Volatile substance abuse

Sections

ABSTRACT
Introduction
Modes of abuse of volatile substances
Clinical toxicology of volatile substance abuse
Sudden death related to volatile substance abuse
Prevalence of volatile substance abuse
Diagnosis of volatile substance abuse
Treatment of volatile substance abusers
Strategies for prevention
Conclusions

Details

Author: R. J. FLANAGAN , R. J. IVES
Pages: 49 to 78
Creation Date: 1994/01/01

Volatile substance abuse

R. J. FLANAGAN Poisons Unit, Guy's and St. Thomas' Hospital Trust, London,
R. J. IVES * National Children's Bureau, London

ABSTRACT

Volatile substance abuse (VSA) (glue sniffing, inhalant abuse, solvent abuse), the deliberate inhalation of volatile substances in order to achieve intoxication, has now been reported from most parts of the world, mainly among adolescents, individuals living in remote communities and those whose occupations give ready access to abusable substances. Solvents from contact adhesives, notably toluene, petrol (gasoline), halogenated solvents, volatile hydrocarbons such as those found in cigarette lighter refills, aerosol propellants, halocarbon fire extinguishers, and inhalational anaesthetics may be abused in this way.

VSA gives rise to dose-related effects similar to those of other hypnosedatives. Small doses can rapidly lead to euphoria and other disturbances of behaviour similar to those caused by ethanol (alcohol), and may also induce delusions and hallucinations. Higher doses may produce life-threatening effects such as convulsions and coma. Death may ensue indirectly after, for example, inhalation of vomit, or from direct cardiac or central nervous system toxicity. Chronic abuse of toluene-containing products and of chlorinated solvents such as 1,1,1-trichloroethane, for example, can produce severe organ damage, especially in the liver, kidneys, and brain.

Drunken behaviour, unexplained listlessness, anorexia and moodiness may result from VSA, especially in children and adolescents. The hair, breath and clothing may smell of solvent, and empty adhesive tubes or other containers, potato crisp bags, cigarette lighter refills, and aerosol spray cans are often found. Toxicological examination of blood and tissue specimens is especially important in confirming a diagnosis of sudden VSA- related death. The development and evaluation of strategies for the treatment of chronic abusers and for prevention are major challenges for the future.

*The authors thank J. Ramsey, St. George's Hospital Medical School, London, for helpful discussions.

Introduction

That volatile substances may be inhaled deliberately in order to achieve intoxication, so-called glue sniffing, inhalant abuse, solvent abuse or VSA, has been known for many years. Diethyl ether and chloroform especially were widely abused in the latter part of the nineteenth century [ 1] . Deliberate inhalation of substances such as trichloroethylene and of products such as petrol (gasoline), was recorded as they became widely available during the twentieth century. VSA has now been reported from most parts of the world, mainly among adolescents, individuals living in remote communities and those whose occupations give ready access to abusable substances.

To be abused by inhalation products must contain a suitably volatile compound (or compounds) which is accessible in sufficient quantity free from overtly toxic components. Solvents from contact adhesives, notably toluene, typewriter correcting fluids and thinners (until recently commonly 1,1,1-trichloroethane), other halogenated solvents, volatile hydrocarbons such as those found in cigarette lighter refills (often liquefied petroleum gas (LPG), largely butane), aerosol propellants, halocarbon fire extinguishers, and inhalational anaesthetics such as enflurane and nitrous oxide are among the compounds or products which may be abused in this way (tables 1 and 2). Petrol (gasoline) is still often abused, especially in remote rural communities.

Petroleum distillates such as white spirit and paraffin (kerosene), and also alcohols and diols such as ethanol, 2-propanol, 2-methoxyethanol (methyl cellosolve) and ethylene glycol are not sufficiently volatile to be abused by inhalation. Amyl (pentyl) and isobutyl nitrites may, however, also be abused by inhalation, often but not exclusively by male homosexuals. The pharmacological effects (vasodilation), and hence the reason for the use of these compounds, are markedly different from those of volatile substances per se, and thus nitrites are not discussed further here. The hazards associated with the abuse of these compounds have been reviewed [ 2] .

Many reviews, monographs, proceedings of meetings and consultation documents on VSA have been published in the last few years [ [ 3] - [ 7] ]. VSA clearly has similarities to other forms of substance abuse, on the one hand, and with ethanol (alcohol) use, on the other. Organic solvents and other abusable volatile compounds can produce dose-related central nervous system (CNS) effects similar to those of other hypnosedatives. Small doses can rapidly lead to euphoria and other disturbances of behaviour which are similar to those caused by ethanol, and may also

Table 1. Selected volatile substances which may be abused by inhalation

Group

Substance

Aliphatic
Acetylene
 
Butane a/
 
Isobutane (2-Methylpropane) a/
 
Hexane b/
 
Propane a/
Alicyclic/
Cyclopropane (trimethylene)
aromatic
Toluene (toluol, methylbenzene, phenylmethane)
 
Xylene (xytol, dimethylbenzene) c/
Mixed
Petrol (gasoline) d/
 
Petroleum ethers e/
Halogenated
Bromochlorodifluoromethane (BCF, FC 12B1)
 
Carbon tetrachloride (tetrachloromethane)
 
Chlorodifluoromethane (FC 22, Freon 22)
 
Chloroform (trichloromethane)
 
Dichlorodifluoromethane (FC 12, Freon 12)
 
Dichloromethane (methylene chloride)
 
1,2-Dichloropropane (propylene dichloride)
 
Ethyl chloride (monochloroethane)
 
Halothane (2-bromo-2-chloro-1,1,1-trifluoroethane)
 
Tetrachloroethylene (perchloroethylene)
 
1,1,1-Trichloroethane (mothylchloroform, Genklene)
 
1,1,2-Trichlorotrifluoroethane (FC 113)
 
Trichloroethylene ("trike", Trilene)
 
Trichlorofluoromethane (FC 11, Freon 11)
Oxygenated
Acetone (dimethyl ketone, propanone)
compounds
Butanone (2-butanone, methyl ethyl ketone, MEK)
 
Butyl nitrite f/
 
Enflurane (2-chloro-1,1,2-trifluoroethyl difluoromethyl ether)
 
Ethyl acetate
 
Diethyl ether (ethoxyethant)
 
