Inhalant

Inhalants are a diverse group of organic solvents, volatile substances, and propellant gases that are intentionally concentrated and inhaled for their psychoactive effects, which range from an alcohol-like intoxication to hallucinations. Inhalant drugs are often used by children, teenagers, incarcerated or institutionalized people, and impoverished people, because these solvents and gases are ingredients in hundreds of legally-available, inexpensive products, such as aerosol spray cans, adhesives and rubber cements, deodorant sprays, hair spray, air fresheners, gasoline, lighter fluid, paint, and paint thinner.

Inhalant drugs can be harmful for users because they were not intended for human inhalation in a concentrated form. Some inhalant users are injured or killed due to the effects of inhaling these solvents or gases themselves, which can cause hypoxia (lack of oxygen (e.g., if a plastic bag sticks to a user's face)), pneumonia, cardiac failure or arrest, or aspiration of vomit. Other inhalant users are injured due to the harmful effects of other chemicals used in these products, such as burns from gasoline vapour, or due to dangerous behaviour while they are intoxicated on these drugs.

Most inhalant solvents and gases are not regulated under illegal drug laws such as the United States' Controlled Substances Act. However, many US states and Canadian cities have placed restrictions on the sale of some solvent-containing products to minors, particularly for products widely associated with "sniffing", such as model cement. The practice of inhaling such substances is sometimes colloquially referred to as huffing, sniffing (or "glue-sniffing") or chroming.

Methods of use and effects
Inhalant users inhale vapors or aerosol propellant gases using plastic bags held over the mouth or by breathing from an open container of solvents, such as gasoline or paint thinner. Nitrous oxide gases from whipped cream aerosol cans and aerosol hairspray or non-stick frying spray is sprayed into plastic bags; some users may filter the aerosolized particles out with a rag. Some gases such as propane and butane gases are be inhaled directly from the canister.

Once these solvents or gases are inhaled, the extensive capillary surface of the lungs rapidly absorb the solvent or gas, and blood levels peak rapidly. The intoxication effects occur so quickly that the effects of inhalation can resemble the intensity of effects produced by intravenous injection of other psychoactive drugs.

The effects of solvent intoxication can vary widely depending on the dose and what type of solvent or gas is inhaled. A person who has inhaled a small amount of rubber cement or paint thinner vapour may be impaired in a manner resembling alcohol inebriation - stimulation, a sense of euphoria and intoxication, followed by a period of depression. A person who has inhaled a larger quantity of solvents or gases, or a stronger chemical may experience to stronger effects such as distortion in perceptions of time and space, hallucinations, and emotional disturbances.

In the short term, many users experience headache, nausea and vomiting, slurred speech, loss of motor coordination, and wheezing. A characteristic "glue sniffer's rash" around the nose and mouth is sometimes seen after prolonged use. An odor of paint or solvents on clothes, skin, and breath is sometimes a sign of inhalant abuse, and paint or solvent residues can sometimes emerge in sweat.

Socioeconomics of inhalant abuse
Inhalants are used by a wide cross section of society, including children, teenagers, and adults, in lower-income, middle-income, and even upper-income settings, because inhalant drugs are a legal and easily available source of a "high." While middle-class and upper-class children and teens may explore recreational inhalant use, they are less likely likely to become chronic, heavy users of inhalants. A small number of people from the upper socioeconomic groups may become inhalant abusers, but it this is uncommon, because people from these groups have can afford to buy other types of drugs, such as marijuana or alcohol.

Chronic, heavy inhalant use is mostly concentrated in marginalized, impoverished communities, where people cannot afford to buy other drugs (e.g., homeless people, street kids) or in settings where there is little access to other drugs (children, incarcerated people, or people living in isolated, poor communities). Young people who become chronic, heavy inhalant abusers are more likely to be those who are isolated from their families and community. This isolation can make it harder to keep in touch with the sniffer and encourage him or her to stop sniffing.

In addition to family problems, there is a wide range of possible social problems associated with inhalant use such as feelings of distress, anxiety and grief for the community; violence and damage to property, violent crime, stresses on the juvenile justice system and stresses on youth agencies and support services.

Some adults who used inhalants when they were children or adolescents have no obvious problems from their inhalant use. Consequently, some communities may not consider inhalant use to be as dangerous or potentially harmful as health staff do. Communities may be more likely to see sniffing as a problem when it is actually causing direct problems in the community - such as severe health problems in the sniffers or disruption or violence in the community.

