Poisons can be absorbed via the digestive tract, skin, lungs, eyes, mucous membranes (such as those of the nose or eye), mammary glands, and uterus, as well as from sites of injection. Toxic effects may be local, or the poison can be absorbed and spread by way of the bloodstream. Some poisons are excreted by the kidneys. Others are excreted in the bile and collect in fat deposits. Still others are excreted in milk. In most cases, the body attempts to detoxify the poison. The liver does most of the metabolic processing that turns compounds into forms the body can use or excrete. This includes the detoxification of some substances. Unfortunately, when some poisons are metabolized, the new compounds created are more toxic than the original compound.