Endocrine disrupting chemicals in seminal plasma and couple fecundity

Disruptive effects of plasticizers bisphenol A, F, and S on steroidogenesis of adrenocortical cells

Introduction

Endocrine disrupting chemicals (EDCs) are known to interfere with endocrine homeostasis. Their impact on the adrenal cortex and steroidogenesis has not yet been sufficiently elucidated. This applies in particular to the ubiquitously available bisphenols A (BPA), F (BPF), and S (BPS).

Methods

NCI-H295R adrenocortical cells were exposed to different concentrations (1nM-1mM) of BPA, BPF, BPS, and an equimolar mixture of them (BPmix). After 72 hours, 15 endogenous steroids were measured using LC-MS/MS. Ratios of substrate and product of CYP-regulated steps were calculated to identify most influenced steps of steroidogenesis. mRNA expression of steroidogenic enzymes was determined by real-time PCR.

Results

Cell viability remained unaffected at bisphenol concentrations lower than 250 µM. All tested bisphenols and their combination led to extensive alterations in the quantified steroid levels. The most profound fold changes (FC) in steroid concentrations after exposure to BPA (>10µM) were seen for androstenedione, e.g. a 0.37±0.11-fold decrease at 25µM (p≤0.0001) compared to vehicle-treated controls. For BPF, levels of 17-hydroxyprogesterone were significantly increased by 25µM (FC 2.57±0.49, p≤0.001) and 50µM (FC 2.65±0.61, p≤0.0001). BPS treatment led to a dose-dependent decrease of 11-deoxycorticosterone at >1µM (e.g. FC 0.24±0.14, p≤0.0001 at 10µM). However, when combining all three bisphenols, additive effects were detected: e.g. 11-deoxycortisosterone was decreased at doses >10µM (FC 0.27±0.04, p≤0.0001, at 25µM), whereas 21-deoxycortisol was increased by 2.92±0.20 (p≤0.01) at 10µM, and by 3.21±0.45 (p≤0.001) at 50µM. While every measured androgen (DHEA, DHEAS, androstenedione, testosterone, DHT) was lowered in all experiments, estradiol levels were significantly increased by BPA, BPF, BPS, and BPmix (e.g. FC 3.60±0.54, p≤0.0001 at 100µM BPF). Calculated substrate-product ratios indicated an inhibition of CYP17A1-, and CYP21A2 mediated conversions, whereas CYP11B1 and CYP19A1 showed higher activity in the presence of bisphenols. Based on these findings, most relevant mRNA expression of CYP genes were analysed. mRNA levels of StAR, CYP11B1, and CYP17A1 were significantly increased by BPF, BPS, and BPmix.

Discussion

In cell culture, bisphenols interfere with steroidogenesis at non-cytotoxic levels, leading to compound-specific patterns of significantly altered hormone levels. These results justify and call for additional in-vivo studies to evaluate effects of EDCs on adrenal gland functionality.

Concentrations, compositional profiles, and health risks of benzophenones among the Taiwanese population based on analysis of 23 daily consumed foods

In this study, we analyzed the occurrence and distribution of 11 benzophenone-type ultraviolet filters (BPs) in 893 food samples spanning 7 food categories in Taiwan. We conducted a Monte Carlo simulation to determine the carcinogenic and noncarcinogenic risks of BPs. The results indicated that cornflakes had the highest mean level of BPs (103 ng/g), followed by bread (101 ng/g) and pastries (59 ng/g). BP was the most prevalent category, followed by 4-methylbenzophenone (4-MBP), 2-hydroxybenzophenone, and benzophenone-3. Estimation of the lifetime cancer risk (LTCR) of BP (average life expectancy of 80 years) placed them in the 50th and 97.5th percentiles [P50 (P97.5)] LTCR of 1.9 × 10-7 (5.7 × 10-6), indicating that BP in food poses a low renal hazard to the Taiwanese population. The noncarcinogenic risk of BPs was evaluated using a hazard quotient and combined margin of exposure (MOET), revealing a P50 (P97.5) hazard index of < 1 for BP, 4-MBP, and methyl-2-benzoylbenzoate. Although the P50 MOET values for all age groups were within the moderate range of concern, with a more conservative extreme (P2.5), the MOET values for the 0-3, 3-6, and 6-12 age groups fell below 100, indicating a high concern for renal degeneration and hyperplasia.

Assessing preconception exposure to environmental chemicals and fecundity: Strategies, challenges, and research priorities

In 2022, approximately one out of six people globally experienced infertility at some point in their life. Environmental chemicals, particularly those with endocrine disrupting activity, may contribute to impaired fecundity and infertility. We review existing prospective cohort studies of environmental chemicals and fecundity, identify methodological challenges and biases, and outline future research priorities. Studies of preconception environmental chemical exposures and fecundity have occurred in US, Singapore, China and Denmark with recruitment as early as 1982-1986, as recent as 2015-2017 and sample sizes ranging from 99 to 936. Higher exposure to certain chemicals (e.g. heavy metals, perfluoroalkyl substances) was associated with longer time to pregnancy; yet the literature is scarce or nonexistent for many chemicals. Furthermore, prospective studies face challenges and potential biases related to recruiting participants prior to conception, measuring environmental chemicals during critical windows of exposure, and ascertaining when pregnancy occurred. Research priorities include expanding the scope of biomonitoring data collected during the preconception period, continuing to develop and validate analytic methods for self-sampled biospecimens in traditional and novel matrices, collecting data in male partners and investigating etiologic associations according to indicators of marginalization.

Cross sectional study on exposure to BPA and its analogues and semen parameters in Czech men

Exposure to bisphenols has been found to have adverse effects on male reproductive function in animals. Human exposure to bisphenols is widespread. Bisphenol A (BPA) and its analogues, including bisphenol S (BPS), bisphenol F (BPF), and bisphenol AF (BPAF) are utilized in various consumer products such as food contact materials and dental resins. The effects of these compounds on male fertility and spermatogenesis are unclear and findings from human studies are inconsistent. In this cross-sectional study, we evaluated the influence of BPA, BPS, BPF, BPAF (BPs) measured in semen on number of spermatozoa, total motility, progressive motility, morphology, and DNA fragmentation. We also examined the association of bisphenols (BPs) exposure with patients' occupation. A total of 358 patients aged 17-62 years with BMI 18-42 were included in the study from 2019 to 2021. BPs were extracted using solvent extraction followed by preconcentration step and determined by high-performance liquid chromatography and tandem mass spectrometry (LC/MSMS). Bisphenols were detected in 343 from 349 analysed samples (98.3% of all the samples). In 6 samples, the concentration of all BPs was under the limit of detection and in 20 samples under the limit of quantification. We did not find a statistically significant relationship between occupation and BPs. However, we observed significant correlations between the concentration of BPA and a lower motility and normal morphology. For BPS, a significant correlation with a lower ejaculate volume and a lower total sperm count was found. BPF and BPAF were detected only in 14.3% and 23.9% of samples, respectively. For BPF and BPAF, no significant correlations with spermiogram parameters were observed. Our results show that BPs are widespread in the male population (more than 90% of analysed samples), independently of an occupation and in case of BPA and BPS having a negative impact on spermiogram parameters.

