According to new research, living near farmland can greatly increase an individual’s exposure to glyphosate, the main component of the commonly used herbicide Roundup. Glyphosate is linked to health issues such as non-Hodgkin lymphoma and a higher risk of premature births. As environmental health scientists, we investigate pesticide exposure in people, including exposure to herbicides. In our recently published study, we monitored glyphosate levels in pregnant women over a period of ten months. We discovered that women living within about one-third of a mile (or 500 meters) of agricultural fields had notably higher glyphosate levels in their urine than those living farther away.
Notably, these differences were observed only during the seasons when glyphosate is applied to the fields, indicating that agricultural spraying is likely the source of this exposure. Our research further revealed that consuming organic food, which is produced without synthetic pesticides, might lower glyphosate levels in women who live far from farm fields, but this was not the case for women living near farms. These findings shed new light on how people are exposed to this prevalent and potentially harmful chemical. Glyphosate is the most extensively used agricultural pesticide worldwide. Its application has significantly increased over the past twenty years with the rise of genetically modified, herbicide-resistant crops.
These crops are designed to survive herbicide treatments like glyphosate, allowing entire fields to be sprayed to kill weeds without harming the crops. This approach differs from past practices where herbicide application needed to be more precise. Although herbicides such as dicamba and 2,4-D are acknowledged to become airborne, glyphosate is not volatile, so there has been less concern about its drift when sprayed on crops. Yet, our research offers the first evidence that agricultural glyphosate use affects nearby populations. It is important to highlight that there is no agreement on whether this widely used herbicide causes cancer. While the International Agency for Research on Cancer, part of the World Health Organization, classifies glyphosate as “probably carcinogenic to humans,” the U.S. Environmental Protection Agency states it is “not likely to be carcinogenic to humans.” This debate continues in U.S. courtrooms, resulting in varied outcomes.
Apart from cancer concerns, four recent studies have linked glyphosate exposure during pregnancy with reproductive effects, such as increased preterm births, shortened gestational periods, and reduced fetal growth. Despite these concerns, researchers know little about the levels and sources of glyphosate exposure in pregnant women. This potential risk and data gap prompted our focus on this group. We collected 1,395 urine samples from 40 pregnant women in southern Idaho, including weekly samples from February to December 2021. Among women living close to fields, we found their urinary glyphosate levels were about 50% higher during the pesticide spray season, May through August, compared to the rest of the year.
During two weeks in June, participants alternated between a week of organic and a week of conventional food, and daily urine samples were collected. For participants living far from fields, glyphosate levels decreased by about 25% after the organic-food week. However, for those near fields, switching to an organic diet did not alter glyphosate levels. The results imply that for city and town residents, an organic diet might reduce glyphosate exposure. In contrast, for those near farms, exposure from local agricultural practices could be more significant. Our discovery that proximity to agricultural land correlates with increased glyphosate levels in the body provides valuable insight into those exposed to this herbicide. However, the exact exposure mechanism remains unknown.
While many pesticides drift through the air, glyphosate might spread differently, perhaps by adhering to soil particles carried indoors. Understanding these pathways is crucial for reducing human exposure to chemicals in farming areas, especially as urban development encroaches on previously farmed land. As new residential areas develop near farmlands, residents find themselves living alongside agricultural fields and their chemicals. This Research Brief provides a concise look at intriguing academic work.