Association of In Utero Exposure to Polybrominated Diphenyl Ethers With the Risk of Hypospadias

The Effect of Various Environmental Pollutants on the Reproductive Health in Children: A Brief Review of the Literature

PURPOSE OF REVIEW

Environmental pollutants in air, water, soil, and food are a significant concern due to their potential adverse effects on fetuses, newborns, babies, and children. These chemicals, which pass to fetuses and babies through trans-placental transfer, breast milk, infant formula, dermal transfer, and non-nutritive ingestion, can cause health problems during childhood. This review aims to discuss how exposure to various environmental pollutants in early life stages can disrupt reproductive health in children.

RECENT FINDINGS

Environmental pollutants can affect Leydig cell proliferation and differentiation, decreasing testosterone production throughout life. This may result in cryptorchidism, hypospadias, impaired semen parameters, and reduced fertility. Although many studies on female reproductive health cannot be interpreted to support causal relationships, exposure to pollutants during critical windows may subsequently induce female reproductive diseases, including early or delayed puberty, polycystic ovary syndrome, endometriosis, and cancers. There is growing evidence that fetal and early-life exposure to environmental pollutants could affect reproductive health in childhood. Although diet is thought to be the primary route by which humans are exposed to various pollutants, there are no adopted nutritional interventions to reduce the harmful effects of pollutants on children's health. Therefore, understanding the impact of environmental contaminants on various health outcomes may inform the design of future human nutritional studies.

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.

Long-term effect of PBDE-99 prenatal exposure on spermatogenic injuries via the dysregulation of autophagy

Although it has been reported that perinatal, especially prenatal exposure to polybrominated diphenyl ethers (PBDEs) alters offspring's fertility, but little is known regarding their longitudinal effects over time. In the current study, we determined the associations between prenatal exposure to 2,2',4,4',5-pentabromodiphenyl ether (PBDE-99) of environmentally relevant levels in pregnant ICR mice and spermatogenic impairments in male offspring on postnatal day 70. Then, we monitored functional injuries in spermatogenic cells (GC-1 spg) exposed to PBDE-99 in vitro. Furthermore, transcriptome sequencing and bioinformatic analysis were used to investigate the underlying mechanism of PBDE-99 exposure to GC-1 spg. Additionally, the expression levels of key genes in the relevant pathways were quantified. Our findings indicated that exposure to PBDE-99 caused significantly spermatogenic injuries, which partly owing to the accumulation of reactive oxygen species, dysregulation of autophagy, and finally induced spermatogenic cell apoptosis. Rescue validation experiments showed that stimulating autophagy could alleviate spermatogenic cell injury induced by PBDE-99. In conclusion, our findings indicated that the dysfunction of autophagy played a significant role in long-term reproductive toxicity following prenatal exposure to environmental concentrations of PBDE-99.

Di-n-butyl phthalate induces oversecretion of vascular endothelium-derived NAP-2 and promotes epithelial-mesenchymal transition of urothelial cells in newborn hypospadias rats

Di-n-butyl phthalate (DBP) is a plasticizer commonly used in industrial production and is present in our daily life. It has been confirmed that DBP causes genitourinary malformations, especially hypospadias. However, the research of hypospadias mainly focusses on the genital tubercle in previous studies. In this study, we found DBP could affect the exocrine function of the vascular endothelium which disturb the development of genital nodules and induced hypospadias. We used cytokine array to find that vascular endothelium-derived NAP-2 may be a major abnormal secreted cytokine with biological functions. The transcriptomic sequencing analysis showed that abnormal activation of the RhoA/ROCK signaling pathway was the main reason for increased NAP-2 secretion. The expression levels of epithelial-mesenchymal transition (EMT) biomarkers and NAP-2 in hypospadias animal models were detected with Immunohistochemistry, Western blot, Immunofluorescence, and ELISA methods. The expression levels of NAP-2, RhoA/ROCK signaling pathway related proteins, reactive oxygen species (ROS) levels in HUVEC cells, EMT biomarkers and migration capacity of urothelial cells cocultured with HUVEC were measured with ELISA, flow cytometry, Western blot or Transwell assay for further cell experiments. The results showed that DBP leaded to NAP-2 oversecretion from vascular endothelium mainly rely on the activation of RhoA/ROCK signaling pathway and ROS accumulation. The RhoA/ROCK inhibitor fasudil could partially decrease ROS production, and both fasudil and N-acetyl-L-cysteine (NAC) could decrease NAP-2 secretion. Meanwhile, the oversecretion of NAP-2 from HUVEC in coculture system promoted EMT and migration capacity of urothelial cells, and TGF-β inhibitor LY219761 could block the aberrant activation of EMT process. Therefore, it could be concluded that DBP increase NAP-2 secretion from vascular endothelium by RhoA/ROCK/ROS pathway, and further promote EMT in urothelial cells through TGF-β pathway. This study provided a novel direction for studying the occurrence of hypospadias and may provide a hypospadias predictive marker in the future.

