Higher mercury levels were found in bigeye tuna and bluefin akami, which is a lean, dark red tuna, than in bluefin toro, a fatty tuna, and yellowfin tuna akami, the researchers said. Mercury tends to accumulate in muscle rather than fat, so mercury content is usually -- but not always -- higher in leaner fish. Yellowfin tuna, for example, is lean, but may accumulate less mercury because it is smaller and harvested earlier than other species, they said.
The seafood industry took a critical view of the report.
"This is a study that tests mercury levels in fish, but stops short of any work exploring what -- if anything -- those levels mean for health," said Gavin Gibbons, director of media relations at the National Fisheries Institute, in an institute statement issued Wednesday.
He added that research has shown that "eating fish as a whole food -- omega-3s, selenium, lean protein, traces of mercury and all -- is a boost to heart and brain health."
In addition, Gibbons said, the U.S. Food and Drug Administration's mercury limit for seafood includes a 1,000 percent safety factor, "and approaching that limit or even slightly exceeding it does not equal health risk," he said.
To learn more about mercury in seafood, see the U.S. Environmental Protection Agency.
-- Margaret Steele
SOURCES: American Museum of Natural History, news release, April 21, 2010; statement, National Fisheries Institute, April 21, 2010
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