Association between ambient PM1 and semen quality: A cross-sectional study of 27,854 men in China

Exposure to ambient particulate matter and ovarian reserve impairment among reproductive age women in China

Ovarian aging, characterized by a decline in ovarian reserve, is a critical concern in female reproductive health. However, the evidence linking ambient air pollution exposure with ovarian reserve impairment remains limited. We aimed to estimate the association between exposure to fine particulate matter (PM2.5) and respirable particulate matter (PM10) and key indicators of ovarian reserve, including antral follicle count (AFC), ovarian volume (OV), anti-Müllerian hormone (AMH), follicle-stimulating hormone (FSH), estradiol (E2), luteinizing hormone (LH), FSH/LH ratio, and inhibin B (INHB). The cohort consisted of women attending an infertility clinic at the Tongji Reproductive and Environmental (TREE) study between 2018 and 2020. We used multivariate linear and Poisson regression models to estimate the association between PM2.5 and PM10 exposure and these ovarian reserve indicators. Our results showed that PM2.5 and PM10 exposure were associated with a reduction in AFC and an increase in E2 levels, highlighting the adverse effects of ambient air pollution on ovarian reserve. Our findings have important public health implications, emphasizing the urgent need for interventions to safeguard female reproductive health and reduce exposure to ambient air pollution.

Individual and joint associations of air pollutants exposure with semen quality: A retrospective longitudinal study in Wenzhou, China

PURPOSE

The impact of air pollution on semen quality has been confirmed, yet the joint effect remains unclear. We evaluate the individual and joint associations of particulate (PM2.5 and PM10) and gaseous pollutants (NO2, SO2, O3 and CO) with semen quality.

METHODS

We included 5,114 men in this study from 2014 to 2022. The individual and joint associations were measured by multiple linear regression models.

RESULTS

Sperm motility and semen volume were inversely associated with pollutant concentrations during every stage of sperm development, especially at lag days 0-9 and 10-14 (all P < 0.05). Stratified analyses showed that the study pollutants (except CO) had a positive effect on semen concentration during the stage of sperm development, especially in spring and autumn, while a decreased total sperm number was associated with CO (all P < 0.05). However, joint associations of particulate and gaseous pollutants with semen quality parameters were not statistically significant (all P > 0.05).

CONCLUSIONS

During all stages of sperm development, particulate and gaseous pollutants had individual negative impacts on sperm motility and semen volume, and these impacts were less pronounced in spring and autumn. Our findings highlight the importance and necessity of reducing the exposure to pollutants especially in the critical stage of sperm development to improve semen quality.

Chemical composition, mutagenicity, and cytotoxicity of urban submicron particulate matter (PM1) in Agra, India

This study, conducted in Agra, India, examined the mass concentrations, chemical compositions, and seasonal variations of submicron particles (PM1). The concentrations of metals, water-soluble inorganic ions (WSIs) including anions (F-, Cl-, NO₃-, SO₄2-) and cations (Ca2+, K+, Mg2+, NH₄+, Na+), organic carbon (OC) and elemental carbon (EC) and polycyclic aromatic hydrocarbons (PAHs) in PM1 extract were determined using Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES), Ion Chromatography, Thermogravimetric Analysis and Gas Chromatography-Mass Spectrometry (GC-MS) respectively. For morphological observation of PM1 particles, Field Emission Scanning Electron Microscopy-Energy Dispersive X-ray spectrometry (FESEM-EDS) was used. The annual average concentration of PM1 was 82.9 ± 33.4 μg/m3, which exceeds the World Health Organisation's (WHO) safe limit for PM2.5 of 5 μg/m3 by a factor of 17. The PM1 mass composition included metals (31 %), WSIs (28 %), OC and EC (9.8 %), and PAHs (0.4 %). Winter recorded the highest PM1 concentration (96.1 ± 25.8 μg/m3), followed by post-monsoon, summer, and monsoon seasons. The average concentration of PAHs was 364.6 ± 226.6 ng/m3. Positive Matrix Factorization (PMF) identified traffic, emissions from biomass/coal and wood combustion, industrial/stationary sources, and secondary aerosols as potential contributors. The Ames test revealed the presence of frameshift mutations and base pair substitutions, especially in winter and post-monsoon. Additionally, PM1 exhibited cytotoxic effects on V-79 cells, with heightened toxicity during winter and prolonged exposure in other seasons. This study underscores the urgent need to address local emission sources and establish regulatory standards for PM1 in urban areas.

Exposure to ambient ozone and sperm quality among adult men in China

BACKGROUND

Limited evidence exists regarding the association between ozone exposure and adverse sperm quality. We aimed to assess the association between ozone exposure and sperm quality, and identify susceptible exposure windows.