BDE-209 disturbed proliferation and differentiation of spermatogonia during mitotic process through estrogen receptor α

Deca-bromodiphenyl ether (BDE-209) exposure caused spermatogenesis disorder resulting in poor sperm quality has become a public concern in recent years. Spermatogenesis refers to the process by which the division of spermatogonia stem cells (SSCs) produces haploid spermatozoa, including mitosis, meiosis, and spermiogenesis. However, the mechanism of mitosis including proliferation and differentiation of spermatogonia dysfunction induced by BDE-209 remains largely unclear. Here, our data showed that BDE-209 exposure caused a decline in sperm quality with seminiferous tubule structure disorder in rats. In addition, BDE-209 exposure damage spermatogonia proliferation and differentiation with decreasing level of PLZF and cKit in testis. Moreover, rats exposed to BDE-209 decreased the expression of ERα, whereas an elevated expression of Wnt3a and Wnt5a. Mechanistically, supplementation with propipyrazole triol (PPT, a selective ERα pathway agonist) rescued sperm quality and attenuated impairment of proliferation and differentiation of spermatogonia in BDE-209-induced rats. Therefore, ERα plays a crucial role in the proliferation and differentiation of spermatogonia during mitotic process. In conclusion, our study clarified the role of ERα in BDE-209-induced spermatogonia proliferation and differentiation in rats and provides a potential therapeutic application on poor sperm quality caused by BDE-209 exposure.

Levels of persistent organic pollutants in breast milk samples representing Finnish and Danish boys with and without hypospadias

Hypospadias is a congenital malformation of penile urethra with unknown etiology in most cases. Persistent organic pollutant (POP) exposure may disrupt endocrine function during a critical window of development of male genitalia. In animal studies, POPs have been associated with male reproductive disorders, including hypospadias, but only few studies have assessed this relationship in humans. The aim of this study is to investigate the association between hypospadias and POP concentration levels in breast milk, as a proxy for prenatal exposure. This is a nested case-control study of Danish and Finnish mother-son pairs. Maternal breast milk samples were collected between 1997 and 2002, and they represent infant boys born with hypospadias [n = 33 (n = 22 Danish and n = 11 Finnish)] and their 1:1 matched controls. Breast milk samples were analyzed for six classes of POPs [including dioxins, polychlorinated biphenyls, flame retardants and perfluorinated alkylated substances (PFAS)]. We estimated odds ratios (ORs) and 95% confidence intervals (CI) for each chemical class using conditional logistic regression. In addition, a composite exposure score system was used to explore the effect of a POP mixture (four chemical classes): The composite score was categorized as low, moderate, or high exposure, and differences between cases and controls were tested with conditional logistic regression. No statistically significant associations were observed between the sums of the chemical classes and hypospadias in either country. The composite score was unable to detect differences in the risk of hypospadias between the tertiles of POP exposure. Levels of PFAS were significantly higher in Danish than in Finnish breast milk samples. This small study does not provide evidence for an association between hypospadias and exposure to POPs but adds information on quantitative exposures. Further development of multi-exposure models is needed for assessing the potential mixture effect associated with multiple chemical exposures.

Birth defects associated with paternal firefighting in the National Birth Defects Prevention Study

BACKGROUND

Few studies have evaluated birth defects among children of firefighters. We investigated associations between birth defects and paternal work as a firefighter compared to work in non-firefighting and police officer occupations.

