Agency Should Act to Address the Higher Levels of Mercury Found in Light Canned Tuna Imports

Statement by Michael Bender
Executive Director
Mercury Policy Project

The most critical current deficiency of the FDA's advisory is its continuing laissez-faire attitude about tuna consumption--especially among pregnant women and children. Tuna fish is the largest source of mercury exposure in the American diet, and this latest round of testing confirms that a significant percentage of light canned tuna contains significantly more mercury than most other popular seafood choices. Based on this, FDA simply can no longer avoid its responsibility to issue clear advice telling pregnant women to limit their own and their children's exposure to this pre-eminent source of mercury in the diet, no matter how intense the pressure from the tuna industry may be to avoid airing this inconvenient truth.

(1) FDA's dietary advice allows, and even encourages consumers to eat varieties and amounts of seafood that would result in exposure to mercury above the EPA's reference dose (RfD.) Conceding that this was true, FDA's David Acheson said at a December 2004 FDA Food Advisory Committee meeting that while FDA endorses the EPA RfD, he sees it as a "useful guideline," not as an essential exposure limit. Acheson and other FDA scientists have expressed a lack of concern that many consumers will exceed the RfD. We believe, considering the high mercury levels recently found in canned light tuna imports, that much more serious concern about exposure above the RfD is warranted, and that FDA's advice should be tailored to guide consumers to keep their mercury intake within the RfD.

(2) The FDA advisory does not effectively protect sensitive populations from mercury in tuna. FDA's advice for limiting canned tuna is not protective enough for pregnant women and young children. Based upon FDA's own 2003 test results from 300 cans of tuna with an average 0.358 parts per million mercury, a single weekly serving of albacore--or light tuna with comparable levels--would provide a dose well in excess of the RfD for many consumers. The EPA RfD, which has been endorsed by the National Research Council as science-based and appropriately protective, is 0.1 µg Hg/kg-bw/day, or 0.7 µg Hg/kg-bw/week.

(3) The advisory does not adequately consider the specific need to manage children's dietary mercury exposure from fish. While FDA advice mentions children, it is still aimed primarily at women of childbearing age. The reference to children's diets is vague--it suggests applying the same guidelines offered for adult women to children, except that the "serving size should be smaller." A clear need exists for separate, specific advice defining safe fish intake for children of various ages, whose smaller bodies mean they can safely eat fewer or smaller portions of mercury-containing seafood. Given the latest evidence from the Faroe Islands that fish consumption during childhood appears to pose an additional risk of mercury toxicity, FDA should explicitly address this need with specific fish consumption guidance based on a child's age and weight.

(4) FDA's advice does not take into account the risks that federally subsidized light canned tuna offerings place on low income families. According to the US Department of Agriculture, canned tuna is the most heavily consumed fish that pregnant women and children eat--hence it is likely to be their largest exposure source of mercury. Therefore, we strongly recommend that alternative animal protein substitutes be provided instead and canned tuna be eliminated from the federally subsidized school lunch program and the federal women, infant and children food package. The tax payer should not be subsidizing the fishing industry at the expense of poisoning America's most poor and vulnerable.

In addition to the critical task of updating its dietary advisory, we also urge FDA to keep collecting data on mercury levels in widely consumed varieties of fish and seafood, and if particular the light canned tuna and to also require the industry to label on the can the species of tuna it contains. The current database is inadequate for assessing the distribution of mercury exposure from many species of interest. To accurately determine how many women and children are exposed to unsafe amounts of mercury in the fish they eat, data are needed on both amounts of various fish species consumed and the range of values for mercury in those fish. We strongly recommend that FDA restart its seafood mercury monitoring program for mercury.

Further, FDA's test data on mercury in canned tuna are based on composite samples. While compositing samples allows a survey to cover more of the food supply and gives a good indicator of average mercury levels to which consumers of different seafood are exposed, compositing also levels out peaks and valleys in the data. Because even short-term peaks in exposure to mercury could have adverse effects on the developing brain (if they occurred at a critical point in brain development), it is important that data also be gathered that reveal the full range of mercury values that consumers may occasionally encounter. Therefore, we urge that FDA's future testing, especially for frequently-consumed items like tuna, look at both values in individual cans and than composite samples.

In conclusion, recent scientific evidence and this latest round of testing of light canned tuna imports has made it even clearer than ever that FDA needs to act assertively to help consumers minimize their mercury exposure from seafood in their diets. Therefore, FDA should thoroughly re-work the dietary advisory until the needs borne out by recent scientific evidence have been effectively addressed. FDA's dietary advice should be crafted in a way that helps the consumer--and especially those vulnerable populations-- enjoy the benefits of a diet rich in fish and seafood, while avoiding excessive exposure to mercury.