A study of more than 2,000 men has found that exposure to common air pollutants is associated with epigenetic changes in sperm DNA, potentially affecting male fertility. The research, presented at the European Society of Human Reproduction and Embryology annual meeting in London, identified ozone and nitrogen dioxide as the pollutants most strongly linked to these changes.
Study Details and Findings
Researchers led by Dr Carrie Nobles from the University of Massachusetts Amherst followed men in Salt Lake City, Utah, between 2013 and 2017. Participants provided semen samples at enrollment and after two, four, and six months. The team estimated exposure to outdoor pollutants—including ozone, nitrogen dioxide, sulfur dioxide, and fine particulate matter—during the three months before each sample, corresponding to sperm production.
Among 1,220 men who provided a sample at six months, scientists identified 39 DNA methylation changes linked to air pollution mixtures. DNA methylation involves chemical tags that regulate gene activity without altering the genetic code. One affected gene, GNAS, has been previously associated with poorer semen quality and fetal development.
Implications for Fertility
Dr Nobles stated: “Our findings suggest that air pollution exposure during key stages of sperm development may be associated with changes in sperm DNA.” She added: “Changes in gene expression have the potential to impact men’s fertility, which is why this area of research is important.” Most epigenetic tags are erased early in embryo development, but some genes remain imprinted, potentially influencing embryo development.
Prof Allan Pacey from the University of Manchester, not involved in the study, noted: “At the present time, it is not possible to conclude whether the observed changes to sperm DNA methylation are clinically meaningful for male infertility.” Prof Richard Lea from the University of Nottingham called it “an important piece of research” that adds to evidence that airborne pollutants adversely affect sperm quality.