METHODS

We analyzed 1997-2011 data from the multi-site case-control National Birth Defects Prevention Study. Cases included fetuses or infants with major structural birth defects and controls included a random sample of live-born infants without major birth defects. Mothers of infants self-reported information about parents' occupations held during pregnancy. We investigated associations between paternal firefighting and birth defect groups using logistic regression to estimate odds ratios (ORs) and 95% confidence intervals (CIs). Referent groups included families reporting fathers working non-firefighting and police officer jobs.

RESULTS

Occupational groups included 227 firefighters, 36,285 non-firefighters, and 433 police officers. Twenty-nine birth defects were analyzed. In adjusted analyses, fathers of children with total anomalous pulmonary venous return (TAPVR; OR = 3.1; 95% CI = 1.1-8.7), cleft palate (OR = 1.8; 95% CI = 1.0-3.3), cleft lip (OR = 2.2; 95% CI = 1.2-4.2), and transverse limb deficiency (OR = 2.2; 95% CI = 1.1-4.7) were more likely than fathers of controls to be firefighters, versus non-firefighters. In police-referent analyses, fathers of children with cleft palate were 2.4 times more likely to be firefighters than fathers of controls (95% CI = 1.1-5.4).

CONCLUSIONS

Paternal firefighting may be associated with an elevated risk of birth defects in offspring. Additional studies are warranted to replicate these findings. Further research may contribute to a greater understanding of the reproductive health of firefighters and their families for guiding workplace practices.

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.

Pre- and post-natal exposure of children to organophosphate flame retardants: A nationwide survey in France

The use of organophosphate flame retardants (OPFRs) has been on the rise ever since many brominated flame retardants were banned, back in the 2000 s. The objectives of this study are to describe the pre- and post-natal exposure of children to OPFRs, and to explore their possible determinants. A total of 259 children aged 3.5 years and 388 mothers from the French ELFE mother-child cohort were included. Both pre- and post-natal exposure to OPFRs were assessed, using OPFR concentrations in the hair of pregnant women (in 2011) and their 3.5-year-old children (in 2014-2015) for 15 OPFRs, of which 9 were detected in > 20 % hair samples. The highest geometric means for pre-natal exposure were 272 ng/g for tris(1-chloro-2-propyl) phosphate (TCPP), 69.7 ng/g for ng/g for triphenyl phosphate (TPP) and 54.4 ng/g for tris(1,3-dichloro-2-propyl) phosphate (TDCPP). The highest geometric means for post-natal exposure were 249.6 ng/g for TCPP, 85.3 ng/g for TDCPP and 83.8 ng/g for 2-ethylhexyl diphenyl phosphate (EHDPP). Correlations were found between both pre-natal exposures, and between pre-and post-natal exposures. No correlation was however found between pre-and post-natal exposures for any given OPFR. Pre-natal exposure to the 9 OPFRs was associated with pre-natal exposure to polybrominated diphenyl ethers 209 (BDE209), and 47 (BDE47). Maternal BMI was associated with pre-natal exposure to OPFRs other than TBEP. Home renovation work prior to birth was also associated with pre-natal exposure to OPFRs, with the exception of EHDPP, tris(2-butoxyethyl) phosphate (TBEP) and triethyl phosphate (TEP). Determinants of post-natal exposure appeared more disparate across OPFRs; although both the type of flooring in children's rooms and pre-natal exposure to polybrominated diphenyl ethers seem to be associated with post-natal exposure. Lastly, higher socioeconomic status appeared to be associated with lower exposure for several (though not all) OPFRs. The high prevalence of exposure to OPFRs suggests the need for studies to assess the health effects of OPFRs exposure, particularly on 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.

