Study Links Common Herbicide to Rising Early-Onset Colorectal Cancer Risk
A recent study has identified a significant association between exposure to the herbicide picloram and the increasing incidence of colorectal cancer in adults under 50 years ancient. Researchers used epigenetic markers to trace environmental exposures, revealing that picloram leaves a detectable molecular footprint linked to early-onset disease.
Understanding the Rise in Early-Onset Colorectal Cancer
Colorectal cancer diagnoses among people younger than 50 have been rising globally over the past two decades. While over 90% of cases still occur in older adults, the trend in younger populations has prompted urgent investigation into contributing lifestyle and environmental factors.
To better understand these influences, scientists from the Vall d’Hebron Institute of Oncology (VHIO) developed a method to assess cumulative environmental and lifestyle exposures—known as the exposome—by analyzing DNA methylation patterns. These epigenetic changes serve as a biological record of past exposures without altering the underlying DNA sequence.
Epigenetic Fingerprints Reveal Herbicide Link
In their analysis, researchers compared methylation profiles between early-onset colorectal cancer patients (diagnosed before age 50) and late-onset cases (diagnosed at age 70 or older). The study confirmed known risk factors such as diet, smoking and educational attainment. More notably, it identified exposure to picloram—a widely used herbicide for controlling woody plants and broadleaf weeds—as a significant factor associated with early-onset disease.
The initial discovery cohort included 31 early-onset and 100 late-onset colorectal cancer patients. Picloram exposure showed a strong statistical association (adjusted P = 4.4 × 10−4). This finding was later validated in a meta-analysis of nine colorectal cancer cohorts involving 83 early-onset and 272 late-onset cases (P = 3.1 × 10−3; adjusted P = 1.5 × 10−2).
Further support came from population-level data across 94 U.S. Counties over 21 years, where higher picloram use correlated with increased early-onset colorectal cancer incidence (P = 4.52 × 10−4). This association remained significant after adjusting for socioeconomic status and other pesticide exposures.
Implications for Prevention and Policy
These findings underscore the role of environmental chemicals in shaping cancer risk, particularly among younger populations. By identifying specific exposome components like picloram through epigenetic signatures, the study opens pathways for targeted prevention strategies.
Experts emphasize the need for both individual awareness and broader regulatory evaluation of herbicide use, especially in agricultural and landscaping contexts where human exposure may occur. Ongoing research continues to explore how modifiable environmental factors contribute to cancer development and how such risks might be mitigated.
As colorectal cancer screening guidelines increasingly consider earlier initiation for high-risk individuals, understanding environmental contributors like picloram may assist refine risk assessment and prevention efforts in the years ahead.