Effects of polychlorinated biphenyls on development and reproduction

The Aryl hydrocarbon receptor mediates reproductive toxicity of polychlorinated biphenyl congener 126 in rats

Polychlorinated biphenyls (PCBs) are endocrine disrupting chemicals with documented, though mechanistically ill-defined, reproductive toxicity. The toxicity of dioxin-like PCBs, such as PCB126, is mediated via the aryl hydrocarbon receptor (AHR) in non-ovarian tissues. The goal of this study was to examine the uterine and ovarian effects of PCB126 and test the hypothesis that the AHR is required for PCB126-induced reproductive toxicity. Female Holzman-Sprague Dawley wild type (n = 14; WT) and Ahr knock out (n = 11; AHR-/-) rats received a single intraperitoneal injection of either corn oil vehicle (5 ml/kg: WT_O and AHR-/-_O) or PCB126 (1.63 mg/kg in corn oil: WT_PCB and AHR-/-_PCB) at four weeks of age. The estrous cycle was synchronized and ovary and uterus were collected 28 days after exposure. In WT rats, PCB126 exposure reduced (P < 0.05) body and ovary weight, uterine gland number, uterine area, progesterone, 17β-estradiol and anti-Müllerian hormone level, secondary and antral follicle and corpora lutea number but follicle stimulating hormone level increased (P < 0.05). In AHR-/- rats, PCB126 exposure increased (P ≤ 0.05) circulating luteinizing hormone level. Ovarian or uterine mRNA abundance of biotransformation, and inflammation genes were altered (P < 0.05) in WT rats due to PCB126 exposure. In AHR-/- rats, the transcriptional effects of PCB126 were restricted to reductions (P < 0.05) in three inflammatory genes. These findings support a functional role for AHR in the female reproductive tract, illustrate AHR's requirement in PCB126-induced reprotoxicity, and highlight the potential risk of dioxin-like compounds on female reproduction.

Ameliorating Effects of Natural Antioxidant Compounds on Female Infertility: a Review

The prevalence of female infertility cases has been increasing at a frightening rate, affecting approximately 48 million women across the world. However, oxidative stress has been recognized as one of the main mediators of female infertility by causing various reproductive pathologies in females such as endometriosis, PCOS, preeclampsia, spontaneous abortion, and unexplained infertility. Nowadays, concerned women prefer dietary supplements with antioxidant properties over synthetic drugs as a natural way to lessen the oxidative stress and enhance their fertility. Therefore, the current review is an attempt to explore the efficacy of various natural antioxidant compounds including vitamins, carotenoids, and plant polyphenols and also of some medicinal plants in improving the fertility status of females. Our summarization of recent findings in the current article would pave the way toward the development of new possible antioxidant therapy to treat infertility in females. Natural antioxidant compounds found in fruits, vegetables, and other dietary sources, alone or in combination with other antioxidants, were found to be effective in ameliorating the oxidative stress-mediated infertility problems in both natural and assisted reproductive settings. Numerous medicinal plants showed promising results in averting the various reproductive disorders associated with female infertility, suggesting a plant-based herbal medicine to treat infertility. Although optimum levels of natural antioxidants have shown favorable results, however, their excessive intake may have adverse health impacts. Therefore, larger well-designed, dose-response studies in humans are further warranted to incorporate natural antioxidant compounds into the clinical management of female infertility.

Engineering Burkholderia xenovorans LB400 BphA through Site-Directed Mutagenesis at Position 283

Biphenyl dioxygenase (BPDO), which is a Rieske-type oxygenase (RO), catalyzes the initial dioxygenation of biphenyl and some polychlorinated biphenyls (PCBs). In order to enhance the degradation ability of BPDO in terms of a broader substrate range, the BphAE_S283M, BphAE_p4-S283M, and BphAE_RR41-S283M variants were created from the parent enzymes BphAE_LB400, BphAE_p4, and BphAE_RR41, respectively, by a substitution at one residue, Ser283Met. The results of steady-state kinetic parameters show that for biphenyl, the k _cat/K_m values of BphAE_S283M, BphAE_p4-S283M, and BphAE_RR41-S283M were significantly increased compared to those of their parent enzymes. Meanwhile, we determined the steady-state kinetics of BphAEs toward highly chlorinated biphenyls. The results suggested that the Ser283Met substitution enhanced the catalytic activity of BphAEs toward 2,3',4,4'-tetrachlorobiphenyl (2,3',4,4'-CB), 2,2',6,6'-tetrachlorobiphenyl (2,2',6,6'-CB), and 2,3',4,4',5-pentachlorobiphenyl (2,3',4,4',5-CB). We compared the catalytic reactions of BphAE_LB400 and its variants toward 2,2'-dichlorobiphenyl (2,2'-CB), 2,5-dichlorobiphenyl (2,5-CB), and 2,6-dichlorobiphenyl (2,6-CB). The biochemical data indicate that the Ser283Met substitution alters the orientation of the substrate inside the catalytic site and, thereby, its site of hydroxylation, and this was confirmed by docking experiments. We also assessed the substrate ranges of BphAE_LB400 and its variants with degradation activity. BphAE_S283M and BphAE_p4-S283M were clearly improved in oxidizing some of the 3-6-chlorinated biphenyls, which are generally very poorly oxidized by most dioxygenases. Collectively, the present work showed a significant effect of mutation Ser283Met on substrate specificity/regiospecificity in BPDO. These will certainly be meaningful elements for understanding the effect of the residue corresponding to position 283 in other Rieske oxygenase enzymes.IMPORTANCE The segment from positions 280 to 283 in BphAEs is located at the entrance of the catalytic pocket, and it shows variation in conformation. In previous works, results have suggested but never proved that residue Ser283 of BphAE_LB400 might play a role in substrate specificity. In the present paper, we found that the Ser283Met substitution significantly increased the specificity of the reaction of BphAE toward biphenyl, 2,3',4,4'-CB, 2,2',6,6'-CB, and 2,3',4,4',5-CB. Meanwhile, the Ser283Met substitution altered the regiospecificity of BphAE toward 2,2'-dichlorobiphenyl and 2,6-dichlorobiphenyl. Additionally, this substitution extended the range of PCBs metabolized by the mutated BphAE. BphAE_S283M and BphAE_p4-S283M were clearly improved in oxidizing some of the more highly chlorinated biphenyls (3 to 6 chlorines), which are generally very poorly oxidized by most dioxygenases. We used modeled and docked enzymes to identify some of the structural features that explain the new properties of the mutant enzymes. Altogether, the results of this study provide better insights into the mechanisms by which BPDO evolves to change and/or expand its substrate range and its regiospecificity.

Association Between Leukocyte Telomere Length and Serum Concentrations of PCBs and Organochlorine Pesticides

Exposure to polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) through food, water, and air occurred during the life, which may change telomere length (TL) in peripheral blood leukocytes. The present study was designed to investigate the association between TL and serum levels of PCBs and OCPs in Tehran male's population. Whole blood samples were randomly taken from 300 adult males, aged between 25 and 40 years. TL was determined by real-time PCR to measure the number of the telomere (T) repeats to the number of a single-copy gene (S). We applied the multivariate linear regression model to compare the effect of each lipid adjusted serum levels of PCBs and OCPs congener on the TL, with adjustment for age, body mass index, education, smoking, and food patterns. Each doubling of the nondioxin-like PCBs, dioxin-like PCBs, and OCPs levels were associated with 1.9% [95% confidence interval (CI) - 0.70 to 5.40%], 2.5% (95% CI 0.30-8.3%), and - 2.4% (95% CI - 0.70 to - 6.2%) variation in the TL, respectively. The percent difference in the TL with exposure to nondioxin-like PCBs, dioxin-like PCBs, and OCPs for participants with older than age 37 years were 6.45% (95% CI  2.81-16.50%), 4.52% (95% CI  1.60-10.54%), and - 7.44% (95% CI - 1.55 to - 15.51%), respectively. Exposures to nondioxin-like PCBs (except for PCB 28 and 52) with high chlorine in structure and dioxin-like PCBs were related to longer TLs. Conversely, serum levels of OCPs can be associated with oxidative stress and systemic inflammation that lead to telomere shortening.