A review of sources, pathways, and toxic effects of human exposure to benzophenone ultraviolet light filters

Benzophenone ultraviolet light filters (BPs) are high-production-volume chemicals extensively used in personal care products, leading to widespread human exposure. Given their estrogenic properties, the potential health risks associated with exposure to BPs have become a public health concern. This review aims to summarize sources and pathways of exposure to BPs and associated health risks. Dermal exposure, primarily through the use of sunscreens, constitutes a major pathway for BP exposure. At a recommended application rate, dermal exposure of BP-3 via the application of sunscreens may reach or exceed the suggested reference dose. Other exposure pathways to BPs, such as drinking water, seafood, and packaged foods, contribute minimal to the overall dose. Inhalation is a minor pathway of exposure; however, its contribution cannot be ignored. Human exposure to BPs is an order of magnitude higher in North America than in Asia and Europe. Studies conducted on laboratory animals and cells have consistently demonstrated the toxic effects of BP exposure. BPs are estrogenic and elicit reproductive and developmental toxicities. Furthermore, neurotoxicity, hepatotoxicity, nephrotoxicity, and carcinogenicity have been reported from chronic BP exposure. In addition to animal and cell studies, epidemiological investigations have identified associations between BPs and couples' fecundity and other reproductive disorders, as well as adverse birth outcomes. Further studies are urgently needed to understand the risks posed by BPs on human health.

Redox mechanisms of environmental toxicants on male reproductive function

Humans and wildlife, including domesticated animals, are exposed to a myriad of environmental contaminants that are derived from various human activities, including agricultural, household, cosmetic, pharmaceutical, and industrial products. Excessive exposure to pesticides, heavy metals, and phthalates consequently causes the overproduction of reactive oxygen species. The equilibrium between reactive oxygen species and the antioxidant system is preserved to maintain cellular redox homeostasis. Mitochondria play a key role in cellular function and cell survival. Mitochondria are vulnerable to damage that can be provoked by environmental exposures. Once the mitochondrial metabolism is damaged, it interferes with energy metabolism and eventually causes the overproduction of free radicals. Furthermore, it also perceives inflammation signals to generate an inflammatory response, which is involved in pathophysiological mechanisms. A depleted antioxidant system provokes oxidative stress that triggers inflammation and regulates epigenetic function and apoptotic events. Apart from that, these chemicals influence steroidogenesis, deteriorate sperm quality, and damage male reproductive organs. It is strongly believed that redox signaling molecules are the key regulators that mediate reproductive toxicity. This review article aims to spotlight the redox toxicology of environmental chemicals on male reproduction function and its fertility prognosis. Furthermore, we shed light on the influence of redox signaling and metabolism in modulating the response of environmental toxins to reproductive function. Additionally, we emphasize the supporting evidence from diverse cellular and animal studies.

Endocrine Disruptors: Focus on the Adrenal Cortex

Endocrine-disrupting chemicals (EDCs) are exogenous substances known to interfere with endocrine homeostasis and promote adverse health outcomes. Their impact on the adrenal cortex, corticosteroids and their physiological role in the organism has not yet been sufficiently elucidated. In this review, we collect experimental and epidemiological evidence on adrenal disruption by relevant endocrine disruptors. In vitro data suggest significant alterations of gene expression, cell signalling, steroid production, steroid distribution, and action. Additionally, morphological studies revealed disturbances in tissue organization and development, local inflammation, and zone-specific hyperplasia. Finally, endocrine circuits, such as the hypothalamic-pituitary-adrenal axis, might be affected by EDCs. Many questions regarding the detection of steroidogenesis disruption and the effects of combined toxicity remain unanswered. Not only due to the diverse mode of action of adrenal steroids and their implication in many common diseases, there is no doubt that further research on endocrine disruption of the adrenocortical system is needed.

Head dysgenesis and disruption of cranial neural crest stem cells behaviour by 4-octylphenol in fire-bellied toad Bombina orientalis embryos

Alkylphenolic endocrine disruptors (Eds) have been known to affect development of the descendants of multipotent neural crest cells (NCCs) in amphibian embryos. To unravel the mechanism of head dysgenesis induced by alkylphenols in amphibians, the effect of 4-octylphenol (OP) on the differentiation of cranial NCCs in developing embryos and tadpoles, ex vivo NC explant, and isolated NCCs was examined in fire-bellied toad Bombina orientalis with 0, 1, 2, 5, 10, 25 and 50 μM concentrations. Following OP treatment, head cartilages were frequently absent together with the decreased col2a1 mRNA level in tadpoles. While the lipid hydroperoxide (LPO), endoplasmic reticulum stress (ERS), apoptosis, and DNA fragmentation were significantly increased in stage 22 neulurae and heads of stage 45 tadpoles. In stage 22 neulurae, OP decreased sox9 mRNA, the master transcription factor for chondrogenic differentiation and increased undifferentiated NCC markers. The ectopic NCCs were found in endoderm while mesodermal SOX10(+) cells were decreased. In cranial NCCs isolated from stage 22 embryos, OP treatment decreased cellular survival and increased apoptosis, epithelial-mesenchymal transition (EMT) and cell migration. In chondrogenic induced cranial NC explants, OP treatment decreased SOX9(+) chondrocytes and cartilage development. Together, OP potentiated oxidative damage, apoptosis, EMT, and ectopic migration of NCCs. Considering that tissue differentiation requires stem cells to activate the molecular mechanism of differentiation at the correct location during embryonic development, these changes caused by OP may inhibit sox9-dependent chondrogenic differentiation of cranial NCCs, leading to head dysgenesis in B. orientalis embryos. Therefore, developing multipotent NCCs could be an important target of OP, provides new direction for the estimation of the risk of EDs exposure in human and wildlife animals.

Exploring the internal exposome of seminal plasma with semen quality and live birth: A Pilot Study

Infertility is clinically defined as the inability to achieve pregnancy within 12 months of regular unprotected sexual intercourse and affects 15% of couples worldwide. Therefore, the identification of novel biomarkers that can accurately predict male reproductive health and couples' reproductive success is of major public health significance. The objective of this pilot study is to test whether untargeted metabolomics is capable of discriminating reproductive outcomes and understand associations between the internal exposome of seminal plasma and the reproductive outcomes of semen quality and live birth among ten participants undergoing assisted reproductive technology (ART) in Springfield, MA. We hypothesize that seminal plasma offers a novel biological matrix by which untargeted metabolomics is able to discern male reproductive status and predict reproductive success. The internal exposome data was acquired using UHPLC-HR-MS on randomized seminal plasma samples at UNC at Chapel Hill. Unsupervised and supervised multivariate analyses were used to visualize the differentiation of phenotypic groups classified by men with normal or low semen quality based on World Health Organization guidelines as well as by successful ART: live birth or no live birth. Over 100 exogenous metabolites, including environmentally relevant metabolites, ingested food components, drugs and medications, and metabolites relevant to microbiome-xenobiotic interaction, were identified and annotated from the seminal plasma samples, through matching against the NC HHEAR hub in-house experimental standard library. Pathway enrichment analysis indicated that fatty acid biosynthesis and metabolism, vitamin A metabolism, and histidine metabolism were associated sperm quality; while pathways involving vitamin A metabolism, C21-steroid hormone biosynthesis and metabolism, arachidonic acid metabolism, and Omega-3 fatty acid metabolism distinguished live birth groups. Taken together, these pilot results suggest that seminal plasma is a novel matrix to study the influence of the internal exposome on reproductive health outcomes. Future research aims to increase the sample size to validate these findings.

Association of triclosan and human infertility: A systematic review

Triclosan (TCS) is a chemical compound, which has antibacterial, antiviral, and antifungal properties. TCS is considered an endocrine-disrupting chemical, which has been shown to interfere with developmental, behavioral, and reproductive outcomes in biological models and cell cultures. However, implications about exposure to TCS and human infertility are rare. Thus, the main of this review is summarize the available evidence of the association between triclosan exposure on human infertility. For this, systematic review was conducted following the recommendations established in Report of Systematic Reviews and Meta-Analyses guide (PRISMA). Initially, an electronic search in MEDLINE (via PubMed) and Science direct was performed. The methodological quality of the included studies was verified through the Joanna Briggs Institute (JBI) checklists. All selection and data extraction processes were carried out independently by two reviewers. The evidence was organized and presented using tables and narrative synthesis. There is lacking evidence about the association between triclosan and human infertility. Overall, no association between triclosan and infertility was found. However, semen quality and ovarian reserve are susceptible to triclosan exposure. Thus, future studies are still needed to better elucidate the associations between triclosan and infertility outcomes.

