Perfluoroheptanoic acid induces Leydig cell hyperplasia but inhibits spermatogenesis in rats after pubertal exposure

Male infertility and perfluoroalkyl and poly-fluoroalkyl substances: evidence for alterations in phosphorylation of proteins and fertility-related functional attributes in bull spermatozoa†

BACKGROUND

Perfluoroalkyl and poly-fluoroalkyl substances (PFAS) are pervasive environmental pollutants and potential threats to reproductive health. Epidemiological studies have established an association between PFAS and male infertility, but the underlying mechanisms are unclear.

OBJECTIVES

Investigate the effect of perfluorooctane sulfonic acid (PFOS), the most prevalent and representative PFAS, on bull sperm protein phosphorylation and function.

METHODS

We exposed bull sperm to PFOS at 10 (average population exposure) and 100 μM (high-exposure scenario), and analyzed global proteomic and phosphoproteomic analysis by TMT labeling and Nano LC-MS/MS. We also measured sperm fertility functions by flow cytometry.

RESULTS

PFOS at 10-μM altered sperm proteins linked to spermatogenesis and chromatin condensation, while at 100 μM, PFOS affected proteins associated with motility and fertility. We detected 299 phosphopeptides from 116 proteins, with 45 exhibiting differential expression between control and PFOS groups. PFOS dysregulated phosphorylation of key proteins (ACRBP, PRKAR2A, RAB2B, SPAG8, TUBB4B, ZPBP, and C2CD6) involved in sperm capacitation, acrosome reaction, sperm-egg interaction, and fertilization. PFOS also affected phosphorylation of other proteins (AQP7, HSBP9, IL4I1, PRKAR1A, and CCT8L2) related to sperm stress resistance and cryotolerance. Notably, four proteins (PRM1, ACRBP, TSSK1B, and CFAP45) exhibited differential regulation at both proteomic and phosphoproteomic levels. Flow cytometric analysis confirmed that PFOS increased protein phosphorylation in sperm and also decreased sperm motility, viability, calcium, and mitochondrial membrane potential and increased mitochondrial ROS in a dose-dependent manner.

CONCLUSIONS

This study demonstrates that PFOS exposure negatively affects phosphorylation of proteins vital for bull sperm function and fertilization.

Per- and polyfluoroalkyl substances (PFAS) and hypertensive disorders of Pregnancy- integration of epidemiological and mechanistic evidence

BACKGROUND

Hypertensive disorders of pregnancy (HDP) remain a significant global health burden despite medical advancements. HDP prevalence appears to be rising, leading to increased maternal and fetal complications, mortality, and substantial healthcare costs. The etiology of HDP are complex and multifaceted, influenced by factors like nutrition, obesity, stress, metabolic disorders, and genetics. Emerging evidence suggests environmental pollutants, particularly Per- and polyfluoroalkyl substances (PFAS), may contribute to HDP development.

OBJECTIVE

This review integrates epidemiological and mechanistic data to explore the intricate relationship between PFAS exposure and HDP.

EPIDEMIOLOGICAL EVIDENCE

Studies show varying degrees of association between PFAS exposure and HDP, with some demonstrating positive correlations, particularly with preeclampsia. Meta-analyses suggest potential fetal sex-specific differences in these associations.

MECHANISTIC INSIGHTS

Mechanistically, PFAS exposure appears to disrupt vascular hemodynamics, placental development, and critical processes like angiogenesis and sex steroid regulation. Experimental studies reveal alterations in the renin-angiotensin system, trophoblast invasion, oxidative stress, inflammation, and hormonal dysregulation - all of which contribute to HDP pathogenesis. Elucidating these mechanisms is crucial for developing preventive strategies.

THERAPEUTIC POTENTIAL

Targeted interventions such as AT2R agonists, caspase inhibitors, and modulation of specific microRNAs show promise in mitigating adverse outcomes associated with PFAS exposure during pregnancy.

KNOWLEDGE GAPS AND FUTURE DIRECTIONS

Further research is needed to comprehensively understand the full spectrum of PFAS-induced placental alterations and their long-term implications for maternal and fetal health. This knowledge will be instrumental in developing effective preventive and therapeutic strategies for HDP in a changing environmental landscape.

