a doubling in prenatal PCB exposure was associated with a decrease in LH of 6% (p=0.03). Prenatal exposure to PCB and DDE showed weak, non-significant inverse associations with testicular size and Tanner stage. DDE was highly correlated with PCB and showed slightly weaker associations with the hormone profile. These findings suggest that delayed puberty with low serum-LH concentrations associated with developmental exposure to non dioxin-like PCBs may be due to a central hypothalamo-pituitary mechanism.

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.

Serum concentrations of p, p'-DDE, HCB, PCBs and reproductive hormones among men of reproductive age

Exposure to polychlorinated biphenyls (PCBs) has been associated with changes in reproductive hormone levels, however most groups studied have been highly exposed. We investigated the association of PCBs, hexachlorobenzene (HCB) and p, p'-DDE with serum sex hormones in 341 adult men from a US infertility clinic with exposure levels consistent with those observed in the general population. In crude regression models we observed several negative associations of PCBs and HCB with steroid hormone-binding globulin (SHBG) and total and free testosterone. After adjustment for lipids, age and BMI, nearly all significant associations were attenuated. A negative relationship remained between PCB 118 and SHBG (p<0.01), and relationships of dioxin-like PCBs with SHBG and total testosterone, and between PCB 118 and total testosterone, were suggestive. These results suggest a minimal relationship between PCB exposures at low background levels similar to those observed in the general population of the US and circulating reproductive hormones.

Do Thyroid Disrupting Chemicals Influence Foetal Development during Pregnancy?

Maternal euthyroidism during pregnancy is crucial for normal development and, in particular, neurodevelopment of the foetus. Up to 3.5 percent of pregnant women suffer from hypothyroidism. Industrial use of various chemicals—endocrine disrupting chemicals (EDCs)—has been shown to cause almost constant exposure of humans with possible harmful influence on health and hormone regulation. EDCs may affect thyroid hormone homeostasis by different mechanisms, and though the effect of each chemical seems scarce, the added effects may cause inappropriate consequences on, for example, foetal neurodevelopment. This paper focuses on thyroid hormone influence on foetal development in relation to the chemicals suspected of thyroid disrupting properties with possible interactions with maternal thyroid homeostasis. Knowledge of the effects is expected to impact the general debate on the use of these chemicals. However, more studies are needed to elucidate the issue, since human studies are scarce.

Internal exposure to pollutants and sex hormone levels in Flemish male adolescents in a cross-sectional study: associations and dose-response relationships

Flanders is densely populated with much industry and intensive farming. Hormonal status of 14- to 15-year-old male adolescents was studied in relation to internal exposure to pollutants. A total of 887 participants were selected as a random sample of the adolescents residing in the study areas. Confounding factors and significant covariates were taken into account. Serum levels of testosterone, free testosterone and estradiol, and the aromatase index showed significant positive associations with serum levels of marker polychlorobiphenyls (sum of PCBs 138, 153, and 180) and of hexachlorobenzene (HCB) and a negative association with urinary cadmium concentration. Serum levels of estradiol also showed a positive association with serum levels of dichlorodiphenyldichloroethylene (DDE). A doubling of serum concentrations of marker PCBs and HCB and of urinary concentration of cadmium were, respectively, associated with an increase of 16.4% (P<0.00001) and 16.6% (P<0.001) and a decrease of 9.6% (P<0.001) in serum testosterone concentration. Similar findings were made after additional adjustment for concurrent exposures. Associations between biological effects and internal exposures were, in terms of the regression coefficient, often stronger at exposures below the median. Environmental exposures to pollutants resulting in "normal" levels of internal exposure were associated with quite substantial differences in hormone concentrations.

