P16 | Animal by-products in the formulation of compound pet food products: contamination by toxic elements and potential implications for food safety

Purpose. Category 3 animal by-products (ABPs), considered low-health-risk, are commonly used in the formulation of products intended for pet food. The chemical-toxicological safety of such materials can vary extremely depending on the animal species, origin, and industrial processing methods used. Specifically, the presence of toxic metals and metalloids represents a critical issue not only for animal health but, indirectly, also for human health, as these substances can originate from animals whose meat has entered the food chain. The aim of this study was to analyze the multi-element profile of 78 commercial samples of complete dry cat food containing by-products of avian origin (n=50), fish origin (n=18), porcine origin (n=4), bovine origin (n=4), and ovine-caprine origin (n=2). Methods. The analyzes were conducted using atomic absorption spectroscopy and inductively coupled plasma mass spectrometry to quantify elements subject to regulatory limits, as well as potentially toxic elements currently unregulated, and to correlate any contamination patterns with the type of SOA used. Results. Products containing SOA derived from fish processing waste showed significantly higher concentrations of highly toxic elements, including arsenic (331–708 µg kg⁻¹), cadmium (84.4–248 µg kg⁻¹), mercury (5.48–11.9 µg kg⁻¹), and lead (154–248 µg kg⁻¹) (p ≤ 0.05). Although these concentrations were below the maximum limits established for pet food products under Directive 2002/32/EC, chronic exposure to such contaminants can lead to bioaccumulation phenomena, posing a long-term risk to animal health. Furthermore, this could suggest the presence of similar concentrations in products intended for human consumption from which these PAHs originate, posing a potential risk to human health as well. For some essential trace elements, an extremely narrow margin of safety has been highlighted between concentrations considered nutritionally adequate and those potentially toxic to the animal. Specifically, 25% of products containing bovine by-products showed copper concentrations exceeding recommended levels. Similarly, zinc concentrations exceeding reference values were found in 50%, 11%, and 4% of samples containing by-products of ovine/caprine, fish, and poultry origin, respectively. Particularly noteworthy is the exceeding of the recommended maximum levels for selenium, observed in 100%, 72%, 50%, and 18% of products containing ovine/caprine, fish, bovine, and poultry by-products, respectively. Conclusions. From an integrated perspective that, in line with the principles of the One Health approach, recognizes the interconnectedness of animal, human, and environmental health, the results obtained highlight the need to strengthen the selection and control criteria for SOAs used in feed production. This intervention is essential to contain the risk of contamination by toxic elements throughout the entire feed and food chain and to ensure the sustainability and safety of agri-food systems as a whole.