In utero and childhood DDT, DDE, PBDE and PCBs exposure and sex hormones in adolescent boys: The CHAMACOS study

Safety evaluation of organochlorine pesticides and polybrominated diphenyl ethers in imported canned fish in Nigeria

Organochlorine pesticide (OCP) and polybrominated diphenyl ether (PBDE) concentrations were measured in thirty popular brands of imported canned fish (mackerel, sardines, and tuna) in Nigeria to ascertain potential threats to humans arising from their consumption. The Σ20 OCP concentrations in mackerel ranged from 0.47 to 7.36 ng g-1, while those of tuna and sardines varied from 1.06 to 2.19 and 0.11 to 12.7 ng g-1, respectively. The Σ39 PBDE concentrations in mackerel varied from 0.06 to 4.21 ng g-1, while those of tuna and sardines ranged from 0.19 to 3.18 and 0.04 to 8.26 ng g-1, respectively. The estimated daily intake (EDI) of OCPs and PBDEs from ingestion of the canned fish by adults and children were in the magnitude of 0.03 to 17.6 ng kg-1 bw day-1 and 9.9 × 10-3 to 11.5 ng kg-1 bw day-1 respectively. The hazard index (HI) and total cancer risk (TCR) values for OCPs and PBDEs from ingestion of the canned fish were less than 1 and 10-6, respectively. The dietary intakes of OCPs and PBDEs from these brands of canned fish by adults and children result in no adverse non-cancer and cancer risks.

Trends in low temperature and non-thermal technologies for the degradation of persistent organic pollutants

The daunting effects of persistent organic pollutants on humans, animals, and the environment cannot be overemphasized. Their fate, persistence, long-range transport, and bioavailability have made them an environmental stressor of concern which has attracted the interest of the research community. Concerted efforts have been made by relevant organizations utilizing legislative laws to ban their production and get rid of them completely for the sake of public health. However, they have remained refractive in different compartments of the environment. Their bioavailability is majorly a function of different anthropogenic activities. Landfilling and incineration are among the earliest classical means of environmental remediation of waste; however, they are not sustainable due to the seepage of contaminants in landfills, the release of toxic gases into the atmosphere and energy requirements during incineration. Other advanced waste destruction technologies have been explored for the degradation of these recalcitrant pollutants; although, some are efficient, but are limited by high amounts of energy consumption, the use of organic solvents and hazardous chemicals, high capital and operational cost, and lack of public trust. Thus, this study has systematically reviewed different contaminant degradation technologies, their efficiency, and feasibility. Finally, based on techno-economic feasibility, non-invasiveness, efficiency, and environmental friendliness; radiation technology can be considered a viable alternative for the environmental remediation of contaminants in all environmental matrices at bench-, pilot-, and industrial-scale.

Adverse outcome pathways of PBDEs inducing male reproductive toxicity

Polybrominated diphenyl ethers (PBDEs) are widely used brominated flame retardants, they are easily released into environment and causing adverse effects to the ecosystem and human health. This review aims to summarize the research status of PBDEs-induced male reproductive toxicity and its mechanisms at various levels such as molecular/cellular, tissue/organ and individual/population. The Adverse Outcome Pathways (AOPs) diagram showed that PBDEs-induced reactive oxygen species (ROS) production, disruptions of estrogen receptor-α (ERα) and antagonism of androgen receptor (AR) were defined as critical molecular initiating events (MIEs). They caused key events (KEs) at the molecular and cellular levels, including oxidative stress, increased DNA damage, damaging mitochondria, increased glycolipid levels and apoptosis, depletion of ectoplasmic specialization and decreased Leydig cells numbers. These in turn lead to followed KEs at the tissue or organ levels, such as the impaired spermatogenesis, impaired blood-testis barrier and reduced testosterone synthesis and function. As a result, reproductive system-related adverse outcomes (AOs) were reported, such as the decreased sperm quantity or quality, shorten male anogenital distance and cryptorchidism in individual and reduced reproduction of the population. This review assembled information on the mechanisms of male reproductive toxicity induced by PBDEs, and constructed a causal mechanism relationship diagram from different levels using the an AOP framework to provide theoretical basis for ecological risk assessment and environmental management of PBDEs. The AOP framework makes it possible to develop risk management strategies based on toxicity mechanisms and support for development of Integrated Approach to Testing and Assessment (IATA) which are available for regulatory purposes.

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

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

Association between exposure to persistent organic pollutants and pubertal timing in boys and girls: A systematic review and meta-analysis

In recent years, the phenomenon of abnormal pubertal timing in children has become increasingly common worldwide. Persistent organic pollutants (POPs) may be one of the risk factors contributing to this phenomenon, but the relationship between them is unclear based on current evidence. The purpose of this study was to determine the association of POPs exposure with pubertal timing in girls and boys by conducting a systematic review and meta-analysis. We searched PubMed and Embase databases for studies before June 1, 2023. Meta-analysis was performed by pooling relative risk (RR) or odds ratio (OR) or prevalence ratio (PR) or hazard ratio (HR) estimates with 95 % confidence intervals (CIs). Subgroup analysis, publication bias assessment and sensitivity analysis were also carried out. A total of 21 studies were included, involving 2479 boys and 8718 girls. The results of meta-analysis showed that exposure to POPs was significantly associated with delayed pubertal timing in girls (RR: 0.85; 95 % CI: 0.79-0.91; p < 0.001). There was no statistically significant association between exposure to POPs and pubertal timing in boys (RR: 1.18; 95 % CI: 0.99-1.40; p = 0.070). Subgroup analysis showed that there may be gender differences in the effects of exposure to POPs on pubertal timing. Our results suggested that exposure to POPs could delay pubertal timing in girls. However, based on current evidence, no significant association was found between POPs exposure and pubertal timing in boys.

Polybrominated Diphenyl Ethers (PBDEs) and Human Health: Effects on Metabolism, Diabetes and Cancer

There is increasing evidence of the role of endocrine disruptors (EDs) derived from commonly employed compounds for manufacturing and processing in altering hormonal signaling and function. Due to their prolonged half-life and persistence, EDs can usually be found not only in industrial products but also in households and in the environment, creating the premises for long-lasting exposure. Polybrominated diphenyl ethers (PBDEs) are common EDs used in industrial products such as flame retardants, and recent studies are increasingly showing that they may interfere with both metabolic and oncogenic pathways. In this article, a multidisciplinary panel of experts of the Italian Association of Medical Diabetologists (AMD), the Italian Society of Diabetology (SID), the Italian Association of Medical Oncology (AIOM), the Italian Society of Endocrinology (SIE) and the Italian Society of Pharmacology (SIF) provides a review on the potential role of PBDEs in human health and disease, exploring both molecular and clinical aspects and focusing on metabolic and oncogenic pathways.

Associations of phthalates, phthalate replacements, and their mixtures with eicosanoid biomarkers during pregnancy

Humans are exposed to complex mixtures of phthalates. Gestational exposure to phthalates has been linked to preeclampsia and preterm birth through potential pathways such as endocrine disruption, oxidative stress, and inflammation. Eicosanoids are bioactive signaling lipids that are related to a variety of homeostatic and inflammatory processes. We investigated associations between urinary phthalates and their mixtures with plasma eicosanoid levels during pregnancy using the PROTECT cohort in Puerto Rico (N = 655). After adjusting for covariates, we estimated pair-wise associations between the geometric mean of individual phthalate metabolite concentrations across pregnancy and eicosanoid biomarkers using multivariable linear regression. We used bootstrapping of adaptive elastic net regression (adENET) to evaluate phthalate mixtures associated with eicosanoids and subsequently create environmental risk scores (ERS) to represent weighted sums of phthalate exposure for each individual. After adjusting for false-discovery, in single-pollutant analysis, 14 of 20 phthalate metabolites or parent compound indices showed significant and primarily negative associations with multiple eicosanoids. In our mixture analysis, associations with several metabolites of low molecular weight phthalates - DEP, DBP, and DIBP - became prominent. Additionally, MEHHTP and MECPTP, metabolites of a new phthalate replacement, DEHTP, were selected as important predictors for determining the concentrations of multiple eicosanoids from different pathway groups. A unit increase in phthalate ERS derived from bootstrapping of adENET was positively associated with several eicosanoids mainly from Cytochrome P450 pathway. For example, an increase in ERS was associated with 11(S)-HETE (β = 1.6, 95% CI: 0.020, 3.180), (±)11,12-DHET (β = 2.045, 95% CI: 0.250, 3.840), 20(S)-HETE (β = 0.813, 95% CI: 0.147, 1.479), and 9 s-HODE (β = 2.381, 95% CI: 0.657, 4.104). Gestational exposure to phthalates and phthalate mixtures were associated with eicosanoid levels during pregnancy. Results from the mixture analyses underscore the complexity of physiological impacts of phthalate exposure and call for further in-depth studies to examine these relationships.

