Scientists in EFSA program look at cross-contamination in the home

Researchers have modeled and estimated cross-contamination in consumer kitchens during a European Food Safety Authority (EFSA) program.

The model was used to work out the impact of cross-contamination routes for different scenarios. Effectiveness of several interventions in reducing the risk of foodborne diseases related to cross-contamination was investigated.

Results found the cutting board route had a higher impact compared to other sources and replacement of kitchen utensils is more effective than other interventions studied.

The project in EFSA’s food risk assessment fellowship program (EU‐FORA) provided new modelling and data on cross-contamination for quantitative microbiological risk assessment (QMRA). This can help risk managers in defining the best advice to reduce the impact of cross-contamination.

Cross-contamination in the home
The European Union 2018 zoonoses report stated that 40.5 percent of strong-evidence outbreaks occurred at home and 15.6 percent of outbreak cases were because of contaminated food within the domestic environment. Cross-contamination was identified as one of the contributory factors of strong-evidence outbreaks.

Past research, which describes bacterial transfer between a contaminated source like meat and recipient such as a cutting board, showed the cross-contamination process is complex and affected by many factors.

Laboratory cross-contamination trials estimated bacterial transfer via cutting, from the external surface of the meat to the cutting surfaces and to the knife. Results show differences in the bacterial transfer to the knife and the cutting surface depending on which side of the meat is contaminated.

The model’s starting point is contaminated raw meat in contact with hands, with the cutting board and the knife during meal preparation. After contact with the contaminated source, hands, the cutting board and the knife can transfer bacteria to other products such as salad, which are not subject to further heat treatment before reaching the consumer’s mouth.

Interventions included are washing hands, cutting board or knife, replacement of the kitchen utensils and the order of actions. The chicken-salad example was the baseline scenario to describe a condition of surface contamination while the ground beef-salad scenario was included for contamination of the surface and the interior of raw meat.

The cross-contamination model is able to estimate the fraction of bacteria that reaches the consumer for the different scenarios and importance of the different cross-contamination routes in transfer of bacteria from contaminated meat to the final dish.

Work was carried out at the Centre for Zoonoses and Environmental Microbiology at the National Institute for Public Health and the Environment (RIVM) in the Netherlands. Applications are open for the next cohort of fellows until Jan. 29, 2021.

A special journal issue has 13 articles including a review of rare earth elements, Thallium and Tellurium in plant‐based foods; a risk assessment of Annona muricata in food supplements, and a study measuring the risk of listeriosis associated with consumption of ready-to-eat dry-fermented sausage.

Risk assessment meeting
Meanwhile, EFSA has published the annual report of the Scientific Network on Microbiological Risk Assessment.

An online meeting in October 2020 covered risk ranking of pathogens in food, Listeria monocytogenes, Staphylococcus aureus and E. coli in cheeses, STEC in flour, Campylobacter in broiler flocks, an overview on food safety reports, and EFSA activities.

A total of 24 EU member states, and Switzerland and Norway as observers, are members of the MRA Network.

The Swedish representative described an analysis of 11 years of reported food poisoning in Sweden. Norwegian officials gave a presentation on risk ranking in foods. Every year, the Norwegian Food Safety Authority (Mattilsynet) monitors and maps foods for infectious agents that can be harmful to people’s health. Publication is expected in June this year.

A presentation from Belgium covered the growth potential of Listeria monocytogenes in Belgian homestead cheeses. The Slovakian delegate talked about results from a study on heat-resistance of S. aureus and E. coli from artisanal stretched cheeses produced from raw milk curd. An official from Switzerland gave a presentation on Shiga toxin-producing E. coli (STEC) in flour with 10 strains isolated from 93 samples.

Establishment of a European food safety model repository was the subject of a talk by a speaker from the German Federal Institute for Risk Assessment (BfR). The tool is expected to be available by March 2021.

The mandate of EFSA’s MRA Scientific Network expired at the end of 2020 but a proposal for renewal was in the process of being put forward when the report was published. The next meeting is planned for autumn this year. An additional online meeting in spring this year was also being considered.

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