News Coverage
FDA cautions pregnant women on tuna
Published July 28, 2002
FORT LAUDERDALE, Fla. -- Pregnant women should limit their consumption of tuna, the nation's most popular seafood, a Food and Drug Administration advisory panel recommended last week, because the fish is among a group that can contain mercury, found to be harmful to the brains of developing fetuses.
But the recommendation stopped short of adding tuna to a list the FDA issued in January 2001 warning pregnant women not to eat swordfish, king mackerel, shark or tilefish.
The advisory panel did ask the agency to determine how much the consumption of canned tuna contributes to methylmercury levels in women. It also suggested the FDA set dietary recommendations for children's consumption of canned tuna and more closely monitor mercury levels in both fish and in people.
The panel also recommended that the FDA clarify for consumers which fish they can safely eat.
The FDA has balked at putting tuna on its don't-eat list for pregnant women even though some scientists, environmental groups and several states already have listed tuna steak as a significant source of mercury.
"Nobody wants to tell people to stop eating tuna fish," said the panel chairman, Sanford Miller of Virginia Tech University. "We're trying to balance the very positive virtues of fish, including tuna fish, with the harms. It's a very hard balance to make."
Industry representatives testified that few pregnant women eat enough fish to absorb enough mercury to affect their babies.
Several states, including Vermont, Minnesota, Michigan and New Jersey, have issued advisories warning pregnant or nursing mothers against consuming more than seven ounces of canned tuna a week, provided that it is the only mercury-containing fish eaten during the period.
The FDA deems fish safe if they contain less than 1 part per million of methylmercury. The four types on the list to avoid exceed that level.
The average commercial fish contains far less -- 0.12 part per million. Canned tuna on average contains only slightly more than that, but amounts can vary to as much as 0.75 part per million.
Joe Sekerke, a toxicologist with the Florida Department of Health, said it is usually the larger, older predator fish that accumulate enough mercury in their tissues to pose a health risk.
"Mercury is a neurotoxin. The developing fetus is at the greatest risk because the protective barrier around the brain is not fixed," Sekerke said.
The heavy metal gets into the food chain from industrial pollution and accumulates in the soil. In a stream or lake, bacteria eat it and turn it into methylmercury, which then moves up the food chain from little fish to bigger fish, Sekerke said.
"Go up eight to 10 levels in the food chain, and it can get into the top predator. In marine waters it's usually sharks; in fresh water, it's usually bass, bowfin and gar," Sekerke said.
Perhaps the worst cases of mercury poisoning occurred in Japan in the 1950s when industrial pollution sent high levels into Minamata Bay, alerting the world to the dangers, he said.
"People who lived around it fished and ate the fish, and those children did have some very severe neurological deficits, including total loss of cognitive power," Sekerke said.
Michael Bender, executive director of the Mercury Policy Project, an environmental group based in Vermont, said fears by the fishing industry that women won't understand the warnings and will stop eating fish altogether are unfounded.