Serum level of PCBs and OCPs and leukocyte telomere length among adults in Tehran, Iran

Exposure to polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) may change leukocyte telomere length (TL) at the end of the DNA sequence. The purpose of this study was to investigate the association between PCBs and OCPs exposure with TL in Tehran adult males. Whole-blood samples were randomly taken from three hundred adult males in population-based cross-section study from October 2016 to November 2017. We studied the serum levels of PCBs, OCPs as well as socio-demographic characteristics of individuals. The quantitative PCR was used to investigate the number of the telomere (T) repeats to the number of a single copy gene. We measured the effect of each PCBs and OCPs congeners on TL using linear regressions adjusted for age, BMI, smoking, and dietary patterns. The median level of the six non-dioxin-likes, five dioxin-likes PCBs three OCPs and TL in the study population were 344.5, 306.0, 45.0 ng/g lipid and 5377.7 ± 573.4 base pairs, respectively. In the adjusted model, the percent difference in the TLs with exposure to Σnon-dioxin-like PCBs, Σdioxin-like PCBs, and OCPs were 1.93 (-0.70 to 5.4), 3.4 (1.8-8.3) and -2.4 (-0.80 to -6.2), respectively. In the fourth quartile compared to the first quartile, the percent difference in the TLs due to Σnon-dioxin-like PCBs, Σdioxin-like PCBs, and OCP exposure were 0.01 (-0.01 to 0.05), 10.3 (2.9-18.1) and -0.20 (-0.10 to -4.5), respectively. Exposures to ndl-PCBs and dl-PCBs (except for PCB28) were related to longer TLs, but OCPs exposure can be related to telomere shortening.

Longitudinal study of age of menarche in association with childhood concentrations of persistent organic pollutants

BACKGROUND

Age at female puberty is associated with adult morbidities, including breast cancer and diabetes. Hormonally active chemicals are suspected of altering pubertal timing. We examined whether persistent organic pollutants (POPs) are associated with age at menarche in a longitudinal study.

METHODS

We analyzed data for females enrolled at age 6-8 years in the Breast Cancer and Environment Research Program from California and Ohio. Participants were followed annually 2004-2013 and provided serum (mean age 7.8 years) for measurement of polychlorinated biphenyl (PCB), organochlorine pesticide (OCP), and polybrominated diphenyl ether (PBDE) concentrations. Age of menarche was assigned based on parental and participant reported dates and ages of menarche. Adjusted hazard ratios (aHRs) for menarchal onset were calculated with Cox proportional regression. Body mass index (BMI), potentially on the causal pathway, was added to parallel analyses.

RESULTS

Age of menarche was later with higher summed PCB levels (median 11.9 years in quartile 1 [Q1] versus 12.7 in quartile 4 [Q4]) and OCP levels (12.1 years versus 12.4, respectively). When adjusting for all covariates except BMI, higher POP concentrations were associated with later age at menarche (Q4 versus Q1 aHRs: PBDEs 0.75 [95% CI 0.58, 0.97], PCBs 0.67 [95% CI 0.5, 0.89], and OCPs 0.66 [95% CI 0.50, 0.89]). Additional adjustment for BMI attenuated aHRs; PCB aHR approached the null.

CONCLUSION

Findings revealed later onset of menarche with higher concentrations of certain POPs, possibly through an association with BMI. Altered pubertal timing may have long lasting effects on reproductive health and disease risk, so continued attention is important for understanding the biological processes affected by hormonally active chemicals.

Neuroimaging signatures of brain plasticity in adults with prenatal exposure to polychlorinated biphenyls: Altered functional connectivity on functional MRI

Prenatal exposure to polychlorinated biphenyls (PCBs), persistent organic pollutants in food chains and environment, exerts negative effects on children's cognitive function. To study the long-term effects, we examined cognitive functions in the male children of women with substantial PCB exposure in Taiwan during 1978-1979 and investigated neural basis of cognitive function changes through structural magnetic resonance imaging (MRI) and functional MRI (fMRI), which included resting-state and task-activated fMRI with two paradigms: a 2-back task and a picture rotation task. Ten men aged 30.0 ± 3.7 years with prenatal exposure to PCBs and 11 unexposed controls aged 28.1 ± 3.1 years participated. Both groups had similar cognitive phenotypes and behavioral results. Structural MRI analysis results showed that the PCB group had increased cortical thickness over the right inferior parietal lobule. In the resting-state study, the PCB group showed alterations in the default mode network. During the tasks, the PCB group showed decreased task-induced deactivation signals in cognition-associated brain areas during the 2-back task but enhanced deactivations during the picture rotation task. This study demonstrated altered structural MRI as well as resting and task-related fMRI in men with prenatal PCB exposure, suggesting altered brain plasticity and compensatory neuropsychological performance.

Perinatal exposure to organohalogen pollutants decreases vasopressin content and its mRNA expression in magnocellular neuroendocrine cells activated by osmotic stress in adult rats

Polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) are environmental pollutants that produce neurotoxicity and neuroendocrine disruption. They affect the vasopressinergic system but their disruptive mechanisms are not well understood. Our group reported that rats perinatally exposed to Aroclor-1254 (A1254) and DE-71 (commercial mixtures of PCBs and PBDEs) decrease somatodendritic vasopressin (AVP) release while increasing plasma AVP responses to osmotic activation, potentially emptying AVP reserves required for body-water balance. The aim of this research was to evaluate the effects of perinatal exposure to A1254 or DE-71 (30mgkg/day) on AVP transcription and protein content in the paraventricular and supraoptic hypothalamic nuclei, of male and female rats, by in situ hybridization and immunohistochemistry. cFOS mRNA expression was evaluated in order to determine neuroendocrine cells activation due to osmotic stimulation. Animal groups were: vehicle (control); exposed to either A1254 or DE-71; both, control and exposed, subjected to osmotic challenge. The results confirmed a physiological increase in AVP-immunoreactivity (AVP-IR) and gene expression in response to osmotic challenge as reported elsewhere. In contrast, the exposed groups did not show this response to osmotic activation, they showed significant reduction in AVP-IR neurons, and AVP mRNA expression as compared to the hyperosmotic controls. cFOS mRNA expression increased in A1254 dehydrated groups, suggesting that the AVP-IR decrease was not due to a lack of the response to the osmotic activation. Therefore, A1254 may interfere with the activation of AVP mRNA transcript levels and protein, causing a central dysfunction of vasopressinergic system.