Solvents
Use of inhalants can cause brain, nerve, liver and other damage to the body. In the short term, death from solvent abuse occurs most commonly from aspiration of vomit while unconscious, or from a combination of respiratory depression and hypoxia, the second cause being especially a risk with heavier than air vapors such as butane or gasoline vapor. Deaths typically occur from complications related to excessive sedation and vomiting. Actual overdose from the drug does occur, however, and indeed inhaled solvent abuse is statistically more likely to result in life-threatening respiratory depression than intravenous use of opiates such as heroin.

Most deaths from solvent abuse could be prevented if individuals were rescusitated quickly when they stopped breathing and their airway cleared if they vomited. However, most inhalant abuse takes place when people inhale solvents by themselves or in groups of people who are intoxicated. Certain solvents are more hazardous than others, such as gasoline or refrigerant gases.

Hypoxia can occur when inhalant users are huffing from a plastic bag over their face, which means that they are not breathing enough fresh air. However, some inhalants are heavier-than-air gases or vapors, and, if regular breathing is not maintained, they will remain in the lungs instead of being naturally expelled. Also, since many solvents are highly flammable (e.g., gasoline, paint thinner), some users have suffered burn injuries and deaths due to fires.

Woman inhalant users who become pregnant may have adverse effects on the fetus. The baby may be smaller, and may need additional health care. There is some evidence of birth defects and disabilities in babies born to women who sniffed solvents such as gasoline. Driving while using solvents presents the same dangers as other types of impaired driving, because many solvents cause an alcohol-type intoxication. In early 1999 in the United States, five high school girls were killed in a car accident outside Philadelphia, and the driver had inhaled computer keyboard cleaner.

Gases
Inhaling butane gas can cause drowsiness, narcosis, asphyxia, cardiac arrhythmia and frostbite. Butane is the most commonly misused volatile solvent in the UK, and caused 52% of solvent related deaths in 2000. By spraying butane directly into the throat, the jet of fluid can cool rapidly to –20 °C by expansion, causing prolonged laryngospasm. Some inhalants can also indirectly cause sudden death by cardiac arrest, in a syndrome known as Sudden Sniffing Death Syndrome. The anesthetic gases present in the inhalants appear to sensitize the user to adrenaline. In this state a sudden surge of adrenaline (e.g., from a frightening hallucination), can cause a fatal cardiac arrhythmia.

Nitrous oxide gas can cause death by asphyxiation if a user inhales directly from a large tank using a mask or tube. Normally with recreational use, users get oxygen because they continue to breathe after inhaling the nitrous oxide from a bag or ballon. However, if a mask is attached to the tank, then the user gets pure nitrous oxide with no way to take in any oxygen. The rapidly-expanding gas causes very cold temperatures which can freeze the lips and throat if the gas is inhaled directly from a tank or "whippit" aerosol container. Releasing the gas into a balloon first allows the gas to expand and warm before it is inhaled.

Mechanism of action
The mechanism of action of most inhalants of abuse has not been well elucidated, but is almost certainly the same as that of anesthetic gases used for surgery, such as nitrous oxide or enflurane. These drugs are believed to induce anesthesia primarily by acting as NMDA antagonists, open channel blockers which bind to the inside of the calcium channels on the outer surface of the neuron, and provide high levels of NMDA receptor blockade for a short period of time.

This makes inhaled anesthetic gases different to other NMDA antagonists such as ketamine, which bind to a regulatory site on the NMDA-sensitive calcium transporter complex and provide slightly lower levels of NMDA blockade, but for a longer and much more predictable duration. This makes a deeper level of anesthesia achievable more easily using anaesthetic gases, but can also make them more dangerous than other drugs used for this purpose.

Some solvents of abuse such as alcohol and GHB are known to act as GABA agonists, and it is likely that other solvents also act here to produce additional depressant effects. The solvent diethyl ether, for instance, has seen historical episodes of both inhalation and drinking, and produces effects suggestive of both kinds of activity. The particular mix of NMDA antagonist vs GABA agonist properties will vary between solvents depending on molecular size or shape, and so the effects of particular solvents will differ, although all tend to share a similar profile.

Of more concern from a toxicological perspective, or from the point of view of an individual considering the recreational use of solvents, is the additional toxicity resulting from either the physical properties of the compound itself, or additional ingredients present in a product. Many solvents of abuse are fairly toxic compounds which often produce liver and brain damage after prolonged use. This is particularly bad with chlorinated compounds such as carbon tetrachloride or chloroform, or when products containing mixtures of many substances such as glue or paint is inhaled.

