Abstract
BACKGROUND: Humans and companion animals are continually exposed to mixtures of synthetic chemicals from household products, textiles, food, and personal care items. Epidemiological studies of emerging contaminants typically rely on invasive blood sampling, whereas saliva presents a non-invasive and cost-effective alternative matrix that reflects both local and systemic physiological changes. In this pilot study, paired dog saliva and blood serum were analysed for two chemical groups of concern, that is, synthetic phenolic antioxidants (SPAs) and per- and polyfluoroalkyl substances (PFAS), to investigate whether saliva can be used for chemical exposome studies. METHODS: Blood serum and saliva samples of a total of 30 dogs were included in this study. All dogs were privately owned, representing different breeds, and were presented to private veterinary clinics in the Murcia Region, Spain. Samples were analysed using acetonitrile for denaturation and extraction, and clean-up using enhanced matrix removal powder. The extracts were analysed using complementary liquid and gas chromatography coupled with mass spectrometers. Dogs were divided into three groups (n = 10 per group): healthy normal-weight dogs, healthy obese dogs, and dogs diagnosed with mammary tumours. RESULTS: Fourteen SPAs (including five metabolites) and eight PFAS were quantified in the dog's saliva and/or serum. Generally, the levels were higher in serum than in saliva. None of the dogs were free of contaminants. The SPA levels were dominated by the 2,4-di-tert-butylphenol (2,4-DBP), found in 93% of saliva and 100% of serum samples, ranging from