Serum Polychlorinated Biphenyls Increase and Oxidative Stress Decreases with a Protein-Pacing Caloric Restriction Diet in Obese Men and Women

The purposes were to compare the effects of a: (1) 12-week P-CR weight loss (WL) diet (Phase 1) between obese men and women and; (2) 52-week modified P-CR (mP-CR) vs. heart healthy (HH) weight maintenance (WM) diet (Phase 2) on serum PCBs and oxidative stress biomarkers (thiobarbituric acid reactive substances, TBARS; total antioxidant capacity, TAC) in 40 obese participants (men, n = 21; women, n = 19). Participants received dietary counseling and monitoring of compliance. PCBs, TBARS, and TAC were assessed at weeks -1 (CON), 12 (WL), and 64 (WM). Following WL (Week 12), concomitant with reductions in TBARS (0.24 ± 0.15 vs. 0.18 ± 0.11 µM; p < 0.01), PCB serum concentrations (86.7 ± 45.6 vs. 115.6 ± 65.9 ng/g lipid; p < 0.01) and TAC (18.9 ± 2.6 vs. 19.9 ± 2.3 nmol/mL; p < 0.02) were increased similarly in men and women. At the end of WM (Week 64), a significant effect of time × group interaction was observed for % change in PCB 170 and 187; whereby mP-CR values were higher compared to HH (PCB170: 19.31% ± 26.48% vs. -6.61% ± 28.88%, p = 0.02; PCB187: -3.04% ± 17.78% vs. -21.4% ± 27.31%, p = 0.04). PCB changes were positively correlated with TBARS levels (r > 0.42, p < 0.05) and negatively correlated with body weight, fat mass, and abdominal fat (r < -0.46, p < 0.02). Our results support mobilization of stored PCBs as well as enhanced redox status following a 12-week P-CR WL diet. Additionally, a 52-week mP-CR WM diet demonstrated an advantage in preventing weight gain relapse accompanied by an increase in circulating PCBs compared to a traditional HH diet.

The classic EDCs, phthalate esters and organochlorines, in relation to abnormal sperm quality: a systematic review with meta-analysis

The association between endocrine disrupting chemicals (EDCs) and human sperm quality is controversial due to the inconsistent literature findings, therefore, a systematic review with meta-analysis was performed. Through the literature search and selection based on inclusion criteria, a total of 9 studies (7 cross-sectional, 1 case-control, and 1 pilot study) were analyzed for classic EDCs (5 studies for phthalate esters and 4 studies for organochlorines). Funnel plots revealed a symmetrical distribution with no evidence of publication bias (Begg’s test: intercept = 0.40; p = 0.692). The summary odds ratios (OR) of human sperm quality associated with the classic EDCs was 1.67 (95% CI: 1.31–2.02). After stratification by specific chemical class, consistent increases in the risk of abnormal sperm quality were found in phthalate ester group (OR = 1.52; 95% CI: 1.09–1.95) and organochlorine group (OR = 1.98; 95% CI: 1.34–2.62). Additionally, identification of official data, and a comprehensive review of the mechanisms were performed, and better elucidated the increased risk of these classic EDCs on abnormal sperm quality. The present systematic review and meta-analysis helps to identify the impact of classic EDCs on human sperm quality. However, it still highlights the need for additional epidemiological studies in a larger variety of geographic locations.

Endocrine-disrupting actions of PCBs on brain development and social and reproductive behaviors

Polychlorinated biphenyls are among the most well-studied endocrine-disrupting chemicals (EDCs) for their neurobehavioral effects, especially neurodevelopment and cognitive performance. In addition, past research has demonstrated effects of PCBs on circulating hormones and associated changes in reproductive behaviors. This article will focus on recent advances that have been made in characterizing developmental PCB effects on reproductive function, broader social and affective behaviors, and the neuroendocrine mechanisms behind such changes. In general, PCBs seem to inhibit reproductive function by suppressing multiple aspects of the associated hypothalamic circuitry. Additionally, PCBs may also reduce motivation for social behaviors and induce depressive-like symptoms via overall reductions in dopaminergic and glutamatergic functions in the limbic system. However, more work with human-relevant exposure paradigms is needed to fully support these conclusions.

Inter-annual variation of persistent organic pollutants (POPS) in an Antarctic top predator Arctocephalus gazella

Persistent organic pollutants (POPs), contaminants that may bioaccumulate in upper trophic level organisms, were detected in the milk of a top predator, the Antarctic fur seal (Arctocephalus gazella). Multiparous females had significantly lower concentrations of certain POPs (trans-nonachlor, p,p'-DDE, and several PCBs) in their milk than primiparous females, likely due to the annual lactational transfer of the POP burden from mother to pup. Furthermore, there were significant interannual differences in POP concentrations in multiparous females' milk from five breeding seasons between 2000 and 2011. Decreasing trends in concentrations of certain POPs over the recent decade coincide with declining global emissions, yet atmospheric concentrations in the Antarctic are not always consistent with global trends, suggesting that additional factors may contribute to temporal trends of POPs in fur seals. Climate shifts and corresponding availability of krill over the past decade were not consistent with trends observed in POP concentrations in fur seal milk, suggesting that climate may not be a key factor. Additional mechanisms, such as variability in the geographic ranges of individual seals during overwintering migrations are discussed and should be explored further.

Polychlorinated Biphenyls, Glycaemia and Diabetes in a Population Living in a Highly Polychlorinated Biphenyls-Polluted Area in Northern Italy: a Cross-sectional and Cohort Study

Conflicts of interests: the authors declare no potential conflict of interests.

Polychlorinated biphenyls (PCBs) in relation to secondary sex ratio--a systematic review of published studies

There is reasonably strong evidence linking reduced secondary sex ratio (proportion of males) and environmental exposures. Polychlorinated biphenyls (PCBs) are persistent contaminants of the environment and several studies have reported an association of PCBs with birth outcomes. A decrease in the male/female sex ratio at birth has been reported in some, but not all studies. The aim of this systematic review was to summarize and pool the research findings about the influence of PCBs on sex ratio. Several article databases and reference lists of identified articles were searched. Studies reporting the proportion of boys and girls born to individuals who were exposed to high PCB concentrations were included. The primary outcome measure was the proportion of males in groups exposed to high or low levels of PCBs. Studies with both direct and indirect surrogate PCB measurements were included. The search and selection resulted in 15 eligible studies on the association between the sex ratio and parental PCB exposures. Analyses of the high exposure groups showed that the sex ratio was not significantly altered from the historical reference range in 13 of the 15 articles. The majority of the exposure studies reported also internal comparisons between high and low PCB exposure levels. The pooled 95% confidence interval estimate for the difference in high and low maternal exposure with direct PCB measure was - 0.048 with 95% CI of (-0.121, 0.026). There was no strong or moderate indication that parental exposure to PCBs alters the sex ratio of the children.

Systematic analysis of the relationship between standardized prenatal exposure to polychlorinated biphenyls and mental and motor development during follow-up of nine children cohorts

Impact of prenatal exposure to polychlorinated biphenyls (PCBs) on mental and motor development has been investigated in various children cohorts, but findings show temporal inconsistencies. Because a direct comparison of results obtained from different cohorts remains difficult, temporal relationship between biological PCB concentrations and long-term developmental effects is still not clearly established. The objective of this research was to use a procedure previously developed to standardize PCB biological concentration data across cohorts in order to perform a systematic analysis of temporal associations between prenatal PCB exposure and mental and motor development from neonatal period (or a young age) until school age. Prenatal exposure data from nine cohorts were standardized in terms of total PCBs per kg of lipids in maternal plasma. Systematic analysis of the "standardized biological concentration-development" relationship during follow-up of each cohort was then conducted through the application of Hill criteria. This led to retain six of the studied cohorts in the final analysis. A biological level of prenatal PCB exposure below which risk of mental or motor development should be negligible was established in the order of 1000μg/kg of lipids in maternal plasma.