Dimethyl ether (DME, metboxymethane)
 
Isobutyl nitrite ("butyl nitrite") f/
 
Isoflurane (1-chloro-2,2,2-trifluaroethyl difluoromethyl ether)
 
Isopentyl nitrite (3-methyl-l-butanol, isoamyl nitrite, "amyl nitrite") f/ g/
 
Methyl acetate
 
Methyl isobutyl ketone (MIBK, isopropyl acetone)
 
Methyl tert.-butyl ether (UTBE)
 
Nitrous oxide (dinitrogen monoxide, "laughing gas")
 
Sevoflurane (fluoromethyl 2,2,2-trifluoro-l-(trifluoromethyl)ethyl ether)
a/Principal components of LPG.
b/Commercial "hexane" mixture of hexane and heptane with small amounts of higher aliphatic hydrocarbons.
c/Mainly meta-xylene (1,3-dimethylbenz4ene).
d/Mixture of aliphatic and aromatic hydrocarbons with boiling range from 40¦deg; to 200¦deg; C
e/Mixtures of pentanes, hexanes etc. with specified boiling ranges (e.g. 40¦deg; to 60¦deg; C).
f/Abused primarily for its vasodilator properties.
g/Commercial amyl nitrite is mainly isopentyl nitrite, but other nitrites are also present.

Table 2. Selected products which may be abused by inhalation

Products

Major volatile components

Adhesives
 
Balsa wood cement
Ethyl acetate
Contact adhesives
Butanone, hexane, toluene and esters
Cycle tyre repair cement
Toluene and xylenes
Polyvinylchloride cement
Acetone, butanone, cyclohexanone, trichloro-ethylene
Woodworking adhesives
Xylenes
Aerosols
 
Air freshener
LPG, DME and/or fluorocarbons
Deodorants, antiperspirants
LPG, DME and/or fluorocarbons
Fly spray
LPG, DME and/or fluorocarbons
Hair lacquer
LPG, DME and/or fluorocarbons
Paint sprayers
LPG, DME and/or fluorocarbons and esters
Anaesthetics and analgesics
 
Inhalational
Nitrous oxide, cyclopropane
 
Diethyl ether, halothane, enflurane, isoflurane
Topical
FC 11, FC 12, monochloroethane
Dust removers ("air brushes")
DME, FC 22
Commercial dry cleaning and degreasing agents
Dichloromethane, FC 113, methanol, 1,1,1-tri-chloroethane, tetrachloroethylene, toluene, trichloroethylene (now rarely carbon tetrachloride, 1,2-dichloropropane)
Domestic spot removers and dry cleaners
Dichloromethane, 1,1,1-trichloroethane, tetrachloroethylene, trichloroethylene
Fire extinguishers
Bromochlorodifluoromethane, FC 11, FC 12
Fuel gases
 
Cigarette lighter refills
LPG
Butane
LPG
Propane
Propane and butanes
Nail varnish and nail-varnish remover
Acetone and esters
Paints and paint thinners
Acetone, butanone, esters, hexane, toluene, trichloroethylene, xylenes
Paint stripper
Dichloromethane, methanol, toluene
Room odorizer
Isobutyl nitrite
Surgical plaster and chewing-gum remover
1,1,1-Trichloroethane, trichloroethylene
Typewriter correction fluids and thinners
1,1,1-Trichloroethane
Whipped cream dispensers
Nitrous oxide

induce more profound effects such as delusions and hallucinations. Higher doses may produce life-threatening effects such as convulsions and coma. Death may ensue indirectly after, for example, inhalation of vomit, or from direct cardiac or CNS toxicity [ 8] .

Deep breathing through the nose and mouth is often involved when volatile substances are abused, not simply "sniffing". Re-breathing exhaled air may add to the effect if the solvent vapour is contained in a plastic or paper bag. It is virtually impossible to assess dosage. It seems likely that the intensity of abuse (and consequent exclusion of oxygen) is a risk factor in sudden deaths. On the other hand, the development of chronic toxicity is related not only to the compounds abused, but also to the intensity and duration of the abuse.

Modes of abuse of volatile substances

The physical form of a product often determines the mode of abuse. Contact adhesives are usually poured into plastic bags such as empty potato crisp packets. The top is then gathered together and placed over the mouth and the vapour inhaled ('bagging"). It is sometimes reported that cans of glue may be heated to increase the yield of vapour. Some abusers may use 4 to 6 litres of adhesive weekly [ [ 9] , [ 10] ]. Petrol and other relatively volatile solvents may be inhaled directly from a container, or poured onto fabric (a coat sleeve or handkerchief), or into cutaway plastic bottles, such as empty detergent or bleach containers, and the vapour inhaled. Plastic bags may be filled from, for example, aerosol cans or halon-containing fire extinguishers. Those products may also be sprayed or released under bedclothes, or inhaled directly. Petrol sniffing especially is associated with a risk of fire and explosion.

Aerosols are usually liquid or solid suspensions supplied in cans containing a liquefied propellant gas. At room temperature one volume of liquid propellant may generate 200 to 300 volumes of vapour. The normal use of the product is largely immaterial to the abuser, although products containing a high proportion of propellant, such as topical analgesic or pain relief sprays (100 per cent propellant), deodorants and fly sprays, rather than those with little (shaving foam, for example) are preferred. If some constituents are not respirable, for example aluminium chlorhydrate (a toxic active ingredient in antiperspirants), then the product may be first bubbled through water, filtered through a cloth held firmly over the mouth, or sprayed into a plastic bag and the aerosol allowed to settle; deaths have occurred from drowning as a result of abuse of aerosols in the bath, the bath water possibly having been used to "scrub" out unwanted aerosol components. Alternatively, the aerosol container may be inverted, allowing direct access to the propellant via the dip tube. Abuse of nitrous oxide from cylinders designed for use, for example, with whipped cream dispensers has also been described. Abuse of propellants used to power spray painting equipment is commonly reported from the United States of America and from Japan, but is very uncommon in the United Kingdom of Great Britain and Northern Ireland.

