Under strong pressure from Big Canned Tuna, the Food and Drug Administration is crazily lax in regulating mercury in tuna. Among many examples: In 2000, a draft advisory to pregnant women listed canned tuna as a product highly contaminated with mercury; after FDA officials met with the three largest tuna companies, the final advisory left tuna off the list. When the FDA’s fish mercury guidelines were revised in 2003, canned light tuna was put in the low-mercury group — mainly, according to an FDA official, “in order to keep the market share at a reasonable level.” The FDA doesn’t require warnings in stores or on tuna cans, issuing advisories mainly through doctor’s-office brochures. However, a recent appeals-court decision could open the door to allowing states to mandate warning labels on tuna — a prospect opposed by both the tuna industry and, sadly, the agency tasked with regulating Americans’ food and drugs.