Exposure to widespread environmental endocrine disrupting chemicals and human sperm sex ratio

Degradation of sulfonamide antibiotic via UV/MgO2 system: kinetic, application, and mechanism

In response to antibiotic residues in the water, a novel advanced oxidation technology based on MgO2 was used to remediate sulfamethazine (SMTZ) pollution in aquatic environments. Upon appropriate regulation, the remarkable removal efficiency of SMTZ was observed in a UV/MgO2 system, and the pseudo-first-order reaction constant reached 0.4074 min-1. In addition, the better performance of the UV/MgO2 system in a weak acid environment was discovered. During the removal of SMTZ, the pathways of SMTZ degradation were deduced, including nitration, ring opening, and group loss. In the mineralization exploration, the further removal of residual products of SMTZ by the UV/MgO2 system was visually demonstrated. The qualitative and quantitative researches as well as the roles of reactive species were valuated, which revealed the important role of ·O2-. Common co-existing substances in actual wastewater such as NO3- HA, Cl-, Fe2+, Co2+, and Mn2+ can slightly inhibit the degradation of SMTZ in the UV/MgO2 system. Finally, the capacity of efficient degradation of SMTZ in actual wastewater by the UV/MgO2 system was proved. The results indicated that the innovative UV/MgO2 system was of great practical application prospect in antibiotic residue wastewater remediation.

Endocrine disrupting chemicals and their effects on the reproductive health in men

Endocrine Disrupting Chemicals (EDCs) are harmful compounds that enter the environment naturally or through anthropogenic activities and disrupt normal endocrine functions in humans, adversely affecting reproductive health. Among the most significant sources of EDC contaminants are the pharmaceutical, cosmetic, and packaging industries. EDCs have been identified to have a deteriorating effect on male reproductive system, as evidenced by the increasing number of male infertility cases. A large number of case studies have been published in which men exposed to EDCs experienced testicular cancer, undescended testicles, a decrease in serum testosterone levels, and poor semen quality. Furthermore, epidemiological evidence suggested a link between prenatal EDC exposure and cryptorchidism or undescended testicles, hypospadias, and decreased anogenital distance in infants. The majority of these findings, however, are incongruent due to the lack of long-term follow-up studies that would demonstrate EDCs to be associated with male reproductive disorders. This review aims to provide an overview on recent scientific progress on the association of EDCs to male reproductive health with special emphasis on its toxicity and possible mechanism of EDCs that disrupt male reproductive system.

Associations between seminal plasma triclosan and low sperm quality: A case-control study

OBJECTIVE

Triclosan (TCS), a novel endocrine disrupter, has induced widespread human exposure due to its widespread use in personal care products. Environmental TCS exposure was suggested to be associated with human semen quality. However, little is known about seminal plasma TCS concentration and the risk of low sperm quality. This case-control study is established to examine the relationship between seminal plasma TCS and the risk of low sperm quality.

STUDY DESIGN

One hundred men with low sperm quality as cases and one hundred normal men as controls were recruited a fertility clinic in Shijiazhuang, China, during 2018-2019. Seminal plasma TCS concentration was determined using an ultrahigh-performance liquid chromatography-tandem mass spectrometer (UPLC-MS/MS). Sperm concentration, sperm count, sperm motility and sperm progressive motility were evaluated according to World Health Organization (WHO) guidelines to assess the sperm quality. We used the Mann-Whitney rank-sum test and Kruskal-Wallis test to assess the differences of seminal plasma TCS concentration between the cases and the controls. In addition, logistic regression analysis was used to estimate the associations between seminal plasma TCS concentrations and low sperm quality risk adjusting for age, body mass index (BMI), abstinence time, smoking, and drinking RESULTS AND CONCLUSIONS: The level of seminal plasma TCS was observed slightly but not significantly higher in the case group than the control group. We also observed significant association between seminal plasma TCS concentrations and semen parameters in both control and case groups. Moreover, the seminal plasma TCS levels at the fourth quartile were found to be more likely to exhibit low sperm quality risk with increased adjusted odds ratios of 2.36 (95% confidence interval 1.03-5.39) compared to the first quartile. Our results reveal that seminal plasma TCS concentration was positively associated with low sperm quality risk.

Establishing the relationship between Polycyclic Aromatic Hydrocarbons (PAHs) exposure and male infertility: A systematic review

It has been demonstrated that human exposure to environmental chemicals may have sperm genotoxic potentiality. Among the different classes, Polycyclic Aromatic Hydrocarbons (PAHs) have been receiving attention in recent years due to reports of sperm geno-toxicity, a series of reproductive defects and male infertility. This review aims to substantiate the effects of PAHs exposure on male infertility, with focus on the sperm characteristics (count, concentration, volume, motility, DNA damage, and morphology). To this end, international databases such as Cochrane Library, PubMed, Web of Science, Embase Ovid, Scopus, and Google Scholar were used to conduct a systematic search for papers on the subject, based on PRISMA guidelines, published up to 24 March 2022. The Newcastle-Ottawa Scale was subsequently used to assess the quality of the studies. The results showed that there is a significant negative relationship between PAHs metabolites and sperm volume, concentration, motility, morphology, as well as an observed DNA degeneration. Also, the CYP1A1 genotype polymorphisms were considered as a representative of PAHs exposure to infertility; the review highlights that polymorphisms of this genotype were more common in the infertile people. In overall, this work provides a solid summary of the existing works correlating PAHs exposure and male infertility, which could impulse further protective measures and informative campaigns on users, workers, and general population.

