Experts on seafood and health, including Harvard scientists and U.S. Food and Drug Administration scientists, have said over and over again that the health benefits of eating fish far outweigh any hypothetical risks. That goes for pregnant women too. But fear-mongering environmentalists who have mastered the art of manipulating food-safety concerns as a way to promote their own agendas and raise money have drowned the experts’ messages out.

In less than a decade, we’ve witnessed the triumph of hype over science in the debate over mercury and seafood. Yet no one seems to be worried about the consequences.

Researchers at my Center for Consumer Freedom have been following the mercury debate very closely over the years. This month, we published a new report offering the first real assessment of the effect that this seafood scare has had on public health. Get ready for a major reality check.

Because of overblown warnings about trace levels of mercury in fish, more than a quarter of a million under-privileged U.S. children were born at risk of having abnormally low IQs in recent years. Our report, “Tuna Melt-down,” contains a detailed breakdown of the stats, but here’s the abbreviated version.

According to data from ACNielsen, 4.4 million U.S. households earning $30,000 or less completely stopped buying canned tuna between 2000 and 2006, the peak years of the activist-driven mercury scare. In those poorest U.S. households, canned tuna was the only affordable source of omega-3 fatty acids, the star of all the recent good news about childhood development, heart health and brain function.

A landmark 2007 study of thousands of children, published in England’s most prestigious medical journal, found that when pregnant women don’t get enough omega-3s, their babies are 29 percent more likely to have abnormally low IQs. In that study, the best-performing kids were born to mothers who ate far more fish than our federal government recommends. Flawed government seafood consumption guidelines and exaggerated activist warnings are hurting children. It’s that simple.

Where’s the outrage?

If our researchers had concluded that pesticides on produce were harming children—do you remember Alar on apples?—this would be a national story. Some of the poorest children in the nation are now worse off because of activist deception and incompetence, but you’d never know it by turning on the nightly news.

The seafood and health issue has become so dominated by activist groups that the only fish topic reporters want to cover is mercury levels in sushi. Never mind what those mercury levels actually mean. If you’d like to know, by the way, ask the Japanese. They eat eight times as much fish as Americans. Of course, their blood-mercury levels are higher than ours. But it doesn’t seem to harm them one bit, unless you believe their kids are cheating to get those stratospheric math and science test scores.

Our own government recognizes this, but it doesn’t seem to have the courage to say it with any gusto. The Environmental Protection Agency’s own data show that a 130-pound woman would have to eat about a pound of swordfish, two pounds of Chilean sea bass, or almost three pounds of fresh or frozen yellowfin tuna—every week, for an entire lifetime—to introduce hypothetical health risks from mercury. Underline “hypothetical.”

Here’s another reality check: There has never been a single case of mercury poisoning from eating commercially available ocean fish in the United States in the published medical literature. Not one.

The mercury “epidemic” that activist groups keep warning us about may be the only one in history without a body count. That includes unborn children. Dr. Ashley Roman of the New York University Medical Center told Reuters last year: “There has been no case of fetal mercury toxicity due to fish consumption reported in the United States.”

There always have been traces of mercury in fish. Princeton University researchers tell us that mercury “pollution” in ocean fish—and most restaurant and retail seafood is ocean fish—comes mostly from volcanoes and mercury-bearing rocks.

As our latest research shows, the only harm associated with trace mercury levels in fish is generated by the green groups driving the fish panic.

It’s quite real, and it’s time we started talking about it.

Richard Berman is president of Berman & Co., a Washington, D.C.-based lobbying firm specializing in research, communications and advertising.