Rare earth elements in dog feed marketed in Southeastern Brazil

Introduction: Canines comprise a significant number of pets worldwide, and the associated pet sector has increased accordingly, with Brazilian pet sector revenues categorized as the third largest economy in terms of worldwide turnover. Industrialized animal feeds are the main food source for domestic dogs living in households, formulated according to nutritional dog needs and classified as standard, premium and super premium, depending on the raw material. However, dog-feed contamination by metals has recently become a concern, and several reports have indicated toxic metal levels in dog feed. No studies on rare earth elements (REE) in this regard are, however, available. Objective: Evaluate REE contents in different standard, premium and super premium dog-feed brands marketed in Southeastern Brazil by inductively coupled plasma mass spectrometry (ICP-MS). Results: Many of the evaluated brands from the three feed classes surpassed the only known maximum permissible concentration for ΣREE (China), many due to high data dispersal. The REE that most contributed to surpassing the stipulated ΣREE limit of 0.7 mg kg−1 were Nd, La and Ce, for all three feed classes, mainly due to inter-lot variability Conclusions: This is one of the only studies available on REE dog feed contents. The source of these elements in the evaluated dog feeds may comprise the raw materials used in the manufacturing process and the addition of functional compounds such as zeolites. Rare Earth Elements exposure from dog feed through inhalation is a possibility, due to volatilization processes, both during dog feed industrial production and during dog feeding events and should be further investigated concerning dog and human health.