Phthalate esters: occurrence, toxicity, bioremediation, and advanced oxidation processes

Phthalic acid esters are emerging pollutants, commonly used as plasticizers that are categorized as hazardous endocrine-disrupting chemicals (EDCs). A rise in anthropogenic activities leads to an increase in phthalate concentration in the environment which leads to various adverse environmental effects and health issues in humans and other aquatic organisms. This paper gives an overview of the research related to phthalate ester contamination and degradation methods by conducting a bibliometric analysis with VOS Viewer. Ecotoxicity analysis requires an understanding of the current status of phthalate pollution, health impacts, exposure routes, and their sources. This review covers five toxic phthalates, occurrences in the aquatic environment, toxicity studies, biodegradation studies, and degradation pathways. It highlights the various advanced oxidation processes like photocatalysis, Fenton processes, ozonation, sonolysis, and modified AOPs used for phthalate removal from the environment.

Re-evaluation of the risks to public health related to the presence of bisphenol A (BPA) in foodstuffs

In 2015, EFSA established a temporary tolerable daily intake (t-TDI) for BPA of 4 μg/kg body weight (bw) per day. In 2016, the European Commission mandated EFSA to re-evaluate the risks to public health from the presence of BPA in foodstuffs and to establish a tolerable daily intake (TDI). For this re-evaluation, a pre-established protocol was used that had undergone public consultation. The CEP Panel concluded that it is Unlikely to Very Unlikely that BPA presents a genotoxic hazard through a direct mechanism. Taking into consideration the evidence from animal data and support from human observational studies, the immune system was identified as most sensitive to BPA exposure. An effect on Th17 cells in mice was identified as the critical effect; these cells are pivotal in cellular immune mechanisms and involved in the development of inflammatory conditions, including autoimmunity and lung inflammation. A reference point (RP) of 8.2 ng/kg bw per day, expressed as human equivalent dose, was identified for the critical effect. Uncertainty analysis assessed a probability of 57-73% that the lowest estimated Benchmark Dose (BMD) for other health effects was below the RP based on Th17 cells. In view of this, the CEP Panel judged that an additional uncertainty factor (UF) of 2 was needed for establishing the TDI. Applying an overall UF of 50 to the RP, a TDI of 0.2 ng BPA/kg bw per day was established. Comparison of this TDI with the dietary exposure estimates from the 2015 EFSA opinion showed that both the mean and the 95th percentile dietary exposures in all age groups exceeded the TDI by two to three orders of magnitude. Even considering the uncertainty in the exposure assessment, the exceedance being so large, the CEP Panel concluded that there is a health concern from dietary BPA exposure.

Benzophenone-3: Comprehensive review of the toxicological and human evidence with meta-analysis of human biomonitoring studies

BACKGROUND

Benzophenone-3 (BP-3) and its major metabolite benzophenone-1 (BP-1) are widely used as UV filters in sunscreens and cosmetics to prevent sunburn and skin damage, or as stabilizers to prevent photodegradation in many commercial products. As a result, their presence is ubiquitous in the environment, wildlife and humans. Based on endocrine disruption concerns, international regulatory agencies are performing a closer evaluation.

OBJECTIVE AND METHODS

This work aimed to comprehensively review the available human relevant evidence for safety issues in MEDLINE/PubMed in order to create a structured database of studies, as well as to conduct an integrative analysis as part of the Human Biomonitoring for Europe (HBM4EU) Initiative.

RESULTS

A total of 1,635 titles and abstracts were screened and 254 references were evaluated and tabulated in detail, and classified in different categories: i) exposure sources and predictors; ii) human biomonitoring (HBM) exposure levels to perform a meta-analysis; iii) toxicokinetic data in both experimental animals and humans; iv) in vitro and in vivo rodent toxicity studies; and v) human data on effect biomarkers and health outcomes. Our integrative analysis showed that internal peak BP-3 concentrations achieved after a single whole-body application of a commercially available sunscreen (4% w/w) may overlap with concentrations eliciting endocrine disrupting effects in vitro, and with internal concentrations causing in vivo adverse female reproductive effects in rodents that were supported by still limited human data. The adverse effects in rodents included prolonged estrous cycle, altered uterine estrogen receptor gene expression, endometrium hyperplasia and altered proliferation and histology of the mammary gland, while human data indicated menstrual cycle hormonal alterations and increased risk of uterine fibroids and endometriosis. Among the modes of action reported (estrogenic, anti-androgenic, thyroid, etc.), BP-3 and especially BP-1 showed estrogenic activity at human-relevant concentrations, in agreement with the observed alterations in female reproductive endpoints. The meta-analysis of HBM studies identified a higher concern for North Americans, showing urinary BP-3 concentrations on average 10 and 20 times higher than European and Asian populations, respectively.

DISCUSSION AND CONCLUSIONS

Our work supports that these benzophenones present endocrine disrupting properties, endorsing recent European regulatory efforts to limit human exposure. The reproducible and comprehensive database generated may constitute a point of departure in future risk assessments to support regulatory initiatives. Meanwhile, individuals should not refrain from sunscreen use. Commercially available formulations using inorganic UV filters that are practically not absorbed into systemic circulation may be recommended to susceptible populations.

Lack of association between endocrine disrupting chemicals and male fertility: A systematic review and meta-analysis

The incidence of infertility currently affects about 15% of the world's population. Male factors are estimated to be responsible for up to 40-50% of these cases. While the cause of these reproductive disorders is still unclear, the exposure to a family of ubiquitous compounds in our daily life, named endocrine disrupting chemicals (EDCs) could be involved. This paper was aimed at performing a systematic review and meta-analysis of population studies exploring whether human male exposure to EDCs affects male fertility. Clinical and observational studies assessing the exposure to EDCs along with sperm quality, the most common reproductive disorders, sperm DNA damage, sperm oxidative stress, fertilization rate, implantation rate, clinical pregnancy rate, live birth rate, and miscarriage rate were included. The quality assessment tool from the NHLBI-NIH was used to assure that studies met standardized quality criteria. Sensitivity analysis and heterogeneity among studies was assessed. Overall, the 32 selected articles, including 7825 individuals in the systematic review, explored 12 families of EDCs. The results revealed a high heterogeneity among studies in relation to the association between exposure to EDCs and the endpoints analyzed. Meta-analyses were performed with data from 7 articles including 479 individuals, 4 articles assessing the association between BPA in urine and sperm quality, and 3 articles evaluating PCB153 in serum and sperm quality. In the meta-analysis, we identified an unpredicted significant positive association between PCB153 exposure and sperm concentration. However, it would not be clinically relevant. No positive or inverse associations were found neither for BPA, nor for PCB153 and the rest of sperm parameters analyzed. The high disparity between studies made difficult to draw conclusions on the potential harmful effects of EDCs on male fertility. Consequently, to delineate the potential relationship that EDCs can have on male fertility, an important condition stressing the health system, further investigations are required.

