Positive association of low-level environmental phthalate exposure with sperm motility was mediated by DNA methylation: A pilot study

Revealing the core suppression effects of various Di (2-ethylhexyl) phthalate exposure on early meiosis progression in postnatal male mice via single-cell RNA sequencing

The male reproductive system has been the subject of considerable attention in recent years due to the adverse effects of Di (2-ethylhexyl) phthalate (DEHP). Although previous research has suggested that DEHP exposure hinders the early meiotic progression of male germ cells, the underlying mechanisms are still not well understood. The transcriptomic changes in testicular cells of postnatal male rodents following DEHP exposure were meticulously analyzed using 10X Genomics single-cell RNA sequencing in this study. For downstream analysis, we acquired 42,000 cells and generated 3172,754,990 reads. DEHP exposure at concentrations of 40 μg/kg/day (DEHP40) and 80 μg/kg/day (DEHP80) substantially decreased the proportion of pachytene and diplotene spermatocytes, indicating a shared inhibitory effect on early meiosis, as demonstrated by our findings. In addition, DEHP exposure disrupted the cellular communication between Sertoli cells and germ cells, which had a significant impact on the p38-MAPK signaling pathway. The expression of key ligand genes Tgfb1 and Tgfb3 in Sertoli cells was significantly reduced. DEHP exposure resulted in a substantial decrease in the expression of the Trp53 gene, which in turn down-regulated three critical downstream genes (Stmn1, Tubb5, and Ccnb1) that are implicated in spindle organization from a mechanistic perspective. This study offers the first comprehensive evidence that DEHP inhibits early meiotic progression in male germ cells through the Trp53-mediated p38-MAPK pathway, providing crucial insights into the molecular mechanisms underlying DEHP-induced male reproductive toxicity. Our results emphasize the enduring negative effects of DEHP exposure on male fertility, which have substantial ramifications for the comprehension and mitigation of the influence of environmental estrogens on reproductive health.

The effect of low-level phthalate mixture on the prevalence of type 2 diabetes mellitus among adults in the US

Type 2 diabetes mellitus (T2DM) is an important public health issue owing to its rising global prevalence. Phthalates cause various health problems and are currently regulated in developed countries. However, studies on the impacts of low-level phthalate exposure under these regulations on T2DM are limited. This study investigated the impacts of combined and single exposures to phthalates and their alternatives on the prevalence of T2DM in 3,005 adults in the United States. The results indicated a positive joint effect of phthalate mixtures on the prevalence of T2DM. The joint effect was primarily attributed to Di-2-ethylhexyl phthalate (DEHP) metabolites, whereas the contributions of others were limited. This study suggests that, despite the stringent regulations on phthalates, low levels of phthalates, including DEHP, still have joint effects on T2DM. The findings highlight the importance of regulating hazardous phthalates and the need for safer alternatives to reduce public health risks.

Ameliorative effects of zinc and vitamin E against phthalates-induced reproductive toxicity in male rats

OBJECTIVE

Phthalates (PEs) could cause reproductive harm to males. A mixture of three widely used PEs (MPEs) was used to investigate the ameliorative effects of zinc (Zn) and vitamin E (VE) against male reproductive toxicity.

METHODS

Fifty male SD rats were randomly divided into five groups (n = 10). Rats in MPEs group were orally treated with 160 mg/kg/d MPEs, while rats in MPEs combined Zn and/or VE groups were treated with 160 mg/kg/d MPEs plus 25 mg/kg/d Zn and/or 25 mg/kg/d VE. After intervention for 70 days, it's was measured of male reproductive organs' weight, histopathological observation of sperms and testes, serum hormones, PIWI proteins and steroidogenic proteins.

RESULTS

Compared with control, anogenital distance, testes weight, epididymides weight, and sex hormones were significantly decreased, while the sperm malformation rate was markedly increased in MPEs group (p < .05); the testicular tissues were injured in MPEs group with disordered and decreased spermatids, and arrested spermatogenesis. PIWIL1, PIWIL2, StAR, CYP11A1 and CYP19A1 were down-regulated in MPEs group (p < .05). However, the alterations of these parameters were restored in MPEs combined Zn and/or VE groups (p < .05).

CONCLUSION

Zn and/or VE improved steroid hormone metabolism, and inhibited MPEs' male reproductive toxicity.

Dibutyl phthalate disrupts glycogen synthase kinase 3α essential for sperm motility

To unravel the toxic mechanism of phthalate ester plasticizer endocrine disruptor in spermatozoa, we examined the effect of dibutyl phthalate (DBP) on the stability and inhibitory phosphorylation of glycogen synthase kinase 3α (GSK3α), a protein kinase crucial for sperm motility in mice. In DBP-treated spermatozoa, reactive oxygen species (ROS) and lipid peroxide were significantly increased. In computer-assisted sperm analysis, DBP at concentrations of 10 - 100 μg/mL significantly decreased total motility and progressive motility of spermatozoa. On western blots, DBP decreased p-GSK3α(Ser21) and increased p-GSK3α(Tyr279) in spermatozoa. Similarly, hydrogen peroxide decreased p-GSK3α(Ser21) but not p-GSK3α(Tyr279) in spermatozoa. Immunofluorescent labeling demonstrated that DBP markedly decreased immunoreactivities of GSK3α and p-GSK3α(Ser21) but increased immunoreactivity of p-GSK3α(Tyr279) in spermatozoa. DBP at a concentration of 100 μg/mL significantly increased phosphatase activity in spermatozoa. Calyculin A, a protein phosphatase 1 and 2 A inhibitor, markedly increased p-GSK3α(Ser21) and sperm motility and attenuated a DBP-induced decrease of p-GSK3α(Ser21) and sperm motility. On western blot, 1-100 μg/mL DBP decreased GSK3α in spermatozoa. On immunoprecipitation western blot, DBP at 10 - 100 μg/mL increased polyubiquitinated sperm proteins including GSK3α. The MG115, proteasome inhibitor attenuated degradation of GSK3α in DBP-treated spermatozoa. Hydrogen peroxide at 10 μM increased polyubiquitinated sperm proteins, suggesting that DBP may increase ubiquitination of GSK3α via ROS induction. Together, DBP may decrease the cellular amount of GSK3α through the ubiquitin-proteasome pathway and p-GSK3α(Ser21) through ROS generation and activation of protein phosphatases, impairing sperm motility.

Microplastics exposure: implications for human fertility, pregnancy and child health

Plastics found in our everyday environment are becoming an increasing concern for individual and population-level health, and the extent of exposure and potential toxic effects of these contaminants on numerous human organ systems are becoming clear. Microplastics (MPs), tiny plastic particles, appear to have many of the same biological effects as their plastic precursors and have the compounded effect of potential accumulation in different organs. Recently, microplastic accumulation was observed in the human placenta, raising important questions related to the biological effects of these contaminants on the health of pregnancies and offspring. These concerns are particularly heightened considering the developmental origins of health and disease (DOHaD) framework, which postulates that in utero exposure can programme the lifelong health of the offspring. The current review examines the state of knowledge on this topic and highlights important avenues for future investigation.

The role of estrogen receptors (ERs)-Notch pathway in thyroid toxicity induced by Di-2-ethylhexyl phthalate (DEHP) exposure: Population data and in vitro studies

BACKGROUND

This study aimed to assess the exposure level and risk of Di-2-ethylhexyl Phthalate (DEHP) among adults in Jilin Province, China, clarify the impact of DEHP on human thyroid function, and to explore the role of estrogen receptors (ERs)-Notch signaling pathway in the effect of DEHP metabolites on thyroid hormones based on population data and in vitro experiments.

METHODS

312 adults participated in this study. Urinary DEHP metabolites were determined by high performance liquid chromatography coupled to a tandem mass spectrometer (HPLC-MS/MS). Two pharmacokinetic models were used to evaluate the estimated daily intake (EDI) and hazard quotient (HQ) of the adults. Multiple linear regression and mediating effect models were used to evaluate the target associations. In cell experiments, thyroid follicular epithelial (Nthy-ori3-1) cells were exposed to mono (2-ethylhexyl) phthalate (MEHP) for testing. The inhibitions of ERα and Notch pathway were conducted by siRNA and Notch pathway inhibitor DAPT.

