The world according to Consumer Reports (CR) magazine is generally a happy place full of “best buy” cars and top-rated toasters — until you turn the page and discover the food section. Where your dinner is concerned, the Consumers Union of the United States (CR‘s parent organization) becomes nearly as meddlesome and negative as the Center for Science in the Public Interest — and just as frequently wrong. Recent Consumers Union scares about mad cow disease, genetically modified food, and acrylamide in fried potatoes have proven baseless. The July CR feature, which needlessly warns Americans about trace amounts of mercury in canned tuna, will likely pan out the same way.

CR‘s fret-fest begins with the observation that about 6 percent of “light” canned tuna tests higher for mercury than the average albacore tuna. It advises pregnant women to avoid eating all canned tuna, and ends with a demand that the FDA require warnings “on canned-tuna labels and in stores and restaurants that sell or serve fish.” Getting from Point A to Points B and C, however, takes some twisted logic. CR assumes that albacore and other tuna are high-mercury fish. (They aren’t.) And it presumes that just one serving of fish — even a high mercury fish — can be a health risk. (It can’t.) This logic is tantamount to warning people that a single slice of cake will make them fat.

Dr. David Acheson, the chief medical officer of the FDA’s Center for Food Safety and Applied Nutrition, told USA Today this morning that “mercury is very much a chronic-exposure concern.” And underscoring the cluelessness of the Consumer Reports warnings, Acheson explained to WebMD Medical News: “We are not aware of any science that would indicate that having an occasional meal at that level would cause any harm, and if that science is out there, I would love to see it.”

Even the hypothetical mercury risk to unborn children (which is outweighed by the known cognitive benefits), Reuters heard from Tufts scientist Dr. Joshua Cohen, “depends not on exposure on any given day but on the average exposure over several weeks.” Cohen co-authored last year’s landmark study comparing the risks and health benefits of seafood consumption.

Despite the public’s habit of relying on Consumer Reports for unbiased analysis, Americans may collectively smell a rat after hearing from former U.S. Health and Human Services Secretary Dr. Louis Sullivan. In this morning’s Chicago Tribune, Dr. Sullivan hinted that the magazine’s advice could have negative consequences for public health. “I don’t know of any science that supports what they’re saying,” said Sullivan. “For all we know they could be relying on high school science students to come up with this.”