Department of Health
Dangerousness of Drugs [2001]
.
 

 

 

Best quotes:

[drugs & crime not causal]

p.7 "the distinction between drug associated effects and drug caused effects. Here the distinction is between those things that are associated with use of the drug (social ostracism, criminal involvement) and those directly caused by the drug (intoxication or withdrawal)".

p.8 "One particularly good example of this, as a ‘drug-associated’ effect, is the relationship between drugs (heroin especially) and crime, in which the complexity of the association precludes a simplistic assertion that criminal involvement is a danger of using drugs".

[powerful organisations and social beliefs may distort data]

p.8 "a powerful lobby, the alcohol industry, has an obvious interest in minimising the number of deaths that are attributed to alcohol. This political pressure acts only to confound what is already a complex question of aetiology".

p.8 "not simply a question of monitoring but of political decision-making, custom and practice and the dominant belief models about the relationships between events".

[prohibition problems: data, discrimination & increased harm, ineffective]

p.8 [if] "prevalence of use is not known for certain substances, then it is not possible to calculate the incidence rate of the problem comparatively across drugs. This is, in part, a result of the legal situation in which many drugs are acquired illicitly and so neither the total population of users nor the total amount consumed can be readily estimated".

p.64 "there is a fundamental dysjunction between the risks associated with readily available legal drugs such as tobacco and alcohol, and the illicit drugs, for which a criminal justice component is inherent in the profiling of dangers. Thus, while swallowing cocaine may be generally less harmful than its injection, this is not the case for the cocaine dealer who swallows a package to avoid criminal detection".

p.32 "Cannabis availability: widely available across the UK and internationally - no clear evidence of both police or custom interventions on supply".

[drugs not inherently dangerous]

p.48 "drugs are not, of themselves, dangerous, with the risk residing in the interaction between the substance, the individual, the method of consumption and the context of use".

[evidence that cannabis is a safer intoxicant than alcohol]

  • p.54 Table 15 – chronic use
  • p.55 Table 16 – dependency - "cannabis is rated as having the lowest ‘addictive’ potential on four of the five criteria identified, with heroin most strongly linked to reinforcement and tolerance, tobacco to dependence and alcohol to intoxication and withdrawal severity".
  • p.59 Table 18 – deaths [in 1997 alcohol killed 30,000, tobacco 120,000, cannabis 13, heroin 255]
  • p.60 Table 19 – capture rates, dependency - "What this would suggest is that tobacco has the greatest potential for dependence followed by heroin, then cocaine and alcohol. Cannabis has the lowest ‘addictability’ of all the drugs listed above".

[cannabis self-medication & mental illness]

p.32 "Cannabis, Social Context/Setting:

  • therapeutic use
  • possible self-medication among psychiatric patients".

[adolescents reject value systems, independence cf drug dependence]

p.61 "most adolescents will go through a brief spell of independence-assertion, called ‘adolescent-limited delinquency’, during which they will reject the value system of their parents. This will lead to a period in which deviance is valued, petty crime committed, where excessive drinking is commonplace and where recreational drug use occurs. In general, early adulthood signals the end of this period, with employment and marriage the most frequent catalysts".

[social factors affecting drug use]

p.62 "background characteristics such as parental drug use and family income, anti-social personality, low intelligence and other factors that may increase the risk of all kinds of lifetime problems".

p.62 "there are also contemporary-contextual factors that influence the decisions made here and now about whether to use a drug. These may include availability, opportunity, peer influence and expectancies about what the drug will do".

p. 62 "the dangerousness of an individual substance is difficult to abstract from the context of its use – a context that is likely to include the individual taking the drug, their expectations and beliefs about the drug, the society that defines these beliefs and the likelihood of sanctions and the state of the individual at the time of consuming the drug".

p.64 "calculation of risk associated with any given substance is a multi-faceted assessment embedded within the typical use patterns and circumstances commonly undertaken in particular societies. This is partly a reflection on both societal and sub-cultural beliefs and preferences, but will also be impacted upon by the legal framework within which use occurs. Thus, there is a fundamental dysjunction between the risks associated with readily available legal drugs such as tobacco and alcohol, and the illicit drugs, for which a criminal justice component is inherent in the profiling of dangers. Thus, while swallowing cocaine may be generally less harmful than its injection, this is not the case for the cocaine dealer who swallows a package to avoid criminal detection".