Involvement of per- and polyfluoroalkyl compounds in tumor development

Per- and polyfluoroalkyl substances (PFAS) are a large group of synthetic persistent chemicals, which are used in many industrial and commercial applications. Hundreds of different PFAS have been identified in the environment and they are commonly found also in human blood. Due to the chemical stability and extensive use, PFAS pose a risk for human health and wildlife. Mounting evidence indicates that PFAS-exposure adversely affects many organs including liver, kidney, and reproductive tissues and induces tumors in laboratory rodents. Epidemiological studies show association between PFAS-exposure and some tumors also in humans. Effects of PFAS-exposure are complex and obviously do not depend only on the concentration and the structure of PFAS, but also on age and sex of the exposed individuals. It has been difficult to show a causal link between PFAS-exposure and tumors. Moreover, molecular mechanisms of the PFAS effects in different tissues are poorly understood. PFAS are not directly mutagenic and they do not induce formation of DNA binding metabolites, and thus are assumed to act more through non-genotoxic mechanisms. In this review, we discuss the involvement of PFAS-compounds in tumor development in tissues where PFAS exposure has been associated with cancer in epidemiological and animal studies (liver, kidney, testicle and breast). We will focus on molecular pathways and mechanisms related to tumor formation following PFAS-exposure.

Endocrine-disrupting chemicals and male reproductive health

Modifiable factors, such as environmental exposures, can impact human fertility. The objective of this review is to summarize the potential effects of exposure to important endocrine-disrupting chemicals on male reproductive health. Most experimental and animal data demonstrate strong evidence for the negative effects of exposure to phenols, phthalates, pesticides, and perfluoroalkyl and polyfluoroalkyl substances on male reproductive health. Although evidence of negative associations in humans was overall strong for phthalates and pesticides, limited and inconclusive relationships were found for the other examined chemical biomarkers. Reasons for the discrepancies in results include but are not limited to, differences in study populations, exposure concentrations, number of samples collected, sample sizes, study design, and residual confounding. Additional studies are needed, particularly for newer phenols and perfluoroalkyl and polyfluoroalkyl substances, given the scarce literature on the topic and increasing exposures over time.

Legacy and Emerging Perfluoroalkyl and Polyfluoroalkyl Substances Regulate Steroidogenesis in the Male Gonad

Perfluoroalkyl and polyfluoroalkyl substances (PFAS) are widely used in a variety of industrial processes and manufacturing of consumer products. Current efforts by the manufacturing industry will limit use of long-chain or legacy PFAS represented by perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) and replace with short-chain or emerging PFAS such as perfluorobutanoic acid (PFBA) and perfluorobutane sulfonic acid (PFBS). However, there is little to no information on the toxicity of new and emerging PFAS. Therefore, we performed experiments in growing Long-Evans male rats to investigate effects of low-dose prepubertal and pubertal exposures to PFAS on gonadal steroid hormone secretion. The results demonstrated that both legacy and emerging PFAS have the capacity to regulate testicular steroidogenesis. For instance, prepubertal exposures to PFOS, PFBA, and PFBS increased serum and testicular testosterone concentrations. Exposure to PFBA increased testicular 17β-estradiol (E2) concentrations, and PFOS and PFBS both decreased serum E2 concentrations while stimulating testicular E2 secretion. The data also demonstrated additive effects due to legacy and emerging PFAS mixtures compared with the individual chemicals. The gonadal effects due to PFAS exposures occurred at nanomolar concentrations, which approximate PFAS levels in the environment. Taken together, the present study supports the need for development of cost-effective and sustainable filtration media for different processes to remove PFAS from water and other sources of exposure. Current action by regulatory agencies such as the US Environmental Protection Agency to limit use of PFAS in the manufacture of consumer products will protect public health.

FDX1 regulates leydig cell ferroptosis mediates PM2.5-induced testicular dysfunction of mice

Epidemiological studies have established an association between chronic exposure to PM2.5 and male infertility. However, the underlying mechanisms were not fully revealed. In this study, we established mice models exposed to PM2.5 for 16 weeks, and a significant decrease in sperm quality accompanied by an increase in testosterone levels were observed after PM2.5 exposure. Moreover, treatment with ferrostatin-1 (Fer-1), a specific ferroptosis inhibitor, effectively mitigated PM2.5-induced testicular dysfunction in mice. And lipid peroxidation and ferritin accumulation were found to be significantly increased in Leydig cells of testes with a PM2.5-dose dependent manner. Further investigations revealed that TM-3 cells, a mouse Leydig cell line, were prone to ferroptosis after PM2.5 exposure, and the cell viability was partly rescued after the intervention of Fer-1. Furthermore, our results supported that the ferroptosis of TM-3 cells was attributed to the upregulation of ferredoxin 1 (FDX1), which was the protein transferring electrons to cytochrome P450 family 11 subfamily A member 1 to aid lysing cholesterol to pregnenolone at initial of steroidogenesis. Mechanically, PM2.5-induced FDX1 upregulation resulted in cellular ROS elevation and ferrous iron overload, which together initiated an autoxidation process of polyunsaturated fatty acids in the cell membrane of Leydig cells until the accumulated lipid peroxides triggered ferroptotic cell death. Simultaneously, upregulation of FDX1 promoted steroidogenesis and let to an increased level of testosterone. In summary, our work suggested that FDX1, a mediator involving steroidogenesis, was a key regulator in PM2.5-induced Leydig cells ferroptosis.

