Melanoma Rates Surge in 15 Pennsylvania Counties Linked to Agriculture

Recent research from the Penn State Cancer Institute reveals a concerning surge in melanoma rates across 15 counties in Pennsylvania, particularly those with significant agricultural activities. The findings suggest that environmental factors, including herbicide use, may contribute to this alarming trend, affecting not only farm workers but also surrounding communities.

The study, published on November 14, 2025, in the journal JCO Clinical Cancer Informatics, analyzed cancer registry data from 2017 to 2021. It found that adults over the age of 50 living in these counties were 57% more likely to be diagnosed with melanoma compared to their peers in other parts of the state. This increase in risk persisted even after accounting for traditional factors such as sunlight exposure.

Environmental Influences on Melanoma Risk

Charlene Lam, an associate professor of dermatology at Penn State Health and co-author of the study, emphasized that the heightened risk is present in both rural and urban settings. “Melanoma is often associated with beaches and sunbathing, but our findings suggest that agricultural environments may also play a role,” she stated. She pointed out that entire communities living near farmland could be affected, regardless of their direct interaction with agricultural practices.

The research specifically correlated greater cultivated acreage and higher herbicide usage with increased melanoma rates. A 10% increase in cultivated land corresponded to a 14% rise in melanoma diagnoses, while a 9% rise in herbicide-treated land was linked to a 13% increase in cases.

Understanding the Mechanisms Behind the Data

According to Eugene Lengerich, emeritus professor of public health sciences at Penn State and senior author of the study, pesticides and herbicides could alter biological systems in ways that promote melanoma development. He noted, “Some of those same mechanisms, like increasing photosensitivity or causing oxidative stress, could theoretically contribute to melanoma development.”

The study highlighted that the risk of chemical exposure is not limited to those directly handling agricultural products. Lam noted that herbicides can drift through the air, settle in household dust, or contaminate water sources, thereby posing a risk to entire populations in agricultural regions.

While the correlation between agricultural activities and increased melanoma rates is evident, Benjamin Marks, the first author and a medical and public health student at Penn State College of Medicine, cautioned that these findings do not establish direct causation. “Think of this as a signal, not a verdict,” he clarified. “The data suggest that areas with more cultivated land and herbicide use tend to have higher melanoma rates, but many other factors could be at play, like genetics or access to healthcare.”

Future Research and Community Health Implications

The implications of this research extend beyond Pennsylvania, as similar patterns have been identified in farming regions in places like Utah, Poland, and Italy. Lam hopes to further explore the relationship between agricultural practices and public health, particularly through studies in rural communities within the affected areas.

She urged individuals living near farmlands to conduct regular skin checks and to use sun-protective clothing and sunscreen as preventative measures. “Cancer prevention can’t happen in isolation,” Lengerich added, emphasizing the necessity for a “One Health” approach. This perspective recognizes the deep connections between human health, environmental factors, and agricultural systems.

The study was co-authored by Jiangang Liao, a professor of public health sciences at Penn State College of Medicine, and Camille Moeckel, a fourth-year medical student and research associate at Penn State College of Medicine. This research received support from the MPH Capstone Program, the Medical Student Research Project at the Penn State College of Medicine, and the University’s Algin B. Garrett Professorship.

As researchers continue to investigate these critical links, the findings underscore the importance of community-wide awareness and proactive measures to mitigate health risks associated with agricultural exposure.