Urinary concentrations of polycyclic aromatic hydrocarbon and phthalate metabolite mixtures in relation to semen quality among men attending an infertility clinic

Previous studies have reported that exposure to phthalates and polycyclic aromatic hydrocarbons (PAHs) is individually associated with altered semen quality, but no human studies have evaluated their joint effects of exposure mixtures, a more real-world scenario. We aimed to explore urinary metabolite mixtures of phthalates and PAHs in associations with semen quality. Repeated spot-urine samples gathered from 695 men attending a fertility clinic were analyzed for urinary metabolites of eight phthalates and ten monohydroxylated-PAHs (OH-PAHs). Principal component analysis (PCA)-multivariable linear regression (MLR) model, quantile g-computation (qg-comp), and Bayesian kernel machine regression (BKMR) were applied to estimate the associations of urinary mixtures of phthalate and OH-PAH metabolites with semen quality. The overall effects of urinary mixtures of phthalate and PAH metabolites on semen quality were not statistically significant. However, hydroxynaphthalene (OHNa) factor identified from PCA was monotonically associated with decreased total sperm count and sperm concentration, whereas di(2-ethylhexyl) phthalate (DEHP) factor was non-monotonically related to increased progressive sperm motility and total sperm motility. Qg-comp and BKMR models confirmed these findings and identified 2-OHNa and 2-OHFlu as the primary negative contributors, whereas MEOHP and MEHP as the primary positive contributors. Our findings suggest that exposure to mixtures of naphthalene and DEHP is associated with altered semen quality. The finding is warranted to confirm in further well-designed epidemiological studies.

Tributyltin chloride exposure to post-ejaculatory sperm reduces motility, mitochondrial function and subsequent embryo development

CONTEXT

Male exposure to environmental toxicants can disrupt spermatogenesis and sperm function. However, consequences of environmentally relevant organotin exposure to post-ejaculatory mammalian spermatozoa on fertility are poorly understood.

AIMS

Determine the consequences of tributyltin chloride (TBT) exposure on post-ejaculatory sperm function and subsequent embryo development.

METHODS

Frozen-thawed bovine sperm were exposed to TBT (0.1-100nM) for 90min (acute) and 6h (short-term) followed by quantification of multiple sperm kinematics via computer aided sperm analysis. JC-1 dye was used to measure mitochondrial membrane potential. Sperm were then exposed to TBT for 90min in non-capacitating conditions, washed several times by centrifugation and applied to gamete co-incubation for in vitro embryo production to the blastocyst stage.

KEY RESULTS

100nM TBT decreased total motility (88 vs 79%), progressive motility (80 vs 70%) curvilinear velocity and beat-cross frequency for 90min with similar phenotypes at 6h (P<0.05). Sperm mitochondrial membrane potential was lower in 10 and 100nM groups after 6h (P≤0.05). Embryos fertilised from TBT-exposed sperm had reduced cleavage rate (80 vs 62%) and 8-16 cell morula development (55 vs 24%) compared to development from unexposed sperm.

CONCLUSIONS

Exposure of post-ejaculatory mammalian sperm to TBT alters sperm function through lowered motility and mitochondrial membrane potential. Fertilisation of oocytes with TBT-exposed sperm reduces embryo development through mechanisms of paternal origin.

IMPLICATIONS

Acute and short-term environmental exposure of post-ejaculatory sperm to organotins and endocrine disrupting chemicals such as TBT contribute to idiopathic subfertility and early embryo loss.

The Association of Certain Seminal Phthalate Metabolites on Spermatozoa Apoptosis: An Exploratory Mediation Analysis via Sperm Protamine

Earlier studies have suggested that exposure to phthalates (PAEs) may induce spermatozoa apoptosis. Sperm protamine as a molecular biomarker during spermatozoa apoptotic processes may mediate the association between PAE exposure and spermatozoa apoptosis. This study aimed to explore whether sperm protamine mediates the association of PAE exposure with spermatozoa apoptosis. We determined sperm protamine levels, 8 PAE metabolite concentrations in seminal plasma, and 3 spermatozoa apoptosis parameters among 111 men from an infertility clinic. The associations of PAEs as individual chemicals and mixtures with sperm protamine were determined. The mediating roles of protamine in the associations between PAEs and spermatozoa apoptosis parameters were examined by mediation analysis. After adjusting for confounders, we observed positive correlations between seminal plasma concentrations of mono(2-ethylhexyl) phthalate (MEHP) and sperm protamine-1 and protamine ratio. Estimates comparing highest vs. lowest quartiles of MEHP concentration were 4.65% (95% CI: 1.47%, 7.82%) for protamine-1 and 25.86% (95% CI: 3.05%, 53.73%) for protamine ratio. The quantile g-computation models showed that the adjusted protamine-1 per quartile increase in PAE mixture was 9.42% (95% CI: 1.00, 20.92) with MEHP being the major contributor. Although the joint association between PAE mixture and protamine ratio was negligible, MEHP was still identified as the main contributor. Furthermore, we found that protamine-2 and protamine ratio levels in the highest quartiles exhibited a decrease of 43.45% (95% CI: 60.54%, -19.75%) and an increase of 122.55% (95% CI: 60.00%, 209.57%) in Annexin V⁺/PI^- spermatozoa relative to the lowest quartiles, respectively. Mediation analysis revealed that protamine ratio significantly mediated 55.6% of the association between MEHP and Annexin V⁺/PI^- spermatozoa elevation (5.13%; 95% CI: 0.04%, 10.52%). Our findings provided evidence that human exposure to PAEs was associated with increased protamine levels which may mediate the process of spermatozoa apoptosis.

Determining the trace-level photoinitiators in juices and milk from various types of packages in Taiwan by a micro-QuEChERS-based UPLC-MS/MS

The distribution of 16 photoinitiators (PIs)-benzophenone (BP) and its five derivatives, 4-methylbenzophenone (4-MBP), methyl-2-benzoylbenzoate (M2BB), 2-ethylhexyl-4-dimethylaminobenzoate (EHDAB), and the other 7 PIs-in packaged juice and milk was assessed using an UPLC-MS/MS with micro-QuEChERS. The validated method demonstrated robust linearity (≥0.9908), LOQs (juice: 0.006-7.26 ng/mL; milk: 0.004-7.14 ng/mL), intra- and inter-day accuracy (93.1%-110.1% for juice and 66.8%-114.6% for milk with relative standard deviations (RSDs) of ≤16.8%), and matrix effect with RSDs of ≤14.8%. BP exceeded the LOQ in 100% of 136 packaged juice (14.22 ± 7.60 ng/mL) and 51 milk (8.45 ± 3.25 ng/mL) samples, and the quantitation rates for M2BB and EHDAB in packaged juice were 100%. Notably, the 4-MBP in both juice and milk was significantly related to the packaging material. The method has been successfully applied to evaluate the occurrence and distribution of PIs in packaged juice and milk.

Endocrine-disrupting chemicals affect sertoli TM4 cell functionality through dysregulation of gap junctional intercellular communication in vitro

The frequencies of adverse outcomes associated with male reproductive health, including infertility and testicular cancer, are increasing. These adverse trends are partially attributed to increased exposure to environmental agents such as endocrine-disrupting chemicals (EDCs). This study addresses effects on EDCs on adjacent prepubertal Sertoli TM4 cells, specifically on 1) testicular gap junctional intercellular communication (GJIC), one of the hallmarks of non-genotoxic carcinogenicity, 2) GJIC building blocks connexins (Cx), and 3) mitogen-activated protein kinases MAPKs. We selected eight representatives of EDCs: bisphenol A and organochlorine chemicals such as pesticides dichlorodiphenyltrichloroethane, lindane, methoxychlor, and vinclozolin, industrial chemical 2,2',4,4',5,5'-hexachlorobiphenyl, and components of personal care products, triclocarban and triclosan. EDCs rapidly dysregulated GJIC in Sertoli TM4 cells mainly via MAPK p38 and/or Erk1/2/pathways by the intermediate hyper- or de-phosphorylation of Cx43 (Ser368, Ser282) and translocalization of Cx43 from the plasma membrane, suggesting disturbed intracellular trafficking of Cx43 protein. Surprisingly, EDCs did not rapidly activate MAPK Erk1/2 or p38; on the contrary, TCC and TCS decreased their activity (phosphorylation). Our results indicate that EDCs might disrupt testicular homeostasis and development via testicular GJIC, junctional and non-junctional functions of Cx43 and MAPK-signalling pathways in Sertoli cells.

Male Infertility in the XXI Century: Are Obesogens to Blame?

