Study Finds Ozone and Nitrogen Dioxide Exposure Linked to Sperm DNA Methylation Changes

Research presented Tuesday at the European Society of Human Reproduction and Embryology conference in London linked exposure to ozone and nitrogen dioxide with epigenetic alterations in sperm DNA. GB News reported that the study examined more than 2,000 men living in Salt Lake City, Utah, between 2013 and 2017.

Participants provided semen samples at enrollment and again at two-, four-, and six-month intervals.

Researchers calculated each man's exposure to ozone, nitrogen dioxide, sulphur dioxide, and fine particulate matter during the three months before each sample, matching the sperm production cycle. Analysis of samples from 1,220 men at the six-month mark found 39 distinct DNA methylation modifications tied to pollutant exposure.

Dr Carrie Nobles, an epidemiologist at the University of Massachusetts Amherst who led the study, said the findings suggest air pollution during key stages of sperm development may be associated with changes in sperm DNA.

She added that changes in gene expression have the potential to affect men's fertility and that future work is needed to connect the methylation shifts directly to fertility outcomes. One gene identified, GNAS, had previously been linked to reduced semen quality and developmental outcomes.

DNA methylation involves chemical markers on DNA that regulate gene activity without changing the underlying code.

Prof Allan Pacey, a professor of andrology at the University of Manchester, said it is not yet possible to determine whether the observed methylation changes are clinically meaningful for male infertility. Prof Richard Lea, a reproductive biology expert at the University of Nottingham, described the work as significant and part of growing evidence that airborne pollutants affect sperm quality.