RESULTS

The detection rate of five DEHP metabolites was 97.1∼100.0%. The HQ value of 0.3% of adults was higher than 1. The levels of urinary DEHP metabolites were significantly correlated with thyrotropin (TSH), thyrotropin-releasing hormone (TRH), total triiodothyronine (TT3), total thyroxine (TT4), free triiodothyronine (FT3) and free thyroxine (FT4) and gene (estrogen receptor α (ERα), Notch1, Dll4) levels. The ERα-Notch pathway played a mediating role in the association between DEHP metabolite levels and FT4. The cell results showed, the levels of FT3 and FT4 in cell supernatant decreased after MEHP exposure, and the downward trend was reversed after ERα and notch pathways were inhibited, notch pathway genes also decreased after ERα inhibition.

CONCLUSION

Adults in the Jilin Province of China were widely exposed to DEHP. ERs-Notch pathway played an important role in the effect of DEHP metabolites on thyroid hormones.

Relationship between degree of methylation of sperm long interspersed nuclear element-1 (LINE-1) gene and alteration of sperm parameters and age: a meta-regression analysis

INTRODUCTION

The long interspersed nuclear element-1 (LINE1) gene is a retrotransposon whose methylation status appears to play a role in spermatogenesis, the outcome of assisted reproductive techniques (ART), and even in recurrent pregnancy loss (RPL). Advanced paternal age appears associated with altered sperm parameters, RPL, poor ART outcomes, and compromised offspring health. The methylation status of LINE1 has been reported to be affected by age. The latest meta-analysis on the LINE1 methylation pattern in spermatozoa found no significant differences in methylation levels between infertile patients and fertile controls. However, to the best of our knowledge, no updated meta-analysis on this topic has been published recently. Furthermore, no comprehensive meta-regression analysis was performed to investigate the association between sperm LINE1 methylation pattern and age.

OBJECTIVES

To provide an updated and comprehensive systematic review and meta-analysis on sperm LINE1 gene methylation degree in patients with abnormal sperm parameters compared to men with normal sperm parameters and to probe the association between sperm LINE1 methylation status and age and/or sperm concentration.

METHODS

This meta-analysis was registered in PROSPERO (registration n. CRD42023397056). It was performed according to the MOOSE guidelines for Meta-analyses and Systematic Reviews of Observational Studies and the Preferred Reporting Items for Systematic Reviews and Meta-Analysis Protocols (PRISMA-P). Only original articles evaluating LINE1 gene methylation in spermatozoa from patients with infertility or abnormalities in one or more sperm parameters compared to fertile or normozoospermic men were included.

RESULTS

Of 192 abstracts evaluated for eligibility, only 5 studies were included in the quantitative synthesis, involving a total of 340 patients and 150 controls. Our analysis showed no significant difference in LINE1 gene methylation degree in patients with infertility and/or abnormal sperm parameters compared to fertile controls and/or men with normal sperm parameters, although there was significant heterogeneity across studies. No significant evidence of publication bias was found, and no study was sensitive enough to alter the results. In meta-regression analysis, we found that the results were independent of both ages and sperm concentration. A sub-analysis examining patients and controls separately was also conducted and we found a trend for a positive correlation between LINE1 methylation and sperm concentration in the control group only.

CONCLUSIONS

The results of this systematic review and meta-analysis do not suggest a determining role of sperm LINE1 gene methylation degree in patients with infertility and/or abnormal sperm parameters. Therefore, we do not suggest including LINE1 in the genetic panel of prospective studies aimed at identifying the most representative and cost-effective genes to be analyzed in couples undergoing ART cycles.

Accumulation, sources, and health risks of phthalic acid esters (PAEs) in road dust from heavily industrialized, urban and rural areas in southern Iran

In this research, a total of 51 road dust samples were collected from three districts (Asaluyeh, Bushehr, and Goshoui) in the south of Iran from April to June 2022 and analyzed for the concentration of 7 phthalic acid esters (PAEs) compounds. Asaluyeh was considered as an industrial area (near gas and petrochemical industries), Bushehr as an urban area, and Goshoui as a rural area (far from pollution sources). The PAEs concentration of the street dust samples was determined using a mass detection gas chromatography (GC/MS). The mean ± SD levels of ƩPAEs in samples from industrial, urban, and rural sources were 56.9 ± 11.5, 18.3 ± 9.64, and 5.68 ± 1.85 μg/g, respectively. The mean concentration levels of ƩPAEs was significantly (P < 0.05) higher in samples from the industrial area than urban and rural areas. The mean levels of di(2-Ethylhexyl) phthalate (DEHP) in industrial, urban, and rural areas were 20.3 ± 8.76, 4.59 ± 1.71, and 2.35 ± 0.98 μg/g, respectively. The results of the PCA analysis indicate that the likely major sources of PAEs in the road dust in the studied areas are the application of various plasticizers in industry, solvents, chemical fertilizers, waste disposal, wastewater (e.g., agricultural, domestic, and industrial), and the use of plastic films and plastic-based irrigation pipes in greenhouses. As well as, it was found that the non-cancer risk of exposure to dust-bound PAEs was higher for children than for adults. These values were <1 for both age groups (children and adults) and the exposure of inhabitants to PAEs in road dust did not pose a notable non-cancer risk. The cancer risk from exposure to DEHP in road dust was below the standard range of 10-6 in all three areas. Further studies that consider different routes of exposure to these contaminants are needed for an accurate risk assessment. Moreover, since higher PAEs level was found in industrial area, decision-makers should adopt strict strategies to control the discharging of pollution from industries to the environment and human societies.

The role of angiotensin I-converting enzyme gene polymorphism and global DNA methylation in the negative associations between urine di-(2-ethylhexyl) phthalate metabolites and serum adiponectin in a young Taiwanese population

BACKGROUND

Adiponectin is a key protein produced in adipose tissue, with crucial involvement in multiple metabolic processes. Di-(2-ethylhexyl) phthalate (DEHP), one of the phthalate compounds used as a plasticizer, has been shown to decrease adiponectin levels in vitro and in vivo studies. However, the role of angiotensin I-converting enzyme (ACE) gene polymorphism and epigenetic changes in the relationship between DEHP exposure and adiponectin levels is not well understood.

METHODS

This study examined the correlation between urine levels of DEHP metabolite, epigenetic marker 5mdC/dG, ACE gene phenotypes, and adiponectin levels in a sample of 699 individuals aged 12-30 from Taiwan.

RESULTS

Results showed a positive relationship between mono-2-ethylhexyl phthalate (MEHP) and 5mdC/dG, and a negative association between both MEHP and 5mdC/dG with adiponectin. The study found that the inverse relationship between MEHP and adiponectin was stronger when levels of 5mdC/dG were above the median. This was supported by differential unstandardized regression coefficients (- 0.095 vs. - 0.049, P value for interaction = 0.038)). Subgroup analysis also showed a negative correlation between MEHP and adiponectin in individuals with the I/I ACE genotype, but not in those with other genotypes, although the P value for interaction was borderline significant (0.06). The structural equation model analysis indicated that MEHP has a direct inverse effect on adiponectin and an indirect effect via 5mdC/dG.

CONCLUSIONS

In this young Taiwanese population, our findings suggest that urine MEHP levels are negatively correlated with serum adiponectin levels, and epigenetic modifications may play a role in this association. Further study is needed to validate these results and determine causality.

Phthalate exposure with sperm quality among healthy Chinese male adults: The role of sperm cellular function

Adverse male reproduction caused by phthalate ester (PAE) exposure has been well documented in vivo. However, existing evidence from population studies remains inadequate to demonstrate the impact of PAE exposure on spermatogenesis and underlying mechanisms. Our present study aimed to explore the potential link between PAE exposure and sperm quality and the possible mediation by sperm mitochondrial and telomere in healthy male adults recruited from the Hubei Province Human Sperm Bank, China. Nine PAEs were determined in one pooled urine sample prepared from multiple collections during the spermatogenesis period from the same participant. Sperm telomere length (TL) and mitochondrial DNA copy number (mtDNAcn) were determined in sperm samples. The sperm concentration and count per quartile increment in mixture concentrations were -4.10 million/mL (-7.12, -1.08) and -13.52% (-21.62%, -4.59%), respectively. We found one quartile increase in PAE mixture concentrations to be marginally associated with sperm mtDNAcn (β = 0.09, 95% CI: -0.01, 0.19). Mediation analysis showed that sperm mtDNAcn significantly explained 24.6% and 32.5% of the relationships of mono-2-ethylhexyl phthalate (MEHP) with sperm concentration and sperm count (β = -0.44 million/mL, 95% CI: -0.82, -0.08; β = -1.35, 95% CI: -2.54, -0.26, respectively). Our study provided a novel insight into the mixed effect of PAEs on adverse semen quality and the potential mediation role of sperm mtDNAcn.