The permanent exposure to environmental contaminants promoting weight gain (i.e., obesogens) has raised serious health concerns. Evidence suggests that obesogens are one of the leading causes of the marked decline in male fertility and are key players in shaping future health outcomes, not only for those who are directly exposed to them, but also for upcoming generations. It has been hypothesized that obesogens affect male fertility. By using an interdisciplinary strategy, combining in silico, in vitro, in vivo and epidemiological findings, this review aims to contribute to the biological understanding of the molecular transformations induced by obesogens that are the basis of male infertility. Such understanding is shaped by the use of Adverse Outcomes Pathways, a new approach that may shift the paradigm of reproductive toxicology, contributing to the improvement of the diagnosis and management of the adverse effects of obesogens in male fertility.

Neonicotinoid insecticide metabolites in seminal plasma: Associations with semen quality

Animal studies have revealed that exposure to neonicotinoid insecticides (NNIs) could compromise male reproductive function; however, related data on the occurrence of NNIs and their specific metabolites in human seminal plasma are scarce. To explore the potential effects of NNI exposure on male semen quality, we determined the concentrations of NNIs and some of their metabolites (collectively defined as mNNIs) in seminal plasma samples collected from men (n = 191) who visited a fertility clinic in Shijiazhuang, North China from 2018 to 2019. Associations between the mNNI concentrations and semen quality parameters were assessed using linear regression models, adjusting for important covariates. In the seminal plasma samples, desmethyl-acetamiprid (DM-ACE, detection frequency: 98.4%), imidacloprid-olefin (IMI-olefin, detection frequency: 86.5%), and desmethyl-clothianidin (DM-CLO, detection frequency: 70.8%) were frequently detected at median concentrations of 0.052, 0.003, and 0.007 ng/mL, respectively; meanwhile other compounds were detected at less than the method detection limits. In the single-mNNI models, the IMI-olefin concentration was associated with decreased progressive motility [IMI-olefin concentration: percent change (%Δ) = -17.0; 95% confidence interval (CI) = -30.3, -0.92; the highest tertile compared with the lowest tertile: %Δ = -21.1; 95% CI = -37.5, -0.23]. Similar results were found in the multiple-mNNIs models. No other inverse associations were found between the other mNNI concentrations and semen quality parameters. This is the first study to identify the occurrence of mNNIs in the seminal plasma and the potential associations of their concentrations with human semen quality parameters. These findings imply an inverse association between the IMI-olefin concentration and semen quality.

Phthalate metabolites: Characterization, toxicities, global distribution, and exposure assessment

Phthalates are plasticizers in various products and regarded as endocrine disruptors due to their anti-androgen effects. Environmental occurrence and toxicities of parent phthalates have been widely reported, while the current state of knowledge on their metabolites is rarely summarized. Based on the available literature, the present review mainly aims to 1) characterize the potential metabolites of phthalates (mPAEs) using the pharmacokinetics evidences acquired via animal or human models; 2) examine the molecular and cellular mechanism involved in toxicity for mPAEs; 3) investigate the exposure levels of mPAEs in different human specimens (e.g., urine, blood, seminal fluid, breast milk, amniotic fluid and others) across the globe; 4) discuss the models and related parameters for phthalate exposure assessment. We suggest there is subtle difference in toxic mechanisms for mPAEs compared to their parent phthalates due to their alternative chemical structures. Human monitoring studies performed in Asia, America and Europe have provided the population exposure baseline levels for typical phthalates in different regions. Urine is the preferred matrix than other specimens for phthalate exposure study. Among ten urinary mPAEs, the largest proportions of di-(2-ethylhexyl) phthalate (DEHP) metabolites (40%), monoethyl phthalate (mEP) (43%) and DEHP metabolites/mEP (both 29%) were observed in Asia, America and Europe respectively, and mono-5-carboxy-2-ethypentyl phthalate was the most abundant compounds among DEHP metabolites. Daily intakes of phthalates can be accurately calculated via urinary mPAEs if the proper exposure parameters were determined. Further work should focus on combining epidemiological and biological evidences to establish links between phthalates exposure and biological phenotypes. More accurate molar fractions (F_UE) of the urinary excreted monoester related to the ingested diesters should be collected in epidemiological or pharmacokinetic studies for different population.

Recent advances in analysis of bisphenols and their derivatives in biological matrices

Biomonitoring is a very useful tool to evaluate human exposure to endocrine-disrupting compounds (EDCs), like bisphenols (BPs), which are widely used in the manufacture of plastics. The development of reliable analytical methods is key in the field of public health surveillance to obtain biomonitoring data to determine what BPs are reaching people's bodies. This review discusses recent methods for the quantitative measurement of bisphenols and their derivatives in biological samples like urine, blood, breast milk, saliva, and hair, among others. We also discuss the different procedures commonly used for sample treatment, which includes extraction and clean-up, and instrumental techniques currently used to determine these compounds. Sample preparation techniques continue to play an important role in the analysis of complex matrices, for liquid matrices the most commonly employed is solid-phase extraction, although microextraction techniques are gaining importance in this field, and for solid samples ultrasound-assisted extraction. The main instrumental techniques used are liquid and gas chromatography coupled with mass spectrometry. Finally, we present data on the main parameters obtained in the validation of the revised methods. This review focuses on various methods developed and applied for trace analysis of bisphenols, their conjugates, halogenated derivatives, and diglycidyl ethers in biological samples to enable the required selectivity and sensitivity. For this purpose, a review is carried out of the most recent relevant publications from 2016 up to present.

Dichlorodiphenyltrichloroethane and the Adrenal Gland: From Toxicity to Endocrine Disruption

Endocrine disruptors are exogenous compounds that pollute the environment and have effects similar to hormones when inside the body. One of the most widespread endocrine disruptors in the wild is the pesticide dichlorodiphenyltrichloroethane (DDT). Toxic doses of DDT are known to cause cell atrophy and degeneration in the adrenal zona fasciculata and zona reticularis. Daily exposure in a developing organism to supposedly non-toxic doses of DDT have been found to impair the morphogenesis of both the cortex and the medulla of the adrenal glands, as well as disturbing the secretion of hormones in cortical and chromaffin cells. Comparison of high and very low levels of DDT exposure revealed drastic differences in the morphological and functional changes in the adrenal cortex. Moreover, the three adrenocortical zones have different levels of sensitivity to the disruptive actions of DDT. The zona glomerulosa and zona reticularis demonstrate sensitivity to both high and very low levels of DDT in prenatal and postnatal periods. In contrast, the zona fasciculata is less damaged by low (supposedly non-toxic) exposure to DDT and its metabolites but is affected by toxic levels of exposure; thus, DDT exerts both toxic and disruptive effects on the adrenal glands, and sensitivity to these two types of action varies in adrenocortical zones. Disruptive low-dose exposure leads to more severe affection of the adrenal function.

Correlation study of parabens in urine, serum, and seminal plasma of adult men in Beijing, China

The adverse effects of parabens raise concerns about their extensive use as preservatives in consumer products, especially in cosmetics. Until now, their distribution and excretion in humans have attracted little attention. Here, we quantified various agents including, for the first time, methyl-; ethyl-; n-propyl-; n-butyl-, and i-butylparaben (MeP, EtP, PrP, n-BuP, i-BuP); methyl- and ethyl-protocatechuate (OH-MeP and OH-EtP); hydroxybenzoic acid (4-HB); and 3,4-dihydroxybenzoic acid (3,4-DHB) in urine, serum, and seminal plasma samples from 50 healthy Chinese men in Beijing, China. Urine paraben concentrations were 1-2 orders of magnitudes higher than those in serum and seminal plasma. MeP and PrP were predominant and correlated with each other in the urine, serum, and seminal plasma. In urine, we observed a significant correlation between MeP and OH-MeP; EtP and OH-EtP; and 4-HB and 3,4-DHB concentrations. All these results provide new information on parabens as biomarkers for the assessment of exposure.