An overview on human exposure, toxicity, solid-phase microextraction and adsorptive removal of perfluoroalkyl carboxylic acids (PFCAs) from water matrices

Perfluoroalkyl carboxylic acids (PFCAs) are sub-class of perfluoroalkyl substances commonly detected in water matrices. They are persistent in the environment, hence highly toxic to living organisms. Their occurrence at trace amount, complex nature and prone to matrix interference make their extraction and detection a challenge. This study consolidates current advancements in solid-phase extraction (SPE) techniques for the trace-level analysis of PFCAs from water matrices. The advantages of the methods in terms of ease of applications, low-cost, robustness, low solvents consumption, high pre-concentration factors, better extraction efficiency, good selectivity and recovery of the analytes have been emphasized. The article also demonstrated effectiveness of some porous materials for the adsorptive removal of the PFCAs from the water matrices. Mechanisms of the SPE/adsorption techniques have been discussed. The success and limitations of the processes have been elucidated.

Association between prenatal exposure to perfluoroalkyl substance mixtures and intrauterine growth restriction risk: A large, nested case-control study in Guangxi, China

Intrauterine growth restriction (IUGR) is an abnormal fetal growth pattern that can lead to neonatal morbidity and mortality. IUGR may be affected by prenatal exposure to environmental pollutants, including perfluoroalkyl substances (PFASs). However, research linking PFAS exposure to IUGR is limited, with inconsistent results. We aimed to investigate the association between PFAS exposure and IUGR by using nested casecontrol study based on Guangxi Zhuang Birth Cohort (GZBC), in Guangxi, China. A total of 200 IUGR cases and 600 controls were enrolled in this study. The maternal serum concentrations of nine PFASs were measured using ultrahigh-performance liquid chromatography-tandem mass spectrometry (UPLCMS). The associations single and mixed effects of prenatal PFAS exposure on IUGR risk were assessed using conditional logistic regression (single-exposure), Bayesian kernel machine regression (BKMR) and quantile g-computation (qgcomp) models. In the conditional logistic regression models, the log10-transformed concentrations of perfluoroheptanoic acid (PFHpA, adjusted OR: 4.41, 95% CI: 3.03-6.41), perfluorododecanoic acid (PFDoA, adjusted OR: 1.94, 95% CI: 1.14-3.32), and perfluorohexanesulfonate (PFHxS, adjusted OR: 1.83, 95% CI: 1.15-2.91) were positively associated with risk of IUGR. In the BKMR models, the combined effect of PFASs was positively associated with IUGR risk. In the qgcomp models, we also found an increased IUGR risk (OR=5.92, 95% CI: 2.33-15.06) when all nine PFASs increased by one tertile as a whole, and PFHpA (43.9%) contributed the largest positive weights. These findings suggested prenatal exposure to single and mixtures of PFASs may increase IUGR risk, with the effect being largely driven by the PFHpA concentration.

Effect of prenatal perfluoroheptanoic acid exposure on spermatogenesis in offspring mice

BACKGROUND

Perfluoroheptanoic acid (PFHpA), a persistent organic pollutant widespread in the environment, is suspected as an environmental endocrine disruptor for its disturbance effect on hormone homeostasis and reproductive development. Whereas the effect of intrauterine PFHpA exposure during gestation on spermatogenesis of male offspring mice is still unknown.

OBJECTIVE

This study aimed to explore the effect of prenatal PFHpA exposure on the reproductive development of male offspring mice and the role of N⁶-methyladenosine (m⁶A) during the process.