Evaluation of the influences of low dose polybrominated diphenyl ethers exposure on human early retinal development

Increasing evidence in animal models has suggested that polybrominated diphenyl ethers (PBDEs), a class of brominated flame retardants, can cause retinotoxicity. However, data on the influence of PBDE treatment on human retinal development are scarce due to the lack of appropriate models. In the present study, we report the utilization of human embryonic stem cell-derived retinal organoids (hESC-ROs) for toxicity assessment of the most common PBDE congener (BDE-47) during the early stages of retinal development. Exposure to BDE-47 decreased the thickness and area of the neural retina (NR) of hESC-ROs in a dose- and time-dependent manner. Abnormal retinal cell distributions, disordered NR structures, and neural rosette-like structures were found on hESC-ROs after low-level BDE-47 exposure. Moreover, BDE-47 exposure decreased cell proliferation, promoted cell apoptosis, and caused abnormal differentiation. Transcriptomic analysis demonstrated that differentially expressed genes, caused by BDE-47, were enriched in extracellular matrix organization. Metabolomic studies of hESC-ROs revealed significant changes in the metabolism of purine and glutathione after BDE-47 exposure for five weeks. This study clarifies the retinotoxicity of low-level BDE-47 treatment and highlights the powerfulness of the hESC-RO model, deepening our understanding of BDE-47-driven human early retina developmental toxicity.

Declining semen quality and polybrominated diphenyl ethers (PBDEs): Review of the literature to support the derivation of a reference dose for a mixture risk assessment

To support a mixture risk assessment for chemicals that interfere with male reproductive health, we reviewed the literature to identify studies of polybrominated diphenyl ethers (PBDEs) and poor semen quality. Several epidemiological studies have shown associations of PBDE exposures with declining semen quality, non-descending testes and penile malformations. In rodent studies, poor semen quality, changes in testosterone levels and reproductive tissues have been observed. In vitro studies with reporter gene constructs show PBDE congeners as androgen receptor antagonists, and mixture studies in these systems have demonstrated that PBDE congeners act together with other androgen receptor antagonists. These observations led us to attempt the estimation of reference doses for specific PBDE congeners that can be used in a future mixture risk assessment for deteriorations of semen quality. While epidemiological studies provide support for such associations, they were uninformative for derivations of reference doses, due to the incompatibility of dose metrics used in exposure assessments. We therefore based our estimates on animal studies. Using a rigorous confidence rating approach, we found robust evidence that BDE-47 produced reductions in semen quality. We identified only one high confidence study of BDE-99 and accordingly evaluated the strength of evidence as moderate. One high confidence, and several medium confidence experimental studies observed declines in semen quality after BDE-209 exposure. Using established risk assessment procedures, we estimated that BDE-47 exposures below 0.15 μg/kg/d are unlikely to lead to reductions in semen quality. The corresponding exposures for BDE-99 and BDE-209 are 0.003 μg/kg/d and 1000 μg/kg/d. It is planned to use these estimates as reference doses in a mixture risk assessment of deteriorations in semen quality, involving multiple other chemicals also contributing to poor semen quality.

Prenatal exposure to environmentally relevant levels of PBDE-99 leads to testicular dysgenesis with steroidogenesis disorders

Polybrominated diphenyl ethers (PBDEs) are a widely used class of brominated flame retardants. Exposure to PBDEs could induce testicular damage in mammals, but the effects and potential mechanism of action of prenatal exposure to environmentally relevant PBDEs on testicular development remain unclear. For the in vivo study, pregnant ICR mice were exposed to environmentally relevant levels of 2,2',4,4',5-pentabromodiphenyl ether (PBDE-99), a major component of commercial PBDE mixtures. We found that the anogenital index and testicular organ coefficient were significantly decreased, the incidence of cryptorchidism was increased, and testicular histology was disturbed in male offspring. Transcriptomic profiling showed that steroidogenesis disorders were significant in all PBDE-99 exposure groups. The testosterone levels, expressions of testosterone regulators, and the number of CYP11A1-positive and 11β-HSD1-positive Leydig cells were significantly decreased after PBDE-99 exposure. For the in vitro study, TM3 Leydig cells were exposed to PBDE-99 at gradient concentrations. Transcriptomic profiling and validation experiments showed that PBDE-99 upregulated reactive oxygen species, activated the ERK1/2 pathway, inhibited the ubiquitination degradation pathway, and finally induced Leydig cell apoptosis. Cumulatively, these findings revealed that prenatal exposure to environmentally relevant levels of PBDE-99 leads to steroidogenesis disorders by inducing the apoptosis of Leydig cells, causing testicular dysgenesis.

