Just like the Meryl Streep commercial about alar horrified new moms away from apples in the late 1980s, fear-mongering messages about mercury in seafood contribute to the woefully low amount of seafood women eat today in the U.S. The distinction is that seafood- and omega-3-deficient diets introduce measurable risks to health. According to a Harvard study published in the Journal of the American Medical Association, "Avoidance of modest fish consumption due to confusion regarding risks and benefits could result in thousands of excess [coronary heart disease] deaths annually and suboptimal neurodevelopment in children."
While alar was a chemical sprayed by humans on fruit to regulate its growth, traces of mercury have existed in ocean fish since the beginning of time from sources like underwater volcanic activity. The mercury generated by coal-fired power plants is a real threat to freshwater fish caught by recreational fishermen in certain lakes and streams, and it is imperative for folks who regularly eat fish caught by friends and family to keep an eye on local U.S. Environmental Protection Agency advisories. But most fish Americans buy in stores and restaurants come from the open ocean or aquaculture, which are not subject to the same contamination issues as enclosed bodies of water. According to a peer-reviewed U.S. Food and Drug Administration report, "Limited data suggest that methylmercury concentrations in commercial fish have not increased or decreased over time."
The scientific community has exhaustively researched the overall effect of eating fish and shellfish, traces of mercury and all. They repeatedly conclude that eating commercial seafood boosts both heart and brain health, and when people don't eat fish they might miss out on these benefits. Specifically: