Ever wonder why pregnant women are advised by doctors to cut down on eating albacore (white) tuna?

Tuna, like other large predator fish, is contaminated with mercury.  Mercury is a potent neurotoxin. Over 400,000 newborns are affected by mercury pollution every year. But how did the mercury get into the tuna–and other fish–in the first place?

The following slides show how mercury contaminates our food–and how mercury can damage the vulnerable developing brain of the fetus.

Coal-fired power plants are the single largest source of toxic mercury; they emit 72% of all toxic mercury air pollution in the United States.

When a coal smokestack is not filtered, mercury and other poisons–arsenic, lead, nickel, chromium and acid gases–are released into the air as coal is burned.

That mercury drifts through the air–across the globe–and rains down into reservoirs, rivers, lakes and the ocean. Every state in the country has issued a fish advisory of some type because of unsafe mercury contamination.

Microorganisms in the water convert the mercury to a highly toxic form, called methylmercury. That bacteria makes the mercury “bio available”–able to be taken up by fish that consume it.

Methylmercury is absorbed by fish through their gills. It is dispersed by their blood through their bodies. It accumulates in fatty tissue.

Contaminated fish is eaten by other fish, birds and mammals–including humans.

Typically, the longer a fish lives, and the larger it is, the more mercury accumulates in its flesh. King mackeral, tilefish, grouper, halibut, tuna, swordfish, shark, ray, barramundi, gemfish, orange roughy contain high levels of mercury.

Once we eat contaminated fish, methylmercury goes directly into the organs that have the most lipids, or fats, where it accumulates.

  • Breasts: Mercury is found in breast milk.
  • Brains: Methylmercury is able to breach the blood-brain barrier–a nearly impenetrable membrane of high-density cells that safeguards our brains.
  • Umbilical cord: Methylmercury crosses the placental barrier to reach the fetus; a baby’s brain has the highest concentrations of lipids of any in its body.

Fetuses and young children–whose brain structures are still developing–are especially vulnerable to methylmercury poisoning. Mercury causes brain neuron degeneration, impairing the growth of the brain in ways that interfere with learning and thinking.

Help Us Tell Polluters to Clean Up their Coal Plants

Mercury poisoning from coal plants can be prevented by installing cost-effective scrubbers to reduce mercury emissions. Many responsible American coal plant operators have already taken this step.

But coal plants in the United States still spew 386,000 tons of hazardous air pollution into the atmosphere.

New EPA regulations to restrict mercury emissions are being considered–and should be supported.

Join Moms Clean Air Force by signing up in the sidebar to let Washington know that mercury poisoning is unacceptable. No child should be born already damaged by mercury poisoning from coal.

For more science on how mercury ions actually alter the cell membrane structure of developing neurons, please go to


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