Study says canned tuna may pose health risks

February 4, 2010 by Danielle Decuir 

Researchers suggest that FDA monitor brands of tuna

Most canned tuna exceed safe consumption levels of mercury set by the FDA, according to UNLV researchers.

The current mercury levels found may be a health hazard for women of child-bearing age, pregnant women and children.

The study was started by UNLV undergraduate student Adam Martinson and funded by an undergraduate research award.

“The FDA unfortunately has a lot of things to do so they can’t scan every can of tuna,” said Joanna Kramer, former UNLV masters of public health graduate student and researcher.

Because mercury is a neurotoxin, Kramer said, it can have many long-term effects on the body, like neurological problems in pregnant women and children, who are especially vulnerable to mercury poisoning.

“Because children’s nervous systems are still developing, it can have a profound effect on them,” Kramer said. “Also, pregnant women are at higher risk of harm because it can affect the neuro-system of the fetus and cause things like cerebral-palsy, autism and mental retardation.”

Mercury doesn’t affect adult males as much because they do not have to bear children, said Kramer.

The environment dictates mercury concentration in tuna and fish because it is a naturally occurring element, but humans increase the amount of mercury in various ways.

“Mercury is present in all water. It is a natural presence,” Kramer said. “But man-made causes can alter it. Like for example, coal plants and other types of mills deposit large amounts of mercury into the environment. This can lead to higher mercury concentration levels.”

Shawn Gerstenberger, executive associate dean of the school of community health sciences and researcher on the study, also talked about how the environment can affect mercury concentration levels in fish.

“Most all mercury changes form when it gets into the water,” Gerstenberger said. “The methyl form is most toxic.”

Gerstenberger said the FDA and EPA make matters more difficult by not establishing a uniform limit for mercury.

“There are different limits on fish that are sport caught which are set by the EPA,” Gerstenberger said. “And there are limits on commercially caught fish set by the FDA. It is a confusing standard and the limits can even vary depending on what state you live in.

Gerstenberger does not believe canned tuna needs to be taken off the market, but rather that more information should be given to consumers so they can make more informed choices on what they eat and feed to their children.

For example, consumers would benefit from knowing that white tuna may be riskier to eat than other types.

“White tuna accumulates more mercury because it is higher in the food chain,” Kramer said. “But light tuna is lower in the food chain and accumulates less mercury than the albacore and the white tuna.”

Kramer and Gerstenberger recommend that the FDA monitor different brands of tuna, and for them to put the mercury level on the label of the can so that consumers are informed on the product they purchase.

“There needs to be a standard mercury consumption limit on all fish no matter who catches it,” Gerstenberger said. “Then it would be less confusing and consumers would have a better idea of what is safe and what is not.”

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