The impacts of organochlorines and other persistent pollutants on thyroid and metabolic health

High prevalence of thyroid and metabolic disorders has been repeatedly observed in the population living in the area of eastern Slovakia highly polluted by a mixture of PCBs, DDE and HCB since about 50 years ago. Among thyroid disorders, increase of thyroid volume as measured by ultrasound volumetry may be suggested as one of notable findings which appeared possibly related to increased OCs levels and to autoimmunity signs (e.g. positive thyroperoxidase antibodies in blood and/or hypoechogenicity image obtained by ultrasound), while some participation of individual susceptibility and also of immunogenic effect of OCs and iodine in this iodine replete country cannot be excluded. Another notable finding has been the increase of blood FT4 and TT3 positively related to high PCBs level. Such increased FT4 level has been found associated with TSH level in hyperthyroid range in about 2% of examined population from polluted area. High prevalence of thyroid autoimmune disorders strongly supported the assumption on impaired immune system and thus also on presumably increased prevalence of other autoimmune disorders in highly exposed population. In addition, markedly increased prevalence of prediabetes and diabetes significantly related to major OCs (PCBs, DDE and HCB) levels and accompanied by increasing level of cholesterol and triglycerides has been observed. The observations also suggested a role of prenatal exposure to OCs in the development of several adverse health signs (e.g. increased prevalence of thyroid antibodies, impaired fasting glucose level, increased thyroid volume, decreased thymus volume, decreased neurobehavioral performance, increased hearing and dental disorders) in young generation born to highly exposed mothers in polluted area.

Exposure to polychlorinated biphenyls (PCBs) and male reproduction

Polychlorinated biphenyls (PCBs) are a class of persistent organic pollutants that were widely used in the mid-20th century. Though their production and use was banned by most countries several decades ago, the general population continues to be exposed due to the persistence and bioaccumulation of PCBs. A number of human epidemiological studies have assessed the relationship between environmental PCB exposure and markers of male reproductive health, namely semen quality parameters (sperm concentration, motility, and morphology), sperm DNA integrity (DNA damage or chromatin fragmentation), and circulating reproductive hormone levels. Despite a wide range of study designs and locations, measurement methods, and PCB exposure levels, reports of inverse associations between PCBs and sperm motility have been consistent which may suggest a lack of exposure threshold for a PCB-related effect on sperm motility. Several studies have also reported inverse associations between PCBs and circulating testosterone levels in men, though the specific form of testosterone (i.e. total, bound, or free testosterone) associated with exposure has not been fully consistent between studies. In conclusion, although PCBs are no longer used and can be considered a legacy chemical, concerns regarding altered male fertility in relation to PCBs remain due to the existing human data demonstrating inverse associations with markers of male reproductive function coupled with recent evidence for continued population exposure.

Endocrine disruptors and thyroid hormone physiology

Endocrine disruptors are man-made chemicals that can disrupt the synthesis, circulating levels, and peripheral action of hormones. The disruption of sex hormones was subject of intensive research, but thyroid hormone synthesis and signaling are now also recognized as important targets of endocrine disruptors. The neurological development of mammals is largely dependent on normal thyroid hormone homeostasis, and it is likely to be particularly sensitive to disruption of the thyroid axis. Here, we survey the main thyroid-disrupting chemicals, such as polychlorinated biphenyls, perchlorates, and brominated flame-retardants, that are characteristic disruptors of thyroid hormone homeostasis, and look at their suspected relationships to impaired development of the human central nervous system. The review then focuses on disrupting mechanisms known to be directly or indirectly related to the transcriptional activity of the thyroid hormone receptors.

The Pine River statement: human health consequences of DDT use

OBJECTIVES

Dichlorodiphenyltrichloroethane (DDT) was used worldwide until the 1970s, when concerns about its toxic effects, its environmental persistence, and its concentration in the food supply led to use restrictions and prohibitions. In 2001, more than 100 countries signed the Stockholm Convention on Persistent Organic Pollutants (POPs), committing to eliminate the use of 12 POPs of greatest concern. However, DDT use was allowed for disease vector control. In 2006, the World Health Organization and the U.S. Agency for International Development endorsed indoor DDT spraying to control malaria. To better inform current policy, we reviewed epidemiologic studies published from 2003 to 2008 that investigated the human health consequences of DDT and/or DDE (dichlorodiphenyldichloroethylene) exposure.

DATA SOURCES AND EXTRACTION

We conducted a PubMed search in October 2008 and retrieved 494 studies.

DATA SYNTHESIS

Use restrictions have been successful in lowering human exposure to DDT, but blood concentrations of DDT and DDE are high in countries where DDT is currently being used or was more recently restricted. The recent literature shows a growing body of evidence that exposure to DDT and its breakdown product DDE may be associated with adverse health outcomes such as breast cancer, diabetes, decreased semen quality, spontaneous abortion, and impaired neurodevelopment in children.