Benzothiazole-Containing Analogues of Triclocarban with Potent Antibacterial Activity

Triclocarban (TCC) is a polychlorinated, aromatic, antimicrobial agent commercially used since the 1950s in personal care products for the prevention of spoilage and infections. Humans are frequently exposed to TCC due to its widespread use, leading to its substantial release into the aquatic environment. With the recent ban of TCC from some personal care products, implemented in 2016, many replacement antimicrobial compounds have been studied by researchers. Herein, we report the synthesis and biological activity of a series of diarylureas, analogues of TCC that bear the benzothiazole nucleus as one of the two aryl moieties. Among the studied compounds, 2bF and 2eC showed the highest antimicrobial activity against Staphylococcus aureus, being also more active than TCC, with MIC values of 8 µg/mL versus 16 µg/mL of TCC. Moreover, compound 2bB was much more active than TCC against Enterococcus faecalis, a Gram-positive bacterium that is, unfortunately, strongly responsible for nosocomial infections. Finally, interesting results were found for compound 2bG that, even though less active than the others, exerts an interesting bactericidal action.

Controversy around parabens: Alternative strategies for preservative use in cosmetics and personal care products

Parabens usage as preservatives in cosmetics and personal care products have been debated among scientists and consumers. Parabens are easy to production, effective and cheap, but its safety status remains controversial. Other popular cosmetics preservatives are formaldehyde, triclosan, methylisothiazolinone, methylchloroisothiazolinone, phenoxyethanol, benzyl alcohol and sodium benzoate. Although their high antimicrobial effectiveness, they also exhibit some adverse health effects. Lately, scientists have shown that natural substances such as essential oils and plant extracts present antimicrobial potential. However, their use in cosmetic is a challenge. The present review article is a comprehensive summary of the available methods to prevent microbial contamination of cosmetics and personal care products, which can allow reducing the use of parabens in these products.

Inverse association of certain seminal phthalate metabolites with semen quality may be mediated by androgen synthesis: A cross-sectional study from the South China

BACKGROUND

Several in vitro and in vivo studies have demonstrated the effects of phthalates on androgen synthesis, and the adverse outcomes of phthalate exposure on male reproductive function have been reported. However, the direct relationship among these three factors remains unknown.

OBJECTIVE

To explore the potential roles of steroids involved in androgen synthesis in the association between phthalate exposure and semen quality.

METHODS

Eighteen phthalate metabolites (mPAEs) and nine steroids were analyzed in semen samples of 403 male participants aged 18-54 years from a hospital in Shenzhen, China. The associations across phthalate metabolites, steroids, and eleven semen quality parameters were evaluated by multivariate linear regression and logistical regression models. The potential contributions of steroids to the associations between phthalate metabolites and semen quality outcomes were explored by mediation effect analysis.

RESULTS

In this cross-sectional study, mono-n-butyl phthalate (MnBP) was inversely associated with nine continuous semen quality parameters in a dose-dependent manner (all p for trend < 0.05). Positive associations were observed between MnBP tertiles and androstenedione (ADD) and pregnenolone (PGL), of which only ADD was significantly associated with sperm quality (i.e., motility, p < 0.05). The estimated average mediated effects of seminal ADD on the associations between MnBP and lower sperm motility parameters (i.e., total motility, TR; progressive motility, PR; curvi-linear velocity, VCL) were 6.4-11.9% (all p < 0.05). The potential mediated effects of ADD on the increasing risks of TR (9.8%) and PR (8.5%) abnormalities induced by MnBP exposure were also observed in logistical regression analysis.

CONCLUSION

Our results indicated that androgen synthesis in reproductive system may be potentially affected by phthalate exposure, thereby resulting in reduced sperm motility in adult men. Further studies are needed to understand the actual roles and underlying mechanism of action of androstenedione on these associations.

The Different Facets of Triclocarban: A Review

In the late 1930s and early 1940s, it was discovered that the substitution on aromatic rings of hydrogen atoms with chlorine yielded a novel chemistry of antimicrobials. However, within a few years, many of these compounds and formulations showed adverse effects, including human toxicity, ecotoxicity, and unwanted environmental persistence and bioaccumulation, quickly leading to regulatory bans and phase-outs. Among these, the triclocarban, a polychlorinated aromatic antimicrobial agent, was employed as a major ingredient of toys, clothing, food packaging materials, food industry floors, medical supplies, and especially of personal care products, such as soaps, toothpaste, and shampoo. Triclocarban has been widely used for over 50 years, but only recently some concerns were raised about its endocrine disruptive properties. In September 2016, the U.S. Food and Drug Administration banned its use in over-the-counter hand and body washes because of its toxicity. The withdrawal of triclocarban has prompted the efforts to search for new antimicrobial compounds and several analogues of triclocarban have also been studied. In this review, an examination of different facets of triclocarban and its analogues will be analyzed.

4-Octylphenol induces developmental abnormalities and interferes the differentiation of neural crest cells in Xenopus laevis embryos

Developmental toxicity of 4-octylphenol (OP), an estrogenic endocrine disruptor was verified using frog embryo teratogenesis assay Xenopus. LC₅₀, EC_{50Malformtion} and EC_{50Melanocyte-dysgenesis} of OP were 9.9, 10.5, and 2.4 μM, respectively. In tadpoles, despite the low teratogenic index, 2 μM OP significantly inhibited head cartilage development and tail malformation. The total length of tadpole was significantly increased at 5 μM and decreased at 10 μM OP. In OP-treated tadpoles, head cartilages were frequently missed and col2a1 mRNA was decreased at 2 μM, indicating a chondrogenic defect in developing head. In the head skin of 1 μM OP-treated tadpoles, number of melanocytes and melanogenic pathway genes expression were significantly decreased. In the head-neck junction of stage 22 embryos, OP increased foxd3 and sox10 mRNA and SOX10(+) neural crest cells (NCCs) in somite mesoderm and endoderm, indicating the inhibition of chondrogenic differentiation, ectopic migration to endoderm, and undifferentiation of NCCs by OP. Together, OP-induced head dysplasia and inhibition of melanogenesis may be attributable to deregulation of neural crest cells in embryos. In tadpoles, OP at 1 μM significantly increased lipid hydroperoxide and induced spliced xbp1 mRNA, an IRE1 pathway endoplasmic reticulum stress (ERS) marker and p-eIF2α protein, a PERK pathway ERS marker. OP at 10 μM induced CHOP mRNA, pro-apoptotic genes expression, DNA fragmentation, and cleaved caspase-3, suggesting that OP differentially induced ERS and apoptosis according to the concentration in embryos. In 5-10 μM OP-treated stage 22 embryos and stage 45 tadpole heads, Ki67 was significantly increased, suggesting the apoptosis-induced proliferation of embryonic cells in the OP-treated embryos. Together, OP should be managed as a developmental toxicant altering the behavior of NCCs in vertebrates.