METHODS

Fifty-six C57BL/6 pregnant mice were randomly divided into 4 groups. During the gestation period, the pregnant mice were exposed to 0, 0.0015, 0.015, and 0.15 mg/kg bw/d PFHpA from gestational day 1 (GD1) to GD16 by oral gavage. The male offspring mice were sacrificed by spinal dislocation at 7 weeks old. The body weight, testicular weight, and brain weight were weighed, and the intra-testicular testosterone was detected. The sperm qualities were analyzed with computer-aided sperm analysis (CASA). The testicular tissues were taken to analyze the pathological changes and examine the global m⁶A RNA methylation levels. Quantitative real-time PCR (qRT-PCR) was adopted to figure out the mRNA expression levels of m⁶A-related enzymes in testicular tissues of different PFHpA treated groups. Methylated RNA immunoprecipitation sequencing (MeRIP-seq) was applied to further explore the m⁶A RNA methylation at a whole-genome scale.

RESULTS

Compared with the control group, no significant differences were observed in body weight, testicular weight, testicular coefficient, and the visceral-brain ratio of testicular tissue in the PFHpA treated groups. And no significant change was observed in intra-testicular testosterone among the four groups. CASA results showed a decrease of sperm count, sperm concentration, and total cell count, as well as an increase of sperm progressive cells' head area after prenatal PFHpA exposure (P < 0.05). Hematoxylin and eosin staining of pathological sections showed seminiferous tubules morphological change, disorder arrangement of seminiferous epithelium, and reduction of spermatogenic cells in the PFHpA treated groups. PFHpA significantly decreased global levels of m⁶A RNA methylation in testicular tissue (P < 0.05). Besides, qRT-PCR results showed significant alteration of the mRNA expression levels of seven m⁶A-related enzymes (Mettl3, Mettl5, Mettl14, Pcif1, Wtap, Hnrnpa2b1, and Hnrnpc) in the PFHpA treated groups (P < 0.05). MeRIP-seq results showed a correlation between prenatal PFHpA exposure and activation and binding of cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP). Cnga3 and Mpzl3 showed differential expression in the enrichment subcategories or pathways.

CONCLUSIONS

Exposure to PFHpA during the gestation period would adversely affect the development of seminiferous tubules and testicular m⁶A RNA methylation in offspring mice, which subsequently interferes with spermatogenesis and leads to reproductive toxicity.

Perfluorooctane sulfonate and perfluorooctanoic acid inhibit progesterone-responsive capacitation through cAMP/PKA signaling pathway and induce DNA damage in human sperm

Perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) are two persistent organic pollutants harmful to human health. They induce negative effects on male reproduction by influencing male hormones, spermatogenesis, and sperm quality. However, their effects and mechanisms on human sperm capacitation and fertilization remain unclear. Here, human sperm were incubated with different concentrations of PFOS or PFOA with progesterone during capacitation. Both PFOS and PFOA inhibited human sperm hyperactivation, sperm acrosome reaction, and protein tyrosine phosphorylation levels. PFOS and PFOA decreased intracellular Ca²⁺ concentration in the presence of progestrone, and subsequently decreased cAMP level, and PKA activity. PFOS and PFOA increased reactive oxygen species production and sperm DNA fragmentation duing the only 3h capacitation incubation. Conclusively, PFOA and PFOS may inhibit human sperm capacitation via the Ca²⁺-mediated cAMP/PKA signaling pathway in the presence of progesterone, and induce sperm DNA damage through increased oxidative stress, which is not conducive to fertilization.

Associations of per- and polyfluoroalkyl substances and their alternatives with bone mineral density levels and osteoporosis prevalence: A community-based population study in Guangzhou, Southern China

BACKGROUND

Evidence concerning associations of per- and polyfluoroalkyl substances (PFASs) exposure with bone mineral density (BMD) and osteoporosis is scarce. Additionally, no study has examined the effects of PFAS isomers and alternatives on bone health.

OBJECTIVES

To evaluate the associations of PFASs and PFAS alternatives with BMD levels and osteoporosis prevalence.

METHODS

A total of 1260 healthy adults from southern China were enrolled. Serum concentrations of 32 legacy PFASs, PFAS isomers, and alternatives were measured using modified liquid chromatography-tandem mass spectrometry. Logistic and linear regression models were applied to evaluate the associations of PFASs with osteoporosis prevalence and BMD levels, respectively, adjusting for confounding factors. We performed stratified analyses to assess potential effect modifications of age and sex. We further used sensitivity analyses to testify the robustness of the main findings.