BDE-209 induced spermatogenesis disorder by inhibiting SETD8/H4K20me1 related histone methylation in mice

Past studies have observed that decabromodiphenyl ether (BDE-209) induces reproductive and developmental toxicity, but the specific mechanism remains unclear. Based on our previous work, male mice were orally given BDE-209 at 75 mg/kg/d via continuous exposure for one spermatozoon development period (50 days) and then stopping exposure for another 50 days. The mouse spermatocyte line GC-2spd was used to examine the toxic effects of BDE-209 on histone methylation and spermatogenesis. The findings indicated that BDE-209 damaged testis and epididymis structure, induced spermatogenic cell apoptosis, and decreased sperm quantity and quality after the 50-day exposure. Furthermore, BDE-209 lowered the levels of SETD8/H4K20me1 and activated the upstream signaling of DNA damage response (Mre11/Rad50/NBS1), thereby causing spermatogenic cell cycle arrest and apoptosis. Downregulation of meiotic promoter Stra8 was associated with a decrease in SETD8 after BDE-209 exposure. After stopping the exposure for 50 days, reproductive system damage and meiosis and cell cycle inhibition due to histone methylation did not improve. In vitro experiments revealed that Setd8 overexpression upregulated the histone methylation and Stra8 expression but did not promote the cell cycle in GC-2 cells. Therefore, BDE-209 exposure impaired spermatogenesis by affecting SETD8/H4K20me1-linked histone methylation and inhibiting meiosis initiation and cell cycle progression, thereby resulting in long-term male reproductive toxicity.

Adipose tissue levels of polybrominated diphenyl ethers in relation to prognostic biomarkers and progression-free survival time of breast cancer patients in eastern area of southern China: A hospital-based study

Evidence indicates that individual or groups of polybrominated diphenyl ethers (PBDEs) are associated with risk of breast cancer (BC). Epidemiological studies of PBDEs and BC progression are scarce. This study aimed to investigate the relationships between PBDE burdens in adipose tissues and prognostic biomarkers of BC as well as progression-free survival (PFS) of patients for the first time. The concentrations of 14 PBDE congeners in breast adipose tissues of 183 cases from the eastern area of southern China were analyzed by gas chromatography-mass spectrometry (GC-MS). Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated by logistic regression models for the associations between PBDE levels and prognostic biomarkers. Kaplan-Meier and Cox regression analyses were conducted to identify the correlations between PBDEs and PFS. The results showed that BDE-99 and 190 levels were positively associated with clinical stage and N stage respectively (OR = 2.61 [1.26-5.40], OR = 2.78 [1.04-7.46]). Concentrations of BDE-28 and BDE-183 were negatively associated with the expression of estrogen receptor (ER) (OR = 0.30 [0.11-0.81]; 0.39 [0.15-0.99]) and progesterone receptor (PR) (OR = 0.36 [0.14-0.92]; 0.37 [0.15-0.91]), and increased BDE-47 was associated with lower human epidermal growth factor receptor 2 (HER2) expression (OR = 0.44 [0.23-0.86]). Adipose levels of BDE-71, 99, 138, 153, 154 and total PBDEs were positively associated with p53 expression (all P < 0.05). Finally, BDE-47, 99 and 183 were considered as independent prognostic factors for shorter PFS in the Cox models (adjusted hazard ratios = 3.14 [1.26-7.82]; 2.25 [1.03-4.94]; 2.60 [1.08-6.25], respectively). The recurrence risk and prognosis of BC may be closely bound to the body burdens of certain PBDE congeners. Further epidemiological and experimental studies are needed for confirmation.

The effect of endocrine-disrupting chemicals on placental development

Endocrine-disrupting chemicals (EDCs) or endocrine disruptors are substances that are either naturally occurring or artificial and are released into the natural environment. Humans are exposed to EDCs through ingestion, inhalation, and skin contact. Many everyday household items, such as plastic bottles and containers, the liners of metal food cans, detergents, flame retardants, food, gadgets, cosmetics, and pesticides, contain endocrine disruptors. Each hormone has a unique chemical makeup and structural attributes. The way that endocrine hormones connect to receptors is described as a "lock and key" mechanism, with each hormone serving as the key (lock). This mechanism is enabled by the complementary shape of receptors to their hormone, which allows the hormone to activate the receptors. EDCs are described as exogenous chemicals or compounds that have a negative impact on organisms' health by interacting with the functioning of the endocrine system. EDCs are associated with cancer, cardiovascular risk, behavioural disorders, autoimmune abnormalities, and reproductive disorders. EDCs exposure in humans is highly harmful during critical life stages. Nonetheless, the effect of EDCs on the placenta is often underestimated. The placenta is especially sensitive to EDCs due to its abundance of hormone receptors. In this review, we evaluated the most recent data on the effects of EDCs on placental development and function, including heavy metals, plasticizers, pesticides, flame retardants, UV filters and preservatives. The EDCs under evaluation have evidence from human biomonitoring and are found in nature. Additionally, this study indicates important knowledge gaps that will direct future research on the topic.

Gene×environment interactions in autism spectrum disorders

There is credible evidence that environmental factors influence individual risk and/or severity of autism spectrum disorders (hereafter referred to as autism). While it is likely that environmental chemicals contribute to the etiology of autism via multiple mechanisms, identifying specific environmental factors that confer risk for autism and understanding how they contribute to the etiology of autism has been challenging, in part because the influence of environmental chemicals likely varies depending on the genetic substrate of the exposed individual. Current research efforts are focused on elucidating the mechanisms by which environmental chemicals interact with autism genetic susceptibilities to adversely impact neurodevelopment. The goal is to not only generate insights regarding the pathophysiology of autism, but also inform the development of screening platforms to identify specific environmental factors and gene×environment (G×E) interactions that modify autism risk. Data from such studies are needed to support development of intervention strategies for mitigating the burden of this neurodevelopmental condition on individuals, their families and society. In this review, we discuss environmental chemicals identified as putative autism risk factors and proposed mechanisms by which G×E interactions influence autism risk and/or severity using polychlorinated biphenyls (PCBs) as an example.

Persistent Organic Pollutant Exposure and Thyroid Function among 12-Year-Old Children

INTRODUCTION

Polychlorobiphenyls (PCBs), organochlorine pesticides (OCPs), and per- and polyfluoroalkyl substances (PFASs) are persistent organic pollutants (POPs) having numerous toxicological properties, including thyroid endocrine disruption. Our aim was to assess the impact of POPs on thyroid hormones among 12-year-old children, while taking puberty into consideration.

METHODS

Exposure to 7 PCBs, 4 OCPs, and 6 PFASs (in µg/L), and free tri-iodothyronine (fT3, pg/mL), free thyroxine (fT4, ng/dL), and thyroid-stimulating hormones (TSH, mIU/L) were assessed through blood-serum measurements at age 12 years in 249 boys and 227 girls of the PELAGIE mother-child cohort (France). Pubertal status was clinically rated using the Tanner stages. For each POP, associations were estimated using linear regression, adjusted for potential confounders.

RESULTS

Among boys, hexachlorobenzene and perfluorodecanoic acid were associated with decreased fT3 (log-scale; β [95% confidence interval] = -0.07 [-0.12,-0.02] and β = -0.03 [-0.06,-0.00], respectively). Intermediate levels of perfluorohexanesulfonic acid (PFHxS) and PCB180 were associated, respectively, with increased and decreased fT4. After stratification on pubertal status, PCBs and OCPs were associated with decreased TSH only in the more advanced Tanner stages (3-5) and with decreased fT3 among early Tanner stages (1-2). Among girls, PFHxS was associated with decreased TSH (log-scale; β = -0.15 [-0.29,-0.00]), and perfluorooctanoic acid was associated with decreased fT3 (β2nd_tercile = -0.06 [-0.10,-0.03] and β3rd_tercile = -0.04 [-0.08,-0.00], versus. 1st tercile).