Androgen receptor signaling and pyrethroids: Potential male infertility consequences

Infertility is a global health concern inflicting a considerable burden on the global economy and a severe socio-psychological impact. Approximately 15% of couples suffer from infertility globally, with a male factor contribution of approximately 50%. However, male infertility remains largely unexplored, as the burden of infertility is mostly assigned to female people. Endocrine-disrupting chemicals (EDCs) have been proposed as one of the factors causing male infertility. Pyrethroids represent an important class of EDCs, and numerous studies have associated pyrethroid exposure with impaired male reproductive function and development. Therefore, the present study investigated the potentially toxic effects of two common pyrethroids, cypermethrin and deltamethrin, on androgen receptor (AR) signaling. The structural binding characterization of cypermethrin and deltamethrin against the AR ligand-binding pocket was performed using Schrodinger's induced fit docking (IFD) approach. Various parameters were estimated, such as binding interactions, binding energy, docking score, and IFD score. Furthermore, the AR native ligand, testosterone, was subjected to similar experiments against the AR ligand-binding pocket. The results revealed commonality in the amino acid-binding interactions and overlap in other structural parameters between the AR native ligand, testosterone, and the ligands, cypermethrin and deltamethrin. The estimated binding energy values of cypermethrin and deltamethrin were very high and close to those calculated for AR native ligand, testosterone. Taken together, the results of this study suggested potential disruption of AR signaling by cypermethrin and deltamethrin, which may result in androgen dysfunction and subsequent male infertility.

Exposure Levels of Pyrethroids, Chlorpyrifos and Glyphosate in EU-An Overview of Human Biomonitoring Studies Published since 2000

Currently used pesticides are rapidly metabolised and excreted, primarily in urine, and urinary concentrations of pesticides/metabolites are therefore useful biomarkers for the integrated exposure from all sources. Pyrethroid insecticides, the organophosphate insecticide chlorpyrifos, and the herbicide glyphosate, were among the prioritised substances in the HBM4EU project and comparable human biomonitoring (HBM)-data were obtained from the HBM4EU Aligned Studies. The aim of this review was to supplement these data by presenting additional HBM studies of the priority pesticides across the HBM4EU partner countries published since 2000. We identified relevant studies (44 for pyrethroids, 23 for chlorpyrifos, 24 for glyphosate) by literature search using PubMed and Web of Science. Most studies were from the Western and Southern part of the EU and data were lacking from more than half of the HBM4EU-partner countries. Many studies were regional with relatively small sample size and few studies address residential and occupational exposure. Variation in urine sampling, analytical methods, and reporting of the HBM-data hampered the comparability of the results across studies. Despite these shortcomings, a widespread exposure to these substances in the general EU population with marked geographical differences was indicated. The findings emphasise the need for harmonisation of methods and reporting in future studies as initiated during HBM4EU.

A systematic review of human biomonitoring studies of 3-phenoxybenzoic acid, a urinary biomarker pyrethroid insecticide exposure, 1997 to 2019

Pyrethroid insecticides are used, for example, in agriculture, indoor environments, and mosquito control programs, resulting in human exposure. Urinary 3-phenoxybenzoic acid (3-PBA) is a nonspecific biomarker for exposure to many pyrethroids. This systematic review identified human biomonitoring studies with 3-PBA that characterize environmental pyrethroid exposures in children and adolescents, pregnant women, and adults or occupational pyrethroid exposures relative to the National Health and Nutrition Examination Survey (NHANES) populations in the United States (US). PubMed, Embase, and SciFinder were searched for "3-phenoxybenzoic acid ", CAS No. 3739-38-6, and urine or urinary or urine level. Duplicate studies and studies meeting the exclusion criteria were removed from the search results based on predetermined exclusion criteria. This screening process identified 57 papers. Twenty-one, thirteen, twenty-two, and eleven manuscripts reported urinary 3-PBA levels in children, pregnant women, environmentally exposed adults, and occupationally exposed adults, respectively. Median 3-PBA levels ranged from 0.2 to 4.7 μg/g creatinine in children (1999-2016), 0.23-1.55 μg/g creatinine in pregnant women (1997-2014), and 0.11-3.34 μg/g creatinine in environmentally exposed adults (1999-2017). 3-PBA levels in occupationally exposed adults were significantly higher than in environmentally exposed populations, ranging from 0.43 to 14 μg/g creatinine (2004-2017). 3-PBA levels in children and adults from the general North American population increased significantly with the sampling year. A decrease in 3-PBA levels was noted in the adult cohorts from PR China and Japan. 3-PBA levels in most studies appeared to be comparable to levels in the NHANES populations; however, some smaller studies had high pyrethroid exposures. Factors contributing to higher 3-PBA levels in the general population included primarily dietary exposures and residential and agricultural pyrethroid applications. These findings demonstrate that pyrethroid exposures are near-ubiquitous worldwide and, in some regions, appear to increase over time. Thus, exposures to pyrethroid insecticides represent a continuing public health concern.