The effects of oxidative stress on female reproduction: a review

Oxidative stress (OS), a state characterized by an imbalance between pro-oxidant molecules including reactive oxygen and nitrogen species, and antioxidant defenses, has been identified to play a key role in the pathogenesis of subfertility in both males and females. The adverse effects of OS on sperm quality and functions have been well documented. In females, on the other hand, the impact of OS on oocytes and reproductive functions remains unclear. This imbalance between pro-oxidants and antioxidants can lead to a number of reproductive diseases such as endometriosis, polycystic ovary syndrome (PCOS), and unexplained infertility. Pregnancy complications such as spontaneous abortion, recurrent pregnancy loss, and preeclampsia, can also develop in response to OS. Studies have shown that extremes of body weight and lifestyle factors such as cigarette smoking, alcohol use, and recreational drug use can promote excess free radical production, which could affect fertility. Exposures to environmental pollutants are of increasing concern, as they too have been found to trigger oxidative states, possibly contributing to female infertility. This article will review the currently available literature on the roles of reactive species and OS in both normal and abnormal reproductive physiological processes. Antioxidant supplementation may be effective in controlling the production of ROS and continues to be explored as a potential strategy to overcome reproductive disorders associated with infertility. However, investigations conducted to date have been through animal or in vitro studies, which have produced largely conflicting results. The impact of OS on assisted reproductive techniques (ART) will be addressed, in addition to the possible benefits of antioxidant supplementation of ART culture media to increase the likelihood for ART success. Future randomized controlled clinical trials on humans are necessary to elucidate the precise mechanisms through which OS affects female reproductive abilities, and will facilitate further explorations of the possible benefits of antioxidants to treat infertility.

Alteration of serotonin system by polychlorinated biphenyls exposure

Although commercial production of polychlorinated biphenyls (PCBs) was banned in 1979, PCBs continue to be an environmental and health concern due to their high bioaccumulation and slow degradation rates. In fact, PCBs are still present in our food supply (fish, meat, and dairy products). In laboratory animals, exposure to single PCB congener or to mixtures of different congeners induces a variety of physiological alterations. PCBs cross the placenta and even exposure at low level is harmful for the foetus by leading to neurodevelopment alterations. Serotonin system which regulates many physiological functions from platelet activation to high cerebral processes and neurodevelopment is one of the targets of PCBs toxicity. The effects of PCBs exposure on serotonin system have been investigated although to a lesser extent compared to its effect in other neurotransmitter systems. This review provides a summary of the results concerning the impact of PCBs exposure (in vitro and in vivo) on serotonin system. Further research is needed to correlate specific deficits with PCB-induced changes in the serotonin system.

Common classification schemes for PCB congeners and the gene expression of CYP17, CYP19, ESR1 and ESR2

BACKGROUND

Reliable techniques to measure polychlorinated biphenyl (PCB) congeners make the clearer definition of their effects on human health possible. Given that PCBs are classified as endocrine disrupters, we sought to explore the expression of some key genes involved in sex steroid metabolism.

OBJECTIVES

To examine common classification schemes of PCB congeners and determine whether exposure to groups classified by mechanism of action alter the gene expression (GE) of CYP17, CYP19, and ESR1 and ESR2.

METHODS

GE and exposure to various classifications of lipid-adjusted PCB congeners were examined in 139 daughters of the Michigan Fisheaters' Cohort. Using mixed models analyses and adjusting for age, menopausal status, and current use of oral contraceptives and hormone replacement therapy, GE data were regressed on exposure to PCB congener groupings based on mechanism of action.

RESULTS

Three novel findings are elucidated: first, that up-regulation of CYP19 expression is associated with exposure to PCB groupings containing dioxin-like, potentially anti-estrogenic, immunotoxic congeners, including PCB IUPAC #74, #105, #118, #138, #156, #157, #158, #167, and #170 from this cohort. Second, that exposure to similar congeners (PCB IUPAC #105, #156, #157, #158, and #167 in this cohort) but using a classification based solely on hormonal mechanisms of action is associated with increased expression of ESR2. Third, that increased expression of CYP17 is of borderline significance when associated with exposure to PCB IUPAC #118, #138, and #156.

CONCLUSIONS

These findings are both counter-intuitive and intriguing. Rather than exhibiting anti-estrogenic effects alone, they suggest that these congeners up-regulate the major enzyme involved in estrogen synthesis and tend to confirm previous findings of links between AhR and ER signaling pathways. Replication of these findings, expansion of the number of genes examined, exploration of mixtures of environmental chemicals, and subsequent study of health outcomes in a larger cohort are future priorities.

Non-dioxin-like polychlorinated biphenyls interfere with neuronal differentiation of embryonic neural stem cells

Developmental exposure to food contaminants, such as polychlorinated biphenyls (PCBs), has been considered as a possible cause of neurodevelopmental disorders. We have investigated the effects of noncytotoxic concentrations of PCBs 153 and 180 on spontaneous differentiation of rat embryonic neural stem cells (NSCs). Upon removal of basic fibroblast growth factor to induce spontaneous differentiation, cells were exposed to 100 nM of the selected PCBs for 48 h and analyzed after 5 days. Both PCBs 153 and 180 induced a significant increase in the number of neurite-bearing Tuj1-positive cells with a concomitant decrease in proliferating cells, as detected by FUCCI transfection and EdU staining. Measurements of spontaneous Ca²⁺ oscillations showed a decreased number of cells with Ca²⁺ activity after PCB exposure, further confirming the increase in neuronal cells. Conversely, exposure to methylmercury (MeHg), which we evaluated in parallel, led to an increased number of cells with Ca²⁺ activity, in agreement with the previously observed inhibition of neuronal differentiation. Analysis with quantitative PCR of the Notch pathway revealed that PCBs have a repressive action on Notch signaling, whereas MeHg activates it. Altogether, the data indicate that nanomolar concentrations of the selected non-dioxin-like PCBs and MeHg interfere in opposite directions with neuronal spontaneous differentiation of NSCs through Notch signaling. Combined exposures to PCBs and MeHg resulted in an induction of apoptosis and an antagonistic interaction on spontaneous neuronal differentiation. NSCs are further proven to be a valuable in vitro model to identify potential developmental neurotoxicants.

Serum concentrations of polychlorinated biphenyls in relation to in vitro fertilization outcomes

BACKGROUND

Human exposure to polychlorinated biphenyls (PCBs) remains widespread. PCBs have been associated with adverse reproductive health outcomes including reduced fecundability and increased risk of pregnancy loss, although the human data remain largely inconclusive.

OBJECTIVE

Our goal was to explore the relationship between serum PCB concentrations and early pregnancy loss among a large cohort of women undergoing in vitro fertilization (IVF) between 1994 and 2003.

METHODS

Concentrations of 57 PCB congeners were measured in serum samples collected during 827 IVF/intracytoplasmic sperm injection cycles from 765 women. Joint statistical models that accommodate multiple outcomes and multiple cycles per woman were used to assess the relationship between serum PCB quartiles and implantation failure, chemical pregnancies (human chorionic gonadotropin level > 5.0 mIU/mL) that did not result in clinical pregnancy, or spontaneous abortion, while also adjusting for confounders.

RESULTS

PCB-153 was the congener present in the highest concentration (median, 46.2 ng/g lipid). Increasing quartiles of PCB-153 and the sum of all measured PCB congeners (ΣPCBs) were associated with significantly elevated dose-dependent odds of failed implantation. Adjusted odds ratios (95% confidence interval) for highest versus lowest quartile were 2.0 (1.2-3.4) for PCB-153 and 1.7 (1.0-2.9) for ΣPCBs. There were suggestive trends for increased odds of implantation failure for PCB-118 and cytochrome P450-inducing congeners (p-values for trend = 0.06). No statistically significant associations between PCBs and chemical pregnancy or spontaneous abortion were found.