DISCUSSION

This cross-sectional study highlights associations between some POPs and thyroid function disruption, which appears consistent with the literature. Considering that the associations were sex-specific and moderated by pubertal status in boys, complex endocrine interactions are likely involved.

Mechanisms of Male Reproductive Toxicity of Polybrominated Diphenyl Ethers

Polybrominated diphenyl ethers (PBDE) are a group of flame retardants used in a variety of artificial materials. Despite being phased out in most industrial countries, they remain in the environment and human tissues due to their persistence, lipophilicity, and bioaccumulation. Populational and experimental studies demonstrate the male reproductive toxicity of PBDEs including increased incidence of genital malformations (hypospadias and cryptorchidism), altered weight of testes and other reproductive tissues, altered testes histology and transcriptome, decreased sperm production and sperm quality, altered epigenetic regulation of developmental genes in spermatozoa, and altered secretion of reproductive hormones. A broad range of mechanistic hypotheses of PBDE reproductive toxicity has been suggested. Among these hypotheses, oxidative stress, the disruption of estrogenic signaling, and mitochondria disruption are affected by PBDE concentrations much higher than concentrations found in human tissues, making them unlikely links between exposures and adverse reproductive outcomes in the general population. Robust evidence suggests that at environmentally relevant doses, PBDEs and their metabolites may affect male reproductive health via mechanisms including AR antagonism and the disruption of a complex network of metabolic signaling.

Mechanochemical debromination of waste printed circuit boards with marble sludge in a planetary ball milling process

An effective management of waste printed circuit board (WCB) recycling presents significant advantages of an economic, social, and environmental nature. This is particularly the case when a suitable valorisation is made of the non-metallic parts of the WCBs, well known for their "hidden" toxicological risks. Such benefits motivate research on techniques that could contribute to mitigating their adverse socio-environmental impacts. In this work, waste printed circuit boards (WCBs) containing tetrabromobisphenol A (TBBPA) as a brominated flame retardant (BFR) underwent debromination using a mechanochemical treatment (MCT) and marble sludge, another recoverable waste, as well as pure CaO as additives. All runs in this work were performed at an intermediate rotation speed of 450 rpm, using additive/WCB mass ratios (R_m) of 4:1 and 8:1, ball to powder ratios (BPR) of 20:1 and 50:1, treatment times from 2.5 h to 10 h, two WCB sizes (powder and 0.84 mm) and marble sludge, from original to precalcined conditioning. Stainless steel jars and balls were used to verify the effect of each parameter on the system and to seek an optimum process. Complete debromination of 0.84 mm WCBs was achieved at 450 rpm, using a R_m of 8:1, a BPR of 50:1, a residence time of 10 h (more than 95% in only 5 h), and a precalcined marble sludge as additive. The results revealed that when using a R_m of 4:1 instead of 8:1, more waste could be effectively treated, per batch with a lesser need for additives, at the expense of a slightly lower level of debromination efficiency. In the same way, an appropriate apparent ball diameter (with respect to the volume of the used jar) should be carefully studied in relation to WCB size in order to achieve a beneficial total amount of energy transfer during milling.

Risk factors on testicular function in adolescents

PURPOSE

Adolescence represents an important window for gonadal development. The aim of this review is to carry out a critical excursus of the most recent literature on endogenous and exogenous risk factors related to testicular function, focusing the research on adolescence period.

METHODS

A comprehensive literature search within PubMed was performed to provide a summary of currently available evidence regarding the impact on adolescence of varicocele, cryptorchidism, cancer, diabetes, lifestyle factors, endocrine disruptors, obesity and sexually transmitted diseases. We focused on human studies that evaluated a possible impact of these factors on puberty timing and their effects on andrological health.

RESULTS

Evidence collected seems to suggest that andrological health in adolescence may be impaired by several factors, as varicocele, cryptorchidism, and childhood cancer. Despite an early diagnosis and treatment, many adolescents might still have symptoms and sign of a testicular dysfunction in their adult life and at the current time it is not possible to predict which of them will experience andrological problems. Lifestyle factors might have a role in these discrepancies. Most studies point out towards a correlation between obesity, insulin resistance, alcohol, smoking, use of illegal drugs and testicular function in pubertal boys. Also, endocrine disruptors and sexually transmitted diseases might contribute to impair reproductive health, but more studies in adolescents are needed.

CONCLUSION

According to currently available evidence, there is an emerging global adverse trend of high-risk and unhealthy behaviors in male adolescents. A significant proportion of young men with unsuspected and undiagnosed andrological disorders engage in behaviors that could impair testicular development and function, with an increased risk for later male infertility and/or hypogonadism during the adult life. Therefore, adolescence should be considered a key time for intervention and prevention of later andrological diseases.

Elevated exposures to persistent endocrine disrupting compounds impact the sperm methylome in regions associated with autism spectrum disorder

Environmental exposures to endocrine disrupting compounds (EDCs) such as the organochlorines have been linked with various diseases including neurodevelopmental disorders. Autism spectrum disorder (ASD) is a highly complex neurodevelopmental disorder that is considered strongly genetic in origin due to its high heritability. However, the rapidly rising prevalence of ASD suggests that environmental factors may also influence risk for ASD. In the present study, whole genome bisulfite sequencing was used to identify genome-wide differentially methylated regions (DMRs) in a total of 52 sperm samples from a cohort of men from the Faroe Islands (Denmark) who were equally divided into high and low exposure groups based on their serum levels of the long-lived organochlorine 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE), a primary breakdown product of the now banned insecticide dichlorodiphenyltrichloroethane (DDT). Aside from being considered a genetic isolate, inhabitants of the Faroe Islands have a native diet that potentially exposes them to a wide range of seafood neurotoxicants in the form of persistent organic pollutants (POPs). The DMRs were mapped to the human genome using Bismark, a 3-letter aligner used for methyl-seq analyses. Gene ontology, functional, and pathway analyses of the DMR-associated genes showed significant enrichment for genes involved in neurological functions and neurodevelopmental processes frequently impacted by ASD. Notably, these genes also significantly overlap with autism risk genes as well as those previously identified in sperm from fathers of children with ASD in comparison to that of fathers of neurotypical children. These results collectively suggest a possible mechanism involving altered methylation of a significant number of neurologically relevant ASD risk genes for introducing epigenetic changes associated with environmental exposures into the sperm methylome. Such changes may provide the potential for transgenerational inheritance of ASD as well as other disorders.

Prenatal Environmental Exposure to Persistent Organic Pollutants and Reproductive Hormone Profile and Pubertal Development in Dutch Adolescents

Persistent organic pollutants (POPs), such as polychlorinated biphenyls (PCBs), may interfere with hormonal processes. Knowledge about the effects of prenatal exposure to PCBs and their hydroxylated metabolites (OH-PCBs) on pubertal development is limited. Therefore, the aim of the current study was to determine whether prenatal environmental PCB and OH-PCB exposure are associated with reproductive hormone levels and pubertal characteristics in 13- to 15-year-old children. In this Dutch observational cohort study, 194 mother–infant pairs were included (1998–2002). Maternal pregnancy serum levels of PCBs, OH-PCBs, and other POPs were measured. At follow-up (2014–2016), we measured serum or plasma levels of reproductive hormones in their children. We assessed Tanner stages and testicular volume (by clinician or standardized self-assessment), and participants completed questionnaires on pubertal onset. In total, 101 adolescents (14.4 ± 0.8 years; 53.7% of invited) participated, and 55 were boys. In boys, higher prenatal PCB levels were associated with higher testosterone levels, higher pubic hair stage, larger testicular volume, and younger age at onset of growth spurt and voice break. In girls, higher prenatal PCB levels were associated with higher stages for breast development. In conclusion, higher prenatal PCB exposure could be associated with more advanced pubertal development in 13- to 15-year-old children.