BDE-209 induce spermatocytes arrest at early-pachytene stage during meiotic prophase I in mice

Deca-brominated diphenyl ether (BDE-209) is a common flame retardant utilized in electronic products, textiles, furniture, and upholstery materials. Environmental BDE-209 exposure results in spermatogenesis disorder, because of the characteristics of bioaccumulation, persistence, and probably toxicity. Meiotic prophase I is a crucial phase during spermatogenesis which is a key influential factor of normal sperm production. However, the effects of BDE-209 on meiotic prophase I during spermatogenesis are poorly understood. The present study aimed to evaluate whether BDE-209 exposure impairs meiotic prophase I during spermatogenesis of spermatocytes. We validated the effects of BDE-209 on alternations of meiotic prophase I in Balb/c male mice. Firstly, we analyzed sperm quality in cauda epididymis with decreasing sperm count, increasing abnormal sperm, and male reproductive dysfunction after exposure to BDE-209. Then, reactive oxygen species (ROS) and malondialdehyde (MDA) levels in testis and GC-2spd cells were significant increased after treated with BDE-209. Furthermore, we found that meiotic prophase I arrest at early-pachytene stage during spermatogenesis with increasing of DSBs damage and trimethylated histone H3 at lysine-4 (H3K4me3) in spermatocytes exposed to BDE-209. Finally, we conducted homologous recombination (HR) analyses to identify the progression of meiosis. The recombination markers, including DMC1 and RAD51, and crossover marker MLH1 were decreased during spermatogenesis after exposure to BDE-209. Collectively, our data indicated that BDE-209 has detrimental impacts on meiotic prophase I of spermatocytes in mice.

Developmental exposure to the DE-71 mixture of polybrominated diphenyl ether (PBDE) flame retardants induce a complex pattern of endocrine disrupting effects in rats

Polybrominated diphenyl ethers (PBDEs) are legacy compounds with continued widespread human exposure. Despite this, developmental toxicity studies of DE-71, a mixture of PBDEs, are scarce and its potential for endocrine disrupting effects in vivo is not well covered. To address this knowledge gap, we carried out a developmental exposure study with DE-71. Pregnant Wistar rat dams were exposed to 0, 40 or 60 mg/kg bodyweight/day from gestation day 7 to postnatal day 16, and both sexes were examined. Developmental exposure affected a range of reproductive toxicity endpoints. Effects were seen for both male and female anogenital distances (AGD), with exposed offspring of either sex displaying around 10% shorter AGD compared to controls. Both absolute and relative prostate weights were markedly reduced in exposed male offspring, with about 40% relative to controls. DE-71 reduced mammary gland outgrowth, especially in male offspring. These developmental in vivo effects suggest a complex effect pattern involving anti-androgenic, anti-estrogenic and maybe estrogenic mechanisms depending on tissues and developmental stages. Irrespective of the specific underlying mechanisms, these in vivo results corroborate that DE-71 causes endocrine disrupting effects and raises concern for the effects of PBDE-exposure on human reproductive health, including any potential long-term consequences of disrupted mammary gland development.

Contribution of prenatal endocrine-disrupting chemical exposure to genital anomalies in males: The pooled results from current evidence

The etiology of hypospadias and cryptorchidism, which are the two most common genital anomalies in males, has not been elucidated. Although prenatal exposure to endocrine-disrupting chemicals (EDCs) may increase the risks of hypospadias and cryptorchidism, the associations have not been confirmed. Therefore, we performed a meta-analysis to establish the relationships between prenatal exposure to EDCs and male genital anomalies. A systematic search of PubMed, EMbase, and Cochrane Library CENTRAL for relevant published studies providing quantitative data on the associations between prenatal EDCs exposure and hypospadias/cryptorchidism in humans was conducted. In total, sixteen case-controlled studies were included. Prenatal exposure to overall EDCs was associated with an increased risk of hypospadias in males (OR, 1.34, 95 % CI 1.12 to 1.60). Although there was no statistically significant association between overall EDCs exposure and cryptorchidism (OR, 1.11, 95 % CI 0.99 to 1.24), exposure to phenol substances was associated with an increased risk of cryptorchidism (OR, 1.81, 95 % CI, 1.12 to 2.93). Using the GRADE tool, we found the overall evidence to be of moderate certainty. In conclusion, the current evidence suggests prenatal EDCs exposure may increase the risk of hypospadias in males.

