Excretion
After undergoing biotransformation many toxic substances are in a form that facilitates excretion. The rate at which excretion of toxic substances occurs is important in determining the toxicity of a substance. The faster a substance is eliminated from the body, the more unlikely a biological effect will be. Excretion of toxic substances occurs by a variety of pathways. The primary organs involved in excretion are the kidneys, liver, and lungs. Minor amounts of substances may leave the body through sweat or milk; they may also be deposited in inactive tissue such as nails, hair, or the outer layer of skin.