RESULTS

There were 204 (16.2 %) participants diagnosed with osteoporosis. Eleven of the studied PFASs (i.e., PFHpA, PFOA, PFBS, PFHpS, total-PFHxS, n-PFHxS, br-PFHxS, br-PFOS, 1m-PFOS, Σ3 + 4 + 5m-PFOS, and 6:2 Cl-PFESA) showed significant and inverse associations with BMD levels (mean differences ranged from -6.47 to -26.07 per one ln-unit increase in the PFASs). Additionally, we observed that each one ln-unit increase in PFHpA was significantly associated a 23 % (OR = 1.23, 95 % CI = 1.04, 1.45) greater odds of osteoporosis. The above associations were consistent in several sensitivity analyses we performed. Stratified analyses showed stronger associations among women and younger compared to their counterparts.

CONCLUSIONS

Our findings suggested that greater PFAS exposure is associated with poorer bone health, especially in women and younger people.

Preconception exposure to perfluoroalkyl and polyfluoroalkyl substances and couple fecundity: A couple-based exploration

Numerous studies have examined the adverse health effects of perfluoroalkyl and polyfluoroalkyl substances (PFAS) but it remains unclear whether preconception exposure to PFAS affects couple fecundity. This prospective preconception cohort study with 936 Chinese couples aimed to comprehensively assess the effects of PFAS on couple fecundity [measured by the time to pregnancy (TTP)] and infertility (i.e., TTP > 12 menstrual cycles) with a focus on the effects of partner-specific exposure and joint-effects of couple-based exposure. Twenty-five PFAS were quantified in plasma from each partner, including seven branched isomers, two chlorinated polyfluoroalkyl ether sulfonic acids, four emerging PFAS replacements [i.e., 6:2 fluorotelomer phosphate diester (6:2 diPAP) and three short-chain alternatives: perfluoro-n-butanoicacid, perfluorobutane sulfonate and perfluoroheptanoic acid (PFHpA)]. Using a two-phase regression approach composed of elastic net regression and principal component analysis, we found that exposure to 6:2 diPAP and PFHpA rather than legacy PFAS in women and the couple-based exposure patterns characterized by high level of female 6:2 diPAP were significantly associated with reduced couple fecundity, which was independent of the adjustment of co-exposed PFAS homogenous from both partners. For example, a ln unit increase in female 6:2 diPAP was associated with 15 % [fecundity odds ratio (FOR) = 0.85, 95 %CI: 0.76, 0.96)] lower odds of couple fecundability (i.e., longer TTP) and 45 % increased risk of infertility [OR = 1.45 (95 %CI: 1.16, 1.81)], respectively. While most PFAS in men were not associated with couple fecundity, certain PFAS (e.g., perfluorohexane sulfonic acid) in men were negatively associated with infertility risk. However, the combined effects of PFAS mixture in couples were nonsignificant. Our findings suggest that PFAS in men and women may exert different impacts on couple fecundity. Preconception exposure to 6:2 diPAP and PFHpA in women may have the potential to impair couple fecundity.

The human fecal microbiome contributes to the biotransformation of the PFAS surfactant 8:2 monosubstituted polyfluoroalkyl phosphate ester

Polyfluoroalkyl phosphate esters (PAPs) can be found throughout society due to their numerous commercial applications. However, they also pose an environmental and health concern given their ability to undergo hydrolysis and oxidation to several bioactive and persistent products, including the perfluorocarboxylic acids (PFCAs). The metabolism of PAPs has been shown to occur in mammalian liver and intestine, however metabolism by the gut microbiome has not yet been investigated. In this study, human fecal samples were used to model the microbial population of the colon, to test whether these anaerobic microbes could facilitate 8:2 monosubstituted PAP (monoPAP) transformation. In vitro testing was completed by incubating the fecal samples with 8:2 monoPAP (400-10,000 nM) up to 120 minutes in an anaerobic chamber. Reactions were then terminated and the samples prepared for GC- and LC-MS/MS analysis. Metabolites of interest were the immediate hydrolysis product, the 8:2 fluorotelomer alcohol (FTOH), and 11 additional metabolites previously shown to form from 8:2 FTOH in both oxic and anoxic environments. The kinetics of 8:2 monoPAP transformation by gut microbiota were compared to those in human S9 liver and intestine fractions, both of which have active levels of hydrolyzing and oxidative enzymes that transform 8:2 monoPAP. Transformation rates from 8:2 monoPAP to 8:2 FTOH were highest in liver S9 > intestine S9 > fecal suspensions. The gut microbiome also produced a unique composition of oxidative metabolites, where the following intermediate metabolites were more abundant than terminal PFCAs: 8:2 fluorotelomer unsaturated carboxylic acid (FTUCA) > 8:2 fluorotelomer carboxylic acid (FTCA) > 7:2 Ketone ≈ perfluorohexanoic acid (PFHxA). Hydrolytic and oxidative metabolites contributed up to 30% of the molar balance after microbial 8:2 monoPAP transformation. Together, the results suggest that the gut microbiome can play a notable role in PAP biotransformation.