CONCLUSIONS

Serum PCB concentrations at levels similar to the U.S. general population were associated with failed implantation among women undergoing IVF. These findings may help explain previous reports of reduced fecundability among women exposed to PCBs.

Postnatal exposure to PCB 153 and PCB 180, but not to PCB 52, produces changes in activity level and stimulus control in outbred male Wistar Kyoto rats

Background

Polychlorinated biphenyls (PCBs) are a class of organic compounds that bioaccumulate due to their chemical stability and lipophilic properties. Humans are prenatally exposed via trans-placental transfer, through breast milk as infants, and through fish, seafood and fatty foods as adolescents and adults. Exposure has several reported effects ranging from developmental abnormalities to cognitive and motor deficiencies. In the present study, three experimental groups of rats were orally exposed to PCBs typically found in human breast milk and then behaviorally tested for changes in measures of stimulus control (percentage lever-presses on the reinforcer-producing lever), activity level (responses with IRTs > 0.67 s), and responses with short IRTs (< 0.67 s).

Methods

Male offspring from Wistar Kyoto (WKY/NTac) dams purchased pregnant from Taconic Farms (Germantown, NY) were orally given PCB at around postnatal day 8, 14, and 20 at a dose of 10 mg/kg body weight at each exposure. Three experimental groups were exposed either to PCB 52, PCB 153, or PCB 180. A fourth group fed corn oil only served as controls. From postnatal day 25, for 33 days, the animals were tested for behavioral changes using an operant procedure.

Results

PCB exposure did not produce behavioral changes during training when responding was frequently reinforced using a variable interval 3 s schedule. When correct responses were reinforced on a variable interval 180 s schedule, animals exposed to PCB 153 or PCB 180 were less active than controls and animals exposed to PCB 52. Stimulus control was better in animals exposed to PCB 180 than in controls and in the PCB 52 group. Also, the PCB 153 and PCB 180 groups had fewer responses with short IRTs than the PCB 52 group. No effects of exposure to PCB 52 were found when compared to controls.

Conclusions

Exposure to PCBs 153 and 180 produced hypoactivity that continued at least five weeks after the last exposure. No effects of exposure to PCB 52 were observed.

Benefits versus risks associated with consumption of fish and other seafood

Fish provide nutrition for much of the world's population, and when not contaminated with chemicals, fish is a very good food. A major benefit of fish is that they are high in polyunsaturated fatty acids (PUFAs), low in saturated fat, and they contain other critical nutrients. Much of the benefit of fish consumption derives from their high levels of long chain omega-3 PUFAs, which are produced by aquatic microorganisms and bioconcentrate in the aquatic food supply. The PUFAs are essential, in that humans and other vertebrates are not able to synthesize them and therefore must obtain them from the diet. The PUFAs particularly concentrate in the nervous system, alter immune system function reduce serum triglyceride levels and have been reported to reduce the risk of sudden death after a myocardial infarction. But the problem is that most fish have at least some degree of chemical contamination with methylmercury, (which binds to muscle) and/or with persistent organic pollutants such as dioxins, polychlorinated biphenyls, polybrominated diphenyl ethers, chlorinated pesticides (which concentrate in fish fat). These chemicals have adverse effects on nervous system function, modulate the immune system, and are associated with elevations in risk of cardiovascular disease. Thus the question of benefits and risk from fish consumption is complex but very important.

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.

Fetal loss and maternal serum levels of 2,2',4,4',5,5'-hexachlorbiphenyl (CB-153) and 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (p,p'-DDE) exposure: a cohort study in Greenland and two European populations

BACKGROUND

In the present study, the aim is to examine the risk of fetal loss related to environmental 2,2',4,4',5,5'-hexachlorobiphenyl (CB-153) or 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (p,p'-DDE) exposure.

METHODS

We related LC/MS/MS measurements of CB-153 and p,p'-DDE in serum samples to interview-data on previous fetal loss in populations of pregnant women from Poland, Ukraine and Greenland.

RESULTS

In total, 1710 women were interviewed, and 678 of these had at least one previous pregnancy. The risk of ever experiencing a fetal loss increased at higher levels of CB-153 and p,p'-DDE exposure, with an adjusted odds ratio (OR) of 2.4; confidence interval (CI) (1.1-5.5) for CB-153>200 ng/g lipid compared to 0-25 ng CB-153/g lipid and OR of 2.5 CI (0.9-6.6) for p,p'-DDE>1500 ng/g lipid compared to 0-250 ng DDE/g lipid. However, no clear dose response associations were observed. The results further suggest that high level of organochlorine serum concentrations may be related to repeated loss.

CONCLUSIONS

The risk of fetal loss may increase at higher levels of CB-153 and p,p'-DDE exposure, although lack of dose response and inconsistencies between countries did not allow for firm conclusions.

Lactational exposure to polychlorinated biphenyls, dichlorodiphenyltrichloroethane, and dichlorodiphenyldichloroethylene and infant growth: an analysis of the Pregnancy, Infection, and Nutrition Babies Study

Polychlorinated biphenyls (PCB), 2,2-bis(p-chlorophenyl)-1,1,1-trichloroethane (p,p'-DDT) and 2,2-bis(p-chlorophenyl)-1,1-dichloroethylene (p,p'-DDE), the most stable metabolite of p,p'-DDT, are persistent organic pollutants and environmental endocrine disruptors. Infant exposure to these chemicals through breast feeding may influence children's growth, but this potential adverse effect could be complicated by the coexisting benefits of breast feeding. This study examined the associations between lactational exposure to these chemicals and infant growth in the first 12 months by using data from the Pregnancy, Infection and Nutrition Babies Study in central North Carolina, United States, 2004-06. The study population was restricted to the infants who were breast fed for 6 months or longer. PCBs, p,p'-DDT and p,p'-DDE were measured in breast milk at 3 months postpartum. Lactational exposure up to 12 months of age was estimated as the product of chemical concentrations and the duration of breast feeding. The infant's weight and length were recorded from the medical record for each routine paediatric well-child visit in the first 12 months. Women-child pairs who breast fed for 6 months or longer and returned the growth card (n = 210) were included in the study. Linear mixed effects models were used to assess the associations between chemical concentrations in breast milk and longitudinal infant weight and length measurements in the first 6 months. Multivariable linear regression models were used to assess the relationships between lactational exposure to chemicals until 12 months of age and the z-scores of infant weight, length and weight-for-length at 12 months. Overall, no association was observed. Breast feeding for 6 months or longer, with lactational exposure to PCBs, p,p'-DDT and p,p'-DDE at the low background level concentrations studied here, resulted in no measurable influence on infant growth in the first 12 months.

Determination of organochlorine pesticide and polychlorinated biphenyl levels in adipose tissue of infertile men

During the recent two decades, a remarkable drop in fertility rates has been noticed almost all over the world. A series of studies have showed that environmental factors had the primary role causing the observed adverse trends in the male reproductive health problems. Especially chlorinated hydrocarbons, for instance polychlorinated biphenyls (PCB) and pesticides, could mimic or antagonize the effects of steroid hormones, like estrogens and androgens and possibly interfering with male reproductive capacity. Organochlorine pesticides (OCPs) (i.e. p.p'-DDT, endosulfan...) and PCBs are widespread used chemicals in agriculture and industry for different purposes all over the world. Although direct evidence is lacking, theoretical considerations and epidemiological evidence implicate these compounds as potential hazards to human and wildlife reproductive health. For this purpose, in this study adipose tissue samples have provided from healthy males which were diagnosed as infertile men living in Ankara, Turkey at least for 5 years. Residual levels of OCPs (alpha-BHC, beta-BHC, gamma-BHC, HCB, Endosulfan I, II, p,p'-DDE, and p,p'-DDT) and seven major persistent PCB congeners (PCB 28, 52, 101, 118, 138, 153, and 180) were measured in 25 infertile men and 21 healthy men's adipose tissue samples by GC-ECD. Levels of OCPs and PCBs in adipose tissue of infertile men compared with those provided from controls. When the concentrations of each of the OCP were compared between the fertile and infertile groups, no statistical significance was obtained. Concentrations of each of the PCB congeners were compared between the fertile and infertile groups, no statistical significance was obtained (p > 0.05), except for 2,2',5,5'-Tetrachlorobiphenyl (PCB 52) (p = 0.032) and 2,2',3,4,4',5,5'-heptachlorobiphenyl (PCB 180) (p = 0.017).