Prenatal low-dose antibiotic exposure and children allergic diseases at 4 years of age: A prospective birth cohort study

BACKGROUND

Based on a medical record or questionnaire survey approach, previous epidemiological studies have investigated associations between maternal antibiotic exposure during pregnancy and childhood allergic diseases. However, biomonitoring studies on the prenatal low-dose antibiotic exposure, mainly from the environment and contaminated food, and in relation to children allergic diseases, are missing.

OBJECTIVES

This research aimed to examine the associations between prenatal low-dose antibiotic exposure measured at multiple time points and children current allergic diseases at 4 years of age.

METHODS

The current study including 2453 mother-child pairs was based on the Ma'anshan Birth Cohort study. Selected 41 antibiotics and their two metabolites, which including human antibiotics (HAs), preferred as human antibiotics (PHAs), veterinary antibiotics (VAs) and preferred as veterinary antibiotics (PVAs), in urine samples from 2453 pregnant women were biomonitored through liquid chromatography-triple quadrupole tandem mass spectrometry. Information on children current allergic diseases were collected via validated questionnaires. Generalized estimating equation were used to explore the associations between the repeated measurements of maternal urinary antibiotic over three trimesters and current allergic diseases in children.

RESULTS

The detection rates of nine individual antibiotics in the three trimester during pregnancy are greater than 10%, and the 90th percentile concentration of the detected antibiotics ranges from 0.07 to 22.34 µg/g, and the 95th percentile concentration ranges from 0.17 to 59.57 µg/g. Among the participants, each one-unit concentration increment of sulfamethazine (adjusted OR=1.28, 95% CI: 1.10, 1.49, P-_FDR=0.014) in the first trimester and ciprofloxacin (adjusted OR=1.17, 95% CI: 1.07, 1.28, P-_FDR=0.008) in the second trimester were associated with an increased risk of current eczema in children. In the third trimester, each one-unit concentration increment of oxytetracycline (adjusted OR=1.90, 95% CI: 1.30, 2.78, P-_FDR=0.014) was associated with an increased risk of current asthma in children. Gender-stratified analyses demonstrated that no gender differences were observed in the associations between prenatal antibiotic exposure and current allergic diseases in children.

CONCLUSIONS

Maternal exposure to certain specific VAs or PVAs (sulfamethazine, ciprofloxacin and oxytetracycline) in different trimesters was associated with an increased risk of current asthma and current eczema in 4-year-old children. No gender differences were found in these associations. Further studies are warranted to confirm our findings and explore the potential mechanisms.

Impact of gestational and parental factors and maternal intake of progesterone on the development of hypospadias: A retrospective case-control study

OBJECTIVE

Impact of environmental, maternal, paternal, and fetal factors on the development of hypospadias have been questioned in association with disrupted hormonal balance. We aimed to examine the association between maternal progesterone use and the associated risk factors and hypospadias.

MATERIALS AND METHODS

There were 429 male children as the cases with hypospadias (n = 280, Group 1) and the controls without hypospadias (n = 149, Group 2). Those working in agriculture and industry, cleaners, and hairdressers were determined as risky occupational groups concerning the exposure of estrogenic endocrine disrupters. The association of progestin usage and the other risk factors with hypospadias were the study outcomes.

RESULTS

The median gestational age was significantly lower in Group 2 (p = 0.019). Prematurity was more common in Group 1 (p = 0.043). Although the median birth weight in Group 1 was significantly lower (p < 0.001), there was no significant difference between the ratios of low birth weight babies in the groups. The risky occupations were more frequently detected in Group 2 (p = 0.001). The rate and duration of progestin usage in Group 1 were significantly higher than that in Group 2 (p < 0.001).

CONCLUSION

Low birth weight and the use and duration of progestins during pregnancy were significantly associated with increased hypospadias risk.

