Particulate matter air pollution affects semen quality and fertility in men of reproductive age: JAMA

China: Particulate matter (PM) exposure may impair sperm motility, highlighting the need for reproductive-aged males to be exposed to less ambient particulate air pollution, says an article published in the Journal of American Medical Association.

The effects of particulate matter exposure on male fertility are unknown. Although there has been a relationship between PM exposure and sperm quality, the results have been mixed. In China, researchers wanted to see if different size fractions of PM (2.5 m [PM2.5], 2.5-10 m [PM2.5-10], and 10 m [PM10]) exposure had any effect on sperm quality.

Yan Zhao and colleagues conducted this retrospective cohort analysis utilizing data on males whose spouses had assisted reproductive technology operations in a tertiary hospital in Shanghai, China, between January 1, 2013, and December 31, 2019. Participants came from 340 Chinese prefecture-level cities and were tracked from their initial visit to December 31, 2019. From December 1, 2020, to May 15, 2021, data was evaluated. During the whole period (0-90 days before semen ejaculation) and important times of sperm development (0-9, 10-14, and 70-90 days before semen ejaculation), participants were exposed to PM2.5, PM2.5-10, and PM10. Semen quality, including sperm concentration, count, and motility were assessed as the main outcomes.

The key findings of this study are as follow:

1. The final study comprised 33 876 males, with an average age of 34.1 years and a wide range of PM exposure.

2. For example, over the whole time of sperm formation, the median exposure to PM2.5 was 46.05μg/m3.

3. Exposure to greater levels of PM was linked to reduced total and progressive sperm motility throughout the whole sperm development process.

4. An IQR increase in PM2.5 exposure was associated with an estimated effect decrease of 3.60% for total sperm motility; an increase in PM2.5-10 exposure was associated with an estimated effect decrease of 0.45%, and an increase in PM10 exposure was associated with an estimated effect decrease of 2.44% for total sperm motility.

5. Similar findings were seen in the case of progressive motility.

6. An IQR increase in PM2.5 or PM10 exposures was linked to a 1.87% and 1.05% reduction in sperm progressive motility, respectively.

7. However, no significant links were found between PM exposure and sperm count or concentration across the whole period of sperm development.

In conclusion, the effects of particle air pollution on sperm quality, particularly sperm motility, during spermatogenesis underline the need to limit ambient particulate air pollution exposure in reproductive-aged males. To establish the biological processes behind the observed relationships, more research is needed.

Reference:

Zhao Y, Zhu Q, Lin J, Cai J. Association of Exposure to Particulate Matter Air Pollution With Semen Quality Among Men in China. JAMA Netw Open. 2022;5(2):e2148684. doi:10.1001/jamanetworkopen.2021.48684