Domestic fuel (natural) gas is rarely abused, primarily because the principal component, methane, does not induce the desired pharmacological effects. However, the gas used in cigarette lighter refills, small blow torches and camping gas stoves (LPG) usually consists of butane with smaller amounts of isobutane and propane. Those products are available in small, inexpensive packs (of about 250 millilitres) and are very attractive to abusers. Use of 5 to 10 cans per day has been described [ 11] . Gas from larger containers (sometimes propane) is also abused. However, these latter containers are filled to relatively high pressures and usually need a valve with which to obtain the gas. LPG cigarette lighter refills, on the other hand, may be misused by simply clenching the nozzle between the teeth and pressing to release the gas. However, if such cans are tilted a jet of fluid cooled to at least 40¦deg; C by expansion may be released, which may cause burns to the mouth [ 12] , and possibly even to the throat and lungs. There is again a risk of fire and explosion associated with the abuse of LPG cigarette lighter refills.

Clinical toxicology of volatile substance abuse

VSA is characterized by a very rapid onset of intoxication and a relatively rapid recovery; a "high" can be maintained for several hours by repeated sniffing. Euphoria, disinhibition and a feeling of invulnerability may be experienced. Higher doses often lead to less pleasant and more dangerous effects such as visual and auditory hallucinations. Blurred vision, tinnitus, dysarthria, ataxia, agitation, limb and trunk incoordination, tremors, unsteady gait, hyperreflexia, confusion, muscle weakness, headache, abdominal cramps, chest pain, irritability, belligerence, impaired judgement and dizziness are often reported. Dangerous delusions such as those of being able to fly or swim may also occur [ 13] . Nausea and vomiting with the risk of aspiration can occur at any stage. Flushing, coughing, sneezing and increased salivation are further characteristic features. Stupor, coma, depressed respiration and even convulsions may ensue in severe cases [ 14] .

Chronic sequelac of VSA way include recurrent epistaxis (nose bleed), halitosis, oral and nasal ulceration, conjunctivitis, chronic rhinitis, bloodshot eyes, and increased bronchial expectoration. Anorexia, thirst, weight loss and fatigue may also occur. Loss of concentration, depression, lethargy, irritability, hostility and paranoia are further reported complications. Psychological dependence is common in chronic users, although withdrawal symptoms are rarely severe. Long-term neurological, intellectual and psychiatric sequelae may also occur [ 7] . In addition, neuropsychological impairment is often present in volatile substance abusers with well-defined neurological abnormalities. Studies have also found that abusers without reported neurological abnormalities obtain lower psychometric test scores than non-abusers, but this may not be caused by VSA but by, for example, cigarette smoking or the consumption of alcoholic drinks [ [ 15] , [ 16] ].

Peripheral neuropathy, cerebellar dysfunction, chronic encephalopathy and dementia have been described after chronic VSA [ 7] . Chronic abuse of toluene-containing products and of 1,1,1-trichloroethene and trichloroethylene have both been associated with permanent organ damage, especially to the kidney, liver and heart [ 4] . Lead poisoning from alkyl leads used as antiknock agents has been reported as a complication of petrol sniffing. However, since virtually all reports of chronic toxicity after VSA feature case studies or small series of patients referred for treatment, the true incidence of morbidity from VSA is unknown.

Sudden death related to volatile substance abuse

The major risk associated with VSA is that of sudden death. Bass [ 17] reported 110 such deaths in the United States from abuse of aerosol propellants and chlorinated solvents during the 1960s. There were at least 114 VSA-related deaths in the United States in 1974 [ 18] . Further series of fatalities have been noted, again from the United States [ [ 19] , [ 20] ], from Scandinavia [ [ 21] , [ 22] ], and more recently from Japan [ 23] . In the United Kingdom, VSA- related sudden deaths have increased from at least 2 in 1971 to 122 in 1991 [ 24] , the latest year for which data are available (figure 1). Annual numbers of deaths rose steeply in the early 1980s but the rate of increase has now diminished.

VSA-related deaths remain relatively rare in the United Kingdom given the numbers of abusers indicated by prevalence studies (see next section). VSA-related deaths occur in all social classes in the United Kingdom and in all parts of the country. Most deaths (88 per cent) have occurred in males. The age at death has ranged from 9 to 76 years, but most deaths (73 per cent) have occurred in adolescents aged less thin 20 years (figure 2). In 1991, in 46 (38 per cent) of 122 VSA-related deaths in the United Kingdom either there was evidence suggesting that death occurred on the first occasion (or on one of the first occasions) of abuse, or there was no evidence of the deceased ever having indulged in VSA before [ 24] .

The compounds encountered in VSA-related deaths in the United Kingdom (1971-1991) are: fuel gases, mainly LPG from cigarette lighter refills (35 per cent of cases); aerosol propellants - fluorocarbons and/or LPG (21 per cent); solvents from adhesives (19 per cent); other solvents, notably 1,1,1-trichloroethane (21 percent); and fire extinguishers (mainly bromochlorodifluoromethane) (4 per cent). Inhalation of alkyl nitrites was responsible for 5 of the 1,237 deaths, all in males aged more than 30 years. * Deaths due to solvents in glues have decreased somewhat following the introduction of legislation aimed at preventing sales to abusers (figure 3). Since 1989, deaths due to fuel gases have shown a slight proportionate decrease (48 per cent, 41 per cent and 38 per cent of VSA-related deaths in 1989, 1990 and 1991, respectively [ 24] ).

Figure I. Sudden VSA-related deaths in the United Kingdom, 1971-1991 (n = 1237)

Full size image: 79 kB, Figure I. Sudden VSA-related deaths in the United Kingdom, 1971-1991 (n = 1237)

Source:J. C. Taylor and others, Trends in Deaths Associated with Abuse of Volatile Substances 1971-1991 (London, St. George's Hospital Medical School, 1993).

Figure II. Sudden VSA-related deaths in the United Kingdom, 1971-1991, by age

Full size image: 74 kB, Figure II. Sudden VSA-related deaths in the United Kingdom, 1971-1991, by age

Source:J. C Taylor and others, Trends in Deaths Associated with Abuse of Volatile Substances 1971-1991 (London, St. George's Hospital Medical School, 1993).

There are no published data on VSA-related deaths from other countries comparable to those available in the United Kingdom, although individual cases and small series of deaths are reported regularly. VSA-related mortality statistics do provide a crude measure of the problem posed by VSA in a particular country, and can thus help to assess the efficacy of prevention programmes. Complicating factors are the many possible circumstances which may lead to death, and the fact that, since the International Classification of Diseases does not have a category specifically for VSA-related deaths, it is necessary to collect data on such deaths separately.

