Inhalants are volatile substances that produce chemical vapors that can be inhaled to induce a psychoactive, or mind-altering, effect. Although other abused substances can be inhaled, the term "inhalants" is used to describe a variety of substances whose main common characteristic is that they are rarely, if ever, taken by any route other than inhalation. This definition encompasses a broad range of chemicals found in hundreds of different products that may have different pharmacological effects. As a result, precise categorization of inhalants is difficult. One classification system lists four general categories of inhalants-volatile solvents, aerosol, gases, and nitrites-based on the form in which they are often found in household, industrial, and medical products.
Many brain systems may be involved in the anesthetic, intoxicating, and reinforcing effects of different inhalants. Nearly all abused inhalants (other than nitrites) produce a pleasurable effect by depressing the CNS. Evidence from animal studies suggests that a number of commonly abused volatile solvents and anesthetic gases have neurobehavioral effects and mechanisms of action similar to those produced by CNS depressants, which include alcohol and medications such as sedatives and anesthetics.
A recent study indicates that toluene, a solvent found in many commonly abused inhalants including airplane glue, paint sprays, and paint and nail polish removers, activates the brain's dopamine system. The dopamine system has been shown to play a role in the rewarding effects of many drugs of abuse. Nitrites, in contrast, dilate and relax blood vessels rather than acting as anesthetic agents.
People who abuse inhalants are found in both urban and rural settings. Research on factors contributing to inhalant abuse suggests that adverse socioeconomic conditions, rather than racial or cultural factors per se, may account for most reported racial and ethnic differences in rates of inhalant abuse. Poverty, a history of childhood abuse, poor grades, and dropping out of school all are associated with inhalant abuse. Native American youths who live on reservations, where socioeconomic distress and school dropout rates are high, typically have higher rates of inhalant abuse than both the general population of young people and those Native American youths who do not live on reservations.
Although the chemical substances found in inhalants may produce various pharmacological effects, most inhalants produce a rapid high that resembles alcohol intoxication with initial excitation, then drowsiness, disinhibition, lightheadedness, and agitation. If sufficient amounts are inhaled, nearly all solvents and gases produce anesthesia, a loss of sensation and even unconsciousness.
The chemicals found in solvents, aerosol sprays, and gases can produce a variety of additional effects during or shortly after use. These effects are related to inhalant intoxication and may include belligerence, apathy, impaired judgment, and impaired functioning in work or social situations. Dizziness, drowsiness, slurred speech, lethargy, depressed reflexes, general muscle weakness, and stupor are other possible effects. Nausea and vomiting are other common side effects.
Inhaled nitrites dilate blood vessels, increase heart rate, and produce a sensation of heat and excitement that can last for several minutes. Other effects can include flush, dizziness, and headache.
A strong need to continue using inhalants has been reported among many individuals, particularly those who abuse inhalants for prolonged periods over many days. Compulsive use and a mild withdrawal syndrome can occur with long-term inhalant abuse. Additional symptoms exhibited by long-term inhalant abusers include weight loss, muscle weakness, disorientation, inattentiveness, lack of coordination, irritability, and depression.
Gender differences in inhalant abuse have been identified at different points in childhood. One study indicates inhalant abuse is higher for boys than girls in grades 4 through 6, occurs at similar rates in grades 7 through 9-when overall use is highest-and becomes more prevalent again among boys in grades 10 through 12. The National Household Survey on Drug Abuse (NHSDA), an annual survey of drug use among the Nation's noninstitutionalized civilians, reports that similar percentages of 12- to 17-year-old boys and girls abused inhalants in 1998. However, the percentage of 18- to 25-year-old males who abused inhalants was more than twice that of females in that age group, suggesting that sustained abuse of inhalants is more common among males.
Volatile solvents are liquids that vaporize at room temperatures. They are found in a multitude of inexpensive, easily available products used for common household and industrial purposes. These include paint thinners and removers, dry-cleaning fluids, degreasers, gasoline, glues, correction fluids, and felt-tip marker fluids.
Inhalants-particularly volatile solvents, gases, and aerosols- are often among the first drugs that young children use. Inhalants also are one of the few substances abused more by younger children than by older ones. Nevertheless, inhalant abuse can become chronic and extend into adulthood.
Generally, inhalant abusers will abuse any available substance. In certain parts of the country, "Texas shoe-shine," a shoe-shining spray containing the chemical toluene, is a local favorite. Silver and gold spray paints, which contain more toluene than other spray colors, also are popular inhalants.
Data from national and state surveys suggest inhalant abuse reaches its peak at some point during the seventh through ninth grades. For example, the American Drug and Alcohol Survey of children in the 4th through 12th grades indicates that the percentage of children who have ever used inhalants peaks in the 8th grade.
Gases include medical anesthetics as well as gases used in household or commercial products. Medical anesthetic gases include ether, chloroform, halothane, and nitrous oxide, commonly called "laughing gas." Nitrous oxide is the most abused of these gases and can be found in whipped cream dispensers and products that boost octane levels in racing cars. Household or commercial products containing gases include butane lighters, propane tanks, whipped cream dispensers, and refrigerants.
Aerosols are sprays that contain propellants and solvents. They include spray paints, deodorant and hair sprays, vegetable oil sprays for cooking, and fabric protector sprays.
Nitrites often are considered a special class of inhalants. Unlike most other inhalants, which act directly on the central nervous system (CNS), nitrites act primarily to dilate blood vessels and relax the muscles. And while other inhalants are used to alter mood, nitrites are used primarily as sexual enhancers. Nitrites include cyclohexyl nitrite, isoamyl (amyl) nitrite, and isobutyl (butyl) nitrite. Cyclohexyl nitrite is found in room odorizers. Amyl nitrite is used in certain diagnostic procedures and is prescribed to some patients for heart pain. Illegally diverted ampules of amyl nitrite are called "poppers" or "snappers" on the street. Butyl nitrite is an illegal substance that is often packaged and sold in small bottles also referred to as "poppers."