Waterborne Chemicals Emerging as Major Food Safety Risk, FAO–WHO Study Reveals

The FAO–WHO report warns that chemical contaminants from natural toxins to industrial pollutants and PFAS are increasingly entering food through irrigation, livestock water and aquaculture as water scarcity drives greater use of alternative water sources. It identifies eleven high-risk contaminants and urges stronger One Health–based regulation, monitoring and water treatment to safeguard global food safety.

The FAO and WHO’s 2025 report on chemical water quality in agrifood systems, developed with key scientific contributions from the University of Campinas, the National Institute of Environmental Studies Japan, Cawthron Institute New Zealand, the University of East Anglia, the University of Alabama, the University of Nairobi, JEFCS UK, Agriculture and Agri-Food Canada and Chung-Ang University, delivers a clear alarm: food safety can no longer be separated from water safety. As agriculture draws more than 70 percent of global freshwater, rising demand, climate disruption and the growing dependence on non-conventional water sources are allowing chemical contaminants, many previously overlooked, to slip into the food supply through irrigation, livestock watering, aquaculture systems, and post-harvest washing.

A Complex Mix of Contaminants Flowing Into Food Systems

The report outlines a dense and evolving chemical landscape. Some contaminants originate in geology, arsenic, cadmium, lead, thallium, uranium, fluoride and radium, which naturally occur in soils but reach hazardous levels when water tables shift, droughts intensify or mining activities disturb subsurface layers. Others stem from biological activity: cyanobacteria release potent toxins such as microcystins, nodularins, cylindrospermopsins, saxitoxins and anatoxin-a, which flourish in warming, nutrient-rich waters and threaten both aquaculture and irrigated crops. Modern agriculture adds herbicides, insecticides, fumigants and veterinary drugs that infiltrate groundwater or wash into rivers, while cities contribute pharmaceuticals, hormones, flame retardants, plasticizers and personal-care chemicals through wastewater. Stormwater drains carry tyre-wear particles, polycyclic aromatic hydrocarbons and microplastics from urban surfaces, and even water distribution systems can introduce contaminants such as chlorate, bromate or heavy metals.

How Chemicals Move From Water to Food

FAO and WHO map out several pathways by which contaminants enter the human diet. Livestock absorb chemicals directly through drinking water, allowing pollutants to accumulate in muscle, organs, milk or eggs. Fish and shellfish, constantly immersed, bioaccumulate both dissolved and particle-bound contaminants, sometimes at levels far exceeding those in the water itself. Crops absorb soluble contaminants from soil or accumulate residues from foliar irrigation, and some pharmaceuticals, carbamazepine being a notable example, survive wastewater treatment and appear in vegetables irrigated with treated effluent. Post-harvest washing with contaminated water allows toxins to bypass biological barriers entirely and adhere directly to food surfaces. These pathways highlight that water quality is not merely an environmental issue but a direct food safety concern.

The Chemicals of Highest Concern

By comparing contamination levels in food with health-based guidance values, the report identifies eleven contaminants of greatest concern, those for which dietary exposure via water sources alone may exceed or approach toxic thresholds. They include arsenic, cadmium, lead, thallium, radium and fluoride, all of which are potent geogenic toxicants associated with chronic disease; the cyanobacterial toxins microcystins, cylindrospermopsins, saxitoxins and anatoxin-a, which can cause severe acute poisoning; and the persistent PFAS chemicals PFOA and PFOS, which accumulate in the environment and human bodies. Medium-priority contaminants such as carbamazepine, perchlorate, nickel, phthalates and PCBs may not exceed limits individually but contribute significantly to cumulative dietary exposure. The report notes that climate change is multiplying the risks, fueling harmful algal blooms, concentrating metals during droughts, and mobilizing industrial contaminants during floods.

A Call for One Health-Based Food Safety Governance

The report concludes that safeguarding future food systems will require an integrated approach linking environmental, animal, and human health. Effective action must begin at pollution sources, with tighter industrial regulation, improved agricultural chemical management, and watershed protection, paired with water treatment technologies capable of removing persistent contaminants, especially PFAS and cyanotoxins. On farms, decisions about irrigation methods, crop selection, and aquaculture water intake must incorporate chemical risk assessments, while post-harvest systems should adopt stricter water-quality standards to prevent direct contamination. As countries increasingly turn to wastewater reuse and controlled-environment agriculture, comprehensive monitoring and strong regulatory frameworks become essential. The overarching message is unequivocal: water safety is now a fundamental pillar of global food safety, and protecting it demands sustained scientific investment, regulatory innovation and international cooperation.