268 Unit 4 Understanding and Avoiding Hazardous Substances Copyright Goodheart-Willcox Co., Inc. Experimentation Initially, people often choose to use a substance such as cigarettes or chewing tobacco “just to try it.” This is the stage of experimentation, when a person is trying a substance and, potentially, using it more regularly. Experimentation with a substance often leads to the regular use of a substance. Regular Use After initially trying a substance, people may gradually increase their substance use. Over time, people who smoke a few cigarettes may slowly increase the amount of times they smoke per week. Users are then likely to develop a regular pattern of smoking cigarettes. Tolerance People who regularly use a substance develop a tolerance for that sub- stance. A tolerance develops when the body needs greater amounts of a substance to experience the effects it felt when a lesser amount was used. The body can quickly develop a tolerance to nicotine and require more cigarettes to achieve the original effect. Dependency and Addiction After repeated use, the body adjusts to—or becomes dependent on—the feelings that result from the presence of nicotine. p Dependence occurs when the body relies on the presence of an addictive substance in the system to function “normally” or feel “normal.” There are two types of depen- dence—physical and psychological. Figure 9.8 Stages of Substance Abuse Stage one: experimentation Experimentation with a substance begins. Substance use may stop at this stage, or may rapidly develop into other stages. Stage two: regular use The user develops a habit of regularly using a substance. Stage three: tolerance The user’s body develops a tolerance to the substance. Gradually, the user feels the need for more and more of a substance to achieve the same effects as before. Stage four: dependence and addiction The user becomes reliant on having the substance present in the body to function normally or feel “normal.” Substance use also interferes with personal responsibilities and relationships. The user is physically and psychologically addicted to the substance. tolerance a condition in which the body adjusts to given substance, requiring increased amounts of the substance to feel its effect dependence a condition in which a person relies on a given substance to function or feel normal