A coalition of consumer groups isrecommending the U.S. Department of Agriculture get tuna out of schoollunchrooms after tests of canned tuna sold to schools found highlyvariable levels of mercury, in some cases higher than federalguidelines.

Tuna industry groups counteredthat canned tuna is safe and wholesome. The real public health issue isthat "we don't eat enough" seafood, says Gavin Gibbons of the NationalFisheries Institute, a seafood industry group in McLean, Va.

TheMercury Policy Project of Montpelier, Vt., is a non-profit working toreduce mercury in the environment. It tested 59 samples of tuna ininstitution-size cans and foil pouches from 11 states. The levels ofmethylmercury were in general close to previous tests done by the Foodand Drug Administration. However, levels of mercury varied widely, evenfrom the same can or pouch. The average methylmercury content rangedfrom 0.02 to 0.64 parts per million in light tuna and between 0.19 and1.27 parts per million in albacore tuna.

"Onany given day in a given school, children eating the same meal could getmercury doses that vary by tenfold," just because of the variability ofthe chunk of meat in the packet," says Edward Groth, author of thereport, released Wednesday. It was sponsored by several groups,including the Center for Science in the Public Interest and Physiciansfor Social Responsibility.

Current federaldietary guidelines urge Americans to eat seafood twice a week becauseseafood is a healthy protein and contains omega-3 fatty acids,important for metabolism, but most people eat it once a week or less,says Gibbons.

"To suggest we're eating toomuch is almost comical," he says. Scaring children away from tuna "at apoint in their life when they're developing their nutrition habits andtheir palates" is damaging.

DianePratt-Heavner of the School Nutrition Association in National Harbor,Md., says she doesn't believe tuna is a big issue because it's notpopular on school lunch menus. She only sees it as an item in deli-stylecounters, mostly in high schools, where it's one choice among many.

Grothagrees that tuna isn't a huge part of school lunches, but wants to makesure kids aren't getting too much. And parents need to be aware of howmuch tuna their children eat, he says. Kids who eat a tuna sandwich amonth aren't at risk but some children, "we don't know how many thereare," love tuna and eat a lot of it, he says. Even four times a monthcould have "subtle adverse effects" on some children. "We're trying toput those kids on the map," he says.

TheEnvironmental Protection Agency's maximum acceptable dose formethylmercury, a potent neurotoxin, is one-tenth of a microgram perkilogram of a person's body weight. Even tiny levels of methylmercuryhave been linked to learning disabilities and developmental delays inchildren, according to EPA scientists.

Toensure that the brains of fetuses and children aren't exposed to levelshigh enough to damage them, the EPA and FDA said in 2004 that women whoare pregnant or might be pregnant can eat up to two meals, or 12 ounces,of fish and shellfish a week. Children should eat "smaller portions,"the guidelines said.

Since the EPA adoptedthat standard, some studies indicate it may be too high. "Our researchsuggests that this limit should be decreased by 50%," says PhilippeGrandjean, a professor of environmental studies at Harvard Universitywho studies mercury in seafood. "If anything, [the Mercury Project]report underestimates the risks associated with regular tuna intake."

Bythe Mercury Project's measure, a 44-pound child who ate just two ouncesof albacore tuna at levels the project found in some tuna would begetting almost half, 47%, of the standard. Based on the emergingevidence, the report recommends that children not eat albacore tuna,which can have more mercury, and that young children eat canned lighttuna only once a month and older children only twice a month. They alsosuggest school lunch programs limit canned tuna servings to twice amonth and phase it out, moving toward lower-mercury seafoods such assalmon and shrimp.

Fish become contaminatedwhen mercury in industrial pollution enters waterways. Bacteriatransform the mercury into methylmercury, a more biologically active anddangerous form of the element, according to the Food and DrugAdministration. Fish eat the bacteria and the mercury accumulates inthe largest and oldest fish, which is why long-lived and large speciessuch as tuna have higher levels. Canned light tuna comes from skipjackspecies of tuna, which are smaller and often younger. They haven't beenaround long enough to accumulate as much methylmercury in their systems.Albacore is harvested older and therefore contains more.