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New research shows that living near farmland can significantly increase people’s exposure to glyphosate, the active ingredient in the widely used herbicide Roundup. This chemical has been linked to health problems including non-Hodgkin’s lymphoma and a higher risk of premature birth.
We are environmental health scientists studying pesticide exposures in human populations. In our newly published research, we tracked glyphosate levels in pregnant women for 10 months.
We found that people living within about one-third (500 metres) of an agricultural field had significantly higher levels of glyphosate in their urine than those living further away. Importantly, we only saw these differences during the time of year when farmers sprayed glyphosate on their fields; We further suggest that agricultural spray was 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 living away from farm fields, but not in women living near farm fields.
The results provide new insight into how people are exposed to this common and potentially harmful chemical.
Why is it important?
Glyphosate is the most used pesticide in the world. Its use has increased dramatically over the past two decades with the increase in the production of genetically modified, herbicide-resistant crops. These crops are designed to withstand the herbicide effects of herbicides such as glyphosate; This means that the entire field can be sprayed with these chemicals and eliminate weeds without damaging the crop itself. This is a change from previous practices, where herbicide applications had to be more targeted.
While herbicides such as dicamba and 2,4-D are known to be airborne, glyphosate is not volatile, so there is less concern about the potential for drift when sprayed on crops.
But our research provides evidence for the first time that agricultural use of glyphosate is still reaching people living nearby.
It is important to note that there is no consensus on whether this widely used herbicide causes cancer.
The International Agency for Research on Cancer, part of the World Health Organization, has determined that glyphosate is “likely carcinogenic to humans,” while the U.S. Environmental Protection Agency has concluded that it is “unlikely to be carcinogenic to humans.” This debate continues in courtrooms across the United States, with mixed results.
In addition to concerns about cancer risk, four recent human studies found that exposure to glyphosate during pregnancy was associated with reproductive effects. These effects included premature birth, shortened gestational age, and reduced fetal growth.
But scientists know little about the levels and sources of glyphosate exposure in pregnant women. The potential risk and lack of data are why our study focused on this group.
How did we do our job?
We collected 1,395 urine samples from 40 pregnant women living in Southern Idaho. This includes weekly urine samples from February to December 2021. We found that among women living near fields, urinary glyphosate levels were approximately 50% higher during insecticide spray season in southern Idaho (May through August in southern Idaho) than during the rest of the year. .
For two weeks in June, we randomly assigned study participants one week of organic food and one week of conventional food and collected daily urine samples. In participants living away from fields, glyphosate levels decreased by approximately 25% from the conventional week to the organic food week. But for women living near fields, switching to an organic diet did not change glyphosate levels.
The results suggest that for people living in cities and towns, an organic diet may be an effective way to reduce exposure to glyphosate. But for people living near farms, exposure to nearby agricultural practices may be more important.
What is still unknown
Our finding that living close to agriculture is associated with higher levels of glyphosate in the body provides important new information about who is exposed to this herbicide. But we still don’t know exactly how this exposure occurs.
While many pesticides are carried by airborne drift, it is possible that glyphosate acts in a different way. For example, it can stick to soil that is blown in or dragged into homes.
Understanding this is critical to reducing human exposure to chemicals in agricultural fields. It is also important because urbanization takes over previously agricultural lands. As new subdivisions and residential areas expand and fragment into farmland, homeowners find themselves neighbors with farmland and their chemicals.
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This article is republished from The Conversation, an independent, nonprofit news organization providing facts and analysis to help you understand our complex world.
Written by: Cynthia Curl, Boise State University and Carly Hyland, University of California, Berkeley.
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Cynthia Curl receives funding from NIEHS, the National Institute of Environmental Health Sciences, 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).