METHODS

We recruited 32,541 men aged between 22 and 65 years old attending an infertility clinic in Wuhan, Hubei Province, China from 2014 to 2020. Ozone data were obtained from a satellite-based spatiotemporal model. Generalized linear models were used to estimate the association between ozone exposure and sperm quality parameters, including sperm concentration, sperm count, sperm total motility, and sperm progressive motility during the entire stage of sperm development (0-90 days before ejaculation) and three crucial stages (0-9 days, 10-14 days and 70-90 days before ejaculation). Stratified analyses were performed to evaluate whether associations varied by age, body mass index, and education levels.

RESULTS

The final analysis included 27,854 adult men. A 10 μg/m3 increase in ozone concentrations during the entire stage of sperm development was associated with a -4.17 % (95 % CI: -4.78 %, -3.57 %) decrease in sperm concentration, -6.54 % (95 % CI: -8.03 %, -5.60 %) decrease in sperm count, -0.50 % (95 % CI: -0.66 %, -0.34 %) decrease in sperm total motility, and -0.07 % (95 % CI: -0.22 %, 0.09 %) decrease in sperm progressive motility. The associations were stronger during 70-90 days before ejaculation and among men with middle school and lower education for sperm concentration.

CONCLUSIONS

Ozone exposure was associated with decreased sperm quality among Chinese adult men attending an infertility clinic. These results suggest that ozone may be a risk factor contributing to decreased sperm quality in Chinese men.

Reduced human fecundity attributable to ambient fine particles in low- and middle-income countries

BACKGROUND

Exposure to ambient fine particulate matter (PM2.5) has been associated with reduced human fecundity. However, the attributable burden has not been estimated for low- and middle-income countries (LMICs), where the exposure-response function between PM2.5 and the infertility rate has been insufficiently studied.

OBJECTIVE

This study examined the associations between long-term exposure to PM2.5 and human fecundity indicators, namely the expected time to pregnancy (TTP) and 12-month infertility rate (IR), and then estimated PM2.5-attributable burden of infertility in LMICs.

METHODS

We analyzed 164,593 eligible women from 100 Demographic and Health Surveys conducted in 49 LMICs between 1999 and 2021. We assessed PM2.5 exposures during the 12 months before a pregnancy attempt using the global satellite-derived PM2.5 estimates produced by Atmospheric Composition Analysis Group (ACAG). First, we created a series of pseudo-populations with balanced covariates, given different levels of PM2.5 exposure, using a matching approach based on the generalized propensity score. For each pseudo-population, we used 2-stage generalized Gamma models to derive TTP or IR from the probability distribution of the questionnaire-based duration time for the pregnancy attempt before the interview. Second, we used spline regressions to generate nonlinear PM2.5 exposure-response functions for each of the two fecundity indicators. Finally, we applied the exposure-response functions to estimate number of infertile couples attributable to PM2.5 exposure in 118 LMICs.

RESULTS

Based on the Gamma models, each 10 µg/m3 increment in PM2.5 exposure was associated with a TTP increase by 1.7 % (95 % confidence interval [CI]: -2.3 %-6.0 %) and an IR increase by 2.3 % (95 %CI: 0.6 %-3.9 %). The nonlinear exposure-response function suggested a robust effect of an increased IR for high-concentration PM2.5 exposure (>75 µg/m3). Based on the PM2.5-IR function, across the 118 LMICs, the number of infertile couples attributable to PM2.5 exposure exceeding 35 µg/m3 (the first-stage interim target recommended by the World Health Organization global air quality guidelines) was 0.66 million (95 %CI: 0.061-1.43), accounting for 2.25 % (95 %CI: 0.20 %-4.84 %) of all couples affected by infertility. Among the 0.66 million, 66.5 % were within the top 10 % high-exposure infertile couples, mainly from South Asia, East Asia, and West Africa.

CONCLUSION

PM2.5 contributes significantly to human infertility in places with high levels of air pollution. PM2.5-pollution control is imperative to protect human fecundity in LMICs.

Ambient fine particulate matter constituents and semen quality among adult men in China

Exposure to ambient fine particulate matter (PM2.5) was associated with decreased semen quality, but the relationship between PM2.5 constituents and semen quality was unclear. We recruited 27,824 adult men attending an infertility clinic in Wuhan, China, between 2014 and 2020. We used a four-dimensional spatiotemporal deep forest model to estimate concentrations of PM2.5 mass and its chemical constituents, including organic matter (OM), black carbon (BC), sulfate (SO42-), nitrate (NO3-), ammonium (NH4+), and chloride (Cl-). We employed linear regression models to estimate the association between PM2.5 mass and its constituents with various sperm parameters. Exposure to PM2.5 was associated with a reduction in sperm quality, with a percent change of - 5.69% (95% confidence interval [CI]: -8.53%, -2.85%) for sperm density, - 15.09% (95% CI: -22.24%, -7.94%) for sperm total count, - 1.63% (95% CI: -2.36%, -0.91%) for sperm progressive motility, and - 2.30% (95% CI: -3.04%, -1.55%) for sperm total motility. Among specific constituents, exposure to OM, BC, Cl-, or NO3- was associated with a reduction in these four semen quality parameters. The association was more pronounced among older men or individuals with lower levels of education. Our findings suggest that PM2.5 mass and each constituent were associated with decreased semen quality in adult men.