The precise mechanism of VSA- related sudden death is seldom clear, but indirect effects such as trauma, aspiration of vomit and asphyxia associated with the use of a plastic bag predominate in deaths associated with solvents from adhesives. In contrast, direct toxic effects predominate in deaths associated with fuel gases, aerosols, and chlorinated (and other) solvents (figure 4). Four modes of "direct" acute VSA-related death can be recognised: anoxia, vagal stimulation leading to bradycardia and cardiac arrest, respiratory depression and cardiac dysrhythmias [ 8] . Of these, cardiac dysrhythmias leading to cardiac or cardiorespiratory arrest are presumed to cause most deaths. Sudden alarm, exercise or sexual activity may precipitate an arrhythmia, since VSA may sensitize the heart to circulating catecholamines; in many VSA-related deaths the immediate ante-mortem event is fright and running [ [ 17] , [ 19] ]. However, this is unlikely to be the whole story, since direct toxic effects of 1,1,2- trichlorotrifluoroethane have been described in isolated perfused rat hearts [ 25] . Death in association with "torch breathing", i.e. igniting inhaled fuel gas (propane, in particular), which resulted in a flash fire has also been described [ 26] . The patient did not suffer burns. Propane was detected in blood and lung tissue.

*Personal communication from J. Ramsay.

Prevalence of volatile substance abuse

VSA is a worldwide problem. In some countries there have been systematic surveys of prevalence. In the United Kingdom, for example, there have been a number of such surveys [ 27] . Most have asked a question which aimed to establish whether the respondent had ever sniffed". Studies which aimed at assessing there liability of self-reported drug use provide evidence of the reliability of the resulting data [ [ 28] , [ 29] ]. Indeed, Whitehead and Smart [ 28] suggest that respondents are inclined to underreport rather than overreport drug use. In addition, a study of 1,900 high school students in Norway found a high degree of stability, both cross-sectionally and longitudinally, in substance abuse self- reporting [ 30] .

Figure III. Sudden VSA-related deaths in the United Kingdom, 1971-1991, by type of product abused

Full size image: 75 kB, Figure III. Sudden VSA-related deaths in the United Kingdom, 1971-1991, by type of product abused

Source:J. C. Taylor and others, Trends in Deaths Associated with Abuse of Volatile Substances 1971-1991 (London, St. George's Hospital Medical School, 1993).

Figure IV. Sudden VSA-related deaths in the United Kingdom, 1971-1991,by mechanism of death and by type of product abused

Full size image: 57 kB, Figure IV. Sudden VSA-related deaths in the United Kingdom, 1971-1991,by mechanism of death and by type of product abused

Source:J. C. Taylor and others, Trends in Deaths Associated with Abuse of Volatile Substances 1971-1991 (London, St. George's Hospital Medical School, 1993).

The phrasing of the question is crucial. Rather than a possibly misleading question about sniffing, some studies asked specifically if the respondents had ever used specified drugs "to get, or try to get, 'high'". That wording is understood by older children [ 31] . There are several different ways of assessing reliability. They have included listing a fictitious drug called "Mop" [ 31] . Only 0.16 per cent of the sample said they had used "Mop" to get "high", implying that few children say they have taken a drug of which they have never heard. There was also a high level of consistency between reported lifetime prevalence and current drug use.

With those points in mind, what do United Kingdom VSA surveys show? Firstly, most young people in the United Kingdom know of VSA - a 1983 survey found that 97 per cent of young people were aware of glue-sniffing [ 32] . However, only a small proportion of young people have actually sniffed. Of 15 - to 16 - year - olds in Wales (n = 2,239) asked about their use of eight different drugs, 11.8 per cent said that they had tried glue or another volatile substance. However, most (8.9 per cent) said that they had done so only once or twice [ 31] . Cannabis was the only drug (apart from alcohol and tobacco) that had a higher lifetime prevalence. Sex differences were small and not statistically significant. Similarly there were no significant differences by social class or by whether or not the young person lived in a one-parent family. Current users made up 4.1 per cent of the sample, but 3 per cent, while describing themselves as current users, had used drugs only once or twice.

Surveys carried out in 1989-1990 covered 9- to 15-year-olds (n = 10,293) -in 475 schools across England [ 33] and 16 - to 19 - year - olds (n = 4,436) interviewed at home [ 34] . Around 2 per cent of the younger sample had experimented with volatile substances, and although boys were more likely to have tried volatile substances than girls, the difference was small. There were no very large age or socio-economic differences, but there were some regional differences. Similar overall prevalence rates were found in the older population: 2 per cent of young women and 4 per cent of young men had actually sniffed. In the 1992 British Crime Survey, 16- to 59- year olds (n = 6,406) and 12- to IS- year olds (n = 948) were asked about their use of drugs and volatile substances [ 35] . The latter substances were more likely to be used by young people in the 16- to 19 - year - olds age group, 6 per cent of whom said that they had actually "sniffed".

Elsewhere in Europe the prevalence of VSA is similar to that in the United Kingdom. A 1990 survey of 15-year-olds in Denmark, for example, reported a 5 per cent VSA prevalence rate. In the Netherlands a 1988-1989 nationwide health study among 10- to 17-year-olds (n = 7,259) found a lifetime prevalence of VSA of 3.6 per cent for boys and 2.4 per cent for girls [ 36] . Some 10 per cent of 15- to 20-year olds at Oslo, had sniffed at some stage [ 37] . An epidemiological study carried out in three secondary schools in Yugoslavia showed that among 14- to 18-year-olds (n=2,254), 15 per cent of boys and 11 per cent of girls were sniffers [ 38] .

