For several years now, women of childbearing age have been told by the U.S. government to avoid eating large species of fish, such as shark, swordfish, king mackerel and tilefish. That's because these big, ocean-dwelling fish live a long time and are prone to absorbing high levels of mercury from polluted waters.
When consumed by a woman who is nursing or pregnant, the mercury in these fish can be passed along to the child and cause nervous-system damage. Mercury can also affect women who are about to become pregnant.
Tuna -- one of the most frequently served seafood dishes in the United States -- has carried a lower warning. The FDA tells women that tuna is safe to eat about two or three times a week.
Now an environmental advocacy group is saying that tuna in sushi isn't all that safe. As the Los Angeles Times reported today, the group GotMercury.org tested 12 samples of tuna sushi from several high-end California restaurants, including the chain restaurant Benihana, for mercury levels.
The group said that all of the samples came back above the recommended FDA standard.
"Our testing shows a pattern of mercury levels being significantly higher than what the FDA reports," Eli Saddler, a public health analyst and attorney for GotMercury.org, told the Times.
Saddler said that tuna used in sushi tended to come from larger fish.
However, such a small sample size -- just 12 samples in all -- makes it difficult to know the true scope of the problem. The organization is pushing for the FDA to do more large-scale testing of fish.