The European Food Safety Authority (EFSA) today released a Scientific Opinion on the risks to human health posed by Salmonella and Norovirus in leafy greens eaten raw as salads. This report, Part 2 of a series of Scientific Opinions evaluating the public health risks posed by pathogens that may contaminate food of non-animal origin, is the result of a request by the European Commission to the EFSA’s Panel on Biological Hazards (BIOHAZ).

The panel was asked to: (i) identify the main risk factors for leafy greens, including agricultural production systems, origin and further processing; (ii) recommend possible specific mitigating options and to assess their effectiveness and efficiency to reduce the risk for humans posed by Salmonella and Norovirus in leafy greens and (iii) recommend, if considered relevant, microbiological criteria for Salmonella and Norovirus in leafy greens.

Leafy greens eaten raw as salads are minimally processed and widely consumed foods. Risk factors for leafy greens contamination by Salmonella spp. and Norovirus were considered in the context of the whole food chain, including agricultural production and processing. Available estimates of the prevalence of these pathogens (together with the use of Escherichia coli as an indicator organism) in leafy greens were evaluated. Specific mitigation options relating to contamination of leafy greens were considered and qualitatively assessed.

The BIOHAZ panel concluded that each farm environment represents a unique combination of numerous characteristics that can influence occurrence and persistence of pathogens in leafy greens production. Appropriate implementation of food safety management systems, including Good Agricultural Practices (GAP), Good Hygiene Practices (GHP) and Good Manufacturing Practices (GMP), should be primary objectives of leafy greens producers.

The relevance of microbiological criteria applicable to production, processing and at retail/catering were considered. The current legal framework does not include microbiological criteria applicable at primary production that will validate and verify GAP and GHP. It is proposed to define a criterion at primary production of leafy greens which is designated as Hygiene Criterion, and E. coli was identified as suitable for this purpose. A Process Hygiene Criterion for E. coli in leafy green packaging plants or fresh cutting plants was considered and will also give an indication of the degree to which GAP, GHP, GMP or HACCP programs have been implemented.

A Food Safety Criterion for Salmonella in leafy greens could be used as a tool to communicate to producers and processors that Salmonella should not be present in the product. Studies on the prevalence and infectivity of Norovirus are limited, and quantitative data on viral load are scarce, making establishment of microbiological criteria for Norovirus on leafy greens difficult.