Poisoning is defined as the exposure to any substance in sufficient quantity to cause adverse health effects. Poisonings can be grouped into several different categories, including intentional, accidental, occupational and environmental, social and iatrogenic. Accidental poisonings are the most common, with more than 90 percent occurring in children at home. Intentional poisonings are usually suicide-related, with carbon monoxide being one of the most frequently used agents. Toxic chemical releases in industrial accidents are an occupational and environmental hazard.