Phthalates and phthalate metabolites in urine from Tianjin and implications for platelet mitochondrial DNA methylation

Background

Phthalates (PAEs) are important synthetic substances in plastics, attracting much attention due to their potential effects on the cardiovascular system.

Methods

In this study, urine and blood samples from 39 individuals were collected in Tianjin, China. Phthalates and phthalate metabolites (mPAEs) were analyzed using gas chromatography-mass spectrometry (GC-MS) and high-performance liquid chromatography-mass spectrometry (HPLC-MS), respectively. The polymerase chain reaction (PCR) products from bisulfite-treated mitochondrial DNA (mtDNA) samples were analyzed using pyrosequencing technology.

Results

The detection frequencies for 9 PAEs varied from 2.56 to 92.31%, and those for 10 mPAEs varied from 30.77 to 100%. The estimated daily intakes (EDIs) and cumulative risk of PAEs were calculated based on the experimental statistics of urinary PAEs and mPAEs. For PAEs, the HIRfD (hazard index corresponding to reference doses) values of 10.26% of participants and the HITDI (hazard index corresponding to tolerable daily intake) values of 30.77% of participants were estimated to exceed 1, suggesting a relatively high exposure risk. The mtDNA methylation levels in the MT-ATP8 and MT-ND5 were observed to be lower than in the MT-ATP6. Mono-ethyl phthalate (MEP) and MT-ATP8 were positively correlated with triglyceride levels (p < 0.05). Based on the association of PAEs, mtDNA methylation, and triglycerides, the mediating role of mtDNA methylation between PAEs and cardiovascular diseases (CVDs) was analyzed in this study, but no mediated effect was observed.

Conclusion

The effects of PAE exposure on cardiovascular diseases (CVDs) should be investigated further.

Mixed exposure to phthalates and organic UV filters affects Children's pubertal development in a gender-specific manner

BACKGROUND

Previous studies showed phthalates and UV filters are endocrine-disruptive and associated with puberty. However, few studies have examined effects of mixed exposure.

METHODS

Six phthalate metabolites and 12 organic UV filters were detected among 223 school-age children. Puberty development was evaluated at baseline and after 18 months of follow-up. Ordered logistic regression models, least absolute shrinkage and selection operator (LASSO) regression and quantile-based g-computation (qgcomp) were used to evaluate relationships between phthalate metabolites or UV filters exposure and pubertal development.

RESULTS

Six phthalate metabolites and 5 UV filters were detectable in urine samples. In boys, BP-3 and 4'-MAP were negatively associated with genital (ORBP-3 = 0.52, (0.27, 0.93), OR4'-MAP = 0.45, (0.25, 0.74)) and pubic hair development (ORBP-3:0.24, (0.05, 0.76), OR4'-MAP:0.24, (0.05, 0.77)). In girls, MEP levels were associated with advanced breast development (OR: 1.29, (1.04, 1.64)). LASSO regression identified BP-3, 4'-MAP, and OD-PABA for inverse associations with pubertal development in boys. MEP was related to an increase in girls' breast development (OR: 1.64, (1.08, 2.63)). Overall mixture was related to a 70% reduction in boys' genital development stage, with a larger effect size than a single chemical in qgcomp. Mixed exposure was associated with girls' earlier puberty onset (OR: 2.61, (1.06, 6.42)).

CONCLUSIONS

Our results suggested higher levels of phthalate metabolites and UV filters were associated with delayed pubertal development in boys but with earlier puberty in girls. Higher effect size of joint exposure than single chemicals suggested phthalates and UV filters might have synergistic effects on puberty and distort adolescent endocrine function together.

Quercetin inhibits testicular toxicity induced by the mixture of three commonly used phthalates in rats

BACKGROUND

Phthalates (PEs), such as butyl benzyl phthalate, dibutyl phthalate and di(2-ethylhexyl) phthalate, are one of the most widely used plasticizers, and humans are increasingly exposed to them. Phytochemical quercetin (Que) is a typical flavonoid with several biological effects, such as antioxidative and anti-inflammatory. The present study was designed to explore the effect of Que on testicular toxicity caused by the mixture of three commonly used PEs (MPEs), and the underlying mechanism. Forty male Sprague-Dawley rats were randomly and equally divided into five groups (n = 8). Rats in control the group were orally treated with the excipient. Rats in the MPEs group were orally administered with 900 mg kg^-1  day^-1 MPEs, whereas rats in the MPEs+L-Que, MPEs+M-Que and MPEs+H-Que groups were simultaneously treated with 900 mg kg^-1  day^-1 MPEs and, respectively, 10, 30 and 90 mg kg^-1  day^-1 Que for 30 days.

RESULTS

Compared with the control group, the testes weight, epididymides weight, serum testosterone, luteinizing hormone, follicle-stimulating hormone and estradiol levels, and anogenital distance in the MPEs group were significantly decreased (P < 0.05). The testicular tissues were injured with atrophy of seminiferous tubules, hyperplasia of Leydig cells and arrest of spermatogenesis in the MPEs group. Testicular steroidogenic proteins (StAR, P450scc, CYP17A1 and 17β-HSD, P450arom) were up-regulated, whereas P-element-induced wimpy testis proteins (PIWIL1 and PIWIL2) were down-regulated in the MPEs group (P < 0.05). However, the alterations of these parameters were inhibited in the MPEs+M-Que and MPEs+H-Que groups.

CONCLUSION

MPEs disturbed steroid hormone metabolism and caused testicular injuries. Que could inhibit testicular toxicity of MPEs, which might relate to the improved regulation of steroid hormone metabolism. © 2022 Society of Chemical Industry.

Phthalates impact on the epigenetic factors contributed specifically by the father at fertilization

BACKGROUND

Preconception exposure to phthalates such as the anti-androgenic dibutyl-phthalate (DBP) impacts both male and female reproduction, yet how this occurs largely remains unknown. Previously we defined a series of RNAs expressly provided by sperm at fertilization and separately, and in parallel, those that responded to high DBP exposure. Utilizing both populations of RNAs, we now begin to unravel the impact of high-DBP exposure on those RNAs specifically delivered by the father.

RESULTS

Enrichment of RNAs altered by DBP exposure within the Molecular Signature Database highlighted cellular stress, cell cycle, apoptosis, DNA damage response, and gene regulation pathways. Overlap within each of these five pathways identified those RNAs that were specifically (≥ fivefold enriched) or primarily (≥ twofold enriched) provided as part of the paternal contribution compared to the oocyte at fertilization. Key RNAs consistently altered by DBP, including CAMTA2 and PSME4, were delivered by sperm reflective of these pathways. The majority (64/103) of overlapping enriched gene sets were related to gene regulation. Many of these RNAs (45 RNAs) corresponded to key interconnected CRREWs (Chromatin remodeler cofactors, RNA interactors, Readers, Erasers, and Writers). Modeling suggests that CUL2, PHF10, and SMARCC1 may coordinate and mechanistically modulate the phthalate response.

CONCLUSIONS

Mediated through a CRREW regulatory network, the cell responded to exposure presenting stressed-induced changes in the cell cycle-DNA damage-apoptosis. Interestingly, the majority of these DBP-responsive epigenetic mediators' direct acetylation or deacetylation, impacting the sperm's cargo delivered at fertilization and that of the embryo.

Association of phthalate exposure with low birth weight in couples conceiving naturally or via assisted reproductive technology in a prospective birth cohort

BACKGROUND

Few studies have investigated the adverse effects of preconception phthalate (PAE) exposure on birth weight in couples receiving assisted reproductive technology (ART) compared to naturally conceived newborns.

OBJECTIVES

We examined the association between parental preconception/prenatal urinary phthalate exposure and low birth weight (LBW) risk in couples who conceived using ART or naturally.

METHODS

From the Jiangsu Birth Cohort Study (China), we recruited 544 couples who conceived after infertility treatment and 940 couples who conceived naturally and gave birth to a singleton infant between November 2014 and December 2019. Seventeen metabolites of phthalate and three metabolites of phthalate alternatives were analyzed in parental spot urine samples. Clinical data were collected from medical records. We used generalized linear models, elastic net regression, Bayesian kernel machine regression, and quantile-based g-computation to examine the individual and joint effects of parental phthalate exposure on birth weight and LBW risk ratios (RR).

