Cats as a biomarker for exposure to POPs in home environments – with focus on brominated chemicals and associations to feline hyperthyroidism

Abstract: In this thesis, body burden of brominated chemicals such as polybrominated diphenyl ethers (PBDEs) and brominated phenolic substances are explored. The external exposure of cats to these compounds from house dust and their food was also investigated. The analytical methodology used for serum extractions was validated for analysis of OH-PBDEs in cat serum.Cats are highly exposed to dust and thereby also to chemicals accumulated in dust, due to their grooming behavior. This makes pet cats, a suitable biomarker for exposure to chemicals in house dust in home environments. Thereby, cats’ exposure to dust is somewhat similar to toddlers, due their hand-to-mouth behavior. Thus, cats’ internal exposure may be used to access that of toddlers. The PBDE pattern in Swedish pet cats show exposure to Penta-, Octa- and DecaBDE and their profile matches that of dust from their homes, suggesting dust to be an important exposure source. Serum concentrations of BDE-47 in the cats were also shown to correlate with house dust from their living rooms.Feline hyperthyroidism (FH) is a common endocrine disease in elderly cats worldwide, still the actual cause(s) has not been established even though environmental pollutants such as PBDEs have been suggested. Difference in contamination load between cats with normal thyroid status and cats diagnosed with FH was performed and higher serum concentrations for some PBDEs (BDE-99, 153, -183) were found in the hyperthyroid cats.Further, the presence of the longtime discontinued flame retardant, decabromobiphenyl (BB-209) in all sampled cats indicates that it is still being circulated. A significant correlation between serum concentrations of BB-209 and matched cat food samples was found.Very few OH-PBDEs were indeed shown in cat serum and the dominating compound, 6-OH-BDE47, is believed to be of natural origin rather than being a metabolite of BDE-47. A significant correlation between serum concentration of 6-OH-BDE47 and cat food was found.