Mercury is bad for you, as it is neurotoxic - limit your consumption in food and avoid broken thermometers.
Mercury takes several different forms. Some are worse for you than others. Scientific American has one of the clearer breakdowns on the web: metal mercury, which is found in thermometers, can give off fumes that do damage to the central nervous system. Mercury salts can do damage to the liver. Organic mercury is the kind that's found in fish - it can accumulate in your flesh and cause problems over time.
Ingestion of mercury salts is relatively rare - unless you're in an industrial workspace, it's probably not a problem. Elemental and organic mercury exposure are more common. Inhaling mercury vapor from a broken thermometer can cause insomnia, memory damage, muscle trembling, headaches, and other problems, according to the World Health Organization.
You may experience similar problems with organic mercury. Mercury atoms attach to molecular rings called methyl groups. They then accumulate in the flesh of fish. The higher the fish is on the food chain, the more methyl mercury it might have in its flesh. Too much fish in your diet, and you too might accumulate methyl mercury in your body. Over time, it can cause damage to your nervous system in the same way as elemental mercury: you might experience tremors, headaches, or problems with memory and cognition.
Mercury exposure is particularly dangerous for children and pregnant women. You'll want to limit your intake to fish with lower levels of mercury - avoid albacore and swordfish - and eat no more than six ounces a week. Canned tuna is generally lower in mercury; you may be able to go up to 12 ounces a week.
Thimerosal is the form of organic mercury that's sometimes used in vaccines as a preservative. The amounts used are very small - a drop in the bucket compared to exposure from other sources. Although they may cause an allergic reaction, thimerosal in vaccines has not been shown to be neurotoxic. There's broad agreement in the international scientific community that there is no credible evidence that thimerosal causes autism. Moreover, the FDA is in the process of phasing thimerosal out of childhood vaccines.
- Mercury salts can damage the liver
- Elemental and organic mercury can damage the central nervous system
- Mercury bioaccumulates in ocean predators
- Pregnant women and children should avoid mercury exposure