The Mercury Policy Project has issued the first ever report on testing for mercury in tuna sold to the nation’s schools. The report, titled “Tuna Surprise: Mercury in School Lunches”, states that canned tuna is the largest source of methyl mercury in the U.S. diet and is a major source of mercury exposure for children.” U.S. children eat twice as much tuna as they do of any fish or seafood.
This high consumption rate, coupled with children’s low body weights, can results in doses of mercury that exceed federal safety standards. No previous research has documented mercury levels in tuna served in schools.
The Project bought 59 samples of canned tuna in 11 states around the country and tested them for mercury. The average mercury level in light tuna was 0.118 micrograms/gram, which was slightly lower than the FDA’s reported average of 0.128 micrograms/gram. The samples of albacore tuna averaged 0.560 micrograms/gram, much higher than the FDA’s reported average of 0.350 micrograms/gram. Most of the samples, 50 out of the 59, contained tuna imported from other countries.
Scientists then modeled an exposure chart to assess the risks from consumption of this tuna. The amount of mercury consumed in various amounts of tuna eaten were compared. If children eat tuna once a day, no matter how small the amount, their risk level is the highest, more than four times the Reference Dose with no upper limit.
Based on that model, they have issued the following recommendations: Children should not eat albacore tuna. That species contains triple the mercury content found in light tuna. Smaller children, who weigh less than 55 pounds, should eat light tuna no more than once a month. Schools and parents should limit most children’s light tuna consumption to twice a month. Children should never be allowed to eat tuna every day. Schools and parents should teach children to enjoy other types of seafood such as shrimp, salmon, and fish fillets. And parents whose children eat tuna once a week or more should have the child’s blood tested for mercury.
The report also recommends that the USDA should phase out subsidies for tuna in the school lunch program. They state that “there is no sound reason why taxpayer dollars should be used to subsidize any part of this risk. Over time, canned tuna can be replaced with low-mercury seafood (e.g. salmon, shrimp) and other protein sources.”
The Mercury Policy Project has advice for the EPA and FDA too. Those bodies should complete their ongoing effort to revise the joint advisory on seafood consumption and mercury exposure, and must address the issue of short-term exposure “spikes”. Schools should try to avoid buying tuna from Ecuador and other Latin American studies, since products from that area has above-average mercury levels. Finally, the FDA should try to figure out why its reported mercury levels in albacore tuna are so much lower than the levels in other studies.