Sept. 19, 2012 -- A coalition of consumer groups says kids should eat much less canned tuna to avoid mercury poisoning.

In a new report issued today, the Mercury Policy Project says children should never eat albacore tuna. It advises parents to limit light tuna to one serving per month for kids under 55 pounds, and to two monthly servings for bigger children.

"Today we unfortunately have to bring consumers a warning about tuna. Despite its popularity, it should be a rare meal for children," Sarah Klein of the Center for Science in the Public Interest, one of the consumer groups in the coalition, said at a news teleconference.

The report includes tests of 59 samples of tuna from 11 states. The researchers purchased the tuna in the large 4-pound cans or foil packages from schools or from companies that supply schools.

The tests showed that mercury concentrations varied widely from can to can. Even separate samples from the same can carried very different amounts of mercury. The study found somewhat lower mercury levels in light tuna than in FDA tests, but higher levels in albacore tuna than the FDA reports.

Despite the study's recommendations, the FDA stands by its own conclusions.

"FDA and EPA recommend that women of childbearing age and children consume no more than 12 ounces a week of canned light tuna and only 6 ounces per week of canned albacore tuna, which is higher in mercury. The average can of tuna holds 6 ounces of fish," the FDA says in a statement.