Toxicity may also result from the pharmacological properties of the drug; excess NMDA antagonism can completely block calcium influx into neurons and provoke cell death through apoptosis, although this is more likely to be a long term result of chronic solvent abuse than a consequence of short term use.

United States
Ether was used as a recreational drug during the 1930s Prohibition era, when alcohol was made illegal in the USA for over 10 years. Ether was either sniffed or drunk, and in some towns replaced alcohol entirely. However the risk of death from excessive sedation or overdose is greater than that with alcohol, and ether drinking is associated with damage to the stomach and gastrointestinal tract.

Use of glue, paint and gasoline was little known before the 1950s. Later, glue sniffing became a worldwide phenomenon; however, it is not known if this popularity was caused by government anti-inhalant campaigns. Drug educators argue that the advertising campaigns designed to prevent drug use may instead promote such use. Abuse of aerosol sprays became more common in the 1980s as older propellants such as CFCs were phased out and replaced by more environmentally friendly compounds such as propane and butane.

Abuse of solvents is widespread in impoverished communities, both in developing countries or in poor communities in developed countries (e.g., Aboriginal communities in northern Canada or in Australia). Because solvents and inhalant gases are legally available and inexpensive, there has long been incidents of teenagers using inhalants recreationally. However, most of the long term abuse, or use by older adults tends to be limited to extremely poor or marginalised groups in society.

Canada
Native children in the isolated Northern Labrador community of Davis Inlet were the focus of national concern in 1993 when many were found to be sniffing gasoline. The federal Canadian and provincial Newfoundland and Labrador governments intervened on a number of occasions, sending many children away for treatment. Despite being moved to the new community of Natuashish in 2002, serious inhalant abuse problems have continued. Similar problems were also reported in Sheshatshiu in 2000.

South East Asia and Africa
Dung sniffing has been noted as a problem in several countries in South East Asia such as Thailand and Malaysia among poor and homeless people. Animal or human dung is placed into a plastic bag or tin and left out in the sun where it starts to decompose, releasing methane gas, which has narcotic properties. Police were unsure of what action could be taken, given that dung is not illegal and would be problematic to restrict supplies.

Dung sniffing has also been seen in some African countries (see Jenkem). Glue sniffing is also a problem in these countries, with dung sniffing generally being a last resort by people too poor to afford glue.

Russia and Eastern Europe
Gasoline sniffing became common on Russian ships following attempts to limit the supply of alcohol to ship crews in the 1980s. The documentary Children Underground depicts the huffing of a solvent called Aurolac by Romanian homeless children. Gasoline sniffing also occurs in some remote indigenous communities in developed countries.

Australia
Gasoline sniffing appears mainly to occur among remote indigenous communities. In these remote, impoverished communities, the ready accessibility of gasoline has helped to make it a common drug for abuse. The practice was first observed there in 1951, and is believed to have been introduced by US servicemen stationed in the nation's Top End during World War II.

In Australia, gasoline sniffing now occurs widely throughout remote communities of the Northern Territory, Western Australia, northern parts of South Australia and Queensland. The number of people sniffing gasoline goes up and down over time as young people experiment or sniff occasionally. 'Boss' or chronic sniffers may move in and out of communities. It is thought they are often responsible for encouraging young people to take it up.

Generally groups of young people will inhale gasoline together. Each person inhales from his or her own can of gasoline or gasoline-soaked cloth until the person is intoxicated. The person may repeatedly inhale gasoline fumes over a period of several hours to maintain the desired level of intoxication. Usually the sniffing stops when the gasoline supply runs out or when the sniffer becomes too hungry or tired to keep it up.

In Australia between 1981-1991, there were 60 Aboriginal males and three Aboriginal females whose deaths were associated with gasoline sniffing. They ranged in age from 11 to 32. The causes of death included pneumonia, cardiac failure/arrest, aspiration of vomit, and burns. In 1985, there were 14 communities in Central Australia reporting young people sniffing. In July 1997, it was estimated that there were around 200 young people sniffing gasoline across 10 communities in Central Australia. Approximately 40 were classified as 'chronic' sniffers.

In some communities many children and youths might try gasoline sniffing at least once or twice. Most of these 'experimental' users will not become regular or long-term sniffers. Recently, there have been reports of young Aboriginal people sniffing gasoline in the urban areas around Darwin and Alice Springs.

Substitution of gasoline by non-sniffable Opal fuel has made a difference in some communities.