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.

From Oxidative Stress to Male Infertility: Review of the Associations of Endocrine-Disrupting Chemicals (Bisphenols, Phthalates, and Parabens) with Human Semen Quality

Exposure to endocrine-disrupting chemicals (EDCs) may result in oxidative stress and endocrine system disturbance, which can have an impact on human reproduction and development. In male reproductive health, EDCs have been related to impaired reproductive function and male infertility, altered fetal development, and testicular germ-cell, prostate, and breast cancers. We conducted an electronic search using PubMed on endocrine disruptors related to oxidative stress and male infertility, and evaluated their association with endocrine-disrupting chemicals (bisphenols, phthalates, and parabens) in 25 articles. Higher levels of urinary bisphenols showed correlation with impaired semen quality and increased DNA damage. Considering phthalates and their metabolites, all studies found a positive association between urinary levels of phthalates and at least one semen parameter indicative of low semen quality; some studies also revealed sperm DNA damage. The studies on parabens less often revealed correlation of urinary parabens concentrations with a decrease in sperm count, as well as motility and DNA damage. Moreover, EDCs can elevate ROS production and lipid peroxidation, increase apoptosis, induce epigenetic modifications, and change the Y:X sperm chromosome ratio and sperm protein composition. Our review revealed detrimental effects of EDCs on semen quality and sperm DNA integrity-especially in BPA and phthalates, but also in parabens.

Di-(2-ethylhexyl) phthalate exposure leads to ferroptosis via the HIF-1α/HO-1 signaling pathway in mouse testes

Di-(2-ethylhexyl) phthalate (DEHP) is an extensively used plasticizer and has been shown to cause reproductive dysfunction in humans and model animals. However, the exact mechanisms of testicular injury induced by DEHP exposure have not been fully clarified. Using gas chromatography-mass spectrometry, we found that mono-2-ethylhexyl ester (MEHP, a major biometabolite of DEHP) and DEHP concentrations were elevated in mouse serum after DEHP exposure. Using RNA-seq, we found that ferroptosis and HIF-1 signaling pathways might be involved in testicular injury due to prepubertal DEHP exposure. Subsequent Western blotting, ferrous iron and MDA measurements, and immunofluorescence of testicular sections verified the RNA-seq findings. Consistently, based on the RNA-seq findings, we found that ferroptosis and HIF-1 signaling pathways might play crucial roles in Leydig and Sertoli cell injury due to MEHP exposure in vitro. Further experiments also confirmed ferroptosis in Leydig and Sertoli cells. Using Western blotting, cellular immunofluorescence and ChIP-qPCR, we found that MEHP exposure caused HIF-1α accumulation and stabilization, resulted in HIF-1α translocation into the nucleus, and induced HIF-1α/Hmox1 binding in Leydig and Sertoli cells. To clarify whether HIF-1α plays a pivotal role in MEHP-induced ferroptosis, we knocked out Hif-1α using the CRISPR/Cas9 technique. We found that Hif-1α knockout rescued MEHP-induced ferroptosis. In summary, our findings certified that prepubertal DEHP exposure led to ferroptosis in mouse testes via the HIF-1α/HO-1 signaling pathway.

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.

LncRNAs activate longevity regulation pathway due to aging of Leydig cells caused by DEHP exposure: A transcriptome-based study

Di-(2-ethylhexyl) phthalate (DEHP), one of the most commonly used endocrine-disrupting chemicals, has been shown to cause reproductive dysfunction in humans and animal models. However, very few studies have investigated the impact of DEHP at the post-transcriptional level in mouse testes, and the underlying mechanisms remain unclear. In the present research, TM3 Leydig cells were treated with 200 µM phthalic acid mono-2-ethylhexyl ester (MEHP, bio-metabolite of DEHP), and then the mRNA and lncRNA sequencing of TM3 Leydig cells was performed. Mice were exposed prepubertally to 0 or 500 mg DEHP/kg/day. RNA sequencing of mouse testes was performed to verify the RNA-seq results in vitro. The expression patterns of relevant genes and proteins were verified using real-time quantitative polymerase chain reaction (RT-qPCR) and western blotting. DEHP and MEHP exposure led to testicular damage and accelerated cell aging via ROS accumulation. RNA sequencing analyses indicated that FOXO signaling and longevity regulation pathways were activated in resistance to ROS accumulation. FOXO signaling and longevity regulation pathway-related genes and proteins were also activated. By constructing a competing endogenous RNA (ceRNA) network, we observed that the ceRNA network might play a role in regulating FOXO signaling and longevity regulation pathways in response to excessive ROS accumulation and cell aging. In summary, our data here suggests that the ceRNA network may play a role in regulating FOXO signaling and longevity pathways in response to DEHP exposure in mouse testes.

