Making Sense Out of Mercury in Fish The mercury content of fresh, sushi-grade tuna may be higher than previously thought. A recent sampling of tuna from stores and restaurants in 23 cities turned up twice the levels of mercury as in previous FDA estimates.

Making Sense Out of Mercury in Fish

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In Your Health today, tuna and concerns over mercury contamination.

NPR's Allison Aubrey reports on the results of some new independent tests on samples of fish bought at grocery stores and restaurants, and what they mean for sushi lovers.

ALLISON AUBREY: Market analysis shows health-conscious young professionals are big on sushi. And as palates evolve, raw fish seems to be making its way into the mainstream, with about one-third of consumers now describing sushi as appealing.

Dr.. KIMBERLY WARNER (Marine Scientist): Here's a lot of packaged fresh sushi in a grocery store.

AUBREY: Marine scientist Kimberly Warner stands at the Grab and Go counter at a busy Washington, D.C. market.

Dr. WARNER: I see a lot of salmon, eel. Here's a spicy tuna roll.

AUBREY: There's a lot of tuna, from the Tokyo roll to the rainbow roll. And Warner's marine conservation group, called Oceana, recently tested samples for mercury contamination. They purchased tuna and sushi from groceries and restaurants in 23 cities around the country. Then they shipped it off to an independent certified lab in Michigan.

Dr. WARNER: We found very high levels of mercury in nearly half the samples. So...

AUBREY: And what does that mean? How high is high?

Dr. WARNER: Well, most of those approached the FDA action level and were above the level that we find in fish that the FDA warns the sensitive groups to avoid.

AUBREY: Sensitive groups mean women who are pregnant, thinking of becoming pregnant, as well as nursing mothers and young children. They're advised by the FDA to avoid four types of fish known to have higher levels of mercury, including swordfish, shark, tilefish and king mackerel. The reason is that mercury at high enough levels can harm a developing fetus and cause problems with brain development.

Tuna is not included on this do-not-eat list. The FDA's toxicologist, Mike Bolger, says they've tested many types of tuna, including the popular sushi and steak-grade yellowfin tuna.

Dr. MIKE BOLGER (Food and Drug Administration): We've heard people say that these tend to have higher levels, and every time we've looked at it we have not been able to confirm that to be the case.

AUBREY: In 2006, the FDA tested only 87 samples of yellowfin. Oceana and other independent testers have sampled even fewer. Since there's a lot of variation from species to species, and even fish to fish, these tests may not be representative of the supply at large.

The FDA's Mike Bolger says he has not reviewed the Oceana study, but he says if there is a pattern of high mercury concentration, he'll look at it.

Dr. BOLGER: Probably as a minimal effort a step would be to go out and get more samples of yellowfin to see where we are in terms of that particular fish and what's in the marketplace right now.

AUBREY: Bolger says the FDA has not evaluated bluefin tuna. Bluefin is the prized, expensive species mostly served in high-end sushi restaurants. Independent tests suggest high mercury levels.

Dr. BOLGER: We have not looked at bluefin because it's such a minor species.

AUBREY: It's minor by percentage of seafood sales, totaling less than 1 percent. But the National Marine Fisheries Database shows about $19 million worth of bluefin was imported to the U.S. in the last two years. So it's clear that some Americans are eating bluefin.

Gavin Gibbons represents the National Fisheries Institute. He says the mercury in bluefin or any other fish should not be of concern to most consumers. He reminds it's women of child-bearing age and their young children who are the target of the advisories, and even for them only a handful of fish are to be avoided.

Mr. GAVIN GIBBONS (National Fisheries Institute): The general public should be encouraged to continue eating a variety of fish and knowing that it is a very safe part of a healthy American diet.

AUBREY: It's a message echoed by nutritionists and researchers who've shown that the omega-3 fatty acids found in fish are very beneficial. The strategy for women of child-bearing age, experts say, is to make informed choices. That's why groups such as Oceana say the FDA needs to increase the frequency of its testing for commonly consumed fish.

Allison Aubrey, NPR News, Washington.

MONTAGNE: You can get the government's full recommendations on what fish are safe to eat. Bluefish could be a problem, looking here at the list. Haddock is fine. So are anchovies. You can get it all at our Web site,

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