Since cavemen first learned to sharpen sticks, fish has been an important part of human nutrition. Eating fish is a healthy habit — our mothers called it “brain food,” after all — but recently the benefits have been overshadowed by fears about hypothetical risks from trace amounts of mercury.

Fish bring well-documented health benefits to adults and children, both born and unborn. Omega-3 fatty acids in fish can help prevent heart disease, arthritis, dementia and other conditions.

According to former Health and Human Services Secretary Dr. Louis Sullivan, there’s a connection between overblown mercury warnings and women who avoid fish, decreasing their Omega-3 intake. And these women deliver most of the premature, low-birth-weight babies in the United States. The March of Dimes reports that low birth weight is a factor in 65 percent of infant deaths.

Even though we know fish is good for us, it’s easy to take the bait about mercury. In extraordinarily high amounts, mercury can be toxic. But the levels in the fish we eat are practically inconsequential to human health. As toxicologists like to say, it’s the dose that makes the poison.

One crucial, but overlooked, feature of the mercury-in-fish debate is the safety factor built into health advisories from the federal government. Mercury “limits” promoted by both the EPA and FDA include ten fold safety factors.

What does this 1,000-percent cushion mean? Very few samples of swordfish or tuna test above the FDA’s “Action Level” for mercury (1 part-per-million), but there’s no cause for concern unless they are literally 10 times over this recommended level.

After 15 years of testing, the FDA has yet to find a single fish that registers high enough to warrant concern. The same can be said of the Maryland Public Interest Research Group’s recent study of fish caught in local waterways. The most “dangerous” catch in the report still affords fishermen a 481-percent safety margin.

MaryPIRG muddied the waters by ignoring the FDA standard entirely and using the Environmental Protection Agency’s advisory level instead (which is meant to measure the cleanliness of water, not fish).

Environmental advocates in general have kept the public in the dark about the safety cushions included in all these advisory levels. Food scares, after all, make for good fundraising and sensational newspaper headlines. So we don’t hear that mercury advisory levels are set at just 10 percent of what might be harmful.

We also don’t hear much about the growing body of research suggesting that our societal fear of mercury doesn’t stand up well under scientific scrutiny.

During February’s annual meeting of the American Association for the Advancement of Science, researchers from the University of Rochester presented new findings from the Seychelles Islands in the Indian Ocean. Residents of the Seychelles eat 10 times as much fish as Americans, and their mercury levels are comparatively higher. But there’s no evidence that it affects their health one bit.

The children of Seychelles women who maintained high-fish diets during their pregnancies are also perfectly healthy. In fact, 15-year-olds whose mothers had the highest pre-natal mercury levels outscored their peers on developmental tests.

“From all the reports we had seen about mercury and its impact on development,” one University of Rochester pediatrician told the AAAS conference, “we thought we would be able to show how bad it was for children. But we didn’t find it at all.”

Evidence from this study and others points to an inescapable conclusion: Even if Americans ate as much fish as Seychelles Islanders, mercury isn’t likely to be a serious human health problem. If anything, we should be eating more fish — not less — of all varieties.

Science has given us iron clad evidence of major health benefits from eating fish, but no real justification for our collective hand-wringing over mercury that we ingest in vanishingly small doses. If more of us continue to overreact and steer clear of fish, this wave of anxiety will produce public health problems for the next generation of Americans.

Fish is still good for you. But swallowing mercury hype may indeed be hazardous to your health.

David Martosko is Director of Research at the Center for Consumer Freedom, a Washington, D.C., nonprofit organization whose www.fishscam.com Web site explores the politics of seafood fears.