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What are the dangers of mercury exposure?

How Can I Avoid Mercury Exposure?

Mercury poisoning doesn't happen every day. As far as environmental dangers go, it's a fairly rare occurrence. Still, it does happen: a spill in a school science lab, a broken thermometer, a faulty old tooth filling, a leak at a factory.

By far, though, the most common route of exposure is through seafood, particularly the largest and oldest fish, which have spent the most time eating smaller fish that have been eating even smaller fish contaminated with methylmercury. The location where the fish is caught matters quite a bit, but in general, the fish to be most wary of include [source: FDA]:


  • King mackerel
  • Shark
  • Swordfish
  • Tile fish

You don't need to cut them out entirely, but careful consumption (no more than one serving per week) is smart.

Mid-range methylmercury fish, which should be limited to two or three servings per week, include:

  • Chilean sea bass
  • Grouper
  • Marlin
  • Orange roughy
  • Tuna

And the fish and shellfish to eat freely include:

  • Crawfish
  • Oysters
  • Salmon
  • Sardines
  • Scallops
  • Shrimp

Of course, pregnancy is a game changer. Most pregnant women choose to avoid the highest-mercury fish altogether, and greatly limit their ingestion of the mid-range fish. But it's important that pregnant women do not eliminate all fish from their diet, because fish contains a lot of omega-3s, which are crucial to a developing baby.

For a complete list of seafood mercury contents, see FDA: Mercury Levels in Commercial Fish and Shellfish.

Other than avoiding the fishiest fish, you can also reduce the risk of mercury poisoning by never vacuuming up mercury from a broken thermometer or fluorescent bulb, asking your dentist about your fillings, avoiding religious rituals (typically voodoo or Santeria) involving mercury sold as azogue or botanicas, and staying away from the pretty mercury-filled glass pendants often sold in Mexico. Really, people -- carrying poison around on your body in a breakable container?

For more information on mercury poisoning and related topics, look over the links below.

Related Articles


  • Global Mercury Budget. Utah Department of Environmental Quality.
  • Mercury Background. Agency for Toxic Substances and Disease Registry.
  • Mercury: Human Exposure. U.S. Environmental Protection Agency.
  • Mercury: Health Effects. U.S. Environmental Protection Agency.
  • ToxFAQs. Agency for Toxic Substances and Disease Registry.
  • A Warning About Continuing Patterns of Metallic Mercury Exposure. ATSDR.