Effects of Polybrominated Diphenyl Ethers on Hormonal and Reproductive Health in E-Waste-Exposed Population: A Systematic Review

Electronic waste management is a global rising concern that is primarily being handled by informal recycling practices. These release a mix of potentially hazardous chemicals, which is an important public health concern. These chemicals include polybrominated diphenyl ethers (PBDEs), used as flame retardants in electronic parts, which are persistent in nature and show bioaccumulative characteristics. Although PBDEs are suspected endocrine disruptors, particularly targeting thyroid and reproductive hormone functions, the relationship of PBDEs with these health effects are not well established. We used the Navigation Guide methodology to conduct a systematic review of studies in populations exposed to e-waste to better understand the relationships of these persistent flame retardants with hormonal and reproductive health. We assessed nineteen studies that fit our pre-determined inclusion criteria for risk of bias, indirectness, inconsistency, imprecision, and other criteria that helped rate the overall evidence for its quality and strength of evidence. The studies suggest PBDEs may have an adverse effect on thyroid hormones, reproductive hormones, semen quality, and neonatal health. However, more research is required to establish a relationship of these effects in the e-waste-exposed population. We identified the limitations of the data available and made recommendations for future scientific work.

Associations between polybrominated diphenyl ethers (PBDEs) levels in adipose tissues and female menstrual cycle and menstrual bleeding duration in Shantou, China

The endocrine-disrupting effects of human exposure to polybrominated diphenyl ethers (PBDEs) have been studied, but their associations with menstrual status were not clearly clarified. This study was to evaluate the associations between PBDE levels in adipose tissues and the menstrual cycle and menstrual bleeding duration alteration. A total of 298 female cases undergoing surgery were recruited from two hospitals in Shantou, China. Demographic, clinical, and pathological information were collected, and adipose tissues were obtained during mammary or abdominal surgery. Gas chromatography with mass spectrometry was used to analyze 14 PBDE congeners in the adipose samples. The associations between PBDE levels and menstrual cycle (MC) and menstrual duration (MD) were analyzed by logistic regression models, estimating odds ratios (ORs) and 95% confidence intervals (CIs). BDE-153 had the highest level in the adipose samples, followed by BDE-209, BDE-183 and BDE-47. Compared with referents, median levels of BDE-47, -71, -153, -183 were higher in women with MC > 30 days (all P < 0.05); BDE-47, -153, -183, -209 were also higher in women with MD > 5.5 days (all P < 0.05). After adjusted for age and parity, BDE-47, -71, -153, -183 were associated with prolonged MC (OR = 1.20, 1.15, 1.12, 1.11, respectively, all P < 0.05) in the logistic regression models; and BDE-47, -153, -183, -209 were associated with the prolonged MD (OR = 1.13, 1.09, 1.10, 1.11, respectively, all P < 0.05). Several individual PBDE congeners in female adipose were found associated with prolonged menstrual cycle and menstrual duration. PBDEs may influence reproductive health of women by altering menstrual status.

Persistent organic pollutants: The trade-off between potential risks and sustainable remediation methods

Persistent Organic Pollutants (POPs) have become a very serious issue for the environment because of their toxicity, resistance to conventional degradation mechanisms, and capacity to bioconcentrate, bioaccumulate and biomagnify. In this review article, the safety, regulatory, and remediation aspects of POPs including aromatic, chlorinated, pesticides, brominated, and fluorinated compounds, are discussed. Industrial and agricultural activities are identified as the main sources of these harmful chemicals, which are released to air, soil and water, impacting on social and economic development of society at a global scale. The main types of POPs are presented, illustrating their effects on wildlife and human beings, as well as the ways in which they contaminate the food chain. Some of the most promising and innovative technologies developed for the removal of POPs from water are discussed, contrasting their advantages and disadvantages with those of more conventional treatment processes. The promising methods presented in this work include bioremediation, advanced oxidation, ionizing radiation, and nanotechnology. Finally, some alternatives to define more efficient approaches to overcome the impacts that POPs cause in the hydric sources are pointed out. These alternatives include the formulation of policies, regulations and custom-made legislation for controlling the use of these pollutants.

Sex specific associations between in utero exposure to persistent organic pollutants and allergy-related outcomes in childhood: The Rhea Mother-Child Cohort (Crete, Greece)

Accumulating evidence suggests that in utero exposures can influence the development of the immune system. Few studies have investigated whether prenatal exposure to persistent organic pollutants (POPs) is associated with allergy-related phenotypes in childhood, nor explored sex differences. We examined the association between prenatal exposure to POPs and offspring allergic outcomes in early and mid-childhood. We included 682 mother-child pairs from the prospective birth cohort Rhea. We measured dichlorodiphenyldichloroethylene (DDE), hexachlorobenzene (HCB) and 6 polychlorinated biphenyl (PCB) congeners in maternal first trimester serum. Parents completed the questionnaires adapted from the International Study on Asthma and Allergy in Childhood (ISAAC) for allergy-related phenotypes when their children were 4 and 6 years old. We used Poisson regression models to estimate Risk Ratios. Prenatal HCB was associated with increased risk for rhinoconjunctivitis at 6 years (RR (95% CI): 2.5; (1.3, 4.8) for a doubling in the exposure). Among girls, prenatal DDE was associated with increased risk for current wheeze, current asthma and current rhinoconjunctivitis at 4 years (RR (95%CI): 1.4 (0.8, 2.6), 1.6 (1.1, 2.4) and 1.8 (1.0, 3.3) and p-interaction = 0.035, 0.027 and 0.059, respectively), with increased risk for current rhinoconjunctivitis at 6 years (RR (95%CI): 1.7 (0.7, 3.8) and p-interaction = 0.028) and total PCBs were associated with increased risk for current eczema at 4 years (RR (95%CI): 2.1 (1.1, 4.2) and p-interaction = 0.028). In boys, prenatal DDE was associated with decreased risk for current wheeze and current asthma at 4 years. Our findings suggest that even low levels of exposure to POPs prenatally may affect the development of childhood allergy-related outcomes in a sex and age-specific manner.

Biological clock and heredity in pubertal timing: what is new?

Puberty represents a milestone during a person's life and is characterized by several physical and psychological changes which end with the achievement of sexual maturation and of fertility. Puberty onset depends on a series of sophisticated, not completely understood, mechanisms certainly involving Gonadotropin-Releasing Hormone (GnRH) and its effects on pituitary gonadotropins. As recent evidence has demonstrated that pubertal timing deeply affects future adult health life, much efforts have been performed in order to clarify the exact actors involved in the onset and progression of puberty. Genetic factors are undoubtedly essential players in the regulation of pubertal development, accounting for approximately 50-80% of its variability. Mutations in genes such as KISS1, MKRN3 and DLK1 have been associated with central precocious puberty. Interestingly, a possible involvement of epigenetic mechanisms has been proposed as additional element able to affect pubertal phase. Environmental factors have recently attracted much attention. Indeed, an overall decrease in the age of puberty has been observed in the last decades. As genetic factors require long time to exert their effect, other players, such as environmental ones, may be involved. Special focus has been posed on nutritional status, endocrine-disrupting chemicals with non-conclusive results. Pubertal timing deeply affects future life, suggesting the need to clarify mechanisms driving pubertal onset and progression, in order to identify tailored therapeutic strategies and targets.

Peripubertal serum levels of dioxins, furans and PCBs in a cohort of Russian boys: can empirical grouping methods yield meaningful exposure variables?

BACKGROUND

Dioxins, furans and polychlorinated biphenyls (PCBs) are endocrine disruptors with half-lives of months to years in humans. Peripubertal exposure to these chemicals may disrupt pubertal timing. Biomarker exposure metrics like the sum of non-dioxin-like PCBs in serum (∑NDL-PCBs) involve chemicals with different hypothetical effects. Empirical exposure metrics represent an alternative that requires no knowledge of biological mechanisms.

METHODS

From 2003 to 2005, 516 Russian boys aged 8-9 residing near a plant that historically produced organochlorine pesticides were enrolled in the Russian Children's Study. At enrollment, blood was collected for measurement of organochlorine chemicals by the Centers for Disease Control and Prevention (CDC). Variable cluster analysis was used to empirically group serum levels of 45 dioxins, furans and PCBs into eight cluster scores. These scores were compared to the sum of dioxin-like toxic equivalents (∑TEQs) and ∑NDL-PCBs using Spearman correlation coefficients.