RESULTS

The relationship between parental phthalate exposure and birth weight was consistent between ART and natural conception. Maternal exposure to mono-ethyl phthalate and mono-carboxyisooctyl phthalate was associated with an increased risk of LBW in ART-conceived infants (RR = 1.27; 95 % confidence interval (CI): 1.03, 1.56; and RR = 1.31; 95 % CI: 1.03, 1.67, respectively). In contrast, in the spontaneously conceived infants, higher paternal prenatal concentrations of mono-benzyl phthalate and mono-carboxyisononyl phthalate were associated with a 40 % and 53 % increase in LBW risk, respectively. Exposure to PAE mixtures was associated with LBW in ART-conceived infants, with the effects primarily driven by di-ethyl phthalate, benzylbutyl phthalate, and di-isononyl phthalate metabolites. Sex-specific LBW was observed, with females appearing to be more susceptible than males.

CONCLUSIONS

Maternal preconception and paternal prenatal exposure to phthalates were associated with increased risk of LBW in infants. Compared with natural conception, ART-conceived fetuses were more sensitive to PAE mixtures, which requires further attention.

A Case-Control Study on the Effects of Plasticizers Exposure on Male Fertility

Male infertility is a serious concern for public health, and the possible role of exposure to plasticizers such as phthalates and bisphenol A in contributing to the condition is widely debated. We have herein enrolled 155 infertility cases attending an infertility center and 211 controls (fathers of a spontaneously conceived newborn) to investigate this issue. The urinary levels of seven phthalates and BPA were analyzed through HPLC/MS/MS. All data were statistically elaborated considering information about clinical situation, life habits, occupational activity, and, for cases, semen parameters (volume, sperm concentration, total count of spermatozoa, and sperm motility). Results showed significantly higher urinary concentrations for all the phthalates in cases compared to controls, except for monoethylphthalate and BPA. In total, 90.07% of cases had sperm motility lower than the WHO reference value (2010), while 53.69%, 46.31%, and 16.56% had sperm total number, concentration, and volume, respectively, out of the reference range. Regarding the possible source of exposure, the use of scents seems to be a significant source of DEP (diethylphthalate). When considering occupational settings, industrial workers, dental technicians, artisans, and farmers using chemicals showed higher risk (OR = 2.766, 95% CI 1.236-6.185), particularly in relation to DnBP (di-n-butyl phthalate) and DEHP (di-ethyl-hexyl phthalate) exposure. No clear quantitative correlation between specific plasticizers and sperm parameters could be demonstrated but these findings call for future studies about the risks associated with exposure to their mixture.

Association of phthalate exposure with all-cause and cause-specific mortality among people with hypertension: The U.S. National Health and Nutrition Examination Survey, 2003-2014

There is growing evidence that phthalate exposure results in a deteriorated effect on human health, while very few studies directly investigate the relationship of phthalate metabolites with mortality among people with hypertension. We aimed to explore whether exposure to phthalates is associated with all-cause and cause-specific mortality among people with hypertension. This study included 4012 people with hypertension from the National Health and Nutrition Examination Survey from 2003 to 2014. Death information was obtained from the National Death Index until 2015. A total of 577 deaths including 196 deaths due to cardiovascular disease (CVD) and 119 deaths due to cancer were documented. Cox proportional hazards regression models were used to estimate hazard ratios (HR) and 95% confidence intervals (CI). After adjustment for potential covariates, participants exposed to mono-ethyl phthalate (MEP) had a higher risk of cancer mortality (HR, 2.06; 95% CI, 1.07-3.95). Participants exposed to mono-n-butyl phthalate (MnBP) had higher risks of all-cause (HR, 1.83; 95% CI, 1.28-2.60), CVD (HR, 2.19; 95% CI, 1.21-3.95), and cancer (HR, 2.35; 95% CI, 1.07-5.17) mortality. Participants exposed to mono-benzyl phthalate (MBzP) had higher risks of all-cause (HR, 2.19; 95% CI, 1.58-3.05) and CVD (HR, 2.36; 95% CI, 1.35-4.13) mortality. Participants exposed to di-2-ethylhexylphthalate (DEHP) had a higher risk of all-cause mortality (HR, 1.69; 95% CI, 1.19-2.39). Our findings suggested that higher levels of specific phthalates were significantly associated with increased risks of all-cause, CVD, and cancer mortality among people with hypertension. Further studies are needed to confirm these findings and identify the underlying mechanisms.

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.

Genotoxic impact of di-n-butyl phthalate on DNA: A comparative study of three generations in the neuronal tissue of Wistar rats

Di-n-butyl phthalate (DBP), one of the plasticizers, is considered a ubiquitous environmental contaminant due to its widespread application in personal-care products and serves as a raw material in many industries for the generation of many plastic products. Several scientific investigations have shown that DBP caused embryotoxicity and cognitive impairments. However, there is less understanding of the genotoxic potential of DBP in neuronal tissue when exposure happens continuously for several generations. The present study was undertaken to investigate the impact of DBP on the nucleic acids of neuronal tissue in one-month-old rats by performing a comet assay and biochemical analyses. By oral gavage, the parental generation (F₀) was administered DBP (500 mg/kg/day) during gestation (GD6-20) and lactation, and exposures were continued for three consecutive generations until the pups were grown to one-month-old. The oxidative stress assessments carried out in discrete brain regions isolated from one-month-old rats (F₁-F₃) following DBP exposure indicated significant inhibition in the levels of antioxidant enzymes (superoxide dismutase and catalase) while oxidant status (malondialdehyde) was elevated significantly. The extent of DNA damage using the comet assay, as measured by the olive moment, tail DNA percentage and tail length, was greater in DBP-treated rats compared with the control group, but RNA/DNA content decreased significantly. The results of this study suggested a strong link between oxidative stress and genetic integrity in the neuronal tissue of rats exposed to DBP generationally. To summarise, DBP exposure during pregnancy caused oxidative stress, which resulted in genetic instability in specific discrete brain regions of the third generation.

TET1 mediated male reproductive toxicity induced by Bisphenol A through Catsper-Ca2+ signaling pathway

Bisphenol A (BPA) exposure has many adverse effects on the reproductive system in animals and humans. Ten-eleven translocation 1 (TET1) is closely related to a variety of biological processes through regulating the dynamic balance of DNA demethylation and methylation. However, the role and mechanism of TET1 during BPA induced reproductive toxicity are largely unknown. In this study, mouse spermatogonia cell line GC-2 was treated with BPA in the final concentration of 0, 20, 40 and 80 μM for 72 h. The cell model of differential TET1 gene expression was established to explore the role and mechanism. We found that the growth rate of GC-2 cells, and the intracellular calcium level decreased significantly with the increase of BPA dose, while TET1 and Catsper1-4 expression level decrease with a dose-dependent relationship. Furthermore, TET1 overexpression promoted the proliferation of GC-2 cell, the increase of calcium ion concentration, and the expression level of Catsper1-4, while knockdown of TET1 leads to the opposite results. Mechanistically, TET1 expression promoted the hydroxymethylation of Catsper1-4 and reduced their methylation level. In addition, the expression level of Catsper1-4 was positively correlated with TET1 gene expression level in semen samples of the population. Our study revealed for the first time that TET1 gene regulates the expression of related molecules in the Catsper calcium signal pathway through its hydroxymethylation modification to affect the calcium level, thereby participating in the process of BPA induced damage. These results indicated that TET1 gene may be a potential biomarker of BPA induced male reproductive toxicity.

Evaluating the Effects of BPA and TBBPA Exposure on Pregnancy Loss and Maternal-Fetal Immune Cells in Mice

BACKGROUND

Bisphenol A (BPA) exposure has been linked to miscarriages and pregnancy complications in humans. In contrast, the potential reproductive toxicity of BPA analogs, including tetrabromobisphenol A (TBBPA), is understudied. Furthermore, although environmental exposure has been linked to altered immune mediators, the effects of BPA and TBBPA on maternal-fetal immune tolerance during pregnancy have not been studied. The present study investigated whether exposure resulted in higher rates of pregnancy loss in mice, lower number of regulatory T cells (Tregs), and lower indoleamine 2,3 deoxygenase 1 (Ido1) expression, which provided evidence for mechanisms related to immune tolerance in pregnancy.

OBJECTIVES

The purpose of this investigation was to characterize the effects of BPA and TBBPA exposure on pregnancy loss in mice and to study the percentage and number of Tregs and Ido1 expression and DNA methylation.

METHODS

Analysis of fetal resorption and quantification of maternal and fetal immune cells by flow cytometry were performed in allogeneic and syngeneic pregnancies. Ido1 mRNA and protein expression, and DNA methylation in placentas from control and BPA- and TBBPA-exposed mice were analyzed using real-time quantitative polymerase chain reaction, immunofluorescence, and bisulfite sequencing analyses.

