Isn't mercury known to be a poisonous substance?
As a single element, mercury is a poisonous metal to which we are all exposed through air, water, soil and food. In dental amalgam, it is bound in an alloy, which also includes silver, copper and tin. Very small amounts of mercury vapour are released from amalgam with chewing. Mercury’s toxicity is related to the amount absorbed. The mercury absorbed from all sources accumulates in body organs and tissues, mostly in the kidneys, but also in the brain, lungs, liver and gastrointestinal tract.