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

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

Phthalate exposure and semen quality in infertile male population from Tianjin, China: Associations and potential mediation by reproductive hormones

Global decline in male fertility and their associations with ubiquitous exposure of phthalates (PAEs) have raised public concerns. However, the current epidemiological data are limited and controversial. Hence, we investigated possible associations between PAE exposure and male infertility. Eleven phthalate metabolites (mPAEs) were determined in urine and serum samples collected from eighty-eight males diagnosed with infertility from Tianjin, China. The median serum levels of mPAE were n.d. -3.63 ng/mL, which were 1-2 orders of magnitude lower than the urinary levels of n.d. -192 ng/mL. Negative associations were identified between urinary follicle-stimulating hormone (FSH) and MiBP and serum MCMHP, as well as testosterone (T) and luteinizing hormone (LH) and the molar concentrations of ∑mPAE, while positive association was found between T and the serum molar concentrations of ∑mDEHP. Positive associations were found between the molar concentrations of serum ∑mPAE and sperm concentration, sperm motility rate, and progressive motility, between mono (2-ethyl-5-carboxypentyl) phthalate (MECPP) and semen volume and total sperm number, and between MCMHP and progressive motility, while negative association was found between mono(2-ethyl-5-oxohexyl) phthalate (MEOHP) and progressive motility. Moreover, FSH was found to mediate the association between serum concentrations of MCMHP and progressive motility (mediation ratio = 41.6%), and LH to mediate the associations between serum concentrations of ∑mPAE and sperm concentration (mediation ratio = 45.7%) and sperm motility rate (mediation ratio = 29.0%). These results also suggested that serum levels of mPAE are a good predictor for male infertility. Further efforts need to be made on toxicological studies to systematically elaborate the internal mechanisms.

The effects of postnatal exposure of endocrine disruptors on testicular function: a systematic review and a meta-analysis

BACKGROUND

Despite many epidemiological studies having been conducted, the impact of postnatal exposure of endocrine disruptors (EDs) on testicular function remains a controversial issue.

AIM

To systematically review the literature and perform a quantitative synthesis to evaluate the effect of EDs on testicular function.

MATERIALS AND METHODS

A comprehensive search was conducted in the MEDLINE, Scopus, and CENTRAL databases. Eligible for the systematic review were observational (cross-sectional and cohort) studies with (i) adult men who had a high probability of postnatal exposure to EDs ("exposed"), (ii) adult men who had a low probability of postnatal exposure to EDs ("non-exposed"), and (iii) an outcome of interest [seminal parameters and reproductive hormone concentrations]. The continuous outcomes in each of the studies were synthesized by the random effects model and expressed as standardized mean difference (SMD) with 95% confidence interval (CI).

RESULTS

Thirteen studies, including 959 exposed and 907 non-exposed men, fulfilled the inclusion criteria. Exposure to EDs was associated with decreased LH [SMD - 0.17, 95% CI - 0.33 to - 0.02, 10 studies (616 exposed, 563 non-exposed), I² 40%, p = 0.09], progressive motility [SMD - 0.45, 95% CI - 0.77 to - 0.13, three studies (133 cases, 153 controls), I² 38%, p = 0.20], and normal morphology [SMD - 0.50, 95% CI - 0.85 to - 0.14, eight studies (562 cases, 540 controls), I² 87%, p < 0.01] compared with non-exposure. No difference was observed between the other study groups.

CONCLUSIONS

Postnatal exposure to EDs is associated with decreased semen quality. Nevertheless, there is no evidence that a disruption of testicular function mediates the deterioration in semen quality.

Environmental contaminants and male infertility: Effects and mechanisms

The escalating prevalence of male infertility and decreasing trend in sperm quality have been correlated with rapid industrialisation and the associated discharge of an excess of synthetic substances into the environment. Humans are inevitably exposed to these ubiquitously distributed environmental contaminants, which possess the ability to intervene with the growth and function of male reproductive organs. Several epidemiological reports have correlated the blood and seminal levels of environmental contaminants with poor sperm quality. Numerous in vivo and in vitro studies have been conducted to investigate the effect of various environmental contaminants on spermatogenesis, steroidogenesis, Sertoli cells, blood-testis barrier, epididymis and sperm functions. The reported reprotoxic effects include alterations in the spermatogenic cycle, increased germ cell apoptosis, inhibition of steroidogenesis, decreased Leydig cell viability, impairment of Sertoli cell structure and function, altered expression of steroid receptors, increased permeability of blood-testis barrier, induction of peroxidative and epigenetic alterations in spermatozoa resulting in poor sperm quality and function. In light of recent scientific reports, this review discusses the effects of environmental contaminants on the male reproductive function and the possible mechanisms of action.

Urinary concentrations and distribution profiles of 21 phthalate metabolites in pet cats and dogs

Phthalates are widely used in several consumer products, including plastics, toys, cosmetics, and medical devices. Little is known about phthalate exposure in pet animals, however, even though they share an indoor environment with humans; this is the first study to measure such exposure. We measured 21 phthalate monoester metabolites (PhMs) in the urine of pet cats (n = 50) and dogs (n = 50) collected from New York State, USA. PhMs were widely detected in all samples, and 12 of 21 PhMs had detection frequencies (Dfs) >80%. The median urinary concentrations of total PhMs in pet cats and dogs were 630 ng/mL and 186 ng/mL, respectively. Monoethyl phthalate (mEP) was the most abundant compound in both cats and dogs. Phthalic acid (PA; a non-specific metabolite of phthalates) was found at very high concentrations in cats (median: 520 ng/mL). The estimated daily intake (EDI) and hazard quotient (HQ) for major phthalates in pets showed that DEHP exposures in cats and dogs were only 2-fold less than the US Environmental Protection Agency suggested reference dose (RfD) for humans.

Phthalate exposure and female reproductive and developmental outcomes: a systematic review of the human epidemiological evidence

OBJECTIVE

We performed a systematic review of the epidemiology literature to identify the female reproductive and developmental effects associated with phthalate exposure.

DATA SOURCES AND STUDY ELIGIBILITY CRITERIA

Six phthalates were included in the review: di(2-ethylhexyl) phthalate (DEHP), diisononyl phthalate (DINP), dibutyl phthalate (DBP), diisobutyl phthalate (DIBP), butyl benzyl phthalate (BBP), and diethyl phthalate (DEP). The initial literature search (of PubMed, Web of Science, and Toxline) included all studies of female reproductive and developmental effects in humans, and outcomes were selected for full systematic review based on data availability.

STUDY EVALUATION AND SYNTHESIS METHODS

For each outcome, studies were evaluated using criteria defined a priori for risk of bias and sensitivity by two reviewers using a domain-based approach. Evidence was synthesized by outcome and phthalate and strength of evidence was summarized using a structured framework.

RESULTS

The primary outcomes reviewed here are (number of included/excluded studies in parentheses): pubertal development (5/13), time to pregnancy (3/4), preterm birth (8/12), and spontaneous abortion (5/0). Among these outcomes, preterm birth had moderate evidence of a positive association with phthalate exposure (specifically DEHP, DBP, and DEP). Exposure levels for BBP, DIBP, and DINP were generally lower than for the phthalates with an observed effect, which may partially explain the difference due to lower sensitivity. Other phthalate/outcome combinations were considered to have slight or indeterminate evidence of an association.

CONCLUSIONS AND IMPLICATIONS OF KEY FINDINGS

Overall, these results support that some phthalates may be associated with higher odds of preterm birth in humans, though there is some remaining inconsistency. More evidence is needed on the mechanism and relevant exposure window for this association. The views expressed are those of the authors and do not necessarily represent the views or policies of the U.S. EPA.

Exposure Assessment of Bisphenols in Chinese Women during Pregnancy: A Longitudinal Study

Bisphenol S (BPS) and bisphenol F (BPF) are increasingly used in manufacturing consumer products to replace the use of bisphenol A (BPA), but exposure data are limited, particularly among pregnant women. Here, we measured BPA, BPS, and BPF levels in urine samples, collected from 941 pregnant women over three trimesters. We examined the correlations, coexposure patterns, variability, and predictors of bisphenols using Spearman's correlation coefficient, percentile analysis, intraclass correlation coefficient, and linear mixed models, respectively. We assessed health risks using average concentrations of bisphenols over three trimesters. The three bisphenols were detected in more than 50% of samples, among which BPA was the predominant one. Cashiers, office workers, teachers, and salespersons had elevated urinary BPS concentrations, while healthcare workers had relatively higher BPA concentrations. About 15 participants had potential health risks induced by exposure to bisphenol mixtures. These findings indicate that exposure to multiple bisphenols at low levels is common over three trimesters. Multiple measurements of urinary BPA and BPS concentrations are needed for more accurate evaluation of the exposure levels during pregnancy, while urinary BPF concentrations during pregnancy are moderately reliable. Occupational exposure should be taken into consideration in future demographic studies.

