Serum from 82 individual cats was analyzed for
decabromobiphenyl (BB-209),
polybrominated diphenyl ethers (
PBDEs), hydroxylated
PBDEs (
OH-
PBDEs), and 2,4,6-TBP in order to study differences in body burden between healthy and sick cats diagnosed with Feline
Hyperthyroidism (FH). Within the study group, 60 of these cats had a euthyroid (n = 23) or
hyperthyroid (n = 37) status, all of which were used in the comparison. This study shows that
hyperthyroid compared to euthyroid cats have higher serum concentrations for some of the investigated
PBDEs (BDE-99, BDE-153, and BDE-183) and
CB-153 on a fat weight basis. Further, it is intriguing, and beyond explanation, why the
flame retardant BB-209 (discontinued in 2000) is present in all of the cat serum samples in concentrations similar to
BDE-209. Median BDE-47/-99 ratios are 0.47 and 0.32 for healthy and euthyroid cats, respectively, which differs significantly from Swedes, where the ratio is 3.5. Another important finding is the occurrence of very low levels or the absence of hydroxylated
PBDE metabolites in the cats. In addition, the major
OH-
PBDE, 6-OH-BDE47, is likely of natural origin, probably ingested via cat food. The statistics indicate an association between elevated
PBDE concentrations in the cats and FH.