by Living near farmland can significantly increase people’s exposure to glyphosate, the active ingredient in the widely used herbicide Roundup, new research shows. This chemical has been linked to health concerns, including non-Hodgkin’s lymphoma and a higher risk of premature birth.
We are environmental health scientists who study pesticide exposure in human populations, including exposure to herbicides. In our newly published research, we tracked glyphosate levels in pregnant women for 10 months.
We found that those who lived within a third of a mile (500 meters) of an agricultural field had significantly higher levels of glyphosate in their urine than those who lived further away. Importantly, we only saw those differences during the time of year when farmers spray glyphosate on their fields, suggesting further agricultural spraying as the source of this exposure.
Our research also found that eating organic food, produced without the use of synthetic pesticides, could reduce glyphosate levels in women who lived far from farm fields – but not in women who lived near farm fields .
Together, the findings provide new insight into how people are exposed to this common and potentially harmful chemical.
Why is it important
Glyphosate is the single most widely used agricultural pesticide in the world. Its use has increased dramatically over the past two decades as production of genetically modified, herbicide-resistant crops has increased. These crops are engineered to withstand the weed-killing effects of herbicides such as glyphosate, meaning that an entire field can be sprayed with these chemicals, getting rid of the weeds without harming the crop itself. This is a change from previous practices, where herbicide applications needed to be more targeted.
While herbicides such as dicamba and 2,4-D are known to become airborne, glyphosate is not volatile, so there is less concern for leaching when sprayed on crops.
However, our research provides evidence for the first time that agricultural use of glyphosate still reaches people living nearby.
It is important to note that there is no consensus on whether or not this widely used herbicide causes cancer.
The International Agency for Research on Cancer, part of the World Health Organization, has determined that glyphosate is “probably carcinogenic to humans,” and the Environmental Protection Agency in the United States has determined that it is “unlikely that it will be carcinogenic to humans.” This debate is playing out in courtrooms across the US, with mixed results.
In addition to concerns about cancer risk, four recent human studies found that glyphosate exposure during pregnancy was associated with reproductive effects. These effects included preterm birth, shortened gestation length and reduced fetal growth.
However, scientists do not know much about the levels and sources of glyphosate exposure among pregnant women. This potential risk and lack of data is why our study focused on this group.
How we did our work
We collected 1,395 urine samples from 40 pregnant women living in southern Idaho. This included weekly urine samples from February to December 2021. Among women living near fields, we found that urinary glyphosate levels were about 50% higher during the pesticide spraying season – May to August in southern Idaho – than they were in the rest of the year. .
For two weeks in June, we provided study participants with one week of organic food and one week of conventional food, in random order, and collected daily urine samples. Glyphosate levels decreased by about 25% from the normal week to the organic food week for participants who lived far from fields. But for the women who lived near fields, the switch to an organic diet did not change their glyphosate levels.
The results suggest that for people living in cities and towns, an organic diet can be an effective way to reduce glyphosate exposure. For people living near farms, however, exposure from nearby agricultural applications may be more important.
What is not known yet
Our finding that living near agriculture is associated with higher levels of glyphosate in the body provides important new insights into who is exposed to this herbicide. However, we do not know exactly how this revelation is happening.
While many pesticides are carried by airborne currents, glyphosate may travel differently. For example, it can adhere to soil that is blown or tracked into homes.
This is essential to reduce human exposure to chemicals in agricultural areas. It is also important because urbanization takes over land that was previously farmed. As new subdivisions and residential areas expand into and break up agricultural areas, homeowners have farm fields, and their chemicals, as neighbors.
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Written by: Cynthia Curl, Boise State University and Carly Hyland, University of California, Berkeley.
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Cynthia Curl receives funding from the National Institute of Environmental Health Sciences (NIEHS), part of the National Institutes of Health (NIH).
Carly Hyland receives funding from the National Institutes of Environmental Health Sciences (NIEHS) and the National Institute for Occupational Health and Safety (NIOSH).
