Living Near Farmland May Increase Risk of Melanoma Skin Cancer: Study

Both rural and urban residents faced higher risks of melanoma skin cancer if they lived in counties with high herbicide use, according to researchers.

New research suggests that individuals living in areas with more cultivated cropland may have a 57% higher likelihood of developing melanoma, raising additional concerns about the side effects of secondary exposure to various herbicides and chemicals commonly applied on farms.

According to findings published in the journal JCO Clinical Cancer Informatics on November 14, increases in herbicide treatment corresponded to an increase in cases of melanoma in both residential and rural areas in a 15-county stretch in South Central Pennsylvania.  

Researchers have long warned about the health risks linked to herbicides containing glyphosate, best known as the active ingredient in Roundup. Studies have associated repeated exposure with cellular damage, endocrine disruption and chronic inflammation, all of which may contribute to the development of non-Hodgkin’s lymphoma and other cancers.

These concerns have led to thousands of Roundup lawsuits against Bayer and Monsanto, alleging the companies downplayed evidence showing that long-term contact with the weed killer could significantly elevate cancer risks. However, various other widely used herbicides have also been linked to serious health risks in recent years.

In May, Mayo Clinic researchers reported that individuals living within one mile of a golf course faced a 126% higher risk of developing Parkinson’s disease, raising new questions about the neurological effects of herbicides and pesticides used in high-maintenance landscapes. Now, these new findings raise concerns about potential skin cancer risks from herbicides.

In this new study, researchers from Penn State Cancer Institute analyzed five years of Pennsylvania cancer registry data from 2017 to 2021. The data included 28 counties in Pennsylvania including a 15-county stretch of cultivated cropland.

Led by Dr. Eugene Lengerich, the team examined agricultural patterns, ultraviolet radiation exposure and demographics as well as herbicide, insecticide, fungicide and manure treatment.

The findings indicate that Pennsylvania counties located near cultivated cropland had significantly higher melanoma rates than other parts of the state. Adults over 50 who lived close to cropland were 57% more likely to develop melanoma, regardless of whether they resided in rural or metropolitan areas. The elevated risk persisted even in urban communities when proximity to agricultural land was a factor.

In the 15 counties examined, there was more cropland and more herbicide treated land than other counties. For comparison, there was 20% cropland in the 15-county stretch compared to 7% in the rest of the state. In that same area, there was 17% more herbicide-treated land compared to 7% in the rest of the state.

For every 10% increase in cultivated land researchers saw a corresponding 14% increase in cases of melanoma cancer, the deadliest form of skin cancer. Similarly, for every 9% increase in herbicide treated acreage there was a 13% increase in melanoma cases.

Melanoma Increases Not Limited to Rural Areas

The data indicates the cancer clusters were in both rural and metropolitan counties, and that the risk did not only apply to remote farmland and agricultural workers. Since the chemicals can drift through the air, settle into household dust, and seep into water supplies, the risk extended to nearby residents, the researchers determined.

Lengerich’s team concluded sunlight exposure was obviously a main factor. However, after they adjusted their data for UV radiation exposure, two other factors stood out. Counties with more cultivated cropland and those with higher herbicide use had higher melanoma rates.

Researchers noted herbicides are designed to alter biological systems and that may extend to human health by increasing oxidative stress, disrupting immune function and damaging DNA. Additionally, the researchers said these findings emphasize a need for a “One Health” approach that considers human health as deeply connected to the environment and agricultural systems.

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