CONCLUSIONS

Although we provide evidence to suggest that DDT and DDE may pose a risk to human health, we also highlight the lack of knowledge about human exposure and health effects in communities where DDT is currently being sprayed for malaria control. We recommend research to address this gap and to develop safe and effective alternatives to DDT.

Polychlorinated biphenyls and thyroid hormones in adults: a systematic review appraisal of epidemiological studies

Reported evidence regarding relationships between polychlorinated biphenyls (PCBs) and thyroid homeostasis in adults has been considered contradictory. The objective of this systematic review is to determine a possible association between PCB exposure and the circulating thyroid hormones and thyrotropin (TSH) levels in adults, by analyzing the quality of published studies. A systematic review of epidemiological papers was conducted using PubMed. An evaluation of the quality of 22 studies was performed, and the papers were classified into two tiers: Tier I for studies with higher quality scores (eight) and Tier II for studies with lower quality scores (14). It appears that PCBs can interfere with thyroid hormone homeostasis; however epidemiological evidence is not entirely clear. For triiodothyronine (T3) and thyroxine (T4), Tier I studies showed either an inverse (four cases for T3; five cases for T4) or no significant association (two cases for T3; five cases for T4) with PCBs. In the case of free thyroxine and TSH, the Tier I papers observed no clear association with PCB levels. Rigorous study design, assessment of potential confounding factors, and fuller reporting of methods and results in future studies will facilitate understanding of whether PCB exposure is associated with changes in thyroid function.

Polychlorinated biphenyls and thyroid hormone serum concentrations among people living in a highly polluted area: a cross-sectional population-based study

BACKGROUND

Polychlorinated biphenyls (PCBs) may interact with several thyroid functions. Severe environmental pollution by PCBs has been observed in Brescia, Italy, due to the presence of a factory that produced these compounds until 1984.

OBJECTIVES

We aimed to investigate the correlation between serum levels of total PCBs and PCB 153 and thyroid hormone serum levels in adults in a cross-sectional population-based study.

METHODS

A total of 527 subjects were enrolled; they were face-to-face interviewed about their history of thyroid disease and provided a blood sample under fasting conditions. The serum levels of free and total triiodothyronine (FT3 and TT3), thyroxine (FT4 and TT4) and thyroid-stimulating hormone (TSH), anti-thyroperoxidase (anti-TPO) and anti-thyroglobulin (anti-TGA), and lipid-adjusted total PCBs and PCB 153 were determined.

RESULTS

There was no statistically significant difference in total PCB and PCB 153 concentrations in subjects with and without thyroid disease. Inverse, weak, statistically significant correlations were found between total PCBs and FT3 (Spearman's r=-0.09) and between total PCBs and PCB 153 and TSH (Spearman's r=-0.16 and -0.12, respectively). However, multiple regression analysis with FT3 and TSH serum levels as dependent variables and total PCBs and PCB 153 serum levels as predictors, including age, gender and BMI, showed a positive, rather than negative, association of PCBs and PCB 153 with FT3 and no association with TSH.

CONCLUSIONS

This study does not support the hypothesis that relatively high PCB environmental exposure can determine substantial alterations in thyroid function among adult people.

Polybrominated diphenyl ethers (PBDE) in serum: findings from a US cohort of consumers of sport-caught fish