Pyrethroids Toxicity to Male Reproductive System and Offspring as a Function of Oxidative Stress Induction: Rodent Studies

Pyrethroids may be related to male reproductive system damage. However, the results of many previous studies are contradictory and uncertain. Therefore, a systematic review and a meta-analysis were performed to assess the relationship between pyrethroid exposure and male reproductive system damage. A total of 72 articles were identified, among which 57 were selected for meta-analysis, and 15 were selected for qualitative analysis. Pyrethroid exposure affected sperm count (SMD= -2.0424; 95% CI, -2.4699 to -1.6149), sperm motility (SMD=-3.606; 95% CI, -4.5172 to -2.6948), sperm morphology (SMD=2.686; 95% CI, 1.9744 to 3.3976), testis weight (SMD=-1.1591; 95% CI, -1.6145 to -0.7038), epididymal weight (SMD=-1.1576; 95% CI, -1.7455 to -0.5697), and serum testosterone level (SMD=-1.9194; 95% CI, -2.4589 to -1.3798) in the studies of rats. We found that gestational and lactational exposure to pyrethroids can reduce sperm count (SMD=1.8469; 95% CI, -2.9010 to -0.7927), sperm motility (SMD=-2.7151; 95% CI, -3.9574 to -1.4728), testis weight (SMD=-1.4361; 95% CI, -1.8873 to -0.9848), and epididymal weight (SMD=-0.6639; 95% CI, -0.9544 to -0.3733) of F1 offspring. Exposure to pyrethroids can increase malondialdehyde (SMD=3.3451; 95% CI 1.9914 to 4.6988) oxide in testes and can reduce the activities of glutathione (SMD=-2.075; 95% CI -3.0651 to -1.0848), superoxide dismutase (SMD=-2.4856; 95% CI -3.9612 to -1.0100), and catalase (SMD=-2.7564; 95% CI -3.9788 to -1.5340). Pyrethroid exposure and oxidative stress could damage male sperm quality. Gestational and lactational pyrethroid exposure affects the reproductive system of F1 offspring.

Environmental exposure to pyrethroid pesticides in a nationally representative sample of U.S. adults and children: The National Health and Nutrition Examination Survey 2007-2012

Pyrethroids are an important class of insecticides, and thousands of tons of these compounds are used in the United States every year. This study characterized exposures to pyrethroids and assessed demographic, socioeconomic, and lifestyle factors that modulate pyrethroid exposure using data from the National Health and Nutrition Examination Survey (NHANES) 2007-2012, a nationally representative survey of the non-institutionalized population of the United States. Urinary levels of commonly used biomarkers of pyrethroid exposure, including 3-phenoxybenzoic acid (3-PBA), 4-fluoro-3-phenoxybenzoic acid (F-PBA), and cis-dibromovinyl-dimethylcyclopropane carboxylic acid (DBCA), were determined by liquid chromatography-tandem mass spectrometry. The detection rate of 3-PBA, a nonspecific metabolite of several pyrethroids, was 78.1% in adults (N = 5233) and 79.3% in children (N = 2295). The detection rates of all other pyrethroid metabolites were <10%. The median urinary level of 3-PBA in adults was 0.47 μg/L (interquartile range, 0.14-1.22 μg/L). For children, the median urinary level was 0.49 μg/L (interquartile range, 0.17-1.29 μg/L). Age, gender, family income-to-poverty ratio (PIR), levels of physical activity, alcohol intake, and body mass index were associated with 3-PBA levels in adults. In children, age, gender, race/ethnicity, and PIR were associated with 3-PBA levels. 3-PBA levels also differed significantly across NHANES cycles, with higher levels observed in NHANES 2011-2012. Geometric mean 3-PBA levels in U.S. adults were 0.41 μg/L in NHANES 2007-2008, 0.41 μg/L in NHANES 2009-2010, and 0.66 μg/L in NHANES 2011-2012. In U.S. children, geometric mean 3-PBA levels were 0.40 μg/L in NHANES 2007-2008, 0.46 μg/L in NHANES 2009-2010, and 0.70 μg/L in NHANES 2011-2012. These results demonstrate that pyrethroid exposures remain a current environmental health concern and lay the foundation for further preclinical and epidemiological studies assessing human health risks associated with pyrethroids.

