Impact of Air Pollution on Sperm DNA Function

Recent research suggests that air pollution may change how sperm genes operate, raising concerns about male fertility. This finding comes from one of the most extensive studies conducted on this topic.

Men exposed to prevalent air pollutants during the development phase of their sperm exhibited subtle alterations in their DNA. These changes influenced whether certain genes were activated or not, indicating that air pollution could potentially be harmful to male reproductive health.

The study’s results were shared on Tuesday at the European Society of Human Reproduction and Embryology’s annual meeting in London. It pinpointed ozone and nitrogen dioxide as the pollutants most significantly associated with these epigenetic changes.

Dr. Carrie Nobles, an epidemiologist at the University of Massachusetts Amherst and the study’s lead investigator, mentioned, “Our findings suggest that exposure to air pollution during crucial stages of sperm development may relate to alterations in sperm DNA.”

This research monitored over 2,000 men in Salt Lake City, Utah, from 2013 to 2017. Participants provided semen samples at enrollment and then again after two, four, and six months.

Researchers calculated each man’s exposure to various outdoor air pollutants—including ozone, nitrogen dioxide, sulfur dioxide, and fine particulate matter—during the three months leading up to each sample collection, a time crucial for sperm production.

While there’s increasing evidence indicating that air pollution might diminish male fertility, the underlying biological processes have remained somewhat unclear. This latest study points to DNA methylation—chemical markers on DNA that regulate gene activity without altering the genetic sequence—as a potential factor.

The analysis focused on sperm DNA methylation in 1,220 men who submitted samples at the six-month mark. They found 39 DNA alterations linked to the mixture of air pollutants, with a notable impact from ozone and nitrogen dioxide.

Although most epigenetic markers disappear early in embryo development, some genes retain these changes, indicating they could affect embryo growth and later stages. Notably, one identified gene, GNAS, has been previously associated with lower semen quality and fetal development challenges.

Nobles emphasized, “Changes in gene expression can affect men’s fertility, which highlights the importance of this research area. Future studies are essential to establish a direct connection between air pollution-related changes in sperm DNA methylation and fertility outcomes.”

Professor Allan Pacey, an andrology expert at the University of Manchester who was not part of the research, highlighted that the study demonstrated a measurable effect.

“At this moment, it’s unclear if the changes to sperm DNA methylation have significant clinical implications for male infertility, so additional research is needed to verify or disprove this,” he commented.

Professor Richard Lea, a reproductive biology expert at the University of Nottingham, remarked that this research adds to the growing evidence indicating that air pollutants negatively impact sperm quality.