[perceived benefits of drug use]

p.64 "the current project does not attempt to enumerate the positive effects that may be associated with substance use, although it readily acknowledges that part of the risk relates to this reinforcing quality and the ‘functionality’ of much substance use".

[List of factors affecting use:

p.5

  • Chemical properties
  • Pattern of use
  • Context of use

Scott p.6:

  • the behaviour of concern
  • the potential damage it causes
  • the probability of the behaviour

Brooks p.6:

  • Type
  • Magnitude
  • Immanence

Hall p.6:

  • Individual & social harm
  • Prevalence of use
  • Relative risk of harm
  • Base rate of harm
  • Drug danger = prevalence x likelihood

Jaffe p.6:

  • Drug properties
  • Dose
  • Route of administration
  • Setting
  • Expectations
  • Past experiences

EMCCDA criteria p.7:

Causes:

    • Substance properties (pharmacology & toxicity)
    • Social factors (regulations, social norms)
    • Methods of use (patterns & context)
    • Individual characteristics (age, gender, personality, genetics)

Consequences:

  • On the user:
      • Biological (toxicity, dependence)
      • Psychological (functional impairment, effects on personality)
      • Behavioural (neglect of social roles, violence etc)
  • On society:
      • Micro-level: Family (disruption, neglect & violence)
      • Meso-level: Neighbourhood (public disorder & insecurity)
      • Macro-level: Society as a whole (economic, health & law)

    Associations (indirect consequences) p.8:

    • Social exclusion
    • Crime

    Measurements of harm:

    • Hospital admissions
    • Death certificates
    • Enforcement statistics
    • Surveys

    Classification used here p.13:

    Acute

    • Physical
      • Mortality
      • Morbidity
    • Psychological
    • Social

    Chronic

    • Physical
      • Mortality
      • Morbidity
    • Psychological
    • Dependence
    • Social

    Other factors

    • Ingestion: route, dose, purity
    • Combination use: other drug use
    • Availability: access & impact on use
    • Law: itself & its implementation
    • Social context: set, setting & class
    • Age & development: effect on harm of age of onset & use
    • Individual vulnerability: susceptible individuals or groups
    • Incapacitation: effect of imprisonment & treatment on use

    Other:

    • Individual: BMI, expectation, dependence, social exclusion, susceptibility to education, development of individual responsibility
    • Drug: purity, quantity, frequency,
    • Method of use: injection, smoking, oral, nasal, multiple drug use
    • Context: social attitudes & action (family, peers, society), law & enforcement, education, drug availability & advertising

     

    Other good quotes:

    Introduction

    drug effects relate not only to chemical properties, but also to the pattern and context of their use.

    Definitions

    [variables]

    for such a systematic analysis of danger to occur, it is necessary to specify clearly the behaviour of concern, the potential damage likely from that behaviour and the probability that it will occur under given circumstances. For Brooks (1984) the key variables are the nature of the harm involved, its magnitude, its imminence, its likelihood and its frequency.

    an appraisal of the personal and public health impact of drug use must account for the prevalence of use, the relative risk of harm and the base rate of the adverse effect.

    the variability in hazard is a consequence of the drug, the dose, the route of administration, the setting as well as the expectations and experiences of the user.

    [EMCDDA harm assessment]

    The European Monitoring Centre for Drugs & Drug Addiction (EMCDDA) published the guidelines for the risk assessment of new synthetic drugs in 1999 which includes the following taxonomies:

    Sources of hazard emanating from:

    • Properties of the substance (pharmacology & toxicity)

    • Measures of social control (regulatory policies & informal norms)

    • Modalities of drug use (patterns & context of use)

    • Individual characteristics of user (age gender genetic personality)

    Hazardous effects of drugs:

    • On the user:

    Biological (toxicity, dependence)

    Psychological (functional impairment, effects on personality)

    Behavioural (neglect of social roles, violence etc)

    • On the social environment:

    Family – micro level (disruption, neglect, violence)

    Neighbourhood & community – meso level (public disorder & insecurity)

    Society at large – macro level (effects on the economy, public health & judicial systems)

    [association v cause]

    the distinction between drug associated effects and drug caused effects. Here the distinction is between those things that are associated with use of the drug (social ostracism, criminal involvement) and those directly caused by the drug (intoxication or withdrawal).