A Review of Biomonitoring of Phthalate Exposures

Phthalates (diesters of phthalic acid) are widely used as plasticizers and additives in many consumer products. Laboratory animal studies have reported the endocrine-disrupting and reproductive effects of phthalates, and human exposure to this class of chemicals is a concern. Several phthalates have been recognized as substances of high concern. Human exposure to phthalates occurs mainly via dietary sources, dermal absorption, and air inhalation. Phthalates are excreted as conjugated monoesters in urine, and some phthalates, such as di-2-ethylhexyl phthalate (DEHP), undergo secondary metabolism, including oxidative transformation, prior to urinary excretion. The occurrence of phthalates and their metabolites in urine, serum, breast milk, and semen has been widely reported. Urine has been the preferred matrix in human biomonitoring studies, and concentrations on the order of several tens to hundreds of nanograms per milliliter have been reported for several phthalate metabolites. Metabolites of diethyl phthalate (DEP), dibutyl- (DBP) and diisobutyl- (DiBP) phthalates, and DEHP were the most abundant compounds measured in urine. Temporal trends in phthalate exposures varied among countries. In the United States (US), DEHP exposure has declined since 2005, whereas DiNP exposure has increased. In China, DEHP exposure has increased since 2000. For many phthalates, exposures in children are higher than those in adults. Human epidemiological studies have shown a significant association between phthalate exposures and adverse reproductive outcomes in women and men, type II diabetes and insulin resistance, overweight/obesity, allergy, and asthma. This review compiles biomonitoring studies of phthalates and exposure doses to assess health risks from phthalate exposures in populations across the globe.

A systematic review: Impact of endocrine disrupting chemicals exposure on fecundity as measured by time to pregnancy

BACKGROUND

Emerging scientific evidence suggests that exposure to environmental pollutants is associated with negative effects on fecundity as measured by time to pregnancy (TTP).

OBJECTIVES

To conduct a systematic review of the literature on the association between selected endocrine disrupting chemicals (EDCs), and fecundity as measured by TTP in humans. Compounds included in this review are: brominated flame retardants (BFRs) such as hexabromocyclododecane, tetrabromobiphenol A and polybrominated diphenyl ethers; organophosphates flame retardants (OPFRs); and phthalates.

METHODS

Scopus, MEDLINE via Ebscohost and EMBASE databases were searched for articles exploring the relationships between selected EDCs and fecundity as measured by time to pregnancy. We assessed the quality of included studies and evidence for causality was graded using the criteria developed by the World Cancer Research Fund.

RESULTS

14 studies of 191 full-text articles assessed for eligibility were included for qualitative synthesis. Five studies examined BFRs and 10 studies examined phthalates. Among the fourteen, one study assessed both BFRs and phthalates. There were no studies which investigated fecundity as measured by TTP on HBCD, TBBPA, or OPFRs. We recorded plausible fecundity outcomes as measured by TTP related to some of these EDCs. BFRs or phthalates increased TTP. However, results were inconsistent.

CONCLUSION

We recorded mostly weak associations between exposure to selected EDCs and fecundity. However, evidence was considered limited to conclude a causal relationship due to inconsistency of results. The health risks posed by these chemicals in exposed populations are only beginning to be recognized and prospective measurement of the environmental effects of the chemicals in large cohort studies are urgently needed to confirm these relationships and inform policies aimed at exposure prevention.

Occurrence of benzophenones, parabens and triclosan in the Yangtze River of China, and the implications for human exposure

Humans could be exposed to ingredients in personal care products (PCPs) via ingestion of water originated from contaminated water source, yet little attention has been focused on the distribution of benzophenones, parabens and triclosan in the Yangtze River water from China so far. Benzophenones, parabens and triclosan were analyzed in the water samples from 20 various sites in the middle reach of the Yangtze River, China from March to July, and September during 2015. Among the targeted compounds, p-hydroxybenzoic acid (PHBA, a paraben metabolite) was found with the highest concentration (median: 510 ng/L), followed by benzophenone-1 (2.79 ng/L), methylparaben (MeP, median 2.72 ng/L) and triclosan (median: 1.85 ng/L). Significant differences were observed in seasonal variations for most observed compounds. Parabens and benzophenones showed higher concentrations in spring while triclosan and PHBA showed higher concentration in summer. Spatial variations of benzophenone-1 were observed among 20 sampling sites, whereas other benzophenones, parabens and triclosan distributed evenly comparatively. Human exposure assessment showed higher estimated daily intake of the detected compounds for infants and toddlers from water than adults, implicating that infants may experience a higher exposed risk than adults. This study provides evidence that parabens, benzophenones and triclosan commonly occurred in the Yangtze River.

Preconception seminal plasma concentrations of endocrine disrupting chemicals in relation to semen quality parameters among male partners planning for pregnancy

BACKGROUND

Some non-persistent endocrine disruptors (EDCs) are adversely associated with semen quality and few studies have measured those EDCs in seminal plasma.

OBJECTIVE

To find an association between EDCs in seminal plasma and semen quality parameters.

METHODS

Five chemical classes of non-persistent EDCs were quantified in seminal plasma from 339 male partners who participated in a prospective pregnancy study. Bisphenols, benzophenone UV-filters, antimicrobials and phthalate diesters and their monoester metabolites were measured using high performance liquid chromatography-tandem mass spectrometry and gas chromatography-mass spectrometry. Semen samples underwent next day analysis using a standardized protocol for the quantification of 35 endpoints. Linear mixed-effects models of EDCs that were log transformed and rescaled by their standard deviations or dichotomized at the 75th percentile for each exposure and outcomes with covariate adjustment were performed. EDCs in seminal plasma were also assessed relative to clinical reference values of semen quality endpoints using logistic regression or generalized estimating equations.

RESULTS

The most consistent findings supporting adverse associations between seminal EDCs and semen quality were observed for some phthalate metabolites. For example, seminal plasma mono-ethyl, mono-n-butyl, mono-2-isobutyl and mono-benzyl phthalate concentrations were associated with decreased odds of having semen volume above clinical reference values (mEP: aOR=0.46; 95%CI= 0.32, 0.66; mBP: aOR=0.40; 95%CI= 0.28, 0.57; miBP: aOR=0.39; 95%CI= 0.27, 0.56), and mBzP: aOR= 0.34; 95%CI= 0.24, 0.49).

CONCLUSIONS

Environmentally relevant concentrations of specific phthalates in seminal plasma were associated with diminished semen volume, sperm motility, viability, and morphological alterations in sperm heads such that semen volume and sperm viability fall below reference values.

Effect of endocrine disruptors on the ratio of X and Y chromosome-bearing live spermatozoa

Although equal numbers of X and Y spermatozoa are produced during spermatogenesis, the sex chromosome ratio in ejaculated spermatozoa can be altered by exposure to endocrine-disrupting chemicals (EDCs), which can be reflected by altered sex ratios at birth. Here, we hypothesized EDCs affect sperm functions and viability of X and Y chromosome-bearing human spermatozoa. After exposure to genistein (Gen), bisphenol A (BPA), 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), dibromochloropropane (DBCP), and diazinon (Diaz), we evaluated motility, viability, capacitation, and differential viability of X and Y spermatozoa. All EDCs tested altered sperm viability, motility, and capacitation. Interestingly, the Y/X ratio of live spermatozoa was significantly lower in sperm treated with TCDD, DBCP, and Diaz than control spermatozoa. Our results suggest that some of EDCs have larger effects on the viability of Y spermatozoa than X spermatozoa, implicating that a reduction in Y sperm viability may result in a female-biased sex ratio of offspring at birth.