Researchers at the Vall d’Hebron Institute of Research (VHIO) in Barcelona have identified a significant association between exposure to the herbicide picloram during childhood and the development of colorectal cancer before age 50, marking the first time this specific pesticide has been linked to early-onset disease.
The study, published in Nature Medicine, analyzed DNA methylation patterns as biomarkers of past environmental exposures in patients with early-onset colorectal cancer. Scientists compared epigenetic profiles from individuals under 50 with those over 50 and confirmed known risk factors such as tobacco apply, diet, alcohol consumption, and education level.
In addition to validating these established factors, the research revealed a robust association between picloram exposure and genetic alterations in younger patients. Picloram, widely used in U.S. Cornfields since the 1960s, was found to induce measurable changes in DNA methylation, suggesting a biological mechanism through which environmental toxins may contribute to cancer development.
The findings are supported by population-level data showing that U.S. Counties with higher historical use of picloram report elevated rates of early-onset colorectal cancer, even after adjusting for socioeconomic factors and exposure to other pesticides like glyphosate, esfenvalerate, nicosulfuron, and atrazine.
Dr. José Antonio Seoane, head of the Computational Biology of Cancer Group at VHIO and lead author of the study, emphasized that the research captures the “exposome”—the totality of environmental and lifestyle exposures—through epigenetic signatures. This approach allows scientists to trace how factors like diet, tobacco, and pesticide exposure leave lasting molecular marks that may influence disease risk decades later.
Colorectal cancer remains the third most common cancer globally and the second leading cause of cancer-related deaths. While 90% of cases are diagnosed in individuals over 50, incidence rates among younger adults have risen sharply in recent years, prompting urgent investigation into environmental drivers beyond genetics.
The study was funded by the “la Caixa” Foundation and the Spanish Association Against Cancer. Researchers note that understanding the role of exposomic factors like picloram could inform future prevention strategies and public health policies aimed at reducing early-life exposure to harmful agricultural chemicals.