    Methodological issues

    [crime associated with drugs, not directly caused]

    To start with the question of attribution of causality, it is important to note that this applies to both ‘drug-associated’ effects and ‘drug-caused’ effects. One particularly good example of this, as a ‘drug-associated’ effect, is the relationship between drugs (heroin especially) and crime, in which the complexity of the association precludes a simplistic assertion that criminal involvement is a danger of using drugs. On the other hand, the recent court cases between tobacco companies and cancer victims have highlighted the problems of asserting causality for what would appear a straight-forward health outcome. The problems are twofold, the first relates to the number of potential mediating variables, while the second is about our confidence in asserting causal status to factors that may be separated by

    both time and circumstances.

    [Social bias]

    One of the most illuminating examples of this comes from the ‘death data’ associated with different drugs. It relates not only to tobacco but also to alcohol, where a powerful lobby, the alcohol industry, has an obvious interest in minimising the number of deaths that are attributed to alcohol. This political pressure acts only to confound what is already a complex question of aetiology – a person who dies from heart disease may well have had their heart weakened by prolonged excessive drinking, but may also have had a poor diet, little exercise and a stressful lifestyle. In this way, alcohol may well be an enabling condition rather than the single causal determinant, complicating the question of accounting. The recording of this death and its inclusion in the statistics of alcohol dangers is therefore not simply a question of monitoring but of political decision-making, custom and practice and the dominant belief models about the relationships between events.

    [prohibition makes data collection difficult]

    This is, however, complicated by the way in which data are recorded and information is gathered. Both Brooks (1984) and Jaffe (1985) emphasised the issue of frequency and prevalence of behaviour, yet this is something around which we have limited information for drug use, relying on epidemiological indicators of prevalence for the baseline against which to measure dangers. The problem this creates is that, if the prevalence of an outcome, like treatment-seeking or mortality is known for all drugs, yet prevalence of use is not known for certain substances, then it is not possible to calculate the incidence rate of the problem comparatively across drugs. This is, in part, a result of the legal situation in which many drugs are acquired illicitly and so neither the total population of users nor the total amount consumed can be readily estimated.

    Even for a legal substance like alcohol, the quantity and prevalence question cannot be readily calculated. Although it is possible to record the total amount of alcohol sold legally, this excludes illegally imported alcohol, that consumed out of the country by UK citizens and tells us little about patterns and prevalence of alcohol consumption.

    [data comparison problems]

    The issue of comparability is not only a question of quality of information (how reliable, representative, up-to-date, etc) but of the type of indicators that are measured across different drugs and by sources with different objectives. Thus, two of the major reference sources utilised in the literature analysis for the project are Home Office statistics on drug misuse (from which the mortality data have been drawn) and the British Crime Survey, a national household survey.

    [top-down reporting v bottom-up reporting]

    The Home Office data are based on reported cases, so they reflect the system of recording and reporting used (changes in these methods will alter the results obtained), as well as the decision-making of those who present the original information (is this a drug death? Does this person qualify as an addict?).

    In contrast, the BCS is a voluntary participation survey in which the data are compiled with the participants’ consent and so is prey to the structural limitations inherent in self-report. Thus while one source is restricted by the methods of reporting and recording the other is prey to the limitations and biases of self-report.

    [caffeine is a drug]

    While a far greater range of substances could have been identified (including caffeine, khat and a number of prescribed drugs that have been abused including ketamine and dihydrocodeine), it was felt that it was important to restrict the project to the drugs or classes of drug that have the greatest impact on health and social behaviour.

    Results

    Dangers associated with use of the target substances were initially categorised as chronic or acute, and further classified under the main domains of physical dangers (morbidity and mortality), psychological/psychiatric dangers and social/contextual negative effects.

    When exploring chronic effects, additional questions about the ‘addictiveness’ of each substance were included. Participants were asked to describe this in terms of how addictive the substance is, the likelihood and circumstances of physical dependence, as well as evidence of tolerance and withdrawal in chronic users.

