A new guide published by the FAO was created to help countries more effectively inform domestic food safety priorities.

Risk ranking helps to identify which food safety issues have the greatest public health impact by taking into account the likelihood and severity, according to the Food and Agriculture Organization of the United Nations (FAO).

The guidance provides direction to national food safety authorities on how to start ranking the public health risk posed by foodborne hazards and foods in their countries using a three-step approach.

It focuses on the ranking of microbial and chemical hazards based on their impact on public health and represents the first step toward a systematic and evidence-based approach to identify the main risks in food safety.

With limited human and financial resources, it is impossible for national authorities to efficiently address all food safety threats. It is important to rank concerns and prioritize efforts so that resources can be allocated to best minimize foodborne illness risks. Several countries have started using risk-based food safety systems.

Three-step approach
Risk ranking provides national authorities with the scientific basis to make informed regulatory decisions; enhance disease surveillance; determine how food inspections are allocated; oversee inspection and enforcement efforts; and inform the public of food safety threats.

The first step is to define the scope and purpose of the risk ranking exercise. Here, hazards and foods to be ranked are seleced and screened for relevance and overall risk potential.

Second is developing the approach. This involves selecting the risk ranking method and the metrics to estimate the dimensions of risk including likelihood and severity and their uncertainty and variability, as well as collection and evaluation of data needed to estimate risk.

The final step is conducting the risk ranking analysis and reporting results. Findings can then be incorporated into prioritization efforts wher other factors, such as social, economic and political issues are considered to further inform decisions. Uncertainty should also be part of the discussion, according to the FAO.

Results may not be actual estimates of risk, but rather relative rankings. For more accurate estimates of risk and the associated uncertainty and variability, full quantitative risk assessments using high quality and representative data are needed.

Need for updates and political uptake
Risk ranking is a complex and data-driven process that must be ongoing as new information becomes available and not a one-time effort, the FAO stresses. Such work will also highlight data gaps and research needs.

It must also be backed by a desire to modernize food safety and political will via a move from government to determine how risk ranking results can be used in decision making on an ongoing basis.

Risk ranking methods can be qualitative that produce outcomes without numerical values such as low, medium or high. They are most applicable wher time is a critical factor and resources and data are limited.

Semi-quantitative method outcomes have numerical values without measurement units. Scores allow items to be ranked, but do not provide an actual measure of risk or burden of illness.

Quantitative methods produce numerical estimates of the likelihood of foodborne illness and severity of outcomes with measurement units. They are not applicable to very broad questions, involving the evaluation of 50 hazards and 50 foods at once.

Two case studies to help understand how the proposed risk ranking approach can be used in practice are included. The first focuses on microbial hazards and the second on chemical contaminants in fish.