I INTRODUCTION
The term inhalant abuse is used to describe a variety of drug-using behaviors that cannot be classified by their
pharmacology or toxicology but are grouped based on their primary mode of administration. Although other
substances can be inhaled (e.g., tobacco, marijuana with or without phencyclidine, and even heroin or crack),
volitilization is not the primary mode of administration; therefore, they do not fall into this classification. Solvent
and propellant products vary by region and Country, and also over time. With such a diverse group of substances
included in a category, it is difficult to identify the chemical substances most prominently used by inhalant
abusers. We will attempt to identify and classify abused chemical substances and the products containing them,
characterize primary disorders and toxicities and discuss treatment issues. Types of products containing abused
inhalants can be grouped as follows: (1) industrial or household cleaning and paint-type solvents including paint
thinners or solvents, degreasers or dry cleaning solvents, solvents in glues, art or office supply solvents such as
correction fluids, and solvents in magic markers (gasoline is similar to these products); (2) fluorocarbon
propellant gases used in household or commercial products, in electronic (personal computer, office equipment)
cleaners or as refrigerant gases; (3) butane/propane hydrocarbons are present in household aerosol sprays such as
paint, hair, and fabric protector sprays, or in cigar lighters; (4) medical anesthetic gases such as ether,
chloroform, halothane, and nitrous oxide {which is also available in whipped cream dispensers (e.g., whippets)
and as octane boosters for car racing} and (5) aliphatic nitrites. Except for nitrites, the foregoing compounds
affect the central nervous worthy system (CNS) directly. As nitrites are mostly used as sexual enhancers rather
than as mood alterants, the discussion of “inhalant abuse” will refer herein to the other volatile substances. Also,
the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV-TR) excludes anesthetics
from the inhalant-related disorders section. Nationally, and in other surveys, anesthetics are included, as almost
all of the inhalants act physiologically as would any anesthetic. With limited studies of the different issues, the
authors do not limit their discussion to either category and try to discuss the issues utilizing the most current and
available data.
Substances Inhaled
Volatile substances (or inhalants) are ubiquitous. The practice of inhalation to produce euphoria can be traced to
the ancient Greeks (Carroll 1977). At the turn of the 19th century, Humphrey Davy in England, experimenting
with the newly discovered gas nitrous oxide, discovered its mind-altering effects (Bergman 1991). Ether and,
later, chloroform parties occurred frequently; at one time, ether was suggested for treatment of alcohol addiction.
These anesthetics are still abused (Hutchens and Kung 1985, Kringsholm 1980, Krenz et al. 2003). The 20th
century brought the use of gasoline and along with it many other volatile mixtures including many solvents,
cleaners, aerosols, degreasers, and glues. Table 58–1 enumerates many of the solvents (frequently noted on the
labels) contained in products currently used for recreational purposes. Despite the widespread availability and
inhalation of these substances, it was not until the 1950s that reporters (Kerner 1988) and judicial action focused
nationwide attention on “glue sniffing.” Although this term is still used today, inhalant abuse has become the
more common term used to describe the abuse of most of these substances. It is important to keep in mind that
there are many different chemicals in many different products, most of which have dissimilar physiological
effects and toxicities as well as unique chemical properties. Sometimes the substances are listed on the product
label; however, many times the container lacks sufficient detail to identify all the potential toxin(s) and may even
miss identifying the substance which induces abuse (Kopstein 2006).
Table 58–1Chemicals Commonly Found in Inhalants
Inhalant
Chemicals
Adhesives
Airplane glue
Toluene, ethyl acetate
Rubber, household glues
Petroleum Distillates, toluene, methyl chloride, acetone, methyl
ethyl ketone, hexane, heptane
Aerosols
Paint sprays
Butane, propane, fluorocarbons, toluene, xylene, hydrocarbons
Hair, deodorant sprays
Butane, propane
Air fresheners
Butane, propane
Analgesic, asthma sprays
Fluorocarbons
Fabric spray
Butane, trichloroethane
PC cleaners (AIR)Dust Removers
Dimethyl ether, hydrofluorocarbons
Head Cleaner
Ethyl chloride
Anesthetics
Gaseous
Nitrous oxide
Liquid
Halothane, enflurane
Local
Ethyl chloride
Cleaning Agents
Dry cleaners
Tetrachloroethylene, trichloroethane
Spot removers
Xylene, petroleum distillates, chlorohydrocarbons
Degreasers
Tetrachloroethylene, trichloroethane, trichloroethylene
Laquer thinners
Acetone, methanol, ethyl acetate, methyl chloride, toluene
Solvents and Gases
Nail polish remover
Acetone, ethyl acetate, (toluene rarely)
Paint remover
Toluene, methylene chloride, methanol, acetone, ethyl acetate
Paint thinners
Petroleum distillates, esters, acetone
Correction fluids and thinners
Trichloroethylene, trichloroethane
Cigar, charcoal lighter gases
Butane, isopropane
Cigar or cigarette lighter fluid
Petroleum distillates
Fire extinguisher propellant
Bromochlorodifluoromethane
Food Products
Whipped cream aerosols
Nitrous oxide
Whippets
Nitrous oxide
Room Odorizers
Poppers, fluids (Rush, Locker Room)
Isoamyl, isobutyl, isopropyl, or butyl nitrite (now illegal) or
cyclohexyl
One of the greatest difficulties in evaluating “inhalants” as an abused or dependent substance is the criteria that
defines an inhalant’s “reinforcing” effects. For most substances, a frequent use of that substance is a basic and
reasonable approach. However, as inhalation is involved herein, there is a question as to what constitutes
sufficient inhalation (e.g. a “dose”) to get “high”. Most importantly, the evaluator has an even greater problem of
differentiating a response of “sniffing” for curiosity from those who are primarily inhaling to get a desired state
of being, the ever elusive “high”. Thus, questionaires are less helpful for these substances (in contrast to most
“drugs of abuse”) in determining any altered state of being. Determination of the ‘duration”, ‘intensity’ or “high
frequency” of use by subject is necessary to establish a ‘dependent state’ for these products. Nevertheless, with
limited resources available, the authors are guided primarily by “ever use” data and first hand knowledge to
focus on which “volatile” products are being used to support dependence..