Correlations between dioxin-like and indicators PCBs: potential consequences for environmental studies involving fish or sediment

Among the numerous PCB congeners, most of the dioxin-like PCBs (DL-PCBs) need to be characterized by hyphenated techniques. It has been shown in several instances that these congeners are well related to the total PCB content in fish. We examined datasets collected mainly in France, on freshwater and marine fish and sediments. A statistical model linking DL- and indicator PCBs was developed for a dataset composed of freshwater fishes, and proved to predict well DL-PCBs from indicator PCBs in all other fish sets, including marine ones. Type II error rates remained low in almost all fish sets. A similar correlation was observed in sediments. Non-dioxin-like PCBs elicit various adverse effects and represent 95% of the total PCBs. A European guideline for them is needed; the correlation between DL- and indicator PCBs could help develop this standard in the future.

Environmental influences on human growth and development: historical review and case study of contemporary influences

Over the past 100 years, the study of environmental influences on human physical growth and development has focused on the influences of social and economic factors; family and household characteristics; urbanization/modernization; nutrition; and features of the physical environment such as altitude, temperature and climate. Continuing in this tradition are current investigations into the roles of pollutants and other aspects of the human-made environment in affecting patterns of human growth and development, specifically the timing of sexual maturation and the development of obesity. Some of the methodological problems in conducting such studies are presented, as are results from an ongoing investigation among one Native American community that show relationships of pollutants to sexual maturation, overweight/obesity and thyroid system function which can impact growth and maturation.

Relationships of putative endocrine disruptors to human sexual maturation and thyroid activity in youth

Endocrine disruption has become a significant human health concern, but is difficult to study outside of the laboratory for several reasons including the multiplicity of exposures, the difficulty in assessing each exposure, and the variety of possible outcomes among human populations. This review summarizes our studies of the relationships of measured persistent organic pollutants (PCBs, p,p'-DDE, HCB and mirex), and heavy metals (lead and mercury), to outcomes directly related to thyroid function and sexual maturation. These studies were conducted in a sample of Native American youth from the Akwesasne Mohawk community. The participants were first studied during puberty (10-16.9 years of age) and then at approximately 18 years of age. Results from these studies show that PCB levels are positively related to TSH and negatively to free T4. Further, these effects are conditioned by breastfeeding history. Anti-thyroid peroxidase antibody levels also are related to PCB levels suggesting elevated risk of autoimmune disease among the exposed. Earlier age at menarche is associated with higher PCB levels while risk of delay is associated with higher lead levels. Some evidence that the timing of exposure produces different effects is presented, and the level of exposure in the participants suggests that effects observed may be relevant to a considerable proportion of the US population. Further investigations are warranted to determine effect thresholds and mechanisms.

Maternal exposure to polybrominated and polychlorinated biphenyls: infant birth weight and gestational age

Understanding the influence of maternal exposures on gestational age and birth weight is essential given that pre-term and/or low birth weight infants are at risk for increased mortality and morbidity. We performed a retrospective analysis of a cohort exposed to polybrominated biphenyls (PBB) through accidental contamination of cattle feed and polychlorinated biphenyls (PCB) through residual contamination in the geographic region. Our study population consisted of 444 mothers and their 899 infants born between 1975 and 1997. Using restricted maximum likelihood estimation, no significant association was found between estimated maternal serum PBB at conception or enrollment PCB levels and gestational age or infant birth weight in unadjusted models or in models that adjusted for maternal age, smoking, parity, infant gender, and decade of birth. For enrollment maternal serum PBB, no association was observed for gestational age. However, a negative association with high levels of enrollment maternal serum PBB and birth weight was suggested. We also examined the birth weight and gestational age among offspring of women with the highest (10%) PBB or PCB exposure, and observed no significant association. Because brominated compounds are currently used in consumer products and therefore, are increasingly prevalent in the environment, additional research is needed to better understand the potential relationship between in utero exposure to brominated compounds and adverse health outcomes.

Polychlorinated biphenyl exposure and CYP19 gene regulation in testicular and adrenocortical cell lines

Exposure to polychlorinated biphenyls (PCBs) disturbs many estrogen-mediated biochemical processes. PCBs may cause these abnormalities by altering expression of the aromatase gene CYP19. This study demonstrated that high concentrations of PCB126 increased basal CYP19 mRNA abundance in mouse testicular Leydig I-10 cells and human adrenocortical H295R cells. Stimulating the cells with chorionic gonadotropin or 8-Br-cAMP concealed the estrogenic effect of PCB126. PCB126 is a powerful ligand for nuclear receptor AhR. Antagonizing the AhR activity of H295R by an inhibitor abolished PCB126-elicited CYP19 induction. However, PCB126 elevated basal CYP19 expression and aromatase activity in a slow progressive manner contrary to the sharp induction of the classic AhR target gene CYP1A1. Exposure of H295R to PCBs with different AhR activation abilities also varied CYP19 and CYP1A1 expression in dissimilar patterns, although the CYP19 mRNA levels were in line with the AhR activation abilities of the congeners. In contrast to PCB126, PCB39, which could not activate AhR and lacked effect on CYP1A1, significantly reduced CYP19 mRNA expression. AhR apparently played an important role in CYP19 gene regulation, but it might regulate CYP19 differently from CYP1A1 in the adrenocortical cells. Regardless of the action mechanism, PCB exposure increases risk for CYP19 dysregulation.

Effects of polychlorinated biphenyls on maternal odor conditioning in rat pups

Polychlorinated biphenyls (PCBs) are pervasive environmental contaminants that can have damaging effects on physiologic, motoric and cognitive function. Results from studies on PCBs and behavior have shown that exposure can alter learning and memory processes and that these shifts in cognitive abilities can be related to changes in hormonal and neural function. Little experimentation has been done on the impact of exposure to PCBs on social and emotional development. Previous work has shown that exposure to PCBs in children can alter play behavior. Importantly, exposure to PCBs has been found to change aspects of maternal-offspring interactions in rodents. The present study examined the impact of PCBs on maternal odor conditioning in rat pups 12-14 days of age. A modified version of the conditioned place preference paradigm was used that incorporated a maternal-associated odor cue (lemon scent) as the conditioned stimulus. PCBs significantly depressed the preference for the maternal-associated cue but did not impair discrimination for a novel odor. These effects could arise due to changes in the social dynamics between the dam and offspring after co-exposure to PCBs. For example, dams exposed to PCBs during gestation have been found to show elevated grooming directed towards pups exposed to PCBs. This change in maternal care can have dramatic effects on behavioral and hormonal systems in the developing rat pup. In conclusion, perinatal PCBs alter important social behaviors of both the mother and pup, and these alterations could have long-lasting effects on behavioral, cognitive and emotional development.

