Chemical interventions involve the application of a substance at a given step during the slaughter and/or cutting process in order to reduce the microbial contamination level of carcasses or meat cuts. These substances can be considered as processing aids, since they are not consumed as a food by itself, and are “intentionally used in the processing of raw materials, foods or their ingredients, to fulfil a certain technological purpose during treatment or processing”. However, these substances and/or their by-products may result in the unintentional but technically unavoidable presence of residues in the final product.

In the EU, according to Regulation 853/2004 of the European Parliament and Council, the use of any substance other than potable water to remove/reduce surface contamination from products of animal origin is not authorized, unless the use of the substance has been approved following an assessment of its safety and efficacy by the risk assessment authority.

Three main aspects are considered when assessing the use of decontamination substances: i) the safety of the intended substance itself; ii) its effect as to the development of antimicrobial resistance; and iii) the efficacy i.e. does the use of the substance in practice decrease the level of contamination of pathogenic microorganisms.

Therefore, the evaluation of the efficacy of the chemical intervention is a central part of the assessment. In general, the use of chemical solutions as decontaminating agents will be regarded efficacious when a reduction of the prevalence and/or numbers of pathogenic target microorganisms set according to determined criteria, is statistically significant when compared to a control group. The achieved reduction should be expected to provide benefits to public health but the satisfactory level of this benefit is a risk management decision.

The assessment of the efficacy of a chemical intervention is a complex process, since efficacy depends on a range of factors, such as the concentration of the decontaminating agent, the microbial pathogen and its load on the surface, contact time, temperature, mode of application (i.e. spraying or dipping) and other conditions of use. For this reason, only studies conducted under conditions directly related to the intended conditions of use of the formulated product application should be considered for the efficacy assessment. Studies must include a comparison of the prevalence and/or numbers of the target pathogenic microorganisms on the food of animal origin to which the formulated product will be applied and on the untreated control food. The only difference must be the presence or absence of the formulated product and not the method of application or other factors. In other words, supporting studies should be performed as close as possible to the real conditions under which the formulated product is intended to be applied.

In the workshop we will go through the different steps of the assessment of the safety and efficacy of chemical interventions. Then, we will carry out a simulated evaluation of the appropriateness and strength of evidence of various scientific studies to demonstrate the efficacy of a given chemical intervention. It is recommended to the attendees, in preparation for the workshop, to read the following EFSA guidance document and opinions, as example of assessments, and the scientific literature below, that will be used during the simulated evaluation exercise.

EFSA related opinions:

• Guidance document on the submission of data for the evaluation of the safety and efficacy of substances for the removal of microbial surface contamination of foods of animal origin intended for human consumption
• Scientific Opinion on the evaluation of the safety and efficacy of lactic acid for the removal of microbial surface contamination of beef carcasses, cuts and trimmings
• Evaluation of the safety and efficacy of the organic acids lactic and acetic acids to reduce microbiological surface contamination on pork carcasses and pork cuts

Scientific papers on the topic:

• Bashor, M.P., Curtis, P.A., Keener, K.M., Sheldon, B.W., Kathariou, S., Osborne, J.A., 2004. Effects of carcass washers on Campylobacter contamination in large broiler processing plants. Poultry Science 83, 1232-1239.
• Chantarapanont, W., Berrang, M.E., Frank, J.F., 2004. Direct microscopic observation of viability of Campylobacter jejuni on chicken skin treated with selected chemical sanitizing agents. Journal of Food Protection 67, 1146-1152.
• Chousalkar, K., Sims, S., McWhorter, A., Khan, S., Sexton, M., 2019. The effect of sanitizers on microbial levels of chicken meat collected from commercial processing plants. International Journal of Environmental Research and Public Health 16.
• Del Río, E., Muriente, R., Prieto, M., Alonso-Calleja, C., Capita, R., 2007. Effectiveness of trisodium phosphate, acidified sodium chlorite, citric acid, and peroxyacids against pathogenic bacteria on poultry during refrigerated storage. Journal of Food Protection 70, 2063-2071.
• Kere Kemp, G., Aldrich, M.L., Guerra, M.L., Schneider, K.R., 2001. Continuous online processing of fecal- and ingesta contaminated poultry carcasses using an acidified sodium chlorite antimicrobial intervention. Journal of Food Protection 64, 807-812.
• Özdemir, H., Gücükoǧlu, A., Koluman, A., 2006. Acidified sodium chlorite, trisodium phosphate and populations of Campylobacter jejuni on chicken breast skin. Journal of Food Processing and Preservation 30, 608-615.
• Özdemir, H., Pamuk, Ş., 2006. Acidified sodium chlorite, trisodium phosphate and populations of Salmonella Typhimurium and Staphylococcus aureus on chicken-breast skin. Journal of Food Processing and Preservation 30, 110-117.
• Purnell, G., James, C., James, S.J., Howell, M., Corry, J.E.L., 2014. Comparison of Acidified Sodium Chlorite, Chlorine Dioxide, Peroxyacetic Acid and Tri-Sodium Phosphate Spray Washes for Decontamination of Chicken Carcasses. Food and Bioprocess Technology 7, 2093-2101.