Thank you for raising this important question. Health risk assessment (HRA) for the use of wastewater in irrigation is indeed a critical area, given the potential exposure to pathogens, heavy metals, organic pollutants, and emerging contaminants such as pharmaceuticals and microplastics.

Several established methods and frameworks can be used:

Regarding your specific question about the RAIS tool (Risk Assessment Information System):

• RAIS is primarily designed for chemical risk assessment in contaminated environmental media (soil, air, groundwater).
• While it can be adapted to evaluate certain chemical risks in wastewater irrigation (e.g., heavy metals, organic pollutants), it is not specifically tailored for microbial risks, which are often the primary concern in wastewater use.
• For a comprehensive assessment, RAIS could be used in parallel with QMRA-based models (such as the USEPA QMRAwiki or WHO recommended tools) to cover both microbial and chemical aspects.

In summary:

• For wastewater irrigation, a combined approach is recommended: QMRA for pathogens + chemical risk assessment (possibly supported by RAIS or EPA frameworks) for toxic compounds.
• WHO guidelines remain the most widely accepted global reference.
• Site-specific monitoring data and exposure scenarios are essential to make the assessment realistic and relevant.

I hope this provides clarity. If needed, I can share some key references and case studies that apply these methods in agricultural contexts.@

Great question—there are established methods, and the best practice is to combine microbial (QMRA) and chemical risk assessments within a “multi-barrier” risk-management framework.

What to use (in short)

• WHO reuse guidelines (Vol. 2) are the global reference for wastewater irrigation. They set health-based targets and show how to meet them via treatment plus on-farm barriers (irrigation method, withholding times, produce washing, etc.). Methodologically, they rely on Quantitative Microbial Risk Assessment (QMRA) for pathogens and standard chemical risk methods for toxicants. World Health Organization+1
• Sanitation Safety Planning (SSP, WHO 2022) gives a practical, step-by-step template to apply those targets on your specific scheme (identify hazards, exposures, barriers, monitoring). World Health OrganizationSSP Learning Hub
• For microbial risks specifically, use QMRA (select reference pathogens, dose–response models, exposure scenarios for workers/consumers; compare calculated risk to WHO targets). See the QMRA Wiki for models/examples and the U.S. EPA Microbial Risk Assessment Guideline for harmonized steps. qmrawiki.orgUS EPA
• For chemical risks (metals, organics, pharmaceuticals), use standard human-health risk methods: estimate exposure (dietary intake from irrigated produce, dermal/inhalation for workers), then compute Hazard Quotients (HQ/HI) and cancer risk (ILCR). The RAIS platform is designed for exactly these chemical (and radionuclide) calculations—screening levels, toxicity values, and risk calculators—though it is not a microbial-risk tool. rais.ornl.gov
• Newer sector standards you can cite: Codex (2023) guidance on safe use/reuse of water in food production (promotes “fit-for-purpose” and QMRA approaches), and reviews on implementing WHO reuse guidance. FAOHomeMDPI

How to structure your assessment (practical template)

So…is RAIS suitable?

• Yes—but only for the chemical part. RAIS is built around chemical/radionuclide toxicity values, exposure calculators, and risk metrics. It does not implement microbial dose–response/QMRA, which you’ll need for pathogens—the dominant health concern in wastewater irrigation. Use RAIS for chemicals + QMRA (WHO/EPA frameworks) for microbes to get a complete assessment. rais.ornl.gov

Quantitative Microbial Risk Assessment (QMRA) is a standard method for evaluating health risks from wastewater irrigation by estimating pathogen exposure and infection risk. The RAIS tool is mainly for chemical and radiological risks and is less appropriate for microbial risk assessment in this context.