Polychlorinated biphenyls and organochlorine pesticides in seafood from the Gulf of Naples (Italy)

Seven target polychlorinated biphenyls (PCBs; IUPAC nos. 28, 52, 101, 118, 138, 153, and 180) and the organochlorine pesticides (OCPs) hexachlorobenzene (HCB) and dichlorodiphenyltrichloroethane (DDT) and its related metabolites (p,p'-DDT, p,p'-DDE, and p,p'-DDD) were quantified in edible tissues from seven marine species (European hake, red mullet, blue whiting, Atlantic mackerel, blue and red shrimp, European flying squid, and Mediterranean mussel) from the Gulf of Naples in the southern Tyrrhenian Sea (Italy). PCBs 118, 138, and 153 were the dominant congeners in all the species examined. The concentrations of all PCBs (from not detectable to 15,427 ng g(-1) fat weight) exceeded those of all the DDTs (from not detectable to 1,769 ng g(-1) fat weight) and HCB (not detectable to 150.60 ng g(-1) fat weight) in the samples analyzed. The OCP concentrations were below the maximum residue limits established for fish and aquatic products by the Decreto Ministerale 13 May 2005 in all the samples analyzed; therefore the OCPs in the southern Tyrrhenian Sea species are unlikely to be a significant health hazard. Conversely, the mean concentrations of PCBs exceeded (greatly in some cases) the current limits (200 ng(-1) fat weight) set by the European Union for terrestrial foods. Although the manufacture and use of PCBs are banned or highly restricted, these compounds still are important persistent chemical contaminants in the Gulf of Naples.

Prenatal Exposure to 3,3',4,4',5-Pentachlorobiphenyl (PCB126) Promotes Anxiogenic Behavior in Rats

Polychlorinated biphenyls (PCBs) are environmental contaminants that have adverse effects on the endocrine and nervous systems. As they are still detected in breast milk and adipose tissue in humans, the accumulated PCBs may transfer from mothers to children and damage central nervous system. It is revealed from epidemiological studies that cognitive and motor functions were damaged in children born to mothers who ingested PCBs-contaminated foods. However, it remains unclear whether prenatal exposure to PCBs affects emotionality. In the present study, we therefore examined the effect of prenatal exposure to 3,3',4,4',5-pentachlorobiphenyl (PCB126) on emotionality in rats by focusing on anxiogenic behavior and response of the hypothalamus-pituitary-adrenal axis to stress. Pregnant rats were treated orally with PCB126 at a dose of 30 microg/kg or corn oil, its vehicle, on gestational day 15, and their male offspring were subjected to the following experiments at 4-5 weeks old. In an open field test, rats with prenatal exposure to PCB126 showed anxiogenic behavioral responses, including decrease in time spent in the center of an open field and the number of rearings and extension of grooming duration. Interactive behavior, which is an index of anxiety level, was shortened in the social interaction test. The increase in the serum corticosterone level induced by forced swim stress was facilitated by prenatal exposure to PCB126. This evidence suggests that PCB126 may exert anxiogenicity on the offspring of exposed dams, and dysfunction of the hypothalamus-pituitary-adrenal axis may at least in part contribute to this abnormality.

Polychlorinated biphenyls and their hydroxylated metabolites (OH-PCBS) in pregnant women from eastern Slovakia

OBJECTIVE

Our aim in the present study was to characterize and quantify the levels of polychlorinated biphenyls (PCBs) and specific polychlorobiphenylol (OH-PCB) metabolites in maternal sera from women delivering in eastern Slovakia.

DESIGN

During 2002-2004, blood samples were collected from women delivering in two Slovak locations: Michalovce district, where PCBs were formerly manufactured, and Svidnik and Stropkov districts, about 70 km north.

PARTICIPANTS

A total of 762 and 341 pregnant women were sampled from Michalovce and Svidnik/Stropkov, respectively, and OH-PCBs were measured in 131 and 31. EVALUATION/MEASUREMENTS: We analyzed PCBs using gas chromatography (GC)/electron capture detection. OH-PCBs and pentachlorophenol (PCP) were determined as methyl derivatives using GC-electron capture negative ionization/mass spectrometry. We characterized distributions in the full cohort using inverse sampling weights.

RESULTS

The concentrations of both PCBs and OH-PCB metabolites of Michalovce mothers were about two times higher than those of the Svidnik/Stropkov mothers (p < 0.001). The median weighted maternal serum levels of the sum of PCBs (sigmaPCBs) were 5.73 ng/g wet weight (Michalovce) and 2.82 ng/g wet weight (Svidnik/Stropkov). The median sum of OH-PCBs (ZOH-PCBs) was 0.55 ng/g wet weight in Michalovce mothers and 0.32 ng/g wet weight in Svidnik/Stropkov mothers. 4-OH-2,2',3,4',5,5',6-Heptachlorobiphenyl (4-OH-CB187) was a primary metabolite, followed by 4-OH-2,2',3,4',5,5'-hexachlorobiphenyl (4-OH-CB146). Only four PCB congeners-CBs 153, 138, 180, and 170--had higher concentrations than 4-OH-CB187 and 4-OH-CB146 (p < 0.001). The median ratio of the sigmaOH-PCBs to the sigmaPCBs was 0.10.

CONCLUSIONS

Mothers residing in eastern Slovakia are still highly exposed to PCBs, and their body burdens of these pollutants and OH-PCB metabolites may pose a risk for adverse effects on health for themselves and their children.

Assessment of dietary intake of polychlorinated biphenyls from a total diet study conducted in Pavia, Northern Italy

The diet is considered to be the main source of body burden of polychlorobiphenyls (PCBs) in the general population. The most cost-effective and reliable way to estimate the dietary intake is based on total diet studies (TDSs). The aim of the present study was to provide a reliable estimate of recent average dietary intakes of PCBs in Northern Italy. Congener-specific analysis of PCBs was undertaken on total diet samples collected at the cafeteria of the University of Pavia. The average daily intake for total PCBs was calculated to be 0.26 microg/person day-1. The major contributor to PCB intake was accounted for by pooled samples of bread, cereals and potatoes, followed by the protein composite, and fruit and vegetables. Although diverse dietary habits and differences in sampling and analytical procedures make comparison between different studies difficult, the daily intake of PCBs in Northern Italy can be located in the lower part of the range for values reported in the literature.

Estrogen-like activity of seafood related to environmental chemical contaminants

BACKGROUND

A wide variety of environmental pollutants occur in surface waters, including estuarine and marine waters. Many of these contaminants are recognised as endocrine disrupting chemicals (EDCs) which can adversely affect the male and female reproductive system by binding the estrogen receptor and exhibiting hormone-like activities. In this study the estrogenic activity of extracts of edible marine organisms for human consumption from the Mediterranean Sea was assayed.

METHODS

Marine organisms were collected in two different areas of the Mediterranean Sea. The estrogenic activity of tissues was assessed using an in vitro yeast reporter gene assay (S. cerevisiae RMY 326 ER-ERE). Concentrations of polychlorinated biphenyls (PCBs) (congeners 28, 52, 101, 118, 138, 153, 180) in fish tissue was also evaluated.

RESULTS

Thirty-eight percent of extracts showed a hormone-like activity higher than 10% of the activity elicited by 10 nM 17b-estradiol (E2) used as control. Total PCB concentrations ranged from 0.002 up to 1.785 ng/g wet weight. Chemical analyses detected different levels of contamination among the species collected in the two areas, with the ones collected in the Adriatic Sea showing concentrations significantly higher than those collected in the Tyrrhenian Sea (p < 0.01).

CONCLUSION

The more frequent combination of chemicals in the samples that showed higher estrogenic activity was PCB 28, PCB 101, PCB 153, PCB 180. The content of PCBs and estrogenic activity did not reveal any significant correlation.

