A San Francisco doctor who evaluated her well-to-do patients' fish-eating habits found most of them had ingested too much mercury.
Dr. Jane Hightower says her patients thought they were doing the right thing by eating pricey menu items like swordfish, sea bass, halibut and tuna steaks. But, those fish have more mercury in them than any others offered consumers.
She says 89 percent of patients with a fish-heavy diet had blood-mercury levels exceeding that deemed safe by the government.
Furthermore, the health benefits of fish come from the fatty varieties, such as salmon, trout and sardines. They have a lot less mercury in them.
Mercury pollution comes from mines, power plants and garbage incinerators. Too much mercury damages the nervous system, especially the brain.
Hightower's findings appear in the journal Environmental Health Perspectives.