In the United States, as in the United Kingdom, considerable variation in VSA prevalence is found. The 1990 National Household Survey on Drug Use in the United States found that 7 to 8 per cent of 12- to 17-year-olds said they had used volatile substances [ 39] . VSA is a particular problem in many South American countries. For example, at Sao Paulo, Brazil, in 1988, of 9- to 18-year-olds (n = 1,836) from a low socioeconomic background, some 24 per cent had abused volatile substances at some stage, and 4.9 per cent had sniffed within the previous month [ 40] . The substances most commonly abused were "lana-perfume" (a mixture of chloroform and diethyl ether) (36 per cent), acetone (34 per cent), petrol (32 per cent), fingernail polish (31 per cent) and glue (25 per cent). VSA has also been reported from Australasia. Among 12- to 15- year-olds (n = 5,240) in Japan, 1.5 per cent had tried VSA (2.1 per cent of boys and 0.9 per cent of girls) [ 41] . In New Zealand in 1990, 2 per cent of 14- to 18-year-olds studied had abused volatile substances [ 42] . In Australia, the 1991 National Campaign Against Drug Abuse household survey of 2,500 people aged 14 years and above found that I per cent had used volatile substances in the past year [ 43] .

There is concern about the abuse of volatile substances by certain groups of young people. The World Health Organization (WHO) Programme on Substance Abuse identified VSA as a particular problem of street children [ 44] , and VSA is thought to have higher-than-average prevalence among gypsy children in eastern Europe [ 36] . VSA by minority ethnic groups is also a concern. In the United States some isolated Native American communities have a very high rate of VSA, and young people of Hispanic origin and Mexican-Americans in the United States also appear to be much more likely to use volatile substances than other youngsters [ 45] . This is also the case in Australia, where many young people of native Australian origin use volatile substances [ 46] . Native New Zealanders may also be more prone to VSA [ 42] . The reasons why such groups are more at risk are unclear, but possible explanations include availability of abusable products, poverty (which restricts access to alcohol and other drugs), the development of a dependency culture, and tolerance of sniffing by parents and other influential adults in the community.

Although sniffing has been associated with inner-city deprivation in the United Kingdom, the connection is not well established and the results of surveys are contradictory. However, it appears that the prevalence of VSA among Afro- Caribbean and Asian groups may be lower than among their white counterparts. One survey [ 33] found that while 2 per cent of white young people and 3 per cent of Asians had experimented with VSA, only I per cent of Afro-Caribbeans had done so. That finding is supported by a New Society magazine survey: 82 per cent of its sample were white, and, of that group, 6 per cent had sniffed; 5 per cent were Asian and 5 per cent of that subgroup had sniffed, but only 2 per cent of the West Indians in the sample (who made up 5 per cent of the total) had sniffed [ 47] . Chadwick and others [ 16] also found lower proportions of Afro-Caribbean young people sniffing, and, although the numbers of Asian young people taking part in the study were small, it appeared that they, too, were underrepresented among the sniffers.

The peak age for experimentation with volatile substances seems to be among 14- to 15-year-olds. However, younger children do sniff - the youngest person suffering a sudden VSA-related death in the United Kingdom was only 9 years old. It has been suggested that sniffing is seasonal in the United Kingdom, being more common in the (generally) warmer summer months, particularly during school holidays. Such a pattern is indeed seen in United Kingdom VSA-related deaths in young people. There are some discrepancies between the findings from United Kingdom prevalence studies and from VSA-related mortality data. In particular, there is a big difference in the sex ratios of those young people who say that they have sniffed and those who suffer sudden VSA-related death. For example, in one study [ 31] 12.6 per cent of 15- to 16-year-old boys, compared to 11.2 per cent of girls, reported that they had used volatile substances. However, most deaths (88 per cent) have occurred in males [ 24] , a strikingly different sex balance. There is at present no satisfactory explanation for the difference.

While adolescent volatile substance abusers are clearly a major cause for concern, a further numerically smaller group is no less worrying. This comprises those who abuse volatile substances encountered in the workplace. Dentists and anaesthetists are prime examples; it has been estimated that some 1 to 1.6 per cent of dentists in the United States were abusing nitrous oxide in 1979, for example [ 48] . Between 1984 and 1987 there were at least 11 workplace fatalities among employees in the United States from abuse of nitrous oxide intended either to power whipped cream dispensers (n = 6) or for dental or hospital use [ 49] . During 1961- 1980, out of 384 cases of workplace poisoning by inhalation of tetrachloroethylene, 1, 1, I - trichloroethane or trichloroethylene, there was evidence of deliberate abuse in nine cases [ 50] . The latter studies will obviously not record incidents such as deaths occurring outside the workplace, even though the habit may have been acquired at work. Some of the problems of assessing, and indeed preventing, VSA in the workplace have been discussed [ 51] . While the risks of VSA to the abusers themselves are obvious, the risks to other employees and to patients and others who might be affected by the actions of an intoxicated employee are no less worrying.

Diagnosis of volatile substance abuse

Many of the problems associated with VSA may appear similar to the normal problems of adolescence. VSA should be suspected in children and adolescents with drunken behaviour, unexplained listlessness, anorexia and moodiness (see above section on clinical toxicology of VSA). The hair, breath and clothing may smell of solvent, and empty adhesive tubes or other containers, potato crisp bags, cigarette lighter refills, or aerosol spray cans are often found. The smell of solvent on the breath is related to the dose and duration of exposure and may last for many hours. The so-called "glue-sniffer's rash" (perioral eczema) is caused by repeated contact with glue poured into a plastic bag. However, in one study only 2 of 300 children who regularly sniffed glue were found to exhibit that feature [ 52] .

Instances where the analytical toxicology laboratory may be asked to perform analyses for solvents and other volatiles in biological samples and related specimens include the following:

  1. In the clinical diagnosis of acute poisoning;

  2. To confirm a suspicion of chronic VSA in the face of denial from the patient or a caretaker;

  3. The investigation of deaths where poisoning by volatile com- pounds is a possibility;

  4. he investigation of rape or other assault, or other offences such as driving a motor vehicle or operating machinery while under the influence of drugs or other agents;

  5. In the investigation of a fire or explosion where VSA might have been a contributory factor; and

  6. In the assessment of occupational or environmental exposure to solvent vapour. VSA-related deaths can easily be overlooked if sudden deaths in children and adolescents are not investigated thoroughly. Post- mortem examination usually reveals little, except perhaps acute lung congestion and possibly cold-induced burns to the mouth and throat. A further factor is that well-meaning friends or parents may remove circumstantial evidence (product abused, plastic bag) from the scene prior to an investigation. In terms of the analytical procedure, headspace gas chromatography provides a valuable method for the analysis of volatiles such as solvents in blood and other biological specimens which may be obtained without using special apparatus such as breath-collection tubes [ 53] .