RESULTS

Clustering appeared to reflect number and position of chlorine atoms. Clusters 4, 7 and 1 contained, respectively, tri/tetra-, tetra/penta-, and hexa/hepta-chlorinated PCBs with chlorines at the 4,4' positions. Clusters 2, 8 and 5 contained, respectively, tetra-to hexa-, hexa/hepta-, and hepta/octa-chlorinated PCBs with chlorines at the 2,2' positions. ∑NDL-PCBs were highly correlated with 4,4'-chlorinated clusters 1 and 7 (Spearman's ρ = 0.8) and less so with all other clusters (Spearman's ρ = 0.4-0.5).

CONCLUSIONS

In this cohort of Russian boys, baseline serum dioxins, furans and PCBs seemed to cluster by chlorination pattern, possibly reflecting shared persistence, metabolism or source of exposure. The widely used measure ∑NDL-PCB seemed most representative of 4,4'-chlorinated PCBs.

Reproductive Health Risks Associated with Occupational and Environmental Exposure to Pesticides

A marked reduction in fertility and an increase in adverse reproductive outcomes during the last few decades have been associated with occupational and environmental chemical exposures. Exposure to different types of pesticides may increase the risks of chronic diseases, such as diabetes, cancer, and neurodegenerative disease, but also of reduced fertility and birth defects. Both occupational and environmental exposures to pesticides are important, as many are endocrine disruptors, which means that even very low-dose exposure levels may have measurable biological effects. The aim of this review was to summarize the knowledge collected between 2000 and 2020, to highlight new findings, and to further interpret the mechanisms that may associate pesticides with infertility, abnormal sexual maturation, and pregnancy complications associated with occupational, environmental and transplacental exposures. A summary of current pesticide production and usage legislation is also included in order to elucidate the potential impact on exposure profile differences between countries, which may inform prevention measures. Recommendations for the medical surveillance of occupationally exposed populations, which should be facilitated by the biomonitoring of reduced fertility, is also discussed.

In vitro effects of the endocrine disruptor p,p'DDT on human choriogonadotropin/luteinizing hormone receptor signalling

Dichlorodiphenyltrichloroethane (p,p'DDT) is an endocrine-disrupting chemical (EDC). Several studies showed an association between p,p'DDT exposure and reprotoxic effects. We showed that p,p'DDT was a positive allosteric modulator of human follitropin receptor (FSHR). In contrast, we demonstrated that p,p'DDT decreased the cyclic AMP (cAMP) production induced by human choriogonadotropin (hCG). This study evaluated further the effects of p,p'DDT on Gs-, β-arrestin 2- and steroidogenesis pathways induced by hCG or luteinizing hormone (LH). We used Chinese hamster ovary cells line stably expressing hCG/LHR. The effects of 10-100 µM p,p'DDT on cAMP production and on β-arrestin 2 recruitment were measured using bioluminescence and time-resolved resonance energy transfer technology. The impact of 100 µM of p,p'DDT on steroid secretion was analysed in murine Leydig tumor cell line (mLTC-1). In cAMP assays, 100 µM p,p'DDT increased the EC₅₀ by more than 300% and reduced the maximum response of the hCG/LHR to hCG and hLH by 30%. This inhibitory effect was also found in human granulosa cells line and in mLTC-1 cells. Likewise, 100 µM p,p'DDT decreased the hCG- and hLH-promoted β-arrestin 2 recruitment down to 14.2 and 26.6%, respectively. Moreover, 100 µM p,p'DDT decreased by 30 and 47% the progesterone secretion induced by hCG or hLH, respectively, without affecting testosterone secretion. This negative effect of p,p'DDT was independent of cytotoxicity. p,p'DDT acted as a negative allosteric modulator of the hCG/LHR signalling. This emphasizes the importance of analyzing all receptor-downstream pathways to fully understand the deleterious effects of EDC on human health.

Low dose of fire retardant, 2,2',4,4'-tetrabromodiphenyl ether (BDE47), stimulates the proliferation and differentiation of progenitor Leydig cells of male rats during prepuberty

2,2',4,4'-Tetrabromodiphenyl ether (BDE47), a flame retardant, is extensively distributed in the food chain. However, whether BDE47 affects Leydig cell development during prepuberty remains unclear. BDE47 was daily gavaged to 21-day-old Sprague-Dawley male rats with 0 (corn oil), 0.1, 0.2, and 0.4 mg/kg for 14 days. BDE47 did not affect the body weight or testis weight of rats. It significantly increased serum testosterone level at 0.4 mg/kg, but decreased luteinizing hormone (LH) level without affecting estradiol level. BDE47 induced Leydig cell hyperplasia (the number of CYP11A1-positive Leydig cells increased), and up-regulated the expression of Scarb1, Star, Hsd11b1, Pcna, and Ccnd1 in the testis. BDE47 significantly reduced p53 and p21 levels but increased CCND1 level. It also markedly increased the phosphorylation of AKT1, AKT2, ERK1/2, and CREB. BDE47 significantly up-regulated the expression of Scarb1, Star, and Hsd11b1 and stimulated androgen production by immature Leydig cells from rats under basal, LH, and 8Br-cAMP stimulated conditions at 100 nM in vitro. In conclusion, BDE47 increased Leydig cell number and up-regulated the expression of Scarb1 and Star, thereby leading to increased testosterone synthesis.

Effects of Environmental Endocrine-Disrupting Chemicals on Female Reproductive Health

Environmental endocrine-disrupting chemicals (EDCs) are xenobiotic compounds that are frequently contacted in daily life. With the species and quantity of substances created and utilized by human beings significantly surpassing the self-purification capacity of nature, a large number of hazardous substances are enriched in the human body through the respiratory tract, digestive tract, and skin. Some of these compounds cause many problems endangering female reproductive health by simulating/antagonizing endogenous hormones or affecting the synthesis, metabolism, and bioavailability of endogenous hormones, including reproductive disorders, fetal birth defects, fetal developmental abnormalities, endocrine and metabolic disorders, and even gynecological malignancies. Therefore, the study of the relationship between environmental EDCs and female reproductive diseases and related mechanisms is of considerable significance to women, children health care, and improve the quality of the population.

Effects of prenatal exposure to polybrominated diphenyl ethers (PBDEs) on the second to fourth digit ratio in children aged 4 years

BACKGROUND

The second to fourth digit ratio (2D:4D) is assumed to be a biomarker of prenatal sex steroid exposure, correlating negatively with prenatal testosterone and positively with prenatal estrogen. The ratio has been suggested to be influenced by endocrine disrupting chemicals (EDCs). However, evidence regarding effects of prenatal exposure to polybrominated diphenyl ethers (PBDEs) on 2D:4D of children was sparse.

OBJECTIVES

We investigated the associations between prenatal exposure to PBDEs and 2D:4D of children aged 4 years.

METHODS

Participants were mother-child pairs from the Shanghai-Minhang Birth Cohort Study (S-MBCS) which enrolled pregnant women at 12-16 weeks of gestation from April to December 2012. Nine PBDE congeners in venous umbilical cord plasma of 340 children were measured. Digit lengths were measured using a vernier caliper in children aged 4 years and 2D:4D for left and right hands and average 2D:4D value of both hands were calculated. A total of 281 children (160 boys and 121 girls) who had data on both 2D:4D and PBDE concentrations were included in the final analysis. Associations between prenatal PBDE exposures and 2D:4D were investigated using multiple linear regression models.

