Boston TV: High Mercury Levels Found In Some Tuna Sushiff

The popularity of sushi is booming, and right along with it comes a concern about the health effects of some of the fish used to make the delicacy, especially tuna.

Some people are concerned about mercury levels in many types of tuna. WBZ-TV decided to investigate by buying tuna sushi from 15 Boston area restaurants and markets. We found levels of mercury that many people would find troubling.

Lapuck Labs in Canton prepared the tuna samples for testing. Dr. Khalil Zadeh heads the lab, and interpreted the results. “It’s a definite cause for concern,” says Dr. Zadeh. “It’s much better to avoid tuna with high mercury,” he adds.

The most troubling results - three of the samples tested above the Food and Drug Administration’s “action level” which means they contain enough mercury that the agency could take legal action to remove the fish from the market. A fourth sample tested just below the action level.

There was enough mercury in several other samples, that eating five or six pieces each week, year after year, would put many people above a level the Environmental Protection Agency says is acceptable.

What is the medical concern about mercury in fish? According to Dr. Kent Lewandrowski, a pathologist at Massachusetts General Hospital who has studied mercury in fish, “It’s linked to toxicity to the nervous system as well as to a number of other organs, kidneys, the liver.”

Dr. Lewandrowski says small children and women who are pregnant or who are going to become pregnant should be particularly cautious. “For children or fetuses, the neurotoxicity is very important because it could ultimately effect the child’s mental development,” according to Dr. Lewandrowski.

While he says the concern is a lot less as we age, Dr. Lewandrowski says that people who eat a lot of fish to benefit their hearts should also be aware. “There have been some studies reported that the mercury contamination of fish virtually eliminates the cardiac protective effect of the fish,” he explains.

Ironically, some tests have show that tuna sushi at high end restaurants can contain the most mercury because those restaurants tend to buy larger, more expensive tuna. Larger fish are older, giving them more time to absorb mercury from the ocean. Despite the concern, some people say we shouldn’t cut back on fish consumption. “These mercury scare stories which have popped up in New York, Houston and now here, are almost irresponsible to the extent that they scare consumers away from seafood,” says Rich Ruais from the East Coast Tuna Association. “Seafood is almost a miracle food,” he adds.

Ruais says government standards are outdated and don’t take into account a trace mineral called selenium which, he says, almost all ocean fish have in abundance. “The evidence is pretty conclusive that selenium provides a protective effect against mercury toxicity,” says Ruais. “Selenium provides a neutralizing or buffering effect, if you will. The mercury binds to the selenium and the selenium passes through the body,” he adds.

Mass. General’s Dr. Lewandrowski admits there is some evidence suggesting that may be the case, but says it’s too early to be definitive. “I think the results of those studies are very preliminary,” says Lewandrowski.

Does this mean sushi lovers should eliminate tuna from their diets? “Just go ahead and continue to love sushi, but please make sure that you eat a variety of sushi. Don’t just stick to tuna,” says Dr. Khalil Zadeh. That way you will be eating other seafood that tends to have lower levels of mercury.

WBZ-TV is not naming the restaurants and markets where we bought our samples because the testing results can change day to day depending on the tuna they happen to have at that moment. However, tests like ours have been done in other areas with similar results.

As you can tell, there is a big debate over mercury in seafood with the industry saying that eating fish is an important part of a healthy diet, and that any risks are outweighed by the benefits. Industry representatives also point out that an individual would have to eat a lot of fish with high mercury levels over a lifetime to face a substantial health risk.