Per-, poly-fluoroalkyl substances (PFASs) pollution in benthic riverine ecosystem: Integrating microbial community coalescence and biogeochemistry with sediment distribution

Per-, Poly-fluoroalkyl substances (PFASs) accumulation in benthic environments is mainly determined by material mixing and represents a significant challenge to river remediation. However, less attention has been paid to the effects of sediment distribution on PFASs accumulation, and how PFASs influence microbial community coalescence and biogeochemical processes. In order to identify correlations between PFASs distribution and benthic microbial community functions, we conducted a field study and quantified the ecological constrains of material transportation on benthic microorganisms. Perfluorohexanoic acid (PFHxA) contributed most to the taxonomic heterogeneity of both archaeal (12.199%) and bacterial (13.675%) communities. Genera Methanoregula (R² = 0.292) and Bacillus (R² = 0.791) were identified as indicators that respond to PFASs. Phylogenetic null modeling indicated that deterministic processes (50.0-82.2%) dominated in spatial assembly of archaea, while stochasticity (94.4-97.8%) dominated in bacteria. Furthermore, spatial mixing of PFASs influenced broadly in nitrogen cycling of archaeal genomes, and phosphorus mineralization of bacterial genomes (p < 0.05). Overall, we quantified the effect of PFASs on community assembly and highlighted the constrains of PFASs influence on benthic geochemical potentials, which may provide new insights into riverine remediation.

Bisphenol B stimulates Leydig cell proliferation but inhibits maturation in late pubertal rats

Bisphenol B (BPB) has been used as a substitute for bisphenol A (BPA) in plastic materials. Whether BPB disrupts the male reproductive system remains unknown. Here, we report the effect of BPB on Leydig cell maturation in late puberty. Male Sprague-Dawley (35 days old) rats were gavaged with BPB at 0, 10, 100, and 200 mg/kg/day for 21 days. BPB significantly reduced body and epididymis weight at 200 mg/kg. BPB markedly decreased serum testosterone levels at 100 and 200 mg/kg and serum luteinizing hormone and follicle-stimulating hormone levels at 200 mg/kg. BPB significantly increased Leydig cell number at 100 and 200 mg/kg, while down-regulating the expression of Leydig cell genes (Cyp11a1 and Hsd3b1) at ≥100 mg/kg and up-regulating the expression of Sertoli cell genes (Pdgfra, Fshr, Sox9) and cell cycle regulators (Pcna, Ccnb1, Cdk2, and Cdk4) at 10-200 mg/kg. BPB markedly increased the phosphorylation of AKT1, AKT2, and ERK1/2 at 200 mg/kg. BPB increased the proliferation of rat immature Leydig cells via promoting the S/M2 phase shift at 100 and 1000 nM after 24-h culture in vitro. In conclusion, BPB disrupts Leydig cell maturation in late puberty by increasing Leydig cell number while inhibiting its maturation.

Perfluoroalkyl Chemicals and Male Reproductive Health: Do PFOA and PFOS Increase Risk for Male Infertility?

Poly- and perfluoroalkyl substances (PFAS) are manmade synthetic chemicals which have been in existence for over 70 years. Though they are currently being phased out, their persistence in the environment is widespread. There is increasing evidence linking PFAS exposure to health effects, an issue of concern since PFAS such as perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) bioaccumulate in humans, with a half-life of years. Many epidemiological studies suggest that, worldwide, semen quality has decreased over the past several decades. One of the most worrying effects of PFOS and PFOA is their associations with lower testosterone levels, similar to clinical observations in infertile men. This review thus focuses on PFOS/PFOA-associated effects on male reproductive health. The sources of PFAS in drinking water are listed. The current epidemiological studies linking increased exposure to PFAS with lowered testosterone and semen quality, and evidence from rodent studies supporting their function as endocrine disruptors on the reproductive system, exhibiting non-monotonic dose responses, are noted. Finally, their mechanisms of action and possible toxic effects on the Leydig, Sertoli, and germ cells are discussed. Future research efforts must consider utilizing better human model systems for exposure, using more accurate PFAS exposure susceptibility windows, and improvements in statistical modeling of data to account for the endocrine disruptor properties of PFAS.