Long-term exposure to lower levels of mercury is a greater threat to overall health, and may be more insidious because it causes harm before symptoms are evident. Mercury has not been shown to cause cancer. Mercury easily enters the body through several routes, but it may take many months for the body to purge itself of the poisonous metal. Mercury vapors can be breathed - among the most hazardous exposures to elemental mercury. Handling the liquid metal also allows mercury to enter the body through pores of the skin.
Mercury leaves the body mostly through the urinary and digestive tracts.
Different forms of mercury and the way in which people are exposed will determine how severe and what kind of effect the poisoning produces. Organic mercury, ingested by eating contaminated fish or grain, may cause greater harm to the brain and to developing fetuses than to kidneys. Exposure to elemental mercury and its vapor may cause greater harm to the brain, while inorganic mercury salts in water supplies and contaminated foods may affect kidneys to a greater extent. Medical professionals test for mercury poisoning by drawing blood and taking urine samples, then examining the specimens with special laboratory equipment. The tests are reliable, accurate and easily available.