RESULTS

BPA and TBBPA exposure resulted in higher rates of hemorrhaging in early allogeneic, but not syngeneic, conceptuses. In allogeneic pregnancies, BPA and TBBPA exposure was associated with higher fetal resorption rates and lower maternal Treg number. Importantly, these differences were associated with lower IDO1 protein expression in trophoblast giant cells and higher mean percentage Ido1 DNA methylation in embryonic day 9.5 placentas from BPA- and TBBPA-exposed mice.

DISCUSSION

BPA- and TBBPA-induced pregnancy loss in mice was associated with perturbed IDO1-dependent maternal immune tolerance. https://doi.org/10.1289/EHP10640.

Toxicological outcome of phthalate exposure on male fertility: Ameliorative impacts of the co-administration of N-acetylcysteine and zinc sulfate in rats

Background

Reports have shown that humans are consistently exposed to environmental toxicants such as phthalate (PHT) during their daily activities. This results in reproductive dysfunction and infertility-related issues as already noted in human and experimental animals. We therefore designed this study to investigate fertility outcome in phthalate-exposed male rats treated with N-acetylcysteine (NAC) and zinc sulfate (ZnSO4) with the view of providing a therapeutic alternative to reproductive toxicity caused by phthalate. The research was done in two phases. In phase 1, thirty-five male Wistar rats were randomly assigned to one of five (n = 7) groups given the following treatments for 21 days: group A was given distilled water as a control, while groups B, C, D, and E were given phthalate (750 mg/kg/day). Animals in groups C to E were also given ZnSO4 (0.5 mg/kg/day), N-acetylcysteine (100 mg/kg/day), and ZnSO4 (0.5 mg/kg/day) + N-acetylcysteine (100 mg/kg/day) in addition to phthalate. In phase 2, animals from groups in phase 1 were mated with females for fecundity testing.

Results

The result shows alteration in testicular and epididymis weight and testis/epididymis ratio, semen parameters, sperm capacitation and acrosome reaction, sperm DNA, serum Zn and Mg, testicular mitochondria apoptosis mechanisms (TNF-α and BCL-2), and testicular Ca2+-ATPase as well as fecundity outcome in the phthalate-treated group. However, ZnSO4 and NAC successfully ameliorated the deleterious effects of phthalate on semen parameters, sperm capacitation and acrosome reaction, serum electrolyte and mitochondria apoptosis mechanisms, and testicular electrogenic Ca2+-ATPase in phthalate-induced male rats with a better outcome in the combined therapy. Pregnancy outcome and litter sizes were also higher in the combined therapy when also compared with the phthalate-treated groups.

Conclusion

According to the result, ZnSO4 and NAC increased fertility outcome in phthalate-treated male rats through enhancement of testicular BCL-2, serum electrolyte, testicular Ca2+ATPase pumps, and cytoprotection.

Global DNA methylation mediates the association between urine mono-2-ethylhexyl phthalate and serum apoptotic microparticles in a young Taiwanese population

Di-(2-ethylhexyl) phthalate (DEHP) has been used as a plasticizer for decades. Recent research evidence has revealed that environmental factors can alter vascular endothelial cell function through DNA methylation. However, no previous in vitro/vivo study has explored the role of DNA methylation in DEHP exposure and vascular endothelial cell function. In the present study, we enrolled 793 subjects aged 12 to 30 years from a young Taiwanese cohort to investigate the association between mono-2-ethylhexyl phthalate (MEHP) (urine DEHP metabolite), 5mdC/dG (global DNA methylation marker), CD31⁺/CD42a^-, CD31⁺/CD42a⁺, and CD14 (apoptotic microparticles of vascular cells). In multiple regression analyses, the levels of mono-2-ethylhexyl phthalate (MEHP) were positively associated with 5mdC/dG and all three apoptotic microparticles. In addition, the regression coefficients between MEHP and the three types of apoptotic microparticles were higher when the 5mdC/dG levels were higher than the 50th percentile. In the structural equation model (SEM), we found that MEHP had a direct correlation with CD31⁺/CD42a^- and an indirect association with CD31⁺/CD42a^- through the effect of 5mdC/dG. Moreover, MEHP only had a direct association with CD31⁺/CD42a⁺ and an indirect association with CD14. In conclusion, the results show that global DNA methylation mediates the relationship between MEHP and apoptotic microparticles. These findings indicate that DNA methylation may play a role in the pathogenesis of DEHP-induced endothelial cell apoptosis in humans. Further studies are needed to clarify the causal inference.

Effect of Environmental Stressors, Xenobiotics, and Oxidative Stress on Male Reproductive and Sexual Health

This article examines the environmental factor-induced oxidative stress (OS) and their effects on male reproductive and sexual health. There are several factors that induce OS, i.e. radition, metal contamination, xenobiotic compounds, and cigarette smoke and lead to cause toxicity in the cells through metabolic or bioenergetic processes. These environmental factors may produce free radicals and enhance the reactive oxygen species (ROS). Free radicals are molecules that include oxygen and disbalance the amount of electrons that can create major chemical chains in the body and cause oxidation. Oxidative damage to cells may impair male fertility and lead to abnormal embryonic development. Moreover, it does not only cause a vast number of health issues such as ageing, cancer, atherosclerosis, insulin resistance, diabetes mellitus, cardiovascular diseases, ischemia-reperfusion injury, and neurodegenerative disorders but also decreases the motility of spermatozoa while increasing sperm DNA damage, impairing sperm mitochondrial membrane lipids and protein kinases. This chapter mainly focuses on the environmental stressors with further discussion on the mechanisms causing congenital impairments due to poor sexual health and transmitting altered signal transduction pathways in male gonadal tissues.

Urinary phthalate metabolites among workers in plastic greenhouses in western China

Agricultural plastic greenhouse (PG) production can extend the growing season of crops to satisfy domestic consumption in countries such as China. Workers in PGs have potential higher phthalate exposure risks than the general population as phthalate accumulation has been observed in greenhouse soil, air, and crops. To date, biomonitoring tests of phthalates for the working population have not been carried out. To address this shortage, we conducted a pilot study in Shaanxi Province, China, among 35 healthy PG workers by follow-up recording their seasonal dietary habits and work activities and urine sample collection and measurement between 2018 and 2019. The objectives were to uncover the association between phthalate metabolites and the population characteristics, seasonal and diurnal variations and causes, and to estimate exposure risks and contributions of exposure pathways from PG production systems. A total of 13 phthalate metabolite concentrations (Σ₁₃ phthalate metabolites) ranged from 102 to 781 (5th-95th) ng/mL (median: 300 ng/mL). Mono-n-butyl phthalate (MNBP) made up 51.3% of Σ₁₃ phthalate metabolites, followed by the sum of four di-2-ethylhexyl phthalate (DEHP) metabolites (24.2%), mono-2-isobutyl phthalate (MIBP) (13.4%), and mono-ethyl phthalate (MEP) (9.8%). The concentrations of MNBP and MIBP in summer were significantly higher than the levels in winter (p < 0.0001). A total of 62.3% of the PG worker population was shown to have exposure risks, and the proportion was as high as 79.4% in summer. Phthalate exposure of the workers from PG production systems constituted over 20% of the total creatinine-based daily intake, and consuming vegetables and fruit planted in PGs and inhalation in PGs were the two largest exposure pathways. Our findings demonstrate that it is important to protect workers in PGs from phthalate exposure risks, and phasing out the use of plastic materials containing phthalates in PGs is imperative, to guarantee food safety in PGs.

DEHP-induced testicular injury through gene methylation pathway and the protective effect of soybean isoflavones in Sprague-Dawley rats

As one of the most important members of Phthalate esters (PAEs), di-(2-ethylhexyl) phthalate (DEHP) is widely used in plastics and known as a male reproductive toxicant. Many studies have shown that soybean isoflavones (SI) can rescue the testicular injury caused by DEHP, but the underlying mechanism is unknown. Because methylation is one of the most important mechanisms for maintaining normal biological functions, we studied whether methylation is involved in testicular injury induced by DEHP and whether SI could counter testicular impairment in peripubertal male Sprague Dawley rats. Compared with the control group, we found that the mRNA levels of testicular Sod2, Gpx1, and Igf-1 significantly decreased in the 900 mg/kg DEHP group (DEHP' group) (P < 0.01); however, in the DEHP + SI group, the mRNA levels of the genes obviously increased compared with the DEHP' group (P < 0.01). Simultaneously, the methylation level changes of testicular Sod2, Gpx1, and Igf-1 were similar to the mRNA levels (P < 0.01). Therefore, DEHP may affect testis and leydig cells via inducing methylation of Sod2, Gpx1, and Igf-1, and SI may rescue the impairments at the methylation level. In summary, SI is supposed to be used in DEHP-induced testicular injury treatment.