Evaluation of 1-year urinary excretion of eight metabolites of synthetic pyrethroids, chlorpyrifos, and neonicotinoids

Synthetic pyrethroids, chlorpyrifos, and neonicotinoids are representatives of non-persistent insecticides ubiquitously used against insects all over the world. Their widespread use causes prevalent exposure to these compounds, which may be hazardous to human health. The insecticides have short biological half-lives and are mostly excreted in urine within 24 h after entering the human body; thus, the urinary concentration of their metabolites is highly dependent on the time elapsed between exposure and sample collection. Considering the within-day fluctuations in urinary concentration, one randomly collected sample may cause misclassification of long-term exposure. We evaluated the variability of excretion of eight insecticide metabolites in 24-h urine samples collected from 14 volunteers once or twice per month over 12 consecutive months. High detection frequency above 70% for non-specific metabolites of pyrethroid, chlorpyrifos, and neonicotinoids confirmed widespread exposure to these insecticides in the studied population. A long-term variability of exposure was assessed based on intraclass correlation coefficient (ICC). We found relatively low variability of excretion for non-specific pyrethroid metabolites and 3,5,6-trichloro-2-pyridinol (ICC > 0.75), but poor repeatability for 6-chloronicotinic acid. Constantly higher ICCs were observed for daily excretion than for unadjusted concentrations. Seasonal differences were observed for 3,5,6-trichloro-2-pyridinol and 6-chloronicotinic acid, with the highest and the lowest median concentration, respectively, in the summer. Due to high ICC values and lack of seasonal variations, one 24-h urine sample was considered sufficient to characterize long-term excretion of non-specific pyrethroid metabolites in non-occupationally exposed population. In addition, we calculated the daily intake (DI) for cypermethrin, permethrin, deltamethrin, and chlorpyrifos. The estimated DI values were mostly below the acceptable daily intake, which indicates that the evaluated exposure is non-hazardous to the population.

From bench to bedside: Biosensing strategies to evaluate endocrine disrupting compounds based on epigenetic events and their potential use in medicine

The relationship between endocrine system disorders and health risks due to chemical environmental compounds has become a growing concern in recent years. Involuntary exposure to endocrine disruptors (EDCs) is associated with the worldwide increase of diseases such as cancer, obesity, diabetes, and neurocortical disorders. EDCs are compounds that target the nuclear hormonereceptors (NHR) leading to epigenetic changes. Consequently, the use of biosensing strategies based on epigenetic events have a great potential to provide outstanding information about the exposition of EDCs and their evaluation in human health. This review addresses the novel trends in biosensing EDCs evaluation based on DNA methylation assays associated with different human diseases.

Endocrine-disrupting chemicals and male reproductive health

BACKGROUND

A number of different types of endocrine-disrupting chemicals (EDCs) including bisphenol A, phthalates, pesticides, and other environmental chemicals have been shown to adversely impact upon male reproductive health. Understanding the potential effects of EDCs on male reproductive health may enable the development of novel treatments and early prevention of the effects of EDCs on male infertility and their potential long-term sequelae. This review critically evaluates the research performed in this area and explores potential harmful effects of EDCs in animals and humans, including the possibility of trans-generational transmission.

METHODS

A literature review was conducted using electronic databases using the following terms: 'endocrine disrupt*' OR 'endocrine disruptors' OR 'endocrine disruptor chemicals' OR 'EDC' AND 'sperm*' OR 'spermatozoa' OR 'spermatozoon' OR 'male reproductive health' OR' male fertility'.

MAIN FINDINGS

Several studies have shown that EDCs have a variety of pathophysiological effects. These include failure of spermatogenesis, embryonic development, the association with testicular cancer, and long-term metabolic effects.

CONCLUSIONS

Several studies observe correlations between chemical doses and at least one sperm parameter; however, such correlations are sometimes inconsistent between different studies. Mechanisms through which EDCs exert their pathophysiological effects have not yet been fully elucidated in human studies.

Association between phthalate exposure and asthma risk: A meta-analysis of observational studies

BACKGROUND

Phthalates are ubiquitously found in numerous environments and have been related to a variety of adverse health effects. Previous studies have suggested that phthalate exposure is associated with asthma risk in humans; however, such findings are inconsistent.

METHODS

The aim of the present meta-analysis was to clarify the association between phthalate exposure and asthma risk. A literature search was conducted using PubMed, EMBASE and Web of Science for relevant studies published up to January 5, 2020. Fixed-effects or random-effects models were applied to combine the results, and several subgroup analyses were used to explore the sources of heterogeneity.

RESULTS

A total of 14 studies containing more than 14,000 participants were included in the present study. A positive, significant association between mono-benzyl phthalate (MBzP) levels and asthma risk was found, and the overall odds ratio (OR) was 1.17 (95% confidence interval [CI]: 1.06-1.28, P-value for overall effect [P_z] = 0.001), with a low heterogeneity (P-value for heterogeneity [P_het] = 0.193, I² = 23.6%). The pooled ORs for mono-(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP) and mono-(2-ethyl-5-carboxypentyl) phthalate (MECPP) concentrations were 1.13 (95% CI: 1.03-1.24, P_z = 0.011) and 1.20 (95% CI: 1.00-1.42, P_z = 0.045), respectively. Children with high levels of MBzP or mono-(carboxynonyl) phthalate (MCNP) were suggested to have increased odds of asthma compared to older populations. In the subgroup analysis by study location, an increased risk for asthma in relation to levels of the sum of di-2-ethylhexyl phthalate (ΣDEHP) was observed in European studies (OR = 1.16, 95% CI: 1.00-1.34, P_z = 0.048) compared to Asia and North America.