RESULTS

Among the nine congeners, BDE-47 had the highest detection rate of 86.12% with the highest median concentration of 0.20 ng/ml lipid. Five PBDE congeners with detection rates greater than or close to 50% (BDE-28, -47, -99, -100 and -153) and Σ₅PBDEs (the sum of them) were included in final analysis. For girls, a consistent pattern for the positive associations between prenatal PBDE exposures and 2D:4D of children was observed mainly for the left hand, where those in the highest exposure groups had higher 2D:4D compared to the lowest exposure groups (a feminizing effect), with statistically significant associations observed for BDE-47 (β = 0.0247, 95% confidence interval (CI): 0.0017, 0.0477), -100 (β = 0.0264, 95% CI: 0.0087, 0.0441) and Σ₅PBDEs (β = 0.0201, 95% CI: 0.0027, 0.0374). For boys, compared with the lowest exposure groups, statistically significantly higher (feminized) 2D:4D for both hands was observed in those with the highest exposure levels of BDE-100 (β = 0.0147, 95% CI: 0.0005, 0.0289 for the left hand; β = 0.0182, 95% CI: 0.0046, 0.0318 for the right hand) and those with the middle and the highest exposure levels of BDE-153 (middle vs. undetected, β = 0.0215, 95% CI: 0.0072, 0.0358 for the left hand; β = 0.0155, 95% CI: 0.0015, 0.0295 for the right hand; highest vs. undetected, β = 0.0162, 95% CI: 0.0017, 0.0307 for the left hand; β = 0.0152, 95% CI: 0.0011, 0.0294 for the right hand).

CONCLUSIONS

Our study provides preliminary evidence that prenatal exposure to PBDEs might be associated with higher 2D:4D in boys and girls.

Polychlorinated Biphenyls (PCBs): Risk Factors for Autism Spectrum Disorder?

Autism spectrum disorder (ASD) includes a group of multifactorial neurodevelopmental disorders defined clinically by core deficits in social reciprocity and communication, restrictive interests and repetitive behaviors. ASD affects one in 54 children in the United States, one in 89 children in Europe, and one in 277 children in Asia, with an estimated worldwide prevalence of 1-2%. While there is increasing consensus that ASD results from complex gene x environment interactions, the identity of specific environmental risk factors and the mechanisms by which environmental and genetic factors interact to determine individual risk remain critical gaps in our understanding of ASD etiology. Polychlorinated biphenyls (PCBs) are ubiquitous environmental contaminants that have been linked to altered neurodevelopment in humans. Preclinical studies demonstrate that PCBs modulate signaling pathways implicated in ASD and phenocopy the effects of ASD risk genes on critical morphometric determinants of neuronal connectivity, such as dendritic arborization. Here, we review human and experimental evidence identifying PCBs as potential risk factors for ASD and discuss the potential for PCBs to influence not only core symptoms of ASD, but also comorbidities commonly associated with ASD, via effects on the central and peripheral nervous systems, and/or peripheral target tissues, using bladder dysfunction as an example. We also discuss critical data gaps in the literature implicating PCBs as ASD risk factors. Unlike genetic factors, which are currently irreversible, environmental factors are modifiable risks. Therefore, data confirming PCBs as risk factors for ASD may suggest rational approaches for the primary prevention of ASD in genetically susceptible individuals.

Toxicity of polybrominated diphenyl ethers (PBDEs) on rodent male reproductive system: A systematic review and meta-analysis of randomized control studies

Polybrominated diphenyl ethers (PBDEs) are a group of environmental endocrine-disrupting chemicals (EDCs). According to recent studies, the associations between PBDEs and rodent male reproductive system are controversial. Therefore, we performed this systematic review and meta-analysis to clarify the effects of PBDEs on rodent male reproductive system. Data were extracted from articles collected from PubMed, Web of Science, and other databases. The pooled standard mean deviation (SMD) with 95% confidence interval (95% CI) was used to evaluate the association between the male rodent reproductive system impairment and PBDE exposure. Ten articles were included in the present meta-analysis and systematic review. The summary SMD of reproductive toxicity associated with PBDEs was -0.46 (95% CI: -0.69, -0.22), and the overall association between DE-71 along with BDE-209 and male reproductive system damage was statistically significant (SMD = -0.7 95% CI: -1.18, -0.21, p = .041; SMD = -0.41, 95% CI: -0.77, -0.05, p = .000). The adverse impact of PBDEs on rodent male reproductive system, especially seminal vesicle (SMD = -1.09, 95% CI: -1.49, -0.49, p = .523) and ventral prostate (SMD = -1.27, 95% CI: -1.88, -0.65, p = .821), were clearly demonstrated. Moderate (SMD = -0.81, 95% CI: -1.182, -0.437, p = .197) and high (SMD = -0.41, 95% CI: -0.76, -0.05, p = .000) dosage may have exerted effect than relatively low (SMD = -0.29, 95% CI: -0.17, 0.12, p = .136) dosage. In conclusion, our meta-analysis and systematic review suggested PBDE toxicity on the male reproductive system.

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.

Gut Microbiota Modulates Interactions Between Polychlorinated Biphenyls and Bile Acid Homeostasis

The gut microbiome is increasingly recognized as a second genome that contributes to the health and diseases of the host. A major function of the gut microbiota is to convert primary bile acids (BAs) produced from cholesterol in the liver into secondary BAs that activate distinct host receptors to modulate xenobiotic metabolism and energy homeostasis. The goal of this study was to investigate to what extent oral exposure to an environmentally relevant polychlorinated biphenyl (PCBs mixture), namely the Fox River mixture, impacts gut microbiome and BA homeostasis. Ninety-day-old adult female conventional (CV) and germ-free (GF) C57BL/6 mice were orally exposed to corn oil (vehicle), or the Fox River mixture at 6 or 30 mg/kg once daily for 3 consecutive days. The PCB low dose profoundly increased BA metabolism related bacteria Akkermansia (A.) muciniphila, Clostridium (C.) scindens, and Enterococcus in the large intestinal pellet (LIP) of CV mice (16S rRNA sequencing/qPCR). This correlated with a PCB low dose-mediated increase in multiple BAs in serum and small intestinal content (SIP) in a gut microbiota-dependent manner (UPLC-MS/MS). Conversely, at PCB high dose, BA levels remained stable in CV mice correlated with an increase in hepatic efflux transporters and ileal Fgf15. Interestingly, lack of gut microbiota potentiated the PCB-mediated increase in taurine conjugated α and β muricholic acids in liver, SIP, and LIP. Pearson's correlation identified positive correlations between 5 taxa and most secondary BAs. In conclusion, PCBs dose-dependently altered BA homeostasis through a joint effort between host gut-liver axis and intestinal bacteria.

Prenatal exposure to PCBs and neurological and sexual/pubertal development from birth to adolescence

Several chemical compounds are resistant to degradation and end up in the food chain. One group of these chemicals is polychlorinated biphenyls (PCBs) which are used as flame retardants and plasticizers. Although PCBs were banned several decades ago, PCBs are still found in environmental media, including in the body of humans. PCBs are transferred from mother to fetus via the placenta during pregnancy. Considering that the prenatal period is a sensitive period during which essential developmental processes take place, exposure to environmental chemicals might have considerable and permanent consequences for outcomes in later life. The aim of this review is to provide an update on the latest insights on the effects of prenatal exposure to PCBs on neurological, sexual and pubertal development in children. We give an overview of recent literature, and discuss it in the light of the findings in a unique Dutch birth cohort, with data on both neurological and pubertal development into adolescence. The findings in the studies included in this review, together with the findings in the Dutch cohort, demonstrate that prenatal exposure to PCBs can interfere with normal child development, not only during the perinatal period, but up to and including adolescence. Higher prenatal exposure to PCBs was found to be both negatively and positively associated with neurodevelopmental outcomes. Regarding pubertal development, higher prenatal PCB exposure was found to be associated with more advanced pubertal development, also in the Dutch cohort, whereas other studies also found delayed pubertal development. These findings raise concern regarding the effects of man-made chemical compounds on child development. They further contribute to the awareness of how environmental chemical compounds can interfere with child development and negatively influence healthy ageing.

Endocrine disrupters and possible contribution to pubertal changes

The onset of puberty strongly depends on organizational processes taking place during the fetal and early postnatal life. Therefore, exposure to environmental pollutants such as Endocrine disrupting chemicals (EDCs) during critical periods of development can result in delayed/advanced puberty and long-term reproductive consequences. Human evidence of altered pubertal timing after exposure to endocrine disrupting chemicals is equivocal. However, the age distribution of pubertal signs points to a skewed distribution towards earliness for initial pubertal stages and towards lateness for final pubertal stages. Such distortion of distribution is a recent phenomenon and suggests environmental influences including the possible role of nutrition, stress and endocrine disruptors. Rodent and ovine studies indicate a role of fetal and neonatal exposure to EDCs, along the concept of early origin of health and disease. Such effects involve neuroendocrine mechanisms at the level of the hypothalamus where homeostasis of reproduction is programmed and regulated but also peripheral effects at the level of the gonads or the mammary gland.

