Which Fish Contain the Highest Levels of Mercury? And the Lowest?

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We’ve all heard the dangers of eating fish contaminated with mercury. But just how do the ocean’s inhabitants become filled with the toxic contaminant? Mother Nature Network explains:

Mercury is released into the air just like CO2 when fossil fuels are burned, and coal-fired power plants are the main source. Rather than drifting up into the atmosphere, though, the heavy metal accumulates in clouds and falls to the earth with rain. Most of it drains into streams, rivers, lakes and oceans, where microorganisms absorb it and convert it to an even more toxic form called methylmercury.

Smaller fish eat up the microbes and the methylmercury and then bigger fish come along and eat up the smaller fish. Meanwhile the level of mercury accumulates and that’s why smaller fish like anchovies and tilapia have the lowest mercury levels while predator fish like shark and swordfish have the highest.

Do the risks of eating fish outweigh the benefits?

Not exactly.

Per the EPA: Fish and shellfish are an important part of a healthy diet. Fish and shellfish contain high-quality protein and other essential nutrients, are low in saturated fat, and contain omega-3 fatty acids. A well-balanced diet that includes a variety of fish and shellfish can contribute to heart health and children’s proper growth and development. So, women and young children in particular should include fish or shellfish in their diets due to the many nutritional benefits.

On the otherhand, Mercury poisoning can cause severe brain, kidney and lung damage to children and adults, but it’s even more dangerous to fetuses. It prevents nerve cells in the brain from forming correctly, which can damage attention span, fine motor function, language skills, visual-spatial abilities and verbal memory. That’s why the FDA and the EPA suggested in a joint 2004 report that women who are pregnant or plan to become pregnant avoid fish with the highest levels of mercury.

In order to safely consume seafood, follow these simple steps.

1) Avoid big fish that are known to contain a lot of mercury: king mackerel, swordfish, shark and tilefish from the Gulf of Mexico or South Atlantic.
2) Eat up to 12 ounces (about two average meals) a week of various fish and shellfish that are low in mercury, such as shrimp, canned light tuna, salmon, pollock and catfish.
3) Check local advisories about the safety of fish caught in lakes, rivers and coastal areas. If no information is available, eat up to 6 ounces (about one meal) per week of locally caught fish, but don’t eat any other fish that week.


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