GLOBAL – The Food and Agriculture Organization of the United Nations and the World Health Organization have released a new framework for identifying chemical hazards in water used across agrifood systems.
Global water supplies are facing mounting pressure. More than 70% of freshwater withdrawals are now used for agriculture, a figure that continues to shape discussions on water sustainability, food production, and trade.
As climate conditions shift, populations expand, and urban consumption increases, farming systems are progressively relying on alternative water sources, including treated wastewater, industrial recycling streams, stormwater capture, and desalinated supplies.
Unlike drinking water, agricultural water is rarely tested for a broad range of chemical hazards before being applied to food production.
Pathogen risks in farm water have been studied extensively, but regulatory guidance for chemical contaminants remains limited.
The new FAO-WHO report, Prioritizing Food Safety Issues Related to Chemical Water Quality in Agrifood Systems, outlines a structured approach for screening, ranking, and tracking waterborne chemicals that enter crops, livestock, aquatic foods, and ultimately diets.
The initiative received funding support from the Government of Canada.
Three-stage model to track chemical uptake
Instead of testing for one chemical at a time, the report introduces a tiered process. The first stage gathers documented chemical hazards reported in irrigation sources, aquaculture ponds, farm wells, and surface waters.
The second stage assesses whether these chemicals are likely to be absorbed by crops or accumulate in animals.
The third stage maps human dietary exposures traced back to waterborne sources that have entered the food chain.
Priority chemical categories
The assessment identifies natural toxins, groundwater-linked contaminants, and industrial compounds as priority groups.
Cyanotoxins, including microcystins and anatoxin-a, are produced during algal blooms and can accumulate in fish, shellfish, and irrigated crops.
Warmer temperatures and changing rainfall patterns continue to increase the likelihood of cyanobacterial bloom activity in surface waters.
Groundwater systems present their own priority list. Arsenic, cadmium, and lead continue to rank highly due to their ability to transfer from water into soil, crops, and animal tissues, where exposure can build over time.
Additional naturally occurring contaminants, such as thallium and radium, are also included in the list of chemicals requiring increased monitoring due to their mobility in water systems and potential to enter the food chain.
The report also names industrial compounds that persist in water environments.
PFAS chemicals, particularly PFOS and PFOA, are highlighted for their durability and widespread detection in water sources near industrial zones. These compounds are sometimes referred to as “forever chemicals” due to their long persistence in the environment.
Chemicals in irrigation water can enter plants through roots or stick to produce surfaces during watering.
Animals drinking contaminated farm water or living in affected water bodies can accumulate chemicals in their tissues, a process known as bioaccumulation. In some cases, chemical concentration can increase further up the food chain, which is described as biomagnification.
Role of new water testing technologies
The report documents the role of non-targeted analysis (NTA), a laboratory method that screens thousands of known and unknown chemicals simultaneously.
This type of testing can detect breakdown products of chemicals that are not captured in conventional single-compound testing.
Experimental water treatment approaches are also being tested globally, including the use of materials like fly ash to filter metals from acid mine drainage for safer agricultural reuse.
Another emerging strategy is fit-for-purpose water use, which matches water quality levels to specific crop types depending on exposure risk.
Regulatory and capacity needs
Many of the identified chemical contaminants do not yet have risk management thresholds, recommended limits, or irrigation safety guidelines, according to the report.
The document also recommends that water risk management strategies follow the One Health model, which recognizes the interconnected nature of water, crops, animals, ecosystems, and human health.
In recent months, FAO has also published a technical landscape mapping report covering the Near East and North Africa (NENA) region, documenting food safety conditions, including chemical water risks, regulatory environments, and emerging data needs across agrifood systems.