Endocrine disruption induced by organochlorines (OCs): field studies and experimental models

Long-range transport of persistent organic compounds by air and ocean currents from industrialized areas resulted in high levels of these pollutants in food webs in the Svalbard area. With the aim to test if organochlorine (OC) exposure in free-living polar bears from Svalbard affected their plasma steroid hormone concentrations, it was found that polychlorinated biphenyls (PCBs) were associated with increased progesterone levels in females. The sum of pesticides (sigma pesticides) and sigma PCBs contributed significantly negative to the variation of the plasma testosterone in males, and the overall contribution of the OCs to the plasma cortisol variation was negative. A second objective was to study the effects of selected OCs (i.e., PCB 153 and PCB 126) on animal health as a consequence of effects on endocrine-regulated functions such as reproduction and immunity in a goat model focusing on long-term and low-level exposure during the periods of fetal development and in the neonatal period. Additionally, acute exposure was studied in adult mice. The results indicated that exposure to low doses of PCB 153 in utero and in the suckling period influenced reproductive functions and both PCB 153 and PCB 126 exerted immunomodulatory effects on the offspring, whereas acute exposure of adult mice had minor effects on male reproductive function.

Induction of CYP1A mRNA in Carp (Cyprinus carpio) from the Kalamazoo River polychlorinated biphenyl-contaminated superfund site and in a laboratory study

The Kalamazoo River Superfund site in Michigan is contaminated with polychlorinated biphenyls (PCBs), which were heavily discharged into the river from several paper companies as part of the deinking process in the 1950s through 1970s. We characterized biomarkers of chronic PCB exposure in a resident fish population using real-time reverse transcriptase-polymerase chain reaction to examine mRNA expression levels of multiple genes in carp (Cyprinus carpio) liver from PCB contaminated and reference sites in the Kalamazoo River. We also measured these same genes in juvenile carp exposed to dietary PCBs for 4 months. Kalamazoo River carp had significantly increased levels of cytochrome P450 1A (CYP1A) mRNA as did carp fed PCBs in the laboratory. No significant mRNA upregulation occurred in the specific oxidative stress genes (gamma-glutamylcysteine synthetase and magnesium superoxide dismutase) and metabolic genes (phosphoenolpyruvate carboxykinase and nucleolin) examined. These data are consistent with the idea that carp from the Kalamazoo River Superfund Site are responding to PCB exposure via upregulation of CYP1A independent of activation of the oxidative stress response genes normally thought to be co-regulated with CYP1A.

Time to pregnancy as a function of male and female serum concentrations of 2,2'4,4'5,5'-hexachlorobiphenyl (CB-153) and 1,1-dichloro-2,2-bis (p-chlorophenyl)-ethylene (p,p'-DDE)

BACKGROUND

Persistent organochlorine pollutants (POP) may affect both the female and male reproductive system in animals as well as in humans.

METHODS

Blood samples were collected from pregnant women and their partners from Greenland, Warsaw and Kharkiv, and from a cohort of Swedish fishermen's wives. Blood samples were analysed for 2,2',4,4',5,5'-hexachlorobiphenyl (CB-153) and 1,1-dichloro-2,2-bis (p-chlorophenyl)-ethylene (p,p'-DDE). Information on the participants' fertility, measured as time to pregnancy (TTP), was collected. In total, 778 men and 1505 women were included in the analyses.

RESULTS

The data from Warsaw, Kharkiv and the Swedish fishermen's wives indicated no effect of either male or female exposure to POP on TTP. However, among men and women from Greenland, there seemed to be an association between serum concentrations of CB-153 and p,p'-DDE and prolonged TTP. Due to the strong intra-individual correlation between CB-153 and p,p'-DDE in the Greenlandic population, it was not possible to determine whether the risk was associated with CB-153 or p, p'-DDE or was an interaction between the two compounds.

CONCLUSIONS

The overall results of the present study create a somewhat ambiguous pattern, but give some support to the idea that dietary POP exposure might be harmful for couple fertility.

Exposure to PCB and p, p′-DDE in European and Inuit populations: impact on human sperm chromatin integrity

BACKGROUND

Persistent organochlorine pollutants (POP), such as polychlorinated biphenyls (PCB) and dichlorodiphenyldichloroethylene (p, p'-DDE), are widely found in the environment and considered potential endocrine-disrupting compounds (EDC). Their impact on male fertility is still unknown.

METHODS

To explore the hypothesis that POP is associated with altered sperm chromatin integrity, a cross-sectional study involving 707 adult males (193 Inuits from Greenland, 178 Swedish fishermen, 141 men from Warsaw, Poland, and 195 men from Kharkiv, Ukraine) was carried out. Serum levels of 2,2',4,4',5,5'-hexachlorobiphenyl (CB-153), as a proxy of the total PCB burden, and of p,p'-DDE were determined. Sperm chromatin structure assay (SCSA) was used to assess sperm DNA/chromatin integrity.

RESULTS

We found a strong and monotonically increasing DNA fragmentation index with increasing serum levels of CB-153 among European but not Inuit men, reaching a 60% higher average level in the highest exposure group. No significant associations were found between SCSA-derived parameters and p, p'-DDE serum concentrations.

CONCLUSION

These results suggest that human dietary PCB exposure might have a negative impact on the sperm chromatin integrity of adult males but additional issues, including differences in the genetic background and lifestyle habits, still need to be elucidated.

The dioxin-like PCB 77 but not the ortho-substituted PCB 153 interferes with chicken embryo thyroid hormone homeostasis and delays hatching

The effects of the dioxin-like polychlorinated biphenyl (PCB) 77 and the ortho-substituted PCB 153 on thyroid hormone availability were investigated during the last week of embryonic development in chicken. High doses of these PCBs (1microg PCB 77 and 20microg PCB 153) were injected into chicken eggs at day 4 of incubation. Blood and tissue samples were collected from day 14 of incubation until 1 day after hatching. We did not observe influences of PCB 153 on thyroid hormone (TH) levels. Treatment with PCB 77, on the other hand, decreased plasma total T(4) concentrations but increased hepatic T(4) levels at day 14 of incubation. Later in development, at stages near the process of hatching, severe decreases of T(4) and T(3) levels were observed in the PCB 77 group, both in plasma and tissues. PCB 77 severely reduced the TH peak that normally coincides with the stage of internal pipping. This reduction was accompanied by a considerable delay in the moment of hatching. We conclude that the dioxin-like PCB 77, but not the ortho-substituted PCB 153, can decrease TH availability towards the end of embryonic development and hence disturb the process of hatching.

The impact of toxicology on public health policy and service: an update

The Division of Toxicology, Agency for Toxic Substances and Disease Registry (ATSDR) has a Congressional mandate to develop toxicological profiles for chemicals of greatest concern at hazardous waste sites. These chemical profiles provide a comprehensive evaluation and interpretation of the health effects, chemical and physical properties, production and use, potential for human exposure, analytical methodologies, and regulations and advisories for those chemicals. In addition, these profiles identify critical gaps in the knowledge base for these chemicals and identify levels of significant human exposure. Health assessors and other public health officials use this information to make critical decisions regarding the potential for adverse health effects at hazardous waste sites and other chemical-release events through such activities as public health assessments, chemical-specific and health-specific consultations, health-guidance-value derivations, database development, and emergency response actions. In a previous paper, we provided an overview of six specific public-health activities conducted by the ATSDR Division of Toxicology and examined how these activities have made unique impacts on public health policy and service. In this paper, we follow up on two of these, ATSDR polychlorinated biphenyls (PCBs) activities and ATSDR mercury activities, and examine their long-term, continually evolving impacts on public health policy and service.