poison, any agent that may produce chemically an injurious or deadly effect when introduced into the body in sufficient quantity. Some poisons can be deadly in minute quantities, others only if relatively large amounts are involved. Factors of importance in determining the severity of a poison include the nature of the poison itself, the concentration and amount, the route of administration, the length of exposure, and the age, size, and physical health of the individual. If poisoning is suspected a physician or poison control center should be called immediately. The remainder of the poison and its container should be saved; the label may list ingredients, first aid measures, or antidotes. For most ingested poisons emptying the stomach is the most important treatment; vomiting is best accomplished in the conscious individual by administering syrup of ipecac with large quantities of water. The major exceptions to this treatment are in cases of ingestion of corrosives, such as lye, and certain hydrocarbons, such as kerosene. In corrosive ingestions a small amount of milk may be given, but vomiting should not be induced since the damage that may have already been sustained by the mucous membranes of the esophagus and stomach may advance to perforation; the patient should be seen by a physician as soon as possible. Hydrocarbons are extremely volatile, and the dangers of their being aspirated into the lungs when vomiting is induced are greater than their toxicity if absorbed into the body. In gas or vapor poisoning the patient should be carried to a nonpolluted atmosphere; artificial respiration should be employed if necessary. If any poison has been absorbed through the skin, all contaminated garments should be removed immediately and the skin washed with soap and water. Poisoning is a significant cause of accidental death in children and is best treated by prevention; potential poisons in the home should be stored in locked cabinets. In chemistry, poison refers to a substance that inhibits or slows a chemical reaction. See separate articles on botulism; carbon monoxide; food poisoning; lead poisoning; mercury poisoning; poison gas; poison ivy; snakebite; toxin.