| Research Abstract |
In order to investigate the origin of halogenated bipyrroles and brominated methoxylated diphenyl ethers in marine environment, we surveyed marine sponge, marine fish, sharks and mass-stranded mammals collected in Japanese coastal water, East Asia (Philippines, Taiwan and Hong Kong), Micronesia (Guam and Palau) and Oceania (Australia, New Zealand and Tahiti). Major persistent natural organohalogen products distributed in the Pacific were identified as halogenated 1-methyl-1',2-bipyrroles, 1,1'-dimethy1-2,2'-bipyrroles, methoxylated tetrabromodiphenyl ethers, dimethoxylated tetrabromobiphenyl. In Japanese mother's milk (n=65), these natural organohalogens were present at similar concentrations to polybrominated diphenyl ethers (PBDEs). These components were found to be widely distributed in marine fish from the Japanese coastal water. The dietary exposure to these compounds was suggested to be via consumption of marine fish. These products may be originated from marine sponge in Micronesia, where some of sponges contained high amounts of PBDE-like compounds. The distribution of these natural organohalogens was geographically different. Chlorinated 1-methyl-1',2-bipyrroles were abundant in marine fish from Oceania (East of Australia), whereas brominated1,1'-dimethyl-2,2'-bipyrroles were localized in the northern Pacific, especially in the Japanese coastal water. Natural PBDE-like compounds were distributed widely in the Pacific coast, but the biomagnification potential of these compounds seemed to be species-specific. The food chain study and toxicological evaluation are needed for natural persistent organohalogens described in this study.
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