Polybrominated diphenyl ethers (PBDEs) have been used as flame retardants in foams, fabrics and plastics, and are common contaminants of household air and dust and bioaccumulate in wildlife, and are detectable in human tissues and in fish and animal food products. In the Great Lakes Basin sport fish consumption has been demonstrated to be an important source of PCB and DDE exposure. PBDEs are present in the same sport fish but prior to our study the contribution to human PBDE body burdens from Great Lakes sport fish consumption had not been investigated. This study was designed to assess PBDE, PCB and 1,1-bis(4-chlorophenyl)-2,2-dichloroethene (DDE) serum concentrations in an existing cohort of 508 frequent and infrequent consumers of sport-caught fish living in five Great Lake states. BDE congeners 47 and 99 were identified in the majority of blood samples, 98% and 62% respectively. summation operatorPBDE levels were positively associated with age, hours spent outdoors, DDE, summation operatorPCB, years of sportfish consumption, and catfish and shellfish intake, and negatively associated with income and recent weight loss. Other dietary components collected were not predictive of measured summation operatorPBDE levels. In multivariate models, summation operatorPBDE levels were positively associated with age, years consuming sport fish, shellfish meals, and computer use and negatively associated with recent weight loss. Having summation operatorPBDE levels in the highest quintile was independently associated with older age, male gender, consumption of catfish and shellfish, computer use and spending less time indoors. summation operatorPCB and DDE were strongly associated suggesting common exposure routes. The association between summation operatorPBDE and summation operatorPCB or DDE was much weaker and modeling suggested more diverse PBDE sources with few identified multi-contaminant-shared exposure routes. In our cohort Great Lakes sport fish consumption does not contribute strongly to PBDE exposure.

Gender differences in the effects of organochlorines, mercury, and lead on thyroid hormone levels in lakeside communities of Quebec (Canada)

Environmental chemicals can disrupt endocrine balance and in particular thyroid hormone (TH) homeostasis. However, studies differ with respect to thyroid profile changes and gender differences are rarely examined. This study investigated the THs, triodothyronine (T3), thyroxine (T4), and thyroid stimulating hormone (TSH), in relation to serum organochlorines (OCs), bioindicators of mercury (Hg) and blood lead (Pb) in 211 freshwater fish consumers (124 men and 87 women) from two communities in Canada. Thyroid hormones were within the normal range and the bioindicators of exposure were low compared to other reports on fish consumers. Stratified analysis showed that for women, serum T3 concentrations were negatively related to serum concentrations of PCB 138, PCB 153, the non-coplanar congeners, Arochlor 1260, and SigmaPCB, as well as p,p'-DDE. No relations were observed between T4 and any of the chemicals measured, but TSH was negatively related to blood Pb. For men, serum T4 was inversely related to PCB 138, non-ortho-substituted (dioxin-like) PCBs and SigmaPCB. A significant positive relationship was observed between serum TSH and different PCB congeners (PCB 138, PCB 180, non-coplanar congeners, mono-ortho coplanar congeners, dioxin-like PCBs), as well as SigmaPCB. Serum TSH increased with hair and blood Hg concentrations and was highest among those in the highest 50th percentile for both Hg and dioxin-like PCB congeners compared to the others. No associations were observed for T3 in men. These findings suggest that even at low concentrations, these environmental contaminants can interfere with thyroid status and effects may differ by gender.

Possible effects of environmental nitrates and toxic organochlorines on human thyroid in highly polluted areas in Slovakia

Heavy environmental pollution resulting from uncontrolled industrial and agricultural activities has occurred in several areas of Slovakia. So far, field surveys focused mainly on the thyroid have been conducted in one area polluted by nitrates and in a large area polluted mainly by organochlorinated toxicants. In children from the high nitrate area (HNA, n = 324) significantly higher thyroid volume (ThV) by ultrasound was found compared with age-matched children from surrounding areas with low nitrate (LNA, n = 764). In blood samples of 324 children from the HNA and of 100 children from the LNA no difference between areas was found in the level of total thyroxine (T4) and free triiodothyronine (T3). However, positive thyroid peroxidase antibodies (TPOAb) were found in 7/324 (2.2%) and thyrotropin (TSH) levels > 4.0 mIU/L in 13/324 (4.0%) of children from the HNA area, while no positive values were obtained in the LNA. In the area heavily polluted by an organochlorine (OC) cocktail consisting of polychlorinated biphenyls (PCBs), 2,2'-bis(4-chlorophenyl)-1,1-dichloroethylene (p,p'-DDE), hexachlorobenzene (HCB), and dioxins and furans (polluted area) and in the background pollution area (background area) a total of 2046 adults were examined. In polluted area very high blood levels of OCs were found as well as increased ThV and prevalence of thyroid hypoechogenicity by ultrasound. For the evaluation of data the level of PCBs was used as a marker of all OCs. Increasing PCB levels were significantly associated with the increase of free T4 (p < 0.001) and total T3 (p < 0.05) in blood, while slight but not significant negative association of PCBs was observed with the level of TSH. In both women and men the prevalence of TPOAb was significantly higher in polluted area. Although the absolute TPOAb prevalence in both areas was higher in women than that in men, the increase in polluted vs. background area was more striking in men. From these data it appears that the effects of environmental pollution on the thyroid cannot be neglected.

