One recent study found that baby rats born to parents that had been exposed to wood smoke could end up with behavioral and cognitive problems. That prompted our team at Boise State University, in collaboration with researchers at Northeastern University, to look closer at what happens to sperm of mice exposed to wildfire smoke.

Our goal was to look for small changes at the cellular level that might show us how negative effects could be passed from parents to the next generation. Mice aren’t humans, of course, but damage to their systems can provide clues about potential harm to ours.

We simulated a wildland fire in the laboratory by burning Douglas fir needles and chose a smoke exposure amount similar to what a wildland firefighter with 15 years of service would experience. We found that this exposure in a mouse resulted in changes in sperm DNA methylation. DNA methylation is a biological mechanism that can regulate how a gene is expressed, kind of like a dimmer switch on a light bulb. Environmental factors can influence DNA methylation, and this can be harmful if it occurs at the wrong time of life or at the wrong gene.