CONCLUSIONS

Urinary levels of MBzP, MEHHP, MECPP, MCNP, and DEHP were positively related to asthma risk. No significant association was observed for the other phthalate metabolites in relation to asthma risk. Further research is needed to verify these findings and shed light on the molecular mechanism by which phthalates are associated with asthma.

Effects of environmental pyrethroids exposure on semen quality in reproductive-age men in Shanghai, China

BACKGROUND

Animal experiments have revealed that pyrethroids (PYRs) exposure could affect semen quality, however evidence on humans being is limited and controversial.

OBJECTS

To explore the potential effects of environmental PYRs exposure on semen quality in reproductive age men.

METHODS

We conducted a cross-sectional study of 346 men who planned to conceive and addressed to hospital for preconception examination. PYRs exposure was assessed by analyzing PYRs urinary metabolites [3-phenoxybenzoic acid (3PBA), trans- and cis-3-(2,2-Dichlorovinyl) -2,2-dimethylcy clopropane carboxylic acid (TDCCA and CDCCA)] levels using gas chromatography-mass spectrometry. Semen quality was assessed by a computer-aided semen analyzer.

RESULTS

For a detection rate of 99.7%, 76.6%, and 22.0%, the median levels (μg/g creatinine) of PYRs metabolites were 0.46 for 3PBA, 0.38 for TDCCA and under detection limit for CDCCA. Linear regression models found negative associations between 3PBA and sperm morphology (β = -2.12, 95% CI: -4.02 to -0.22) as well as between TDCCA and log-transformed total sperm count (β = -0.09, 95% CI: -0.16 to -0.01). In logistic regression models, men with the highest quartile of 3PBA had higher risk of poor semen quality (having below-reference semen parameter, OR = 2.40, 95% CI: 1.26 to 4.54; having below-reference sperms morphology, OR = 3.08, 95% CI: 1.10 to 8.60) compared to men in the lowest quartile.

CONCLUSIONS

Our study suggests that environmental PYRs exposure might adversely affect semen parameters of reproductive age men in Shanghai, China. Further studies are needed to confirm our findings and demonstrate a causal relationship between PYRs exposure and semen quality.

A review of environmental and occupational toxins in relation to sex ratio at birth

A biased sex ratio at birth in human populations has been associated with numerous economic, psychosocial, environmental and demographic factors, and has been declining in most developed countries. One of the most often invoked explanation for this decline has been the growing environmental and occupational exposure to man-made chemicals that affect the reproductive physiology, putatively leading to altered sex ratios at birth. In this paper the current state of knowledge on the association between toxins and sex ratio at birth is presented and critically assessed. The evidence for the effect of toxins on sex ratio at birth is conflicting, with paternal exposure showing more promising results than maternal exposure. The obstacles in establishing more direct relation between toxins and sex ratio at birth involve different hormonal responses of mothers and fathers under the influence of toxins, the specific metabolic action of toxins, and the constraints of observational studies.

Local/traditional uses, secondary metabolites and biological activities of Mashua (Tropaeolum tuberosum Ruíz & Pavón)

ETHNOPHARMACOLOGICAL RELEVANCE

Tropaeolum tuberosum Ruíz & Pavón (Tropaeolaceae). Sim (commonly called Mashua) is an indigenous plant that has medicinal values for various ethnic groups of the regions of the Andes mountain range of South America, which use it for the treatment of diseases venereal, lung and skin; for the healing of internal and external wounds; and as an analgesic for kidney and bladder pain.

AIM OF THE REVIEW

We critically summarised the current evidence on the botanic characterisation and distribution, ethnopharmacology, secondary metabolites, pharmacological activities, qualitative and quantitative analysis, and toxicology of T. tuberosum.

MATERIALS AND METHODS

The relevant information on T. tuberosum was gathered from worldwide accepted scientific databases via electronic search (Google scholar, Elsevier, SciFinder, ScienceDirect, PubMed, SpringerLink, Web of Science, Scopus, Wiley Online, Mendeley, Scielo and Dialnet electronic databases). Information was also obtained from the literature and books as well as PhD and MSc dissertations. Plant names were validated by 'The Plant List' (www.theplantlist.org).

