Q:Should I be tested for mercury? I hear a lot about its danger—from fish, dental fillings and pollution.
A:Not unless you know you’ve had high exposure to mercury—for instance, if you work with heavy metals at your job—and/or you have symptoms that your doctor thinks may be caused by mercury poisoning.
Mercury occurs naturally in the environment and also comes from industrial pollution. Since it’s widespread, almost all people have traces of it in their bodies. At high levels, mercury can cause gastrointestinal, kidney and neurological damage and death. Even relatively low levels can harm fetuses, infants and young children.
Routine screening for mercury is not recommended. There are different types of mercury and different ways to measure it. The choice of test depends largely on how a person was likely exposed. Urine tests, for example, can’t detect methylmercury (the type in fish), but blood tests can measure it. Hair, saliva and breath tests tend to be least reliable. In addition, no one knows what to do about mildly elevated levels.
The symptoms of mercury poisoning vary greatly—from subtle to severe—so it’s easy to blame nearly any problem on it. Thus, misleading results from mercury testing can be used to frighten people into having unnecessary, useless and/or dangerous procedures, such as chelation therapy to remove heavy metals from the blood.
Because amalgam (“silver”) dental fillings contain mercury for strength and durability, some dentists or other practitioners do dubious mercury tests as a step toward removing all the fillings. Amalgam may release minuscule amounts of mercury, but there is no clear evidence that these amounts are toxic or that they cause disease or other harm.