Treatment of volatile substance abusers

Most adolescents who sniff only do so a few times, and most of the small minority who become regular sniffers abandon VSA after a few months or years. For the latter, treatment may not be required, although VSA even at this level can lead to disruption of family and community life, and even criminal activity such as theft or driving a motor vehicle while intoxicated [ 54] . Some young people, however, continue to abuse solvents, perhaps heavily, and some may turn to alcohol or controlled drugs in addition to, or instead of, volatile substances [ [ 55] - [ 57] ]. For them, more comprehensive treatment and intervention may be required.

Treatment of the intoxicated sniffer requires a calm and firm approach. The product being abused should be taken away, but not if this would lead to conflict. Evidence from the study of sudden VSA-related deaths indicates that death may occur when the abuser exerts himself or herself, or where anger or hostility raises the emotional temperature [ 17] . Therefore never chase an intoxicated sniffer, and always try to maintain a calm atmosphere. Fresh air should help. If the sniffer collapses, appropriate first aid should be administered, and in particular the airway should be kept clear. There is little point in trying to have a serious conversation with a severely intoxicated abuser, but calming and reassuring talk may help. After 5 to 20 minutes without inhalation, the abuser should begin to sober up, unless alcohol or other drugs have also been used.

Subsequently, the sniffer may need medical help. Counselling may also be helpful, but many abusers are unwilling to accept such help. Traditional drug abuse treatment services are often oriented towards older users of illegal drugs, and many are, not well equipped to help young volatile substance abusers, who may have a very different outlook on life compared with their more familiar clients. On the other hand, many specialist services for young people are not at ease dealing with problematic volatile substance abusers. This often means that sniffers are passed from one service to another and are not offered treatment to help them "kick the habit" and deal with other problems in their lives.

While experimental or occasional sniffing may occur out of curiosity or in response to pressure from peers, chronic, long-term sniffing is nearly always a response to life's difficulties. Often it is other problems which first need attention, and until these are dealt with the abuser may not be able or willing to give up sniffing, even if he or she recognizes the harm VSA is doing. Consequently, giving help to young volatile substance abusers is best done by generic services for children and young people, supported where necessary by specialist agencies.

Various agencies use a range of approaches which offer different treatment options. But these should be appropriate to the needs of the abuser, be delivered by a practitioner with expertise in the chosen method, have clear and realizable goals, have defined boundaries, for example, of time; be adequately funded, and involve significant others, particularly the family and the peer group, where appropriate. Individual or group counselling may be appropriate, and has been conducted from a psychotherapeutic or behavioural perspective. Where there are family problems associated with VSA, and where the practitioner is experienced in work with families, family therapy or counselling may be offered [ [ 58] , [ 59] ]. Self -help groups along the lines of alcoholism support groups and peer support groups have shown great promise. Some successful schemes have been community- based. Temporarily removing young people at risk from their local area and providing them with alternative activities to sniffing, such as rock-climbing and other outdoor pursuits, may be particularly effective where the home or community environment is grim [ [ 58] - [ 60] ].

VSA is, for most young people, only a passing phase, and many experiment with volatile substances once or just a few times. Therefore, no treatment may be necessary. But, since even experimental VSA is potentially very dangerous (from 20 to 30 per cent of VSA-related deaths in the United Kingdom occur in first-time or near-first-time users [ 24] ), prevention strategies aimed at stopping people from experimenting with VSA (and minimizing the risk if they do) are even more important.

Strategies for prevention

Any VSA prevention strategy must take into account the connection between VSA and other forms of substance abuse. First, volatile substances may be used in combination not only with illicit drugs, but also with alcohol and/or tobacco. Secondly, volatile substances are often the first intoxicant tried by young people, and thus may act as a gateway drug leading to other forms of substance abuse [ [ 55] - [ 57] ]. Thirdly, the reasons underlying chronic VSA may be similar to the reasons underlying the chronic use of other drugs and thus may be susceptible to similar treatment. It follows that it may be wrong to develop VSA prevention strategies without taking into account the potential or actual abuse of other substances. However, drug abuse prevention is an extremely broad topic, and thus the ensuing discussion is confined to measures specific to VSA.

In the United Kingdom public concern about VSA was first expressed in the early 1980s. A great deal of pressure was exerted on the

Government to "do something". Early hopes that laws making it illegal to sniff, that laws requiring manufacturers to modify their products, or that controls on the sale of abusable products would reduce or even eliminate the problem, have not been fulfilled. In 1983 the Government took expert advice and decided not to introduce legislation. In 1984 voluntary guidelines on the sale of abusable products were issued by manufacturers. However, that did not prevent the introduction of a private member's bill in Parliament. The bill became law as the Intoxicating Substances (Supply) Act, 1985, which made it an offence; "to supply or offer to supply to a person under 18 a substance (other than a controlled drug) when the supplier knows, or has reasonable cause to believe, that the substance or its fumes are likely to be inhaled for the purpose of causing intoxication".

The Act applies to England and Wales; similar legislation is in force in Northern Ireland. The maximum penalties for infringement are six months' imprisonment and a fine of 5,000 pounds. The legislation was aimed at shopkeepers who sold abusable products to young people, but the loose wording of the Act was deliberate so that it might be used to catch anyone who sells or gives abusable products to youngsters. No list of products is included in the Act. By 1992 there had been 55 prosecutions and 36 convictions. In many cases the threat of legal action has been enough to stop those few shopkeepers who attempted to profit from glue and solvent sales to volatile substance abusers.

It has been argued that control of supply is not effective. There are many places where young people can purchase abusable products, it is not easy for shopkeepers to recognize solvent abusers, and it is hard for them to know whether a young person will use a product for sniffing rather than for its legitimate purpose. Although most abusers are aged under 18 years, many are older and are therefore not covered by the law on sales. Of 1,237 VSA-related deaths between 1971 and 1991, 40 per cent (498) were over 18 years old [ 24] . It is also difficult to keep track of all the products that can be abused. Surveys of retailers find that less than half are aware that substances other than glue can be abused. Thus, even if the legislation has had some effect in controlling the sales of glues (because most adults are aware of glue sniffing), the restrictions on sales of glue mean that young people who are determined to sniff can purchase other products to which retailers are not alerted.

