Pesticide exposure may affect the health of a baby even before a person becomes pregnant, according to a new study released last week.

The study, led by researchers at the University of Arizona, relied on birth certificate data and the state’s pesticide use registry to figure out whether people who lived near farms where pesticides had been sprayed, both before and after they became pregnant, were more likely to have babies that had low Apgar scores. The Apgar score is a metric used by doctors to quickly determine the health of a baby at birth. 

The research focused on three classes of commonly used pesticides — organophosphates, pyrethroids and carbamates — and found that several ingredients were linked to lower Apgar scores for women who gave birth and lived within roughly 500 yards of where pesticides had been sprayed on crops. Research has found that lower Apgar scores can indicate a higher likelihood of neurological anomalies like cerebral palsy.  

Melissa Furlong, a lead author of the study and assistant professor of environmental health sciences at the University of Arizona, said she was surprised to discover some of these stronger associations between certain pesticides and lower Apgar scores, particularly in the window of preconception. “It’s particularly problematic from a public health perspective, just because many pregnancies are unplanned,” she said. 

And the impact could extend beyond the person who becomes pregnant, Furlong said. More research needs to be done to determine how exposure affects both eggs and sperm. Men who live within the buffer area of approximately 500 yards from an agricultural spray could also find that this affects the health of their future offspring, she said. 

While the study focused on those living near agricultural spraying, Furlong said a lot of the ingredients they studied are also found in common household insecticides. The population could also be exposed to these ingredients when eating fruits and vegetables that have been sprayed. 

“This is just one metric of exposure to these pesticides, but it’s concerning because the general population is still exposed to these ingredients,” she said. “The research would have implications for household use and for residues on fruits and vegetables.”

Furlong said that those living in rural agricultural counties like Yuma, which abuts the U.S. border with Mexico and where much of the country’s leafy greens are grown, were more likely to be exposed to these pesticides. But Maricopa County, where the suburbs are encroaching on agricultural land, also had a significant overlap between pregnancies and pesticide sprays, she said. 

Deborah Bennett, a professor of environmental health at the University of California, Davis, who has studied how exposure to pesticides and other toxic chemicals affects pregnancies, praised the study for using a state database of birth certificates. This robust data set allowed for the analysis of over a million births that took place between 2006 and 2020.

The other benefit, according to Bennett, is that the study looks at exposure before conception and throughout pregnancy. Other popular methods of studying the impact of exposure to pesticides tend to be limited to a 24-hour period.

A study like this one, that is able to look at potential public health impacts, is only possible because Arizona is one of two states, along with California, that require tracking agricultural pesticide use. The rest of the states are essentially “flying blind,” Furlong said, which impacts what pesticides can be studied because they vary based on what is grown in each state. 

Furlong said she hopes her work can help shape policies by singling out the health impact of certain ingredients present in pesticides. This more granular data could help target at least the most harmful chemicals. “The closer we get to specific ingredients, I think the better we’ll get towards balancing public health and farmers’ needs,” she said. 

The study did have some limitations. It only focused on 10 percent of the over 300 pesticides applied annually in the state, for example. Furlong also said her lab is looking at ways to improve that exposure assessment by using models that could also capture the drift of pesticides, beyond the buffer zone used in the study. 

While Furlong said she doesn’t like to put the burden on pregnant people, she does have some tips for those living near farms where pesticides are being sprayed: “Change your air filters, take your shoes off inside, keep your children’s toys inside, not outside during spray season, and vacuum and dust both your home and your car regularly.”