The FAO and the WHO have put out draft guidance on microbiological risk assessment for food for public comment.

It is intended to provide guidance and a framework for carrying out each of the four components of a microbiological risk assessment, whether as part of a full risk assessment, as part of other evaluations, or as a stand-alone process, according to officials.

The four areas are hazard identification, hazard characterization, exposure assessment and risk characterization.

The primary audience is the global community of scientists and risk assessors, and risk managers or others responsible for decision making and/or communication.

The United Nations’ Food and Agriculture Organization (FAO) and the World Health Organization (WHO) established the Joint Expert Meetings on Microbiological Risk Assessment (JEMRA) to provide advice on risk assessment of microbiological hazards in foods.

Hazard identification and characterization
The document covers undertaking risk assessment of all microbial hazards which may adversely affect human health in foods along the supply chain.

Risk analysis, consisting of risk assessment, management, and communication, is used to develop an estimate of the risks to human health, identify and implement measures to control them, and communicate about the risks and measures applied.

Hazard identification is usually the first step in risk assessment. It is an examination of the foodborne hazard and associated potential adverse health outcomes due to specific foodborne exposure, which is supported by a review of knowledge about the hazards and/or food in question.

Hazard characterization provides a description of the adverse effects that may result from ingestion of a hazard, whether that is a microorganism or its toxin. For emerging hazards it may be less certain than for well-established ones, such as Campylobacter, because of the lack of data and information, and may require more frequent updates to reflect increasing knowledge.

Exposure assessment and risk characterization
The goal of exposure assessment is to deduce, from available information, the probability and magnitude of exposure to the hazard. This may be in a given population or be limited to evaluation of one or a few processing steps. The risk manager may also wish to limit the scope to specific regions, populations, or periods of time.

It considers the factors that have a direct effect on consumer exposure to the hazard. These include frequency of consumption of the product; pathway, frequency and levels of contamination with the hazard; the range of doses; and factors that affect it such as potential for microbial growth, inactivation during cooking, and seasonal and regional influences.

Risk characterization integrates the findings from the other three parts to estimate levels of risk, which can be used to make risk management decisions. It can include one or more estimates of risk, risk descriptions, and evaluations of risk management options.

The guidance gave examples of risk assessments including one in 2004 on Bovine Spongiform Encephalopathy (BSE) and Transmissible Spongiform Encephalopathy (TSE) in goat milk and milk-derived products by the European Food Safety Authority (EFSA). Another was seafood safety using RiskRanger, a decision support software tool, in Australia. In 2014, the FAO and the WHO looked at 24 parasites in food and their public health and trade impact with work, including development of a quantitative ranking tool using expert opinion.

The USDA-FSIS estimated whether blade-tenderized steak posed a greater risk from E. coli O157:H7 than its equivalent non-tenderized steak in 2002. A 2001 study simulated the exposure of the Dutch population to Shiga-toxin producing E. coli O157 in steak tartare and EFSA studied the public health risk posed by Salmonella in table eggs in 2014. The FAO and the WHO work on Listeria monocytogenes in ready-to-eat foods and Vibrio vulnificus in raw oysters was also mentioned.