SR XLVII: "CLEAR!"

Mercury levels

Mercury content in tuna can vary widely. For instance, testing by Rutgers University reportedly found that a can of StarKist had 10 times more mercury than another can of similarly-identified tuna. This has prompted a Rutgers University scientist whose staff conducted the mercury analysis to say, "That's one of the reasons pregnant women have to be really careful ... If you happen to get a couple or three cans in the high range at a critical period when you are pregnant, it would not be good." Among those calling for improved warnings about mercury in tuna is the American Medical Association, which adopted a policy that physicians should help make their patients more aware of the potential risks.^[70]

A study published in 2008 found that mercury distribution in the meat of farmed tuna is inversely related to the lipid content, suggesting that higher lipid concentration within edible tissues of tuna raised in captivity might, other factors remaining equal, have a diluting effect on mercury content.^[71] These findings suggest that choosing to consume a type of tuna that has a relatively higher natural fat content might help reduce the amount of mercury intake, compared to consuming tuna with a low fat content.

The industry-sponsored group Center for Consumer Freedom, which doesn't release the names of its contributors, claims the health risks of methylmercury in tuna might be dampened by the selenium found in tuna,^[72] although the mechanism and effect of this still is largely unknown.^[73]

Due to their high position in the food chain and the subsequent accumulation of heavy metals from their diet, mercury levels can be high in larger species such as bluefin and albacore.^{[citation needed]}

In 2009 a California appeals court upheld a ruling that canned tuna does not need warning labels as the methylmercury is naturally occurring.^[74]

In March 2004, the United States FDA issued guidelines recommending that pregnant women, nursing mothers, and children limit their intake of tuna and other predatory fish.^[75] The Environmental Protection Agency provides guidelines on how much canned tuna it is safe to eat. Roughly speaking, the guidelines recommend one 6 oz. can of light tuna a week for those weighing less than 110 pounds and two cans a week for the rest of us.^[76]

In 2007 it was reported that some canned light tuna such as yellowfin tuna^[77] is significantly higher in mercury than skipjack, and caused Consumers Union and other activist groups to advise pregnant women to refrain from consuming canned tuna.^[78]

The Eastern little tuna (Euthynnus affinis) has been available for decades as a low-mercury, less expensive canned tuna. However, of the five major species of canned tuna imported by the United States it is the least commercially attractive, primarily due to its dark color and more pronounced 'fishy' flavor. Its use has traditionally been restricted to institutional (non-retail) commerce.

A January 2008 investigation conducted by the New York Times found potentially dangerous levels of mercury in certain varieties of sushi tuna, reporting levels "so high that the Food and Drug Administration could take legal action to remove the fish from the market."^[79]

A book by Jane Hightower, Diagnosis Mercury: Money, Politics and Poison, published in 2008, discusses human exposure to mercury through eating large predatory fish such as large tuna.^[80][81][82]