Pre- and Postnatal Polybrominated Diphenyl Ether Concentrations in Relation to Thyroid Parameters Measured During Early Childhood

Background: Penta-brominated diphenyl ethers (PentaBDEs) are endocrine-disrupting chemicals that structurally resemble thyroid hormones and were widely used as flame retardants in household consumer products from 1975 to 2004. Polybrominated diphenyl ethers (PBDEs) cross the placenta, and evidence suggests that for many children, body burdens may peak during the toddler years. This study aimed to understand the impact of exposure timing by examining both pre- and postnatal exposure to BDE-47, the predominant penta-brominated diphenyl ether congener detected in humans, in relation to thyroid hormone parameters measured during early childhood. Methods: The Columbia Center for Children's Environmental Health Mothers and Newborns Study is a prospective birth cohort of African American and Dominican maternal-child pairs. Pregnant women were recruited from two prenatal clinics in Northern Manhattan and the South Bronx between 1998 and 2006. Participants included 158 children with (i) plasma PBDE concentrations measured at birth and in the toddler years (age 2-3 years), and (ii) serum thyroid parameters measured at three and/or five years of age. Outcomes included concentrations of serum thyrotropin, free thyroxine, and total thyroxine. Results: Children with high exposure to BDE-47 during the prenatal period (-17% [confidence interval -29 to -2]) or toddler age (-19% [confidence interval -31 to -5]) had significantly lower geometric mean thyrotropin levels compared to children with low BDE-47 exposure throughout early life. Associations with thyroxine were also inverse; however, they did not reach statistical significance at the p = 0.05 level. Sex-stratified models suggest associations with postnatal exposure may be stronger among boys compared to girls. Conclusions: The thyroid regulatory system may be sensitive to BDE-47 during pre- and postnatal periods.

Prenatal polybrominated diphenyl ethers exposure and anogenital distance in boys from a Shanghai birth cohort

BACKGROUND

Polybrominated diphenyl ethers (PBDEs) are major brominated flame retardant (BFR) chemicals with endocrine-disrupting properties. One small-scale study on humans has suggested that prenatal exposure to PBDEs is adversely related to anogenital distance (AGD) a sensitive marker for prenatal androgen exposure. The aim of the present study was to examine the associations between prenatal exposure to PBDEs and AGD among boys 0-4 years of age in a cohort study.

METHODS

In the Shanghai-Minhang Birth Cohort Study (S-MBCS), nine PBDE congeners were measured in cord plasma of 192 male infants. We measured anopenile distance (AGD_AP) and anoscrotal distance (AGD_AS) at birth, 6 months, 12 months, and 48 months of age. A total of 190 boys with neonatal concentrations of PBDEs (ng/g lipid) who had at-least one AGD measurement were included in our study. Information on potential confounding variables were collected through in-person interviews. Multiple linear regression models and generalized estimating equation (GEE) models were used to evaluate the associations between prenatal PBDEs concentrations and AGD.

RESULTS

Among the nine congeners, BDE-47 had the highest detection rate (83.68%) and the highest median concentration (0.18 ng/g lipid). Boys who had neonatal concentration of BDE-47 or Σ₄PBDEs (sum of BDE-47, BDE-99, BDE-100, and BDE-153) in the higher quartile generally had shorter AGD_AP and AGD_AS than those in the first quartile. Significant inverse associations were found between AGD_AS and fourth quartile BDE-47 levels among boys 12 months and 48 months of age (β = -5.57, 95% confidence interval (CI): -9.89, -1.25 for 12 month of age; β = -4.32, 95% CI: -8.18, -0.46 for 48 month of age). Inverse associations were also observed between AGD_AS and fourth quartile Σ₄PBDEs levels among boys 12 months of age (β = -5.13, 95% CI: -9.89, -1.25). In GEE models, similar patterns of association were also observed between BDE-47 and AGD_AS.

CONCLUSIONS

Our findings provide preliminary evidence that prenatal exposure to BDE-47 and Σ₄PBDEs, even at low environmental levels, may be associated with shorter AGD in boys. This data suggest that prenatal exposure to PBDEs may have adverse effects on male reproductive development. Further studies should be conducted to validate these results.

PBDE-47 and PBDE mixture (DE-71) toxicities and liver transcriptomic changes at PND 22 after in utero/postnatal exposure in the rat

Pentabromodiphenyl ethers (PBDE) are found in human tissue, in household dust, and in the environment, and a particular concern is the potential for the induction of cancer pathways from these fat-soluble persistent organic pollutants. Only one PBDE cancer study has been conducted and that was for a PBDE mixture (DE-71). Because it is not feasible to test all PBDE congeners in the environment for cancer potential, it is important to develop a set of biological endpoints that can be used in short-term toxicity studies to predict disease outcome after long-term exposures. In this study, PBDE-47 was selected as the test PBDE congener to evaluate and compare toxicity to that of the carcinogenic PBDE mixture. The toxicities of PBDE-47 and the PBDE mixture were evaluated at PND 22 in Wistar Han rat (Crl: WI (Han)) pups after in utero/postnatal exposure (0, 0.1, 15, or 50 mg/kg; dams, GD6-21; pups, PND 12-PND 21; oral gavage daily dosing). By PND 22, PBDE-47 caused centrilobular hypertrophy and fatty change in liver, and reduced serum thyroxin (T4) levels; similar effects were also observed after PBDE mixture exposure. Transcriptomic changes in the liver included induction of cytochrome p450 transcripts and up-regulation of Nrf2 antioxidant pathway transcripts and ABC membrane transport transcripts. Decreases in other transport transcripts (ABCG5 & 8) provided a plausible mechanism for lipid accumulation, characterized by a treatment-related liver fatty change after PBDE-47 and PBDE mixture exposure. The benchmark dose calculation based on liver transcriptomic data was generally lower for PBDE-47 than for the PBDE mixture. The up-regulation of the Nrf2 antioxidant pathway and changes in metabolic transcripts after PBDE-47 and PBDE mixture exposure suggest that PBDE-47, like the PBDE mixture (NTP 2016, TR 589), could be a liver toxin/carcinogen after long-term exposure.

Prenatal exposure to polychlorinated biphenyl and umbilical cord hormones and birth outcomes in an island population

Prenatal exposure to polychlorinated biphenyl (PCB) is suspected to interfere with fetal development including reproductive and thyroid function and birth outcomes, but published evidence are still sparse. We designed a cross-sectional study to analyze the associations between PCB levels in umbilical cord sera and hormones and birth outcomes of mothers and newborns who are residents from an island. Seven indicator-PCB (PCB-28, 52, 101, 118, 138, 153, 180), and five reproductive hormones including luteotropic hormones (LH), estradiol (E2), testosterone (T), follicle-stimulating hormones (FSH) and anti-Mullerian hormones (AMH), and three thyroid hormones including tri-iodothyronine (T3), tetra-iodothyronine (T4) and thyroid stimulating hormones (TSH) were measured in 106 cord sera specimens. Birth outcomes include birth weight, length, head circumference, and gestational age. Multiple linear regression and quartile regression were used to analyze the associations between PCB and each of the hormones and birth outcomes, adjusting for selected potential confounders. The median value of total PCB in umbilical cord sera was 2.02 μg L^-1 (IQR, 1.13-4.64). Several negative associations between PCB exposure and reproductive hormones were found. Among them, the β value of PCB-101 for FSH reached -0.38 (95%CI, -0.69, -0.07; p = 0.02). Moreover, we also found some sex-specific associations i.e. PCB-28 was negatively correlated with LH and T and PCB-118 was negatively correlated with T in male newborns but not in female newborns. The associations between PCB and birth outcomes seem to differ by molecular weight of the PCB congeners i.e. the low-chlorinated PCB congeners were negatively associated with gestational age and head circumference while high-chlorinated PCB congeners were positively associated birth weight and gestational age. In this study, we found that PCB congeners with different molecular weight has different associations with hormones and birth outcomes, and future studies are recommended to investigate underlying mechanisms of these associations.