The law is different in Scotland. Before 1985, courts had established that supplying such substances was an offence under Scottish common law, which classifies as criminal those actions deemed wilful and reckless and causing real injury to another person. Additional legislation is also in force. Under the Solvent Abuse (Scotland) Act, 1983, VSA is one of the conditions which, if satisfied, might justify referring a young person to a quasi-judicial children's hearing which has powers to take a young person into care or otherwise make recommendations for treatment.

What else might be done to control access to abusable substances? Some legislators have tried to make the sale of such products illegal. They argue that alternatives to solvent-based glues, for example, should be manufactured, or that products which could be abused should have a substance added to them to give them an unpleasant smell. The technical difficulties with these suggestions are great. Many unpleasant-smelling substances, for example, are dangerous to health, and it would be inappropriate to add unpleasant odours to products such as hair sprays, deodorants and air fresheners.

There are several possibilities for mechanical modification of abusable products including: modification of the delivery system of aerosol products to prevent the gaseous propellant being extracted from the container separately from the product; the use of non-abusable propellants (such as carbon dioxide) via a modified delivery system; and dispensers that only issue a limited amount of the product, enough for the job, but not enough to get "high" on. Some of those methods are technically feasible for some, but not all, aerosol products, but would be more expensive and would need agreement from the partners of the United Kingdom in the European Union. Other changes that might be made include replacement of easily abusable products with safer ones. For example, correcting pens or water-based correcting fluid can be used instead of solvent-based products. However, some new products are not as good as the old ones for the job for which they are intended.

Many of the substances which can be abused by inhalation remain in widespread use. However, since the 1970s concern about the environ- mental consequences of the release of volatile compounds such as chlorofluorocarbon (CFC) refrigerants and aerosol propellants into the atmosphere has led to the planned phased withdrawal of many CFCs, chlorinated solvents, and halocarbon fire extinguishers. Deodorized LPG and dimethyl ether (DME), which is often used together with chlorodi- fluoromethane to form a non -flammable azeotrope, have already largely replaced fully halogenated CFCs as aerosol propellants in some countries. These latter compounds have just the same abuse potential as CFCs. On the positive side, however, some aerosol products which used to contain a propellant gas are now also available in pump-action containers. Thus there is no need for a propellant. Similarly, if halocarbon fire extinguishers are replaced by extinguishers containing carbon dioxide, and if 1,1,1-trichloroethane-based correction fluids are replaced by water- or oil- based products then two further sources of abusable volatiles will have been removed.

There have been calls in the United Kingdom for sniffing to be made an offence, but that is generally considered impractical. Proscription would make volatile substance abusers even more secretive and harder to help. The police in the United Kingdom do have powers to intervene in certain cases, however. The Public Order Act, 1936 curbed insulting or threatening behaviour, and section 5 of the Public Order Act, 1986 gave the police powers to deal with "harassment, alarm or distress," where "awareness impaired by intoxication" was not a defence, intoxication being defined as by "drink, drugs or other means". The Road Traffic Act, 1988 enables prosecution of those who drive motor vehicles under the influence of volatile substances. Sometimes, archaic laws have been used to deal with abusers, such as the Ecclesiastical Courts Jurisdiction Act, 1860. By-laws controlling behaviour in public parks and intoxication on British Railways property have also been used. The Children Act, 1989 has implications for the welfare of young people who are sniffing, and would also apply in some cases where parents of young children abused volatile substances.

Various other action has been and is being taken. A programme of retailer education has produced a video recording for retailer training and point-of-sale stickers. Leaflets for retailers are available in English and in a number of minority languages, because many small shopkeepers do not speak English as their first language. Some large retailers have their own staff training programmes, and some manufacturers include warning leaflets for retailers in the outer packaging of their products. Many aerosols now carry a warning message. The argument that such messages serve to draw attention to the possibilities for abuse has been largely rejected on the basis of evidence that young people already have high levels of awareness of the abuse potential of household products. The British Retail Consortium, a trade association, is preparing a voluntary code of practice on the sale of butane-gas-lighter refills which would prevent their sale to those aged under 16 years.

In other countries, statutory or voluntary controls have been implemented. In Belgium, for example, some products have been withdrawn, and the size and types of available substances have been limited. In the United States, 40 states have laws to control the sale or use of solvents. Some United States towns have local controls on sales; for example, San Antonio, Texas, has an ordnance which restricts the sales of substances to young people. In Australia, most state Governments have adopted some form of controlling legislation, although not always specifically directed at sales. Warning labels are legally required on a range of products. In Japan "the consumption or inhalation of poisonous or deleterious substances or possession of such substances for the purpose of consumption or inhalation" is a criminal offence punishable by up to two years' imprisonment, or a fine of up to 50,000 yen, or both. The sale or supply of specified substances to juveniles is also an offence; 2,785 people in 1990, and 3,479 in 1991, were arrested for knowingly selling or giving thinners or other solvents to juveniles. In addition, industry takes part in voluntary restraint, and there are warning labels on many products.

Attempts to control supply are fraught with difficulty, and may have unexpected and harmful effects. There is increasing awareness that measures to control supply are only a part of strategies for reducing the harm of substance misuse. As former United States President Ronald Reagan pointed out: "We will know we have won the war on drugs, not when we take drugs away from our children, but when we take our children away from the drugs." Demand reduction measures are therefore increasingly looked to, and school education is seen as an important vehicle for communicating information about drugs and volatile substances. Unfortunately, there is little consensus about effective ways of doing this. A large-scale study in Scotland which evaluated different models of drugs education concluded: "There was no apparent effect of drug education on drinking, smoking, solvent abuse or illegal drug use [ 61] ." A recent review of prevention strategies concluded that the international evidence for the effectiveness of drug education was weak [ 62] . It was suggested that prevention programmes should include enforcement, community involvement and information as part of a multi- agency package addressing locally agreed objectives. In other words education is not a panacea.

The apparent failure of drugs education in schools has not stopped the development of innovative programmes. Many are aimed at younger children on the-grounds that because young people know about drugs and volatile substances from an early age, they should therefore know of their dangers. An additional reason for an early start to education about volatile substances in particular is that, because those products are in most people's homes (unlike illegal drugs), very young children have legitimate access to them. Education about volatile substances can therefore be part of first-school education concerned with safer living in a society-full of potential dangers.