Endocrine-Disrupting Chemicals and Disorders of Penile Development in Humans

This paper reviews the current knowledge on the environmental effects on penile development in humans. The specific focus is on endocrine-disrupting chemicals (EDCs), a heterogeneous group of natural or manmade substances that interfere with endocrine function, and whether they can induce hypospadias and micropenis in male neonates. Epidemiological data and animal observations first raised suspicions about environmental effects, leading to the testis dysgenesis syndrome (TDS) hypothesis. More recent research has provided stronger indications that TDS may indeed be the result of the direct or indirect effects of EDCs. Drawing on epidemiological and toxicological studies, we also report on the effects of maternal diet and substances like pesticides, phthalates, bisphenol A, and polychlorinated biphenyls. Proximity to contamination hazards and occupational exposure are also suspected to contribute to the occurrence of hypospadias and micropenis. Lastly, the cumulative effects of EDCs and the possibility of transgenerational effects, with the penile development of subsequent generations being affected, raise concerns for long-term public health.

A preliminary study on the mechanism of the neurosteroid-mediated ionotropic receptor dysfunction in neurodevelopmental toxicity induced by decabromodiphenyl ether

The mechanism of neurodevelopmental toxicity of decabromodiphenyl ether (BDE209) remains unclear. Recent evidence suggests that neurosteroids disorders play a vital role in BDE209 induced-neurodevelopmental toxicity. To explore the mechanism of it, pregnant ICR mice were orally gavaged with 0, 225, and 900 mg kg^-1 BDE209 for about 42 days. Spatial learning and memory abilities of offspring were tested on postnatal day (PND) 21. Offspring were euthanized at PND26, the neuronal structure, neurosteroids level, and related proteins including neurosteroids synthase, ionotropic receptors and cAMP-response element binding protein (CREB) pathway were evaluated, as well as Ca²⁺ concentration and the mitochondrial membrane potential (Mmp). Our results showed that BDE209 impaired learning and memory abilities and disrupted neuronal structure. Meanwhile, BDE209 decreased the pregnenolone (PREG), dehydroepiandrosterone (DHEA), progesterone (PROG) and allopregnanolone (ALLO) levels in the serum and brain, as well as the mRNA and protein levels of cholesterol-side-chain cleavage enzyme (P450scc), steroid 17α-hy-droxylase (P450C17), 3β-hydroxysteroid dehydrogenase (3β-HSD) and steroid 5α-reductase of type I (5α-R) in the hippocampi. Also, BDE209 suppressed mRNA and protein levels of NR1, NR2A and NR2B subunits of the N-methyl-D-aspartic acid receptor (NMDAR) and α1 subunit of the Gamma-amino butyric acid A receptor (GABAAR), but increased the levels of β2 and γ2 subunits of the GABAAR in the hippocampi. Moreover, BDE209 increased the Ca²⁺ concentration and phosphorylation extracellular regulated protein kinases (P-ERK) 1/2 level, but decreased the P-CREB and Mmp level in the hippocampi. These results indicate that BDE209 exposure during pregnancy and lactation is possible to affect learning and memory formation of offspring by the neurosteroid-mediated ionotropic receptors dysfunction.

Endocrine disrupting chemicals in the pathogenesis of hypospadias; developmental and toxicological perspectives

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Penis development is regulated by a tight balance of androgens and estrogens.

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EDCs that impact androgen/estrogen balance during development cause hypospadias.

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Cross-disciplinary collaborations are needed to define a mechanistic link.

Hypospadias is a defect in penile urethral closure that occurs in approximately 1/150 live male births in developed nations, making it one of the most common congenital abnormalities worldwide. Alarmingly, the frequency of hypospadias has increased rapidly over recent decades and is continuing to rise. Recent research reviewed herein suggests that the rise in hypospadias rates can be directly linked to our increasing exposure to endocrine disrupting chemicals (EDCs), especially those that affect estrogen and androgen signalling. Understanding the mechanistic links between endocrine disruptors and hypospadias requires toxicologists and developmental biologists to define exposures and biological impacts on penis development. In this review we examine recent insights from toxicological, developmental and epidemiological studies on the hormonal control of normal penis development and describe the rationale and evidence for EDC exposures that impact these pathways to cause hypospadias. Continued collaboration across these fields is imperative to understand the full impact of endocrine disrupting chemicals on the increasing rates of hypospadias.