Environmental Exposure to Endocrine Disrupting Chemicals Influences Genomic Imprinting, Growth, and Metabolism

Genomic imprinting is an epigenetic mechanism that results in monoallelic, parent-of-origin-specific expression of a small number of genes. Imprinted genes play a crucial role in mammalian development as their dysregulation result in an increased risk of human diseases. DNA methylation, which undergoes dynamic changes early in development, is one of the epigenetic marks regulating imprinted gene expression patterns during early development. Thus, environmental insults, including endocrine disrupting chemicals during critical periods of fetal development, can alter DNA methylation patterns, leading to inappropriate developmental gene expression and disease risk. Here, we summarize the current literature on the impacts of in utero exposure to endocrine disrupting chemicals on genomic imprinting and metabolism in humans and rodents. We evaluate how early-life environmental exposures are a potential risk factor for adult metabolic diseases. We also introduce our mouse model of phthalate exposure. Finally, we describe the potential of genomic imprinting to serve as an environmental sensor during early development and as a novel biomarker for postnatal health outcomes.

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.

DNA methylation in human sperm: a systematic review

BACKGROUND

Studies in non-human mammals suggest that environmental factors can influence spermatozoal DNA methylation, and some research suggests that spermatozoal DNA methylation is also implicated in conditions such as subfertility and imprinting disorders in the offspring. Together with an increased availability of cost-effective methods of interrogating DNA methylation, this premise has led to an increasing number of studies investigating the DNA methylation landscape of human spermatozoa. However, how the human spermatozoal DNA methylome is influenced by environmental factors is still unclear, as is the role of human spermatozoal DNA methylation in subfertility and in influencing offspring health.

OBJECTIVE AND RATIONALE

The aim of this systematic review was to critically appraise the quality of the current body of literature on DNA methylation in human spermatozoa, summarize current knowledge and generate recommendations for future research.

SEARCH METHODS

A comprehensive literature search of the PubMed, Web of Science and Cochrane Library databases was conducted using the search terms 'semen' OR 'sperm' AND 'DNA methylation'. Publications from 1 January 2003 to 2 March 2020 that studied human sperm and were written in English were included. Studies that used sperm DNA methylation to develop methodologies or forensically identify semen were excluded, as were reviews, commentaries, meta-analyses or editorial texts. The Grading of Recommendations, Assessment, Development and Evaluations (GRADE) criteria were used to objectively evaluate quality of evidence in each included publication.

OUTCOMES

The search identified 446 records, of which 135 were included in the systematic review. These 135 studies were divided into three groups according to area of research; 56 studies investigated the influence of spermatozoal DNA methylation on male fertility and abnormal semen parameters, 20 studies investigated spermatozoal DNA methylation in pregnancy outcomes including offspring health and 59 studies assessed the influence of environmental factors on spermatozoal DNA methylation. Findings from studies that scored as 'high' and 'moderate' quality of evidence according to GRADE criteria were summarized. We found that male subfertility and abnormal semen parameters, in particular oligozoospermia, appear to be associated with abnormal spermatozoal DNA methylation of imprinted regions. However, no specific DNA methylation signature of either subfertility or abnormal semen parameters has been convincingly replicated in genome-scale, unbiased analyses. Furthermore, although findings require independent replication, current evidence suggests that the spermatozoal DNA methylome is influenced by cigarette smoking, advanced age and environmental pollutants. Importantly however, from a clinical point of view, there is no convincing evidence that changes in spermatozoal DNA methylation influence pregnancy outcomes or offspring health.

WIDER IMPLICATIONS

Although it appears that the human sperm DNA methylome can be influenced by certain environmental and physiological traits, no findings have been robustly replicated between studies. We have generated a set of recommendations that would enhance the reliability and robustness of findings of future analyses of the human sperm methylome. Such studies will likely require multicentre collaborations to reach appropriate sample sizes, and should incorporate phenotype data in more complex statistical models.

An exposomic approach with 138 chemical and non-chemical exposures to predict 32 biomarkers of male reproductive damages: A case study of college students in Chongqing, China

Male reproductive damage in the general population comprises different disorders in various biomarkers, which could be respectively caused by a number of exposure factors. However, researchers considering the environmental/behavioral/psychological exposures together to evaluate their contribution to male reproductive damage are still lacking. The present study investigated the comprehensive association between 138 environmental/behavioral/psychological exposures and 32 male reproductive biomarkers in 796 young Chinese men using graph-guided fused lasso (GFLASSO) and hierarchical clustering methods. All biomarkers were found to be associated with various exposures. A combination of these exposures not only predicted the levels of single biomarkers in another test dataset, but also identified the comprehensive reproductive features by clustering the men into five subgroups with distinct damages representing disrupted spermatogenesis with abnormal sperm morphology, low sperm motility with DNA fragmentation, chromatin immaturity, aberrant endocrine, or DNA strand breakage. The findings can be used to suggest a novel way to identify the males with a high risk of reproductive damage and develop personalized preventive strategies.

Food emulsifier glycerin monostearate aggravates phthalates’ testicular toxicity by disrupting tight junctions’ barrier function in rats

Objectives

This study aimed to investigate the effect of the widely used food emulsifier glycerin monostearate (GM) on testicular toxicity caused by the mixture of three commonly used phthalate esters (MPEs) in rats, and further to explore the underlying mechanism.

Materials and Methods

Thirty male Sprague–Dawley rats were randomly divided into three groups. Rats were orally treated with 160 mg/kg/d MPEs in the MPEs group; coinstantaneously treated with 160 mg/kg/d MPEs and 200 mg/kg/d GM in the MPEs + GM group; and treated with the excipient in the control group. The intervention lasted for 5 weeks. Testis weight, epididymis weight, testicular histopathology, and serum testosterone were detected for testicular toxicity evaluation. The testicular ultrastructure, the tight junction proteins zonula occluden (ZO)-1, and claudin were measured for the mechanism exploration.

Results

The body weight, epididymis, serum testosterone level, and anogenital distance in the MPEs + GM group were significantly decreased compared with control group (P &lt; 0.05); Testicular histopathological observation showed that shed spermatids were observed in the MPEs + GM group. Ultrastructural observation of testicular cells showed that the cristae number was decreased in some mitochondria in the MPEs group, whereas the cristae were fused and disappeared in most mitochondria in the MPEs + GM group. The tight junctions were broken in the MPEs + GM group; meanwhile, the expression of ZO-1 and claudin were altered in the MPEs + GM group (P &lt; 0.01).

Conclusions

The results from this study indicated that GM aggravated MPEs’ testicular toxicity, which might relate to the injured mitochondria and damaged tight junctions in testicular tissue.

Phthalates in Albumin from Human Serum: Implications for Assisted Reproductive Technology

Albumin, a vital protein in cell culture systems, is derived from whole blood or blood products. The culture of human gametes and developing embryos for assisted reproduction (ART) uses albumin of human origin. Human serum albumin (HSA) is derived from expired blood obtained from blood banks. This blood has been stored in polyvinyl chloride bags made clear and flexible with di-2-ethylhexyl phthalate (DEHP). But DEHP can leach from the bags into stored blood and co-fractionate with HSA during albumin isolation. DEHP and its metabolite mono-ethylhexyl phthalate (MEHP), are known endocrine disruptors that are reported to have negative effects when directly supplemented in media for IVF using gametes from a variety of animals. Therefore, the contamination of ART media with DEHP and MEHP through HSA supplementation may have effects on the outcomes of ART procedures. While the embryology laboratory is strictly monitored to prevent a wide variety of contamination, phthalate contamination of HSA has not been broadly examined. This review outlines the function of HSA in ART procedures and the production of HSA from whole blood. Finally, the review highlights the effects of acute phthalate exposures on gametes during in vitro procedures.

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.