Possible effects of persistent organochlorinated pollutants cocktail on thyroid hormone levels and pituitary-thyroid interrelations

In polluted district of Michalovce in East Slovakia (POLL) and two districts with background pollution (BCGR) 2046 adults (834 males and 1212 females aged 20-75 years) were examined. Serum levels of thyrotropin (TSH), free thyroxine (FT4), total triiodothyronine (TT3) and antithyroperoxidase antibodies (TPOab) were estimated by electrochemiluminiscent assay and also these of 15 polychlorinated biphenyl congeners (PCBs), p,p'-DDE, p,p'-DDT, hexachlorobenzene (HCB) and hexachlorocyclohexane were measured by high resolution gas chromatography/mass spectrometry. In addition, also dioxins, furans, coplanar- and mono-ortho-PCBs as well as selected hydroxylated and methylsulphonated PCBs and DDE metabolites were measured by appropriate methods based on gas chromatography/mass spectrometry principle. In POLL significantly higher levels of all organochlorines were found than these in BCGR. When pooled values from both areas were stratified in terms of PCBs level and treated as continuous variables, positive association of PCBs with FT4 and TT3 was found, the latter two being also mutually associated. However, within the category of PCBs level <530 ng/glipid (n=232) the association between PCBs and both the FT4 (p<0.09) and TT3 (p<0.03) was negative and any association of these was not found within the category of PCBs level of 531-1000 ng/g (n=691). In contrast, in the category of 531-2000 ng/g (n=1307) positive association appeared between PCBs and FT4 (p<0.001) as well as TT3 (p<0.05). Highly significant association of PCBs with FT4 (p<0.001) was further found in the categories with PCBs level of 1001-101414 ng/g (n=1307) and 2001-101414 (n=1123), while significant association with TT3 was observed only in the category of 531-2000 ng/g. Such findings suggest possible threshold level in positive effect of PCBs on FT4 and TT3 level which seems to be individual and located somewhere around the PCBs level of 1000 ng/g. However, highly significant negative association of both FT4 and TT3 with TSH was found in each of above indicated PCBs categories. Considerable difference in FT4 and TT3 level between large groups of subjects with the same range of PCBs level was also found suggesting different individual susceptibility to the effects of organochlorines. Among a total of 26 cases from POLL with very low TSH level (<0.5 mU l(-1)) 13 cases showed very high level of PCBs, FT4 and TT3, thus supporting a hypothesis on a novel sporadic form of high PCBs related peripheral subclinical hyperthyroidism possibly resulting from the long-term disruption of equilibrium between bound and free thyroxine in plasma by high PCBs level followed by a striking inhibition of TSH release from the pituitary.

Relationships of thyroid hormones with polychlorinated biphenyls, dioxins, furans, and DDE in adults

BACKGROUND

Thyroid hormone homeostasis can be disrupted by exposure to ubiquitous and bioaccumulative organochlorines such as polychlorinated biphenyls (PCBs) and polychlorinated dibenzo-p-dioxins (PCDDs). Whereas investigations of health effects have generally focused on human populations with relatively high exposures through occupation, accident, or high fish consumption, general population exposures may also carry risk.

METHODS

We studied associations of total thyroxine (T(4)) and thyroid-stimulating hormone (TSH) with PCBs, dioxin-like toxic equivalents (TEQs), and p,p'-diphenyldichloroethene (DDE) in adult participants without thyroid disease who participated in the 1999-2002 National Health and Nutrition Examination Survey, a cross-sectional survey examining a random sample representative of the U.S. population.

RESULTS

We found inverse associations of total T(4) with exposure to TEQs in both sexes, with stronger associations in females. In women, mean T(4) was 8.2 microg/dL, and levels were on average 0.75 microg/dL lower (95% confidence interval, 0.04-1.46) in women in the highest quintile of TEQ exposure compared with the lowest two quintiles. Effects were stronger in people > 60 years of age, with negative associations of T(4) with PCBs and TEQs, and positive associations of TSH with PCBs and TEQs in older women, and a negative association of TSH with PCBs in older men.