RESULTS

T. tuberosum has diverse uses in local and popular medicine, specifically for relieving pain and infections in humans. Regarding its biological activities, polar extracts (aqueous, hydroalcoholic) and isolated compounds from the tubers have exhibited a wide range of in vitro and in vivo pharmacological effects, including antibacterial, antioxidant, anti-inflammatory activities. Quantitative analysis (e.g., NMR, HPLC, GC-MS) indicated the presence of a set of secondary metabolites, including hydroxybenzoic acids, tannins, flavanols, anthocyanins, glucosinolates, isothiocyanates, phytosterols, fatty acids and alkamides in the tubers of T. tuberosum. Likewise, glucosinolates have been identified in the seeds and isothiocyanates have been detected in leaves, flowers and seeds.

CONCLUSIONS

T. tuberosum has been tested for various biological activities and the extracts (tubers in particular) demonstrated a promising potential as an antibacterial, antioxidant, anti-inflammatory and inhibitors of benign prostatic hyperplasia. A lack of alignment between the ethno-medicinal uses and existing biological screenings was observed, indicating the need to explore its potential for the treatment against respiratory affections, urinary affections and blood diseases. Likewise, it is necessary to analyse deeply the relationship that exists between the different tuber colours of T. tuberosum and its use for the treatment of certain diseases. Validation of clinical studies of the antibacterial, antioxidant/anti-inflammatory, anti-spermatogenic activities and as inhibitors of benign prostatic hyperplasia is required. Moreover, studies on the toxicity, bioavailability, and pharmacokinetics, in addition to clinical trials, are indispensable for assessing the safety and efficacy of the active metabolites or extracts obtained from T. tuberosum. Other areas that need investigation are the development of future applications based on their active metabolites, such as neurodegenerative diseases (Alzheimer's disease, Parkinson's disease, Huntington's disease). Finally, the work purposes to motivate other research groups to carry out a series of scientific studies that can fill the gaps that exist with respect to Mashua properties, and thus be able to change the focus of T. tuberosum (Mashua) that currently has in the consumer society.

The extent and predictors of phthalate exposure among couples undergoing in vitro fertilization treatment

Phthalates are chemicals used as plasticizers and solvents in many consumer products but are suspected of disrupting the endocrine system and are known for their reproductive/developmental health risks. This study examined the extent and predictors of phthalate exposure among 599 couples undergoing in vitro fertilization. A questionnaire was administered to obtain sociodemographic, health, and lifestyle data, and two spot urine samples were collected from the couples to analyze eight phthalate metabolites, cotinine (COT) as a smoking index, and creatinine to adjust for urine dilution. Seven phthalate metabolites were detected in > 94% of the urine samples, and monobenzyl phthalate (MBzP) was found in 24% of the women and 26% of their male partners. Median phthalate levels were highest for monoethyl phthalate (MEP), at 333.26 μg/l in women and 290 μg/l in male partners, and lowest for MBzP, at 1.17 μg/l in women and 1.14 μg/l in male partners. Correlation coefficients of ≥ 0.4 between the women and their male partners for the eight urinary phthalate metabolites may indicate a shared source of exposure. A multivariate regression model was used to assess the association between predictors and each urinary phthalate metabolite. Several potential predictors for the variations in specific urinary phthalate metabolites were identified, including the body mass index, age, socioeconomic status, and regional distribution for both women and their male partners but with slightly different patterns. Women with a history of breastfeeding, using bottled water for cooking and storing food in plastic bags had lower MEP (8.7%), mono-(2-ethyl-5-carboxypentyl) phthalate (MECPP) (9.2%), and both mono-iso-butyl phthalate and MECPP (8.2 and 8.1%). A history of contraceptive use was associated with an increase in MECPP (8.7%), mono-(2-ethyl-5-hydroxyhexyl) phthalate (11.4%), mono-(2-ethyl-5-oxohexyl) phthalate (7.6%), and the molar sum of bis (2-ethylhexyl) phthalate metabolites (8.9%). Urinary COT levels were associated with an increase of 10-16% in all urinary metabolites in women but of only 10.5% in mono-(2-ethylhexyl) phthalate in male partners. More than 95% of the couples reported the use of cosmetics, perfumes, and personal-care products, but we were not able to find associations with urinary phthalate metabolites, perhaps due to their short half-lives. MEP levels associated with the use of household cleaning products were 11.2% higher in male partners. Our levels were generally higher than those reported elsewhere, perhaps due to different lifestyles, cultural practices, dietary habits, use of personal-care products, and governmental legislation.

Graphene oxide based molecularly imprinted polymers modified with β-cyclodextrin for selective extraction of di(2-ethylhexyl) phthalate in environmental waters

Graphene oxide based molecularly imprinted polymers modified with β-cyclodextrin were prepared as solid-phase extraction column sorbents for specific recognition and sensitive detection of di(2-ethylhexyl) phthalate in water samples. The morphology and composition of synthesized sorbents were characterized by scanning electron microscopy, thermo-gravimetric analysis, Raman spectroscopy, and Fourier-transform infrared spectroscopy. The conditions affecting the performance of extraction procedures such as desorption solvent types and volume, sample pH and volume were investigated. The loading capacity (8.2 μg/mg) of the prepared sorbents increased eight times after modification with β-cyclodextrin. The developed extraction procedures coupled to high-performance liquid chromatography exhibited good linearity (0.2-500 μg/L), low limit of detection (0.052 μg/L), and good precision (relative standard deviation˂5.7%) under optimized conditions. The developed solid-phase extraction technique with prepared sorbents has been successfully applied in extracting trace di(2-ethylhexyl) phthalate from real natural waters with high efficiency, good selectivity, and desirable recoveries.