Effects of the environmental endocrine disruptors di-2-ethylhexyl phthalate and mono-2-ethylhexyl phthalate on human sperm function in vitro

Di-2-ethylhexyl phthalate (DEHP), a plastic-derived, endocrine-disrupting chemical, has been shown to exhibit male reproductive toxicity. However, its effects on human mature spermatozoa are largely unknown. In this study we investigated the invitro effects of DEHP and mono-2-ethylhexyl phthalate (MEHP; the main metabolite of DEHP) on sperm function and the mechanisms involved. Human spermatozoa were exposed to phthalates invitro at the doses that cover the concentrations detected in human semen: 20nM-8 μM DEHP, 1nM-20 μM MEHP or a mixture of 20nM-8 μM DEHP and 1nM-20 μM MEHP. DEHP and MEHP, alone or in combination, had no effect on the viability, membrane integrity, motility, homeostasis of reactive oxygen species or mitochondrial activity of human spermatozoa. Interestingly, 1nM-20 μM MEHP and combinations of 20nM-8 μM DEHP and 1nM-20 μM MEHP enhanced penetration ability, hyperactivation and the spontaneous acrosome reaction of human spermatozoa, and increased intracellular free Ca2+ concentrations ([Ca2+]i) and tyrosine phosphorylation, two key signalling pathways that regulate sperm function. The findings of this study suggest that invitro exposure to MEHP metabolised from DEHP affects human sperm function by inducing increases in sperm [Ca2+]i and tyrosine phosphorylation, which adds to our understanding of the effects of DEHP on male reproduction.

The role of epigenetics in the reproductive toxicity of environmental endocrine disruptors

Environmental endocrine disruptors (EEDs) seriously endanger human health by interfering with the normal function of reproductive systems. In males, EEDs can affect sperm formation and semen quality as well spermatogenesis, ultimately reducing fertility. In females, EEDs can affect uterine development and the expression levels of reproduction-related genes, ultimately reducing female fertility and the normal development of the fetus. There are a large number of putative mechanisms by which EEDs can induce reproductive toxicity, and many studies have shown the involvement of epigenetics. In this review, we summarize the role of DNA methylation, noncoding RNAs, genomic imprinting, chromatin remodeling and histone modification in the reproductive toxicity of EEDs.

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 association between urine di-(2-ethylhexyl) phthalate metabolites, global DNA methylation, and subclinical atherosclerosis in a young Taiwanese population

Di-(2-ethylhexyl) phthalate (DEHP) has been utilized in many products for years. DEHP exposure has been linked to cardiovascular diseases (CVD) and its risk factors. Recent evidence has found a crucial role for epigenetics, including DNA methylation, in CVD. Moreover, DEHP exposure has proved to alter DNA methylation in epidemiological studies. However, the interplay between DEHP exposure, global DNA methylation, and atherosclerosis has never been reported. In this current study, we enrolled 793 participants (12-30 years) from a Taiwanese population to investigate the association between concentrations of DEHP metabolites, 5mdC/dG (global DNA methylation marker) and the carotid intima-media thickness (CIMT). The results showed urine mono-2-ethylhexyl phthalate (MEHP) level was positively correlated with 5mdC/dG and CIMT, respectively. In logistic regression models, the odds ratios (OR) of thicker CIMT (greater than 75^th percentile) with one unit increase in ln-MEHP level was higher when levels of 5mdC/dG were above 50%. In structural equation model, the result showed urine MEHP levels are directly associated with CIMT. Moreover, MEHP had an indirect association with CIMT through the 5mdC/dG after adjusting other confounding effects. In the current study, urine DEHP metabolite levels were positively correlated with 5mdC/dG, and CIMT. Our results showed DEHP had a direct and indirect association with CIMT through the 5mdC/dG. The finding implies that DNA methylation may mediate the association between DEHP exposures and subclinical atherosclerosis in this young population. Future effort is needed to elucidate the causal relationship between DEHP exposure, DNA methylation and CVD.

Critical Review on the Presence of Phthalates in Food and Evidence of Their Biological Impact

Phthalates are a huge class of chemicals with a wide spectrum of industrial uses, from the manufacture of plastics to food contact applications, children's toys, and medical devices. People and animals can be exposed through different routes (i.e., ingestion, inhalation, dermal, or iatrogenic exposure), as these compounds can be easily released from plastics to water, food, soil, air, making them ubiquitous environmental contaminants. In the last decades, phthalates and their metabolites have proven to be of concern, particularly in products for pregnant women or children. Moreover, many authors reported high concentrations of phthalates in soft drinks, mineral waters, wine, oil, ready-to-eat meals, and other products, as a possible consequence of their accumulation along the food production chain and their accidental release from packaging materials. However, due to their different physical and chemical properties, phthalates do not have the same human and environmental impacts and their association to several human diseases is still under debate. In this review we provide an overview of phthalate toxicity, pointing out the health and legal issues related to their occurrence in several types of food and beverage.

Early life lessons: The lasting effects of germline epigenetic information on organismal development

BACKGROUND

An organism's metabolic phenotype is primarily affected by its genotype, its lifestyle, and the nutritional composition of its food supply. In addition, it is now clear from studies in many different species that ancestral environments can also modulate metabolism in at least one to two generations of offspring.

SCOPE OF REVIEW

We limit ourselves here to paternal effects in mammals, primarily focusing on studies performed in inbred rodent models. Although hundreds of studies link paternal diets and offspring metabolism, the mechanistic basis by which epigenetic information in sperm programs nutrient handling in the next generation remains mysterious. Our goal in this review is to provide a brief overview of paternal effect paradigms and the germline epigenome. We then pivot to exploring one key mystery in this literature: how do epigenetic changes in sperm, most of which are likely to act transiently in the early embryo, ultimately direct a long-lasting physiological response in offspring?

MAJOR CONCLUSIONS

Several potential mechanisms exist by which transient epigenetic modifications, such as small RNAs or methylation states erased shortly after fertilization, could be transferred to more durable heritable information. A detailed mechanistic understanding of this process will provide deep insights into early development, and could be of great relevance for human health and disease.

In utero exposure to low doses of genistein and di-(2-ethylhexyl) phthalate (DEHP) alters innate immune cells in neonatal and adult rat testes

BACKGROUND

Although humans are exposed to mixtures of endocrine disruptor chemicals, few studies have examined their toxicity on male reproduction. We previously found that fetal exposure to a mixture of the phytoestrogen genistein (GEN) and the plasticizer di(2-ethylhexyl) phthalate (DEHP) altered gene expression in adult rat testes.

OBJECTIVES

Our goal was to investigate the effects of fetal exposure to GEN-DEHP mixtures at two doses relevant to humans on testicular function and transcriptome in neonatal and adult rats.

MATERIALS AND METHODS

Pregnant SD rats were gavaged with vehicle, GEN or DEHP, alone or mixed at 0.1 and 10 mg/kg/day, from gestation day 14 to birth. Fertility, steroid levels, and testis morphology were examined in neonatal and adult rats. Testicular transcriptomes were examined by gene array and functional pathway analyses. Cell-specific genes/proteins were determined by quantitative real-time PCR and immunohistochemistry.

RESULTS

GEN-DEHP mixtures increased the rates of infertility and abnormal testes in adult rats. Gene array analysis identified more genes exclusively altered by the mixtures than individual compounds. Altered top canonical pathways included urogenital/reproductive developmental and inflammatory processes. GEN-DEHP mixtures increased innate immune cells and macrophages markers at both doses and ages, more strongly and consistently than DEHP or GEN alone. Genes exclusively increased by the mixture in adult testis related to innate immune cells and macrophages included Kitlg, Rps6ka3 (Rsk2), Nr3c1, Nqo1, Lif, Fyn, Ptprj (Dep-1), Gpr116, Pfn2, and Ptgr1.

DISCUSSION AND CONCLUSION

These findings demonstrate that GEN-DEHP mixtures at doses relevant to human induce adverse testicular phenotypes, concurrent with age-dependent and non-monotonic changes in testicular transcriptomes. The involvement of innate immune cells such as macrophages suggests immediate and delayed inflammatory responses which may contribute to testicular dysfunction. Moreover, these effects are complex and likely involve multiple interactions between immune and non-immune testicular cell types that will entail further studies.

The preconception environment and sperm epigenetics

BACKGROUND

Infertility is a common reproductive disorder, with male factor infertility accounting for approximately half of all cases. Taking a paternal perceptive, recent research has shown that sperm epigenetics, such as changes in DNA methylation, histone modification, chromatin structure, and noncoding RNA expression, can impact reproductive and offspring health. Importantly, environmental conditions during the preconception period has been demonstrated to shape sperm epigenetics.

OBJECTIVES

To provide an overview on epigenetic modifications that regulate normal gene expression and epigenetic remodeling that occurs during spermatogenesis, and to discuss the epigenetic alterations that may occur to the paternal germline as a consequence of preconception environmental conditions and exposures.

MATERIALS AND METHODS

We examined published literature available on databases (PubMed, Google Scholar, ScienceDirect) focusing on adult male preconception environmental exposures and sperm epigenetics in epidemiologic studies and animal models.