Exposure to air pollution is associated with DNA methylation changes in sperm

Exposure to air pollutants has been associated with adverse health outcomes in adults and children who were prenatally exposed. In addition to reducing exposure to air pollutants, it is important to identify their biologic targets in order to mitigate the health consequences of exposure. One molecular change associated with prenatal exposure to air pollutants is DNA methylation (DNAm), which has been associated with changes in placenta and cord blood tissues at birth. However, little is known about how air pollution exposure impacts the sperm epigenome, which could provide important insights into the mechanism of transmission to offspring. In the present study, we explored whether exposure to particulate matter less than 2.5 microns in diameter, particulate matter less than 10 microns in diameter, nitrogen dioxide (NO2), or ozone (O3) was associated with DNAm in sperm contributed by participants in the Early Autism Risk Longitudinal Investigation prospective pregnancy cohort. Air pollution exposure measurements were calculated as the average exposure for each pollutant measured within 4 weeks prior to the date of sample collection. Using array-based genome-scale methylation analyses, we identified 80, 96, 35, and 67 differentially methylated regions (DMRs) significantly associated with particulate matter less than 2.5 microns in diameter, particulate matter less than 10 microns in diameter, NO2, and O3, respectively. While no DMRs were associated with exposure to all four pollutants, we found that genes overlapping exposure-related DMRs had a shared enrichment for gene ontology biological processes related to neurodevelopment. Together, these data provide compelling support for the hypothesis that paternal exposure to air pollution impacts DNAm in sperm, particularly in regions implicated in neurodevelopment.

Exposure to PM2.5, seminal plasma metabolome, and semen quality among Chinese adult men: Association and potential mediation analyses

Exposure to ambient fine particulate matter (PM2.5) has been linked to a decline in semen quality, but the underlying mechanisms for this association remain unclear. We aimed to examine whether specific metabolites act as mediators in the association between PM2.5 exposure and changes in semen quality. We conducted untargeted metabolomics analysis using LC-MS/MS platforms to identified seminal plasma metabolites associated with various semen quality parameters among 200 Chinese adult men. Additionally, we performed mediation analyses to examine the effects of the seminal plasma metabolites on the association between PM2.5 exposure and semen quality. We identified 140 differential metabolites between the normal and abnormal semen groups, involving two metabolic pathways: Alanine, aspartate and glutamate metabolism, and Aminoacyl-tRNA biosynthesis. We additionally identified 7 specific seminal plasma metabolites that were associated with discrepant metabolic networks related to semen quality. The mediation analysis revealed that D-Aspartate might play a mediating role in the adverse effects of ambient PM2.5 exposure on both total and progressive motility during spermatogenesis period (70-90 days before ejaculation), with a proportion of mediation up to 16% and 17%, respectively. Exposure to PM2.5 was associated with alterations in D-Aspartate levels, which might partially mediate the association between PM2.5 and reduced sperm motility.

Implications of Exposure to Air Pollution on Male Reproduction: The Role of Oxidative Stress

Air pollution, either from indoor (household) or outdoor (ambient) sources, occurs when there is presence of respirable particles in the form of chemical, physical, or biological agents that modify the natural features of the atmosphere or environment. Today, almost 2.4 billion people are exposed to hazardous levels of indoor pollution, while 99% of the global population breathes air pollutants that exceed the World Health Organization guideline limits. It is not surprising that air pollution is the world's leading environmental cause of diseases and contributes greatly to the global burden of diseases. Upon entry, air pollutants can cause an increase in reactive oxygen species (ROS) production by undergoing oxidation to generate quinones, which further act as oxidizing agents to yield more ROS. Excessive production of ROS can cause oxidative stress, induce lipid peroxidation, enhance the binding of polycyclic aromatic hydrocarbons (PAHs) to their receptors, or bind to PAH to cause DNA strand breaks. The continuous and prolonged exposure to air pollutants is associated with the development or exacerbation of pathologies such as acute or chronic respiratory and cardiovascular diseases, neurodegenerative and skin diseases, and even reduced fertility potential. Males and females contribute to infertility equally, and exposure to air pollutants can negatively affect reproduction. In this review, emphasis will be placed on the implications of exposure to air pollutants on male fertility potential, bringing to light its effects on semen parameters (basic and advanced) and male sexual health. This study will also touch on the clinical implications of air pollution on male reproduction while highlighting the role of oxidative stress.