The children studied were California agricultural communities

A common type of pesticide used in agriculture may contribute to decreased lung function in children, making it harder for them to breathe and exercise, according to new research.

Researchers, writing in the journal Thorax, found an 8% decrease in lung function for every 10-fold increase in concentration of organophosphate pesticides. That decrease in functioning is close to the effect caused by second-hand smoking.

The study’s researchers measured exposure to those pesticides in pregnant women and their offspring in California’s agricultural Salinas Valley until children reached age 5. Researchers then assessed children’s lung functioning at age 7 and found the decreased lung functioning. To know whether that effect lasts longer-term would require further study.

The children in the study were likely exposed to a greater quantity of the pesticide than the average American child because of their proximity to abundant farming. Still, children living far away from agricultural regions who are exposed to residue on food may still be at risk, according to study author Brenda Eskenazi, a professor at the University of California, Berkeley.

“Remember these kids aren’t farmworkers,” says Eskenazi. “We know that this population is somewhat more exposed than the general U.S. population, but what we’re seeing from children in these areas may also have implications for residue in food.”