CONCLUSIONS

The data show a dose-dependent decrease in total T(4) with exposure to TEQs at levels similar to those found in the general U.S. population. The effects were stronger in women. The results suggest that older adults, who have a high risk of thyroid disease, may be more at risk for disruption of thyroid hormone homeostasis by dioxin-like organochlorines than younger adults.

Fish from industrially polluted freshwater as the main source of organochlorinated pollutants and increased frequency of thyroid disorders and dysglycemia

In a certain area of Michalovce district in East Slovakia, heavy industrial pollution by polychlorinated biphenyls (PCBs) developed in 1955-1984 and very high PCB levels in environmental and human samples are still persisting. Recently, a total of 2045 adults from this and the surrounding background pollution area have been examined using questionnaire data, thyroid volume by ultrasound (ThV), urinary iodine and serum levels of 15 PCB congeners, hexachlorobenzene (HCB), 2,2'-2-bis(4-chlorobiphenyl)-1,1-dichloroethylene (DDE), 2,2'-bis(4-chlorophenyl)-1,1,1-trichloroethane (DDT), alpha-, beta- and gamma-hexachlorocyclohexane (HCH), thyrotropin (TSH), free thyroxine (FT4), anti-thyroperoxidase antibodies (TPOab) and fasting glucose. As based on our previous findings of strikingly high level of PCBs in fish from high pollution area (e.g. mean level of 375430 ng/g lipid) and considerably lower, but still relatively high level in background pollution area (e.g. mean PCB level of 5150 ng/g), the information on the frequency of fish meals and approximate annual consumption of fish from local waters was obtained by questionnaires. The association of contaminated fish consumption with very high blood levels of PCBs, DDE and HCB and increased ThV as well as with increased frequency of positive TPOab, high values of FT4 and impaired fasting glucose (IFG) was found. These associations were also confirmed in 16 marital pairs from high pollution area with very high PCB level in both members associated with high fish consumption. It was concluded that, due to persistent heavy pollution of waters, soil and food chain namely by PCBs, but also by pesticides (e.g. DDE and HCB) resulting from their previous extensive use in agriculture, the fish from local waters still remains the most important source of these toxic pollutants which results in considerable adverse health effects.

Perinatal exposure to PCB 153, but not PCB 126, alters bone tissue composition in female goat offspring

The aim of this study was to investigate if environmentally relevant doses of the putative estrogenic non dioxin-like PCB 153 and the dioxin-like PCB 126 caused changes in bone tissue in female goat offspring following perinatal exposure. Goat dams were orally dosed with PCB 153 in corn oil (98 microg/kg body wt/day) or PCB 126 (49 ng/kg body wt/day) from day 60 of gestation until delivery. The offspring were exposed to PCB in utero and through mother's milk. The suckling period lasted for 6 weeks. Offspring metacarpal bones were analysed using peripheral quantitative computed tomography (pQCT) after euthanisation at 9 months of age. The diaphyseal bone was analysed at a distance of 18% and 50% of the total bone length, and the metaphyseal bone at a distance of 9%. Also, biomechanical three-point bending of the bones was conducted, with the load being applied to the mid-diaphyseal pQCT measure point (50%). PCB 153 exposure significantly decreased the total cross-sectional area (125 mm(2)+/-4) versus non-exposed (142 mm(2)+/-5), decreased the marrow cavity (38 mm(2)+/-4) versus non-exposed (50 mm(2)+/-3) and decreased the moment of resistance (318 mm(3)+/-10) versus non-exposed (371 mm(3)+/-20) at the diaphyseal 18% measure point. At the metaphyseal measure point, the trabecular bone mineral density (121 mg/cm(3)+/-5) was increased versus non-exposed (111 mg/cm(3)+/-3). PCB 126 exposure did not produce any observable changes in bone tissue. The biomechanical testing of the bones did not show any significant changes in bone strength after PCB 153 or PCB 126 exposure. In conclusion, perinatal exposure to PCB 153, but not PCB 126, resulted in altered bone composition in female goat offspring.