RESULTS

The preconception period is a sensitive developmental window in which a variety of exposures such as toxicants, nutrition, drugs, stress, and exercise, affects sperm epigenetics.

DISCUSSION AND CONCLUSION

Understanding the environmental legacy of the sperm epigenome during spermatogenesis will enhance our understanding of reproductive health and improve reproductive success and offspring well-being.

Zinc supplement ameliorates phthalates-induced reproductive toxicity in male rats

People are inevitably exposed to phthalates (PEs) ubiquitously existing in environment. Our previous studies, simulating the actual situations of people exposure to PEs, have shown that the sub-chronic exposure to low-doses PEs mixture (MIXPs) impaired reproductive function in male rats. Zinc is an important element in maintaining male reproductive functions. However, it is still unknown whether zinc supplement could mitigate PEs-induced male reproductive toxicity or not with sub-chronic low-dose mixture exposure. This study aimed to explore the effect of zinc supplement on the reproductive toxicity caused by sub-chronic MIXPs exposure (160 mg/(kg•body weight)/d, for 90 days) in male rats, and further to reveal the underlying mechanisms. Testosterone (T), FSH and LH in serum, early toxicity indicators in urine, PIWI proteins (PIWIL1 and PIWIL2) expression in testes and pathological examination were performed for toxicity evaluation. Steroidogenic proteins (17β-HSD, StAR, CYP17A1, P450scc and SRD5A) were measured for mechanisms of exploration. The results indicated that zinc supplement could inhibit the T, LH, FSH level decreases in serum, abolish the effect of 5 early toxicity indicators' levels in urine, restrain the alteration of PIWI proteins expression and improve the constructional injury of testes. These effects might be relevant with the suppressed alteration of the expression of steroidogenic proteins induced by MIXPs in rat testicular cells. This work may offer further insights into reducing health risks of MIXPs exposure.

Transient exposure to environmentally realistic concentrations of di-(2-ethylhexyl)-phthalate during sensitive windows of development impaired larval survival and reproduction success in Japanese medaka

Di-(2-ethylhexyl) phthalate (DEHP) is a well-known endocrine disruptor and it is ubiquitously distributed in the environment. However, very few studies have investigated the effects of short-term exposure to environmentally realistic concentrations of DEHP during early developmental stages and its chronic effects. This study monitored the long-term effects of transient exposure to DEHP in early life stages (F0 generation) and its subsequent fertilization success in F1 generation using Japanese medaka, Oryzias latipes, as model organism. Embryos (4 h post-fertilization, 4 hpf) of Japanese medaka were exposed to 0.001 ppb, 0.1 ppb, or 10 ppb DEHP for 21 days and returned to control water (without DEHP) for maturation (4 months old). At day 9 of the exposure study, mortality was significantly increased in medaka embryos (before hatching) treated with 0.001 ppb and 10 ppb DEHP. Continual exposure of young hatchlings for an additional 12 days (a total of 21 days of exposure) resulted in a significant increase in mortality in fish exposed to 0.001 ppb, 0.1 and 10 ppb DEHP. Significant reduction in egg production was observed in adult female medaka (4 months old) with prior exposure to 0.1 ppb and 10 ppb DEHP for 21 days during early development. Fertilization and hatching success were also significantly reduced in breeding pairs with prior exposure to 0.001 ppb, 0.1 ppb and 10 ppb DEHP during early life stage. Histological analysis of adult male gonads revealed a significant decline in mature sperm count accompanied by an increase in interstitial space in fish exposed to 0.1 ppb and 10 ppb DEHP during early development. Likewise, the amount of vitellogenic (mature) oocytes observed in the ovaries of adult female with transient exposure to 0.1 ppb and 10 ppb DEHP was significantly reduced when compared with the solvent control group. Our data suggest that transient exposure to ultra low concentrations of DEHP during sensitive time windows of development results in irreversible reproductive impairment which may impact fish populations negatively.

Cross Sectional Study on Exposure to BPA and Phthalates and Semen Parameters in Men Attending a Fertility Center

Among the possible risk factors for male reproduction, exposure to phthalates and alkylphenols is widely documented. This study evaluated the possible association between chemical exposure and the quality of the seminal fluid of 105 subjects in a fertility clinic. The urinary levels of seven phthalate metabolites (monoethylphthalate, MEP; monobenzylphthalate, MBzP; mono n-butylphthalate, MnBP; mono-(2-ethylhexyl) phthalate, MEHP; mono(2-ethyl-5-hydroxyhexyl) phthalate, MEHHP; mono-n-octylphthalate, MnOP; mono-isononylphthalate, MiNP) and bisphenol A (BPA), were analysed by high performance liquid chromatography/tandem mass spectrometry HPLC/MS/MS. The regression analysis showed that the semen volume was positively associated with MnBP, MnOP and BPA levels while was negatively associated with MiNP levels. The sperm concentration had a significant inverse relationship with MEP levels. A negative association was found between the use of plastic containers for food storage (p = 0.037) and semen volume (3.06 vs. 2.30 mL as average values, never vs daily). A significant positive correlation emerged (p < 0.005) between the consumption of canned food and the levels of BPA (2.81 vs. 0.14 µg/g creat as average values, daily vs. never) and between the use of perfumes and levels of MEP (389.86 vs. 48.68 µg/g creat, as average values, daily vs. never). No further statistically significant associations were found, even considering the working activity. Some evidence emerged about the possible link between exposure and seminal fluid quality: further case/control or prospective studies will allow us to confirm this causality hypothesis.

Phthalate esters (PAEs) in atmospheric particles around a large shallow natural lake (Lake Chaohu, China)

The pollution of phthalate esters (PAEs) remains an important issue in the world. Current studies mainly focused on atmospheric PAEs in urban area with strong anthropogenic activities, but there were no studies on PAEs in the ambient air around large natural lake. This paper focused on two sites around Lake Chaohu to investigate the monthly occurrence, composition and source of PAEs in the atmospheric particles around large shallow natural lake. New insights into atmospheric PAEs in large shallow natural lake and the overall fate of PAEs in lake ecosystem were given. The concentrations of the Σ₁₃PAEs in atmospheric particles were at a significantly low level ranging from 2740 to 11,890 pg·m^-3 and 2622 to 15,331 pg·m^-3 in ZM (the lakeshore site) and HB (the downtown site), respectively. There were no statistically significant differences of PAEs between ZM and HB. The highest atmospheric PAE concentrations in August were likely related to the long-range transport from Guangdong Province. Di(2-ethylhexyl) phthalate (DEHP), diisobutyl phthalate (DIBP) and dibutyl phthalate (DBP) were the main PAE congeners. Temporally, DIBP and DBP had the highest fractions in winter and the lowest fractions in summer. It might be justified by the condensation of DIBP and DBP from gas phase to particulate phase at low temperature. Multimedia comparison of PAE profiles in Lake Choahu revealed that low molecular weight (LMW) congeners were transported mainly through water while high molecular weight (HMW) congeners were transported mainly through atmosphere.

Association between semen quality among men with different occupational exposures and risk of recurrent spontaneous abortion in island residents

Objective: This study aimed to evaluate the semen quality of male adults whose spouses suffer from recurrent spontaneous abortion (RSA) in the island area, and to explore the association between RSA and occupational exposures.

Methods: A total of 131 male patients were recruited and divided into two groups: spouse with recurrent spontaneous abortion group (RSA group, [Formula: see text]) and the normal fertility group (control group, [Formula: see text]). Information such as height, weight and occupational exposure history of 131 men were obtained. Semen samples were collected and analyzed. Differences in semen parameters and DNA fragmentation index (DFI) between the two groups were compared. Odds ratios (ORs) and their corresponding 95% confidence intervals were calculated to evaluate the association between occupational exposures and RSA status.

Results: Overall, no significant difference was found in sperm concentration, progressive motility and normal morphology rate between RSA and control groups. Only DFI was observed to be significantly higher in the RSA group. Evaluation of the receiver operating characteristic (ROC) curve showed DFI (AUC: 0.623, [Formula: see text]) could discriminate between males from the couples with RSA and without RSA.

Conclusion: The analysis of conventional semen parameters could not directly reflect their influence on embryonic development, and test of integrity of the sperm DNA is of paramount importance to fully understand male fertility. It is crucial to conduct studies regarding occupational exposures and pregnancy loss and/or RSA risk, since it will provide population-level data to aid in the identification of important risk factors that warrant further mechanistic investigation, and eventually lead to effective prevention and treatment strategies.