Agricultural Runoff and Waterborne Disease in Primary Care: A Review

Contamination of agricultural water poses significant health risks that are often underrecognized in clinical practice. This review synthesizes peer-reviewed literature from biomedical and environmental sciences. It examines the pathways by which nitrates and zoonotic pathogens contaminate rural drinking water and delineates the resulting spectrum of acute and chronic health risks relevant to primary care. Agricultural practices are a primary source of nitrates and pathogens (e.g., Escherichia coli, Cryptosporidium, Giardia) in rural water supplies. Nitrate nitrogen exposure is linked not only to acute infant methemoglobinemia but also to chronic conditions like colorectal and thyroid cancers and adverse birth outcomes. These risks are observed at concentrations below the current United States Environmental Protection Agency regulatory limit of 10 mg L−1 NO3−–N. Pathogen exposure leads to acute gastrointestinal illness and can trigger long-term sequelae, including irritable bowel syndrome. Agricultural communities are uniquely vulnerable because they rely heavily on unregulated private wells, which are more prone to contamination than public systems. Evidence suggests a substantial and often underrecognized burden of waterborne disease in agricultural communities. The findings highlight a critical need for clinical vigilance regarding low-level nitrate nitrogen exposure and long-term post-infectious syndromes. By identifying these patterns, family physicians serve as essential sentinels for both individual patient safety and community public health.