India and South Asia
In India and South Asia, three of the most widely abused inhalants are the Dendrite brand and other forms of superglue manufactured in Kolkata, toluenes in paint thinners and Iodex - a muscle stress relieving balm.

Elsewhere
In several parts of the world where glue-sniffing is widespread, terms for glue-sniffers have arisen based on brand-names of substances, such as aurolaci in Romania from the brand name Aurolac, or resistoleros in Brazil from the brand name Resistol. These terms are often used even in English-language writing about substance abuse in those regions.

Common inhalants
Solvents and gases used as inhalants are found in a range of inexpensive, legally-available household, office, industrial, and automotive products.

A number of household and office products contain solvents that are used as inhalants, such as toluene and acetone. These products include correction fluids such as Liquid Paper, nail polish removers (acetone), and permanent markers (xylene). Propellant gases used as inhalants in household and office products include freon and compressed hydrofluorocarbons, which are used in various household and office products that come in aerosol spraycans, such as air freshener, computer keyboard cleaner spray (canned air), non-stick cooking spray, aerosol insecticides, and aerosol hairspray. Another household product which contains propellant gases that are used as an inhalant is aerosol whipped cream cans, which contain nitrous oxide gas.

Several nitrite drugs called "poppers" are used for their euphoric effect in the gay subculture and in the rave dance scene. While nitrite drugs are regulated by a variety of federal and local regulations and legal restrictions, several nitrite products can be found in legally-available products. Amyl nitrite is available as an over-the-counter drug in some areas; butyl nitrite is sold as a room deodorizers under trade names as "RUSH" and "Locker Room"; and alkyl nitrite is an ingredient in video head cleaner or some brands of nail polish remover.

Industrial and automotive products also contain solvents and propellant gases that are used as inhalants. Solvents such as toluene are found in turpentine, gasoline, paint, spraypaint, an a range of quick-drying adhesives and cements (e.g., rubber cement and plastic cement). The solvent diethyl ether is used in an aerosol product called automotive starting fluid, which is used to help carburetor engines start in frigid weather. Canisters of butane are used in inexpensive home welding kits.

History of inhalants
Solvents were such as chloroform and diethyl ether and gases such as nitrous oxide were first used for medical purposes, such as providing anesthesia. These solvents' psychoactive and hallucinogenic effects at sub-anesthetic levels was also noted, which led to recreational use. Nitrous oxide particularly was popularised by the scientist Sir Humphry Davy who held nitrous oxide parties where users could enjoy the euphoric properties of the gas. Davy, noting the anesthetic effects, proposed that the gas could be used for operations, although this was not tried for another half century.

Chloroform was used as an anaesthetic, but it fell into disuse due to its high toxicity and narrow dose margin. Nitrous oxide and diethyl ether were adopted by the medical mainstream and became the standard anesthetics in use for many years. Other gases such as cyclopropane were also used for anesthesia. Non-flammable gases such as halothane replaced flammable anaesthetics such as ether. Halothane is now rarely used in humans due to problems with liver damage and a rare condition called malignant hyperthermia, but it is still widely used in veterinary medicine.

In modern times newer anesthetics such as isoflurane and sevoflurane have been developed for medical use which lack both the flammability of ether and the toxicity of halothane, and research in the area is ongoing. Nitrous oxide is still widely used as a dental anaesthetic, to reduce patient anxiety during dental work and minor dental surgery. Other medical anesthetics and inhaled medicinal drugs include xenon, enflurane,isoflurane, sevoflurane, desflurane, methoxyflurane salbutamol, and fluticasone.

Music and musical culture
The Ramones sang "Now I Wanna Sniff Some Glue" about adolescent ennui. The punk fanzine "Sniffin' Glue" takes its name from the song but, the fanzine is not about inhalants. In the Nirvana song, "Dumb", Kurt Cobain sings a that "my heart is broke/But I have some glue/ help me inhale /And mend it with you". Primus's 1998 song Lacquer Head is about adolescents who use inhalants to get high.

Films and books
In the 1996 film Citizen Ruth, the character Ruth sniffs patio sealant from a paper bag. In the movie Love Liza, the main character, played by Philip Seymour Hoffman, develops a gasoline addiction. In the book Fear and Loathing in Las Vegas and in the film version, the two main characters inhale Diethyl Ether as one of various recreational drugs they take on their trip. In the David Lynch film Blue Velvet, Dennis Hopper's character uses a mask to inhale some type of psychoactive or anaesthetic gas.