title: Organohalogen Compounds in Pet Dog and Cat: Do Pets Biotransform Natural Brominated Products in Food to Harmful Hydroxlated Substances?
abstract: There are growing concerns about the increase in hyperthyroidism in pet cats due to exposure to organohalogen contaminants and their hydroxylated metabolites. This study investigated the blood contaminants polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) and their hydroxylated and methoxylated derivatives (OH-PCBs, OH-PBDEs, and MeO-PBDEs), in pet dogs and cats. We also measured the residue levels of these compounds in commercially available pet foods. Chemical analyses of PCBs and OH-PCBs showed that the OH-PCB levels were 1 to 2 orders of magnitude lower in cat and dog food products than in their blood, suggesting that the origin of OH-PCBs in pet dogs and cats is PCBs ingested with their food. The major congeners of OH-/MeO-PBDEs identified in both pet food products and blood were natural products (6OH-/MeO-BDE47 and 2'OH-/MeO-BDE68) from marine organisms. In particular, higher concentrations of 6OH-BDE47 than 2'OH-BDE68 and two MeO-PBDE congeners were observed in the cat blood, although MeO-BDEs were dominant in cat foods, suggesting the efficient biotransformation of 6OH-BDE47 from 6MeO-BDE47 in cats. We performed in vitro demethylation experiments to confirm the biotransformation of MeO-PBDEs to OH-PBDEs using liver microsomes. The results showed that 6MeO-BDE47 and 2'MeO-BDE68 were demethylated to 6OH-BDE47 and 2'OH-BDE68 in both animals, whereas no hydroxylated metabolite from BDE47 was detected. The present study suggests that pet cats are exposed to MeO-PBDEs through cat food products containing fish flavors and that the OH-PBDEs in cat blood are derived from the CYP-dependent demethylation of naturally occurring MeO-PBDE congeners, not from the hydroxylation of PBDEs.
authors.affiliation: Center for Marine Environmental Studies (CMES), Ehime University , Bunkyo-cho 2-5, Matsuyama, Ehime 790-8577, Japan.
authors.forename: Hazuki
authors.initials: H
authors.lastname: Mizukawa
authors.affiliation: Center for Marine Environmental Studies (CMES), Ehime University , Bunkyo-cho 2-5, Matsuyama, Ehime 790-8577, Japan.
authors.forename: Kei
authors.initials: K
authors.lastname: Nomiyama
authors.affiliation: Nakatsu Veterinary Surgery, 2-2-5, Shorinjichonishi, Sakai-ku, Sakai-shi, Osaka 590-0960, Japan.
authors.forename: Susumu
authors.initials: S
authors.lastname: Nakatsu
authors.affiliation: Center for Marine Environmental Studies (CMES), Ehime University , Bunkyo-cho 2-5, Matsuyama, Ehime 790-8577, Japan.
authors.forename: Hisato
authors.initials: H
authors.lastname: Iwata
authors.affiliation: Center for Marine Environmental Studies (CMES), Ehime University , Bunkyo-cho 2-5, Matsuyama, Ehime 790-8577, Japan.
authors.forename: Jean
authors.initials: J
authors.lastname: Yoo
authors.affiliation: Diagnostic Center for Animal Health and Food Safety, Obihiro University of Agriculture and Veterinary Medicine , Inada-cho, Obihiro, Hokkaido 080-8555, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Kubota
authors.affiliation: Center for Marine Environmental Studies (CMES), Ehime University , Bunkyo-cho 2-5, Matsuyama, Ehime 790-8577, Japan.
authors.forename: Miyuki
authors.initials: M
authors.lastname: Yamamoto
authors.affiliation: Laboratory of Toxicology, Graduate School of Veterinary Medicine, Hokkaido University , Kita 18, Nishi 9, Kita-ku, Sapporo, Hokkaido 060-0818, Japan.
authors.forename: Mayumi
authors.initials: M
authors.lastname: Ishizuka
authors.affiliation: Laboratory of Toxicology, Graduate School of Veterinary Medicine, Hokkaido University , Kita 18, Nishi 9, Kita-ku, Sapporo, Hokkaido 060-0818, Japan.
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Ikenaka
authors.affiliation: Laboratory of Toxicology, Graduate School of Veterinary Medicine, Hokkaido University , Kita 18, Nishi 9, Kita-ku, Sapporo, Hokkaido 060-0818, Japan.
authors.forename: Shouta M M
authors.initials: SM
authors.lastname: Nakayama
authors.affiliation: Center for Marine Environmental Studies (CMES), Ehime University , Bunkyo-cho 2-5, Matsuyama, Ehime 790-8577, Japan.
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Kunisue
authors.affiliation: Center for Marine Environmental Studies (CMES), Ehime University , Bunkyo-cho 2-5, Matsuyama, Ehime 790-8577, Japan.
authors.forename: Shinsuke
authors.initials: S
authors.lastname: Tanabe
mesh_terms: D000821:Animal Feed; D000818:Animals; D001711:Biotransformation; D002415:Cats; D004285:Dogs; D055768:Halogenated Diphenyl Ethers / Q000097:blood / Q000737:chemistry / Q000378:metabolism; D006900:Hydroxylation; D011078:Polychlorinated Biphenyls / Q000097:blood / Q000737:chemistry / Q000378:metabolism
chemical_list: D055768:Halogenated Diphenyl Ethers; D011078:Polychlorinated Biphenyls