Revisiting the Trivers-Willard theory on birth sex ratio bias: Role of paternal condition in a Malagasy primate

Within current theories on potential adaptive manipulation of offspring sex ratio, giving birth to a male or to a female is assumed to depend on the capacity of the mother to invest in offspring to maximize her fitness. The active role of the father in sex ratio bias at birth has been neglected until recently. The human sex ratio at birth is biased towards sons, although in occidental populations, the ratio has decreased regularly for 30 years and could be the consequence of the adverse effects of environmental chemicals on male hormones. In a Malagasy primate, the lesser mouse lemur, the potential effect of paternal testosterone levels on sex ratio bias at birth was tested on 130 litters (278 babies) produced in 52 mixed-sex groups. For each group, social dominance among males was characterized based on aggressive interactions and sexual behaviours. Using a multi correspondence analysis, high testosterone levels in grouped males, particularly those of the dominant male, were significantly correlated with more infants produced in male-biased litters, independent of the female condition. According to these results, predictions for sex ratio bias towards one sex or the other in mouse lemurs were discussed considering the influence of both parents.

Pyrethroid epidemiology: a quality-based review

Pyrethroids are commonly used around the home and in agricultural production to control insects. Human contact to one or more pyrethroid insecticides is likely. Numerous epidemiology studies have evaluated the association between health outcomes in humans and pyrethroid exposure. The purpose of this review was to identify and evaluate the quality of pyrethroid-related epidemiology studies that addressed chronic health effects, and compare findings with animal toxicology studies. We evaluated the quality of 61 studies published between 2000 and 2016 by using elements of outcome, exposure metric, exposure level, and study design. None of the 61 publications demonstrated strong quality for all elements. A few of the outcome measures were strong, particularly those relying upon medical diagnoses. Most of the pyrethroid epidemiology studies used a poor exposure metric, relying upon a single sample of pyrethroid urinary metabolites, which is subject to misclassification of past exposures. In addition, many studies were a cross-sectional design, preventing an evaluation of the temporality of the exposure-disease association. Furthermore, none of the effects observed in the epidemiological literature was concordant with toxicological effects noted in extensive testing of pyrethroids in animals. In order to provide more robust data on potential health outcomes from low dose exposure to pyrethroid insecticides, future epidemiological studies should fully characterize an adverse outcome, include exposure validation components, and quantify exposure over time.

Air Pollution and Human Sperm Sex Ratio

The present study was designed to address the hypothesis that exposure to specific air pollutants may impact human sperm Y:X chromosome ratio. The study population consisted of 195 men who were attending an infertility clinic for diagnostic purposes and who had normal semen concentration of 15–300 mln/ml (WHO, 2010). Participants represented a subset of men in a multicenter parent study conducted in Poland to evaluate environmental factors and male fertility. Participants were interviewed and provided a semen sample. The Y:X ratio was assessed by fluorescent in situ hybridization (FISH). Air quality data were obtained from the AirBase database. In multivariate analysis the significant reduction was observed in the proportion of Y/X chromosome bearing sperm and exposure to particulate matter >10 μm in aerodynamic diameter PM₁₀ (p = .009) and particulate matter <10 μm in aerodynamic diameter PM_2.5 (p = .023). The observed effects of a lower Y:X sperm chromosome ratio among men exposed to air pollution support the evidence that the trend of declining sex ratio in several societies over past decades has been due to exposure to air pollution; however due to limited data on this issue, the obtained results should be confirmed in longitudinal studies.

A review of the established and suspected causes of variations in human sex ratio at birth

The human sex ratio (proportion male) at birth (SRB) varies with many variables. Some of this variation has an established proximate cause. For instance, low SRB (more females) at birth are associated with various forms of stressful events or circumstances during or prior to pregnancy. These low SRB are almost certainly mainly caused by maternal-stress-induced male foetal loss. Other types of SRB variation are thought to be caused by hormonal variation in either or both parents around the time of conception. One or other of these two types of proximate cause seems to be responsible for most of the established variation of SRB. This will be illustrated here in respect of some selected forms of SRB variation. It seems likely that a clarification of the hormonal causes of SRB variation will also help explain the striking (apparent) inconsistencies in the results of reported tests of the influential Trivers-Willard hypothesis. It is further proposed that an appreciation of the evidence that parental hormones influence SRB may enhance understanding of several important pathologies (hepatitis B, toxoplasmosis, testicular cancer, prostate cancer and autism).