WITHDRAWN: Hypospadias induced by medications and environmental exposures- A scoping review

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Endocrine Disrupting Chemicals and Reproductive Health in Boys and Men

Male reproductive health has declined as indicated by increasing rates of cryptorchidism, i.e., undescended testis, poor semen quality, low serum testosterone level, and testicular cancer. Exposure to endocrine disrupting chemicals (EDCs) has been proposed to have a role in this finding. In utero exposure to antiandrogenic EDCs, particularly at a sensitive period of fetal testicular development, the so-called 'masculinization programming window (MPW)', can disturb testicular development and function. Low androgen effect during the MPW can cause both short- and long-term reproductive disorders. A concurrent exposure to EDCs may also affect testicular function or damage testicular cells. Evidence from animal studies supports the role of endocrine disrupting chemicals in development of male reproductive disorders. However, evidence from epidemiological studies is relatively mixed. In this article, we review the current literature that evaluated relationship between prenatal EDC exposures and anogenital distance, cryptorchidism, and congenital penile abnormality called hypospadias. We review also studies on the association between early life and postnatal EDC exposure and semen quality, hypothalamic-pituitary-gonadal axis hormone levels and testicular cancer.

Meeting report on the NIDDK/AUA Workshop on Congenital Anomalies of External Genitalia: challenges and opportunities for translational research

Congenital anomalies of the external genitalia (CAEG) are a prevalent and serious public health concern with lifelong impacts on the urinary function, sexual health, fertility, tumor development, and psychosocial wellbeing of affected individuals. Complications of treatment are frequent, and data reflecting long-term outcomes in adulthood are limited. To identify a path forward to improve treatments and realize the possibility of preventing CAEG, the National Institute of Diabetes and Digestive and Kidney Diseases and the American Urological Association convened researchers from a range of disciplines to coordinate research efforts to fully understand the different etiologies of these common conditions, subsequent variation in clinical phenotypes, and best practices for long term surgical success. Meeting participants concluded that a central data hub for clinical evaluations, including collection of DNA samples from patients and their parents, and short interviews to determine familial penetrance (small pedigrees), would accelerate research in this field. Such a centralized datahub will advance efforts to develop detailed multi-dimensional phenotyping and will enable access to genome sequence analyses and associated metadata to define the genetic bases for these conditions. Inclusion of tissue samples and integration of clinical studies with basic research using human cells and animal models will advance efforts to identify the developmental mechanisms that are disrupted during development and will add cellular and molecular granularity to phenotyping CAEG. While the discussion focuses heavily on hypospadias, this can be seen as a potential template for other conditions in the realm of CAEG, including cryptorchidism or the exstrophy-epispadias complex. Taken together with long-term clinical follow-up, these data could inform surgical choices and improve likelihood for long-term success.

Exposure pathways, levels and toxicity of polybrominated diphenyl ethers in humans: A review

Polybrominated diphenyl ethers (PBDEs) are extensively used as brominated flame retardants (BFRs) in different types of materials, which have been listed as Persistent Organic Pollutants (POPs) by the Stockholm Convention in 2009 and 2017. Due to their ubiquities in the environment and toxicities, PBDEs have posed great threat to both human health and ecosystems. The aim of this review is to offer a comprehensive understanding of the exposure pathways, levels and trends and associated health risks of PBDEs in human body in a global scale. We systematically reviewed and described the scientific data of PBDE researches worldwide from 2010 to March 2020, focusing on the following three areas: (1) sources and human external exposure pathways of PBDEs; (2) PBDE levels and trends in humans; (3) human data of PBDEs toxicity. Dietary intake and dust ingestion are dominant human exposure pathways. PBDEs were widely detected in human samples, especially in human serum and human milk. Data showed that PBDEs are generally declining in human samples worldwide as a result of their phasing out. Due to the common use of PBDEs, their levels in humans from the USA were generally higher than that in other countries. High concentrations of PBDEs have been detected in humans from PBDE production regions and e-waste recycling sites. BDE-47, -153 and -99 were proved to be the primary congeners in humans. Human toxicity data demonstrated that PBDEs have extensively endocrine disruption effects, developmental effects, and carcinogenic effects among different populations.