Abstract
The health effects of exposure to particulate matter (PM) on male fertility remain unclear. Although PM exposure has been linked with semen quality, the results were inconsistent. To examine the association of different size fractions of PM (<2.5 μm [PM2.5], 2.5-10 μm [PM2.5-10], and ≤10 μm [PM10]) exposure with semen quality in China. This retrospective cohort study was conducted using data on men whose wives underwent assisted reproductive technology procedures in a tertiary hospital in Shanghai, China, from January 1, 2013, to December 31, 2019. Participants were from 340 prefecture-level cities of China and were followed up from the date of their first visit until December 31, 2019. Data were analyzed from December 1, 2020, to May 15, 2021. Exposure to PM2.5, PM2.5-10, and PM10 during the entire period (0-90 days before semen ejaculation) and key periods of sperm development (0-9, 10-14, and 70-90 days before semen ejaculation). Semen quality, including sperm count, concentration, and motility. A total of 33 876 men were included in the final analysis, with a mean (SD) age of 34.1 (5.7) years and large variation of PM exposure. For example, the median exposure to PM2.5 during the entire period of sperm development was 46.05 (IQR, 34.38-61.65) μg/m3. During the entire period of sperm development, exposures to higher levels of PM were significantly associated with lower total and progressive sperm motility. For total sperm motility, an IQR increase in PM2.5 exposure was associated with an estimated effect decrease of -3.60% (95% CI, -3.93% to -3.26%); an increase in PM2.5-10 exposure, with an estimated effect decrease of -0.45% (95% CI, -0.76% to -0.14%); and an increase in PM10 exposure, with an estimated effect decrease of -2.44% (95% CI, -2.91% to -1.96%). Similar results were observed for progressive motility. An IQR increase in PM2.5 or PM10 exposures was associated with an estimated effect decrease on sperm progressive motility of -1.87% (95% CI, -2.37% to -1.36%) and -1.05% (95% CI, -1.45% to -0.64%), respectively. However, no significant associations were observed between PM exposure during the entire period of sperm development and sperm count or concentration. These findings suggest that PM exposure may adversely affect sperm motility and highlight the need to reduce ambient particulate air pollution exposure for reproductive-aged men.
Highlights
Infertility is becoming a global public health issue, affecting approximately 10% of all reproductiveaged couples worldwide.[1,2] The World Health Organization estimates that pure male factors, mainly poor semen quality, could account for 50% of infertility cases.[3]
An IQR increase in PM2.5 exposure was associated with an estimated effect decrease of −3.60%; an increase in PM2.5-10 exposure, with an estimated effect decrease of −0.45%; and an increase in PM10 exposure, with an estimated effect decrease of −2.44%
An IQR increase in PM2.5 or PM10 exposures was associated with an estimated effect decrease on sperm progressive motility of −1.87% and −1.05%, respectively
Summary
Infertility is becoming a global public health issue, affecting approximately 10% of all reproductiveaged couples worldwide.[1,2] The World Health Organization estimates that pure male factors, mainly poor semen quality, could account for 50% of infertility cases.[3] In recent years, extensive evidence has suggested a global downward trend in semen quality, and multiple studies have reported significant declines in sperm concentration, count, and motility in recent decades.[4,5,6,7] Both genetic background and environmental factors contribute to poor semen quality.[8,9,10,11] The remarkable changes in sperm concentration, count, and motility over a relatively short period suggest that the global downward trend in semen quality is more likely to be related to environmental factors than genetics.[12,13]. Most previous studies were conducted in single regions with relatively small sample sizes, which may limit the generalizability of their findings
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