Parents must be involved in prevention campaigns. Studies in the United Kingdom have shown that many parents are not aware of the potential for abuse of household products other than glue. In 1992 an information campaign by the United Kingdom Department of Health provided parents with basic facts about solvents through a nationally distributed booklet [ 63] . Post-campaign research indicated increased parental awareness of VSA, and some evidence that parents had discussed VSA with their children as a result of the campaign, although these conversations had generally been short and unsophisticated. Subsequently, attempts have been made to use public campaigns to improve the quality of the parents' conversations. An educational campaign early in 1994 stressed how important it was for parents to talk with, and listen to, their children. The leaflet for parents, Drugs and Solvents: You and Your Child [ 64] , exhorted: "If you don't talk to your child about drugs, someone else will".

In the United States, parents are given a central role in the prevention of young people's drug use. One leaflet [ 65] sums up the United States approach to parental involvement by providing the following ten steps to help your child say "No":

  1. Talk with your child about alcohol and other drugs;

  2. Learn to really listen to your child;

  3. Help your child feel good about himself or herself;

  4. Help your child develop strong values;

  5. Be a good role model example;

  6. Help your child deal with peer pressure;

  7. Make family rules;

  8. Encourage healthy, creative activities;

  9. Team up with other parents;

  10. Know what to do if you suspect a problem.

Thus, more recent public campaigns aimed at prevention have not focused on drug abuse or VSA, but on more general issues of parenting.

One objection to such campaigns is that the focus on parents is unhelpful. Public education campaigns, it is argued, should aim to address issues faced by young people and their families in today's complex society. The programme of the Federal Centre for Health Education (FCHE) in Germany deliberately avoided addressing parents alone. Rather, the advertising campaign was directed towards all adults in contact with children and young people. The campaign did not provide information about drugs, but sought to increase understanding of young people's motivations for taking drugs. As FCHE points out: "Neither shock nor accusation is used in the advertisement texts or pictures. Rather, they try to show understanding for the fact that the demands placed on the target groups are tough ones" [ 59] .

That coherent and effective prevention strategies are needed is apparent from consideration of the following. The United Kingdom is the only reliable source of data on sudden VSA -related deaths. At present 100 to 150 such deaths occur each year in the United Kingdom, 40 per cent in 14- to 16-year-olds [ 24] . In the United Kingdom there are some 1,800,000 people in the latter age group. Prevalence data [Section 5] suggest that 10 per cent (i.e. 180,000) of these will have experimented with VSA, and that some 0.5 to 1 per cent (i.e. 9,000 to 18,000) will be current sniffers. There is nothing to suggest that a similarly acute mortality rate (say 40 deaths per 180,000 experimenters) does not apply elsewhere. That might appear a relatively low risk (0.02 per cent), but worldwide it represents a problem of substantial proportions.

Prevention is thus an important although difficult area, and perhaps what is most difficult to accept is that whatever is done there will be some young people who will abuse volatile substances and some who will suffer and even die as a consequence. The aim of prevention is to minimize the numbers who abuse volatile substances and to minimize the harm that may arise to those who do. Thus prevention strategies must respond to the changing experiences of those who are at risk. That requires imagination and creativity in designing prevention campaigns, together with dispassionate evaluation of the evidence of the effectiveness of prevention initiatives.

Conclusions

Clearly the major risk from VSA is that of sudden death. Up to 30 to 40 per cent of VSA-related-sudden deaths in the United Kingdom occur in first-time or near-first-time users. Conversely, experience with VSA does not provide complete protection against the risk of sudden death. In addition, evidence associating repeated VSA with a range of chronic disorders continues to accumulate. The widespread availability of abusable substances, often in pure form and at. relatively low cost (petrol, for example), means that it is very difficult to control the practice by limiting supply. Treatment of the chronic abuser and, if possible, prevention through education, counselling and by other means thus assumes great importance. A holistic approach in which volatile sub- stances are considered together with alcohol, tobacco and other drugs seems the best way forward.

There is a need for regular national studies of drug and volatile substance abuse which use consistent methodology. As the recent United Kingdom Home Office Advisory Council on the Misuse of Drugs report on drug education in schools [ 66] argued: 'Without adequate data on the prevalence and trends in school-age drug misuse, the development of an effective prevention strategy will be fundamentally handicapped. It will be impossible to know whether the situation is improving or deteriorating, either generally or in relation to particular age groups, geographical regions or the use of particular drugs, and it will not be possible to set objective targets. Regular national surveys should be carried out covering data such as the age of onset, once -ever or regular/ frequent drug misuse, attitudes to and exposure to drugs."

Attempts should be made to set national and international standards for the collection and presentation of data on VSA. The WHO collaborative survey of young people's health behaviour [ 31] is an important step forward. WHO collaborative surveys on drug abuse are planned at four- year intervals. The next survey takes place in 1994 when 25 countries will take part. The survey has a set of core questions which cover alcohol and tobacco, but not VSA. It would be useful to include a question on VSA in this survey to enable cross-European comparisons. The Commission of the European Communities has carried out "Eurobarometer" public opinion surveys twice a year across the European Community and has sometimes asked questions on drug awareness.

Research is needed on the patterns of VSA among special groups, such as street children, and among minority ethnic and cultural groups, for example gypsies and indigenous peoples. The WHO Substance Abuse Programme [ 44] , the Council of Europe Pompidou Group initiative on VSA [ 36] and the Council of Europe Study Group on Street Children [ 67] are taking up some of those issues on an international basis. International comparisons are of course useful for estimating the size of the problem posed by VSA. If surveys are repeated at regular intervals, they also give an opportunity to compare the effects of different prevention strategies. That is already happening with attempts to reduce tobacco consumption. The situation in each country raises different questions, but in the case of VSA all countries have a common interest in addressing them.

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064

United Kingdom Department of Health, Drugs and Solvents: You and Your Child (London, Her Majesty's Stationery Office, 1993).

065

United States Department of Health and Human Services, Quick List: 10 Steps to Help -Your Child Say "No" (Washington, D.C., U.S. Department of Health and Human Services, 1986).

066

United Kingdom Home Office, Drug Education in Schools: the Need for a New Impetus (London, Her Majesty's Stationery Office, 1993).

067

Council of Europe, Study Group 1 on Street Children: Second Meeting of the Study Group (Strasbourg, Council of Europe, 1992).