News | Air Pollution and Male Infertility: Sperm Damage May Account for Over 50% of the Effect
Male infertility rates have continued to rise worldwide, and environmental pollution is considered an important factor. A recent study by Chinese researchers suggests that sperm damage caused by air pollution may account for more than 50% of its contribution to male infertility. The study shows how air pollution may increase infertility risk by impairing sperm quality.
Background and Objective
Air pollution is a major environmental challenge to reproductive health. According to the World Health Organization (WHO), infertility affects 15% of people worldwide, or about 60-80 million couples, with male factors accounting for roughly 40%-70% of cases. Animal studies have shown that pollutants such as particulate matter (PM) and sulfur dioxide (SO2) can impair sperm quality and spermatogenesis. Human evidence on how much pollution-related sperm damage contributes to male infertility remains limited.
This study therefore assessed the effects of several air pollutants on semen parameters and their potential contribution to male infertility risk.
Study Design
This prospective cohort study included 3,940 men aged 22-49. Participants enrolled between November 2018 and April 2021 and provided semen samples at enrollment. Eight parameters were analyzed: semen volume, sperm concentration, total sperm count, progressive motility, total motility, sperm vitality, morphology, and the teratozoospermia index.
During 12 months of follow-up, researchers assessed infertility, defined as failure to achieve pregnancy after 12 months of intercourse without contraception.
Machine-learning algorithms estimated exposure to multiple pollutants and linked the estimates to participant data. Pollutants included PM2.5, PM10, sulfur dioxide (SO2), nitrogen dioxide (NO2), ozone (O3), and carbon monoxide (CO).
Findings and Key Observations
SO2 and O3 had significant negative associations with sperm morphology and motility, respectively. The effect of SO2 on morphology extended across the full 90-day period of spermatogenesis, while O3 was associated with key changes in progressive motility and vitality throughout the process.
PM2.5, PM10, and NO2 were also associated with sperm morphology, while O3 and NO2 were associated with the teratozoospermia index. Effects of PM and NO2 varied by stage of spermatogenesis, including the spermatogonial and motility-development stages.
When pollution exposure was assessed against infertility risk, changes in sperm morphology linked to SO2 significantly increased male infertility risk. These changes mediated about 60% of SO2's total effect on infertility.
Significance and Outlook
This study is the first systematic analysis of how multiple air pollutants affect male semen parameters across different exposure windows. It identifies SO2 as a pollutant of particular concern because of its significant negative association with sperm morphology throughout spermatogenesis. SO2-related morphological changes may be an important contributor to male infertility.
However, the observational design cannot establish causality between pollutants and semen parameters. All participants also came from one research center, which may limit representativeness. Larger, more diverse studies are needed to confirm the findings and assess long-term effects on male reproductive health.
Conclusion
The effects of air pollution on male reproductive health warrant attention. This study adds insight into how pollutants, especially SO2, may impair sperm morphology and motility. As air pollution increases globally, stricter air-quality standards and protective measures may help improve male reproductive health and reduce infertility risk.
News | Air Pollution and Male Infertility: Sperm Damage May Account for Over 50% of the Effect
News | Air Pollution and Male Infertility: Sperm Damage May Account for Over 50% of the Effect
Male infertility rates have continued to rise worldwide, and environmental pollution is considered an important factor. A recent study by Chinese researchers suggests that sperm damage caused by air pollution may account for more than 50% of its contribution to male infertility. The study shows how air pollution may increase infertility risk by impairing sperm quality.
Background and Objective
Air pollution is a major environmental challenge to reproductive health. According to the World Health Organization (WHO), infertility affects 15% of people worldwide, or about 60-80 million couples, with male factors accounting for roughly 40%-70% of cases. Animal studies have shown that pollutants such as particulate matter (PM) and sulfur dioxide (SO2) can impair sperm quality and spermatogenesis. Human evidence on how much pollution-related sperm damage contributes to male infertility remains limited.
This study therefore assessed the effects of several air pollutants on semen parameters and their potential contribution to male infertility risk.
Study Design
This prospective cohort study included 3,940 men aged 22-49. Participants enrolled between November 2018 and April 2021 and provided semen samples at enrollment. Eight parameters were analyzed: semen volume, sperm concentration, total sperm count, progressive motility, total motility, sperm vitality, morphology, and the teratozoospermia index.
During 12 months of follow-up, researchers assessed infertility, defined as failure to achieve pregnancy after 12 months of intercourse without contraception.
Machine-learning algorithms estimated exposure to multiple pollutants and linked the estimates to participant data. Pollutants included PM2.5, PM10, sulfur dioxide (SO2), nitrogen dioxide (NO2), ozone (O3), and carbon monoxide (CO).
Findings and Key Observations
SO2 and O3 had significant negative associations with sperm morphology and motility, respectively. The effect of SO2 on morphology extended across the full 90-day period of spermatogenesis, while O3 was associated with key changes in progressive motility and vitality throughout the process.
PM2.5, PM10, and NO2 were also associated with sperm morphology, while O3 and NO2 were associated with the teratozoospermia index. Effects of PM and NO2 varied by stage of spermatogenesis, including the spermatogonial and motility-development stages.
When pollution exposure was assessed against infertility risk, changes in sperm morphology linked to SO2 significantly increased male infertility risk. These changes mediated about 60% of SO2's total effect on infertility.
Significance and Outlook
This study is the first systematic analysis of how multiple air pollutants affect male semen parameters across different exposure windows. It identifies SO2 as a pollutant of particular concern because of its significant negative association with sperm morphology throughout spermatogenesis. SO2-related morphological changes may be an important contributor to male infertility.
However, the observational design cannot establish causality between pollutants and semen parameters. All participants also came from one research center, which may limit representativeness. Larger, more diverse studies are needed to confirm the findings and assess long-term effects on male reproductive health.
Conclusion
The effects of air pollution on male reproductive health warrant attention. This study adds insight into how pollutants, especially SO2, may impair sperm morphology and motility. As air pollution increases globally, stricter air-quality standards and protective measures may help improve male reproductive health and reduce infertility risk.
Source:
Collected online