Another issue, for surveys and evaluation, unique for this “drug” is that the category of “Inhalants” includes
many different types of substances. Different subanalyses have helped to clarify the types of substances being
abused. Thus, an analysis of questionnaire responses of lifetime use in surveys regarding the inhalation of
various products (Table 58–2) indicate that gasoline and glue are the most popular for ages 12-17 (Substance
Abuse and Mental Health Services Administration 2001, 2006). In contrast, nitrous oxide is prominently used by
college students. Although these numbers may not be accurate in defining the potential of these substances for
producing dependencies/toxicities, the “lifetime” data (in contrast to frequent use) is the most statistically valid
group for this analysis. Other surveys may vary somewhat in which products are most widely used. A recent
study of incarcerated adolescents identified gasoline and PC duster sprays as the products most heavily abused
(Howard et al submitted 2007). However, a common perception from the street name referring to these products
as “Air” sprays, doesn’t convey the potential hazard related to the presence of fluorocarbons.
It is difficult to identify which chemical in a product is the one which produces the “high” (may be more than
one), or to quantitate the extent of abuse by collectively grouping all the products containing any one substance
to evaluate the relative degree of that substance in inhalant dependency. With that caveat, a tentative order of
preference of select chemicals will be delineated using historical human and animal reports and surveys:”. (1)
Toluene is the most commonly used substance and is found in many commercial products.
It is “often
considered” to be nontoxic in spite of many studies/reports to the contrary. The use of pure toluene on the streets
attests to it’s popularity; this is enhanced by the availability of pure toluene, both in hardware stores and at
warehouses; (2) If you group together cigarette lighter gases and all aerosols which contain butane propellants
(most now do), the abuse of “butane-type” gases is very high (see below), especially the use of lighter-refill gas
cartridges; (3) gasoline for many reasons, mostly availability, has been and still is widely abused; (4) What has
been most prevalent in the past, fluorocarbons, are not now widely used in the U.S. as a propellant. However,
with the manufacture of partly hydrogenated-fluorocarbons, this could increase their availability in many aerosol
products (note as in PC sprays). Another related abuse is that asthma inhalers (containing fluorocarbons) have
been used to get “high” (Thompson et al. 1983, O'Callaghan and Milner 1988); (5) Nitrous oxide has been a
favorite for many years in many situations, from the release of this gas from whipped cream aerosols to
“whippets” (small compressed nitrous oxide “bombs”) to commercial compressed tanks of N 2O; sold by the
“ballon-full” to “college-age” groups; and lastly, (6) Chlorohydrocarbons (non-fluoro-) have been a problem in
the past in the dry-cleaning industry, as was the abuse of correction fluid products; they are now present in head
cleaner products {the latter product reportedly produced a “mental status change” and walking instability in a
subject (Finch and Lobo 2005)}.
Table 58–2 Percentage in the U.S. population reporting having used different types of inhalants in their lifetime
(Percent), 2000, 2006 Data
Age 12–17 Yr
Solvent or Gas
Age 18–25 Yr
Life-1999
Life-2005
Life-1999
3.4
3.6
2.7
2.5
0.9
1.3
Spray paint
2*
3.0
1.3
1.2
0.3
0.5
Glue or Toluene
3.8
4.3
2.4
2.0
1
1.2
Correction
2.1
2.2
1.9
1.4
0.6
0.6
Nitrous oxide
2.0
1.6
9.5
9.2
2.8
4.6
Aerosol sprays
1.8
2.2
1.4
2.1
0.4
0.5
Thinners
1.7
1.7
1.5
1.1
0.5
0.5
Butane, Propane
1.1
1.2
1.1
0.7
0.2
0.3
Organic nitrites
1.8
1.6
3.3
2.3
3.6
3.8
Gasoline,
L.
Life-2005
Age 26–36 Yr
Life-1999
Life-2005
fluid
fluids