Associations between PBDEs exposure from house dust and human semen quality at an e-waste areas in South China-A pilot study

Previous studies have confirmed that house dust is one of the main sources of polybrominated diphenyl ethers (PBDEs) exposure, and also indicated that PBDEs might affect human semen quality. The aim of this study was to explore the association between PBDEs concentration in house dust and the semen quality of male resident. Results showed that the semen qualities of the residents living around the e-waste dismantling workshops for a long time (3-17years) at the e-waste areas in South China significantly decreased, and the DNA damage of sperms were aggravated. The adjusted correlation analysed by multiple linear regression model showed that the sperm concentration and count both had negative correlation with BDE47 level in semen (β = -0.295, 95%CI: -0.553∼-0.036; β = -0.400, 95%CI: -0.708∼-0.092, respectively). In addition, the sperm progressive motility [(A+B)%] and sperm viability both had negative correlation with BDE100 level in dust (β = -0.360, 95%CI: -0.680∼-0.040; β = -0.114, 95% CI: -0.203∼-0.025, respectively). And there were significant linear positive correlation between PBDE congener (e.g. BDE28, 47, 153) concentrations in dust and in paired semen samples (r_s = 0.367-0.547, p < 0.05). This study suggested that exposure to PBDEs from house dust might have adverse effects on human semen quality. But the results need to be confirmed in further studies with a large-scale sampling, and find out more direct and convincing evidence.

Are endocrine disrupting compounds environmental risk factors for autism spectrum disorder?

Recent research on the etiology of autism spectrum disorder (ASD) has shifted in part from a singular focus on genetic causes to the involvement of environmental factors and their gene interactions. This shift in focus is a result of the rapidly increasing prevalence of ASD coupled with the incomplete penetrance of this disorder in monozygotic twins. One such area of environmentally focused research is the association of exposures to endocrine disrupting compounds (EDCs) with elevated risk for ASD. EDCs are exogenous chemicals that can alter endogenous hormone activity and homeostasis, thus potentially disrupting the action of sex and other natural hormones at all stages of human development. Inasmuch as sex hormones play a fundamental role in brain development and sexual differentiation, exposure to EDCs in utero during critical stages of development can have lasting neurological and other physiological influences on the developing fetus and, ultimately, the child as well as adult. This review will focus on the possible contributions of EDCs to autism risk and pathogenesis by first discussing the influence of endogenous sex hormones on the autistic phenotype, followed by a review of documented human exposures to EDCs and associations with behaviors relevant to ASD. Mechanistic links between EDC exposures and aberrant neurodevelopment and behaviors are then considered, with emphasis on EDC-induced transcriptional profiles derived from animal and cellular studies. Finally, this review will discuss possible mechanisms through which EDC exposure can lead to persistent changes in gene expression and phenotype, which may in turn contribute to transgenerational inheritance of ASD.

Thyroid-disrupting chemicals and brain development: an update

This review covers recent findings on the main categories of thyroid hormone-disrupting chemicals and their effects on brain development. We draw mostly on epidemiological and experimental data published in the last decade. For each chemical class considered, we deal with not only the thyroid hormone-disrupting effects but also briefly mention the main mechanisms by which the same chemicals could modify estrogen and/or androgen signalling, thereby exacerbating adverse effects on endocrine-dependent developmental programmes. Further, we emphasize recent data showing how maternal thyroid hormone signalling during early pregnancy affects not only offspring IQ, but also neurodevelopmental disease risk. These recent findings add to established knowledge on the crucial importance of iodine and thyroid hormone for optimal brain development. We propose that prenatal exposure to mixtures of thyroid hormone-disrupting chemicals provides a plausible biological mechanism contributing to current increases in the incidence of neurodevelopmental disease and IQ loss.

Endocrine disrupters and pubertal timing

PURPOSE OF REVIEW

The current review summarizes recent epidemiologic data demonstrating the effects of endocrine disrupting compounds (EDCs) on the timing of puberty and highlights the complexity of understanding the interplay of environmental and genetic factors on pubertal timing.

RECENT FINDINGS

In girls, there have been mixed results, with some exposures being associated with earlier timing of puberty, and some with later puberty. In boys, prepubertal exposures to nondioxin-like polychlorinated biphenyls accelerate puberty, whereas levels of insecticides, dioxin-like compounds, organochlorine pesticides, and lead delay puberty.

SUMMARY

The effects of EDCs on pubertal timing are sexually dimorphic, compound specific, and varies according to the window of exposure. These studies confirm that low-level exposures to a mix of environmental compounds may mask the effects of individual compounds and complicate our ability to translate data from animal studies to human health and to fully understand the clinical implications of environmental epidemiology studies.

Association of prenatal and childhood PBDE exposure with timing of puberty in boys and girls

BACKGROUND

Polybrominated diphenyl ether (PBDE) flame retardants are endocrine-disrupting chemicals that exhibit estrogenic and androgenic properties and may affect pubertal timing.

METHODS

Study subjects were participants between 1999 and 2013 in the Center for the Health Assessment of Mothers and Children of Salinas (CHAMACOS), a longitudinal cohort study of predominantly Mexican origin families in Northern California. We measured serum concentrations of four PBDEs (BDE-47, -99, -100, -153) in blood collected from mothers during pregnancy (N=263) and their children at age 9years (N=522). We determined timing of pubertal onset in 309 boys and 314 girls using clinical Tanner staging every 9months between 9 and 13years of age, and timing of menarche by self-report. We used Poisson regression for relative risk (RR) of earlier puberty and parametric survival analysis for time ratios (TR) of pubertal milestones.

RESULTS

Prenatal concentrations of all 4 congeners and ƩPBDEs were associated with later menarche in girls (RR_{earlier menarche}=0.5, 95% confidence interval (CI): 0.3, 0.9 for ƩPBDEs) but earlier pubic hair development in boys (RR_{earlier pubarche}=2.0, 95% CI: 1.3, 3.3 for ƩPBDEs). No associations were seen between prenatal exposure and girls' breast or pubic hair development or boys' genital development. Childhood PBDE exposure was not associated with any measure of pubertal timing, except for an association of BDE-153 with later menarche.

CONCLUSIONS

We found that prenatal PBDE exposure was associated with later menarche in girls but earlier pubarche in boys, suggesting opposite pubertal effects in girls and boys.

Prenatal phthalate exposure and 8-isoprostane among Mexican-American children with high prevalence of obesity

Oxidative stress has been linked to many obesity-related conditions among children including cardiovascular disease, diabetes mellitus and hypertension. Exposure to environmental chemicals such as phthalates, ubiquitously found in humans, may also generate reactive oxygen species and subsequent oxidative stress. We examined longitudinal changes of 8-isoprostane urinary concentrations, a validated biomarker of oxidative stress, and associations with maternal prenatal urinary concentrations of phthalate metabolites for 258 children at 5, 9 and 14 years of age participating in a birth cohort residing in an agricultural area in California. Phthalates are endocrine disruptors, and in utero exposure has been also linked to altered lipid metabolism, as well as adverse birth and neurodevelopmental outcomes. We found that median creatinine-corrected 8-isoprostane concentrations remained constant across all age groups and did not differ by sex. Total cholesterol, systolic and diastolic blood pressure were positively associated with 8-isoprostane in 14-year-old children. No associations were observed between 8-isoprostane and body mass index (BMI), BMI Z-score or waist circumference at any age. Concentrations of three metabolites of high molecular weight phthalates measured at 13 weeks of gestation (monobenzyl, monocarboxyoctyl and monocarboxynonyl phthalates) were negatively associated with 8-isoprostane concentrations among 9-year olds. However, at 14 years of age, isoprostane concentrations were positively associated with two other metabolites (mono(2-ethylhexyl) and mono(2-ethyl-5-carboxypentyl) phthalates) measured in early pregnancy. Longitudinal data on 8-isoprostane in this pediatric population with a high prevalence of obesity provides new insight on certain potential cardiometabolic risks of prenatal exposure to phthalates.