Air pollution linked to DNA changes in sperm, research shows
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- Dr Carrie Nobles led the study tracking more than 2,000 men in Salt Lake City between 2013 and 2017, presented at the European Society of Human Reproduction and Embryology's annual meeting in London, finding that exposure during sperm development was associated with subtle DNA methylation changes.
- Researchers analyzed sperm DNA from 1,220 men who provided a six-month follow-up sample and identified 39 DNA methylation changes linked to air pollution mixtures, with ozone and nitrogen dioxide showing the strongest influence over gene activity.
- The GNAS gene was among those flagged for pollution-linked epigenetic changes — Nobles noted it has previously been associated with poorer semen quality and foetal development, and most imprinted genes resist the erasure that normally clears epigenetic tags early in embryonic development.
- Prof Allan Pacey of the University of Manchester, who was not involved in the work, said the study demonstrated a measurable effect but cautioned it is 'not possible to conclude whether the observed changes to sperm DNA methylation are clinically meaningful for male infertility.'
- Prof Richard Lea of the University of Nottingham called the research 'an important piece of research that adds to a growing body of evidence that sperm quality is adversely affected by airborne pollutants.'
- Nobles estimated each participant's exposure to outdoor pollutants including ozone, nitrogen dioxide, sulphur dioxide and fine particulate matter during the three months before each semen sample, corresponding to the period of sperm production.
Why it matters: The study offers the strongest molecular lead yet on how air pollution could reduce male fertility, a link growing evidence has supported but left biologically unexplained. By identifying 39 specific DNA methylation changes — including GNAS, already tied to semen quality — the research gives reproductive scientists a concrete set of gene targets to test whether these epigenetic tags translate into measurable fertility problems.
