Glyphosate, a widely used herbicide in U.S. farming, might be linked to low birth weights and pre-term births among babies born in rural communities, a new study has found.
Environmental economists compared farming data and birth records in rural U.S. counties to investigate the link between glyphosate and birth outcomes.
"We had heard some pretty broad claims about the effects of pesticides on health that seemed to be based more on correlations than on causal effects," Emmett Reynier—an author of the paper and a doctoral candidate at the University of Oregon, supported by the U.S. Environmental Protection Agency (EPA)—said in a statement.
"We know people are concerned, and we wanted to make sure we were looking at this rigorously," Reynier said.
The health effects of glyphosate exposure have been debated for some time. The EPA first approved glyphosate for use as an herbicide in the U.S. in 1974, and the agency in 2020 determined that it posed no risks to human health if used according to label directions.
However, in 2022, those findings were challenged in court and voided by the U.S. Court of Appeals. Now, they remain under review.
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Previous research has linked glyphosate to the possible increased risks of cancer, tumor growth and hormone disruption.
Farmers continue to use glyphosate in large amounts to kill weeds among crops that have been genetically modified to survive it.
Since the introduction of genetically modified crops in 1996, the annual glyphosate use in the U.S. has increased by approximately 750 percent, according to a report by the U.S. Geological Survey.
In this study, the economists gathered data on the suitability of agricultural counties to grow genetically modified corn, cotton and soybeans to estimate those that used more glyphosate.
They took data from the U.S. Department of Human and Health Services on more than 9 million births that took place in rural counties from 1990 to 2013.
Reynier and Edward Rubin—the study's co-author Edward Rubin and an assistant professor at Oregon's Department of Economics—found that before 1996 trends in birthweight and gestation remained similar in rural counties, regardless of how suitable they were for growing genetically modified crops.
But after 1996, infant health deteriorated sharply in counties that were more suited to growing these crops using glyphosate as an herbicide.
At average levels of glyphosate exposure, pregnancy was one day shorter and birthweight was 1oz lighter than in counties unsuited to growing crops with glyphosate.
Historically disadvantaged groups and babies expected to be born smaller were disproportionately affected by this association, their analysis found.
"It's like being sick and then getting hit with another illness," Rubin said in a statement. "You're more vulnerable."
Reynier and Rubin said that regulations needed to catch up with scientific evidence about glyphosate's harms.
"I think something has to change," said Rubin. "Regulators could admit that glyphosate exposure presents some concerns for human health. There's mounting evidence that it could be detrimental.
"We're still not tracking it in water. We're not tracking it when it's applied. It does seem like, even if we're not ready to regulate it in a serious way, we could monitor it."
This study was published in the scientific journal Proceedings of the National Academy of Sciences on January 14, 2025.
Is there a health problem that's worrying you? Do you have a question about glyphosate? Let us know via health@newsweek.com. We can ask experts for advice and your story could be featured in Newsweek.
Reference
Reynier, E., Rubin, E. (2025). Glyphosate exposure and GM seed rollout unequally reduced perinatal health, PNAS, 122(3): e2413013121. https://doi.org/10.1073/pnas.2413013121
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