    To reduce abstraction, participants were also asked to consider the factors that would mediate or moderate the main effects of the substance. This was an attempt to account for individual or group vulnerabilities and dangers associated with the ways in which drugs were used (such as the route of administration and popular combinations). However, it is important to note that there are also factors which may reduce the risk associated with particular drugs and these were included as moderating variables. The main framework for this analysis is outlined in Box 2 opposite:

    Box 2: Framework for typology of dangerousness of drugs

    • Acute adverse effects – dangers regardless of frequency of use
  • Physical
  • • Mortality

    • Morbidity

  • Psychological/psychiatric

    Social

    • Chronic adverse effects – dangers that are cumulative with increased use
  • Physical
  • • Mortality

    • Morbidity

  • Psychological/psychiatric

    Dependence, tolerance, withdrawal

    Social

    • Factors that may mediate or moderate dangers
  • • Aspects of ingestion (route of administration, dose and purity)

    • Combination use (use with other drugs either concurrently or consecutively)

    • Availability (how easily accessible is the substance and how this impacts upon use)

    • Legal situation (both the law and its implementation around use of the substance)

    • Social context (consequences of set, setting & social milieu on the dangerousness)

    • Age & developmental issues (the likely impact of age of onset & use on danger)

    • Individual vulnerability (particular individuals or groups susceptible to specific harms)

    • Incapacitation (the effect of imprisonment or treatment on patterns of use – including the substitution of other drugs)

  • The consideration of target drugs was then completed by an estimation of the adequacy of the information and the severity or likelihood of each risk factor for each drug.

     

     

    [alcohol tables p.15-17 v cannabis p.30-32: cannabis safer intoxicant]

     

     

    [p.48:] Strengths & limitations of tabular approach

    [problems with this analysis]

    there are fundamental limitations to this approach – drugs are not, of themselves, dangerous, with the risk residing in the interaction between the substance, the individual, the method of consumption and the context of use. Among the main variables that will shape risk relating to substance are amount and purity, mediated by physiological and psychological factors in the user (such as tolerance, expectation and body mass), whether the drug is swallowed or injected or whether it is used in a safe and familiar environment.

    it is not possible to list all of these possible combinations for each of the drugs (and more crucially for all of the possible drug interactions).

    [harm risk = prevalence and likelihood]

    In order to gain an accurate picture of the potential dangers associated with use of certain substances, we also require a probability risk estimation to assess the likelihood of an adverse effect occurring in any one individual. This is the area in which prevalence of use impacts upon the salience of certain types of danger. Hall (1999) highlighted the fact that the danger of a drug is related to both the prevalence of its use and the likelihood of any harms.

    An alternative approach – ranking the dangers

    In their chapter in "The Health Effects of Cannabis" (Kalant et al, 1999), Hall, Room and Bondy undertake a comparison of the health and psychological risks of alcohol, cannabis, nicotine and opiates. They do however point out a number of limitations with this approach:

    1. difficulties in making causal inferences about the use of a drug and adverse effects.

    2. lack of information about the extent or seriousness of drug risks.

    3. the difficulties of making comparative appraisals of the public health significance of identified risks.

    4. the recognition that different drugs are used in different ways.

    5. the difficulty of predicting the consequences of changes in either the prevalence of use of specific drugs or in their routes of administration.

    Their first summary was of the "main adverse affects of regular heavy use of the most harmful form of each type of drug, as commonly used for non-medical purposes" (p487). They did this firstly on the basis of a literature review, differentiating between important effects (in terms of number of heavy users affected, marked as **) or those effects that are less well established or less important numerically (marked as *), see Table 15:

    Table 15: Hall et al (1999) assessment of comparative adverse effects for heavy users of the most harmful form of alcohol, nicotine, opiates and cannabis.

     

    Cannabis

    Alcohol

    Tobacco

    Heroin

    Traffic and other accidents

    *

    **

     

    *

    Violence and suicide  

    **

       
    Overdose death  

    *

     

    **

    HIV and liver infections  

    *

     

    **

    Liver cirrhosis  

    **

       
    Heart disease  

    *

    **

     
    Respiratory disease

    *

     

    **

     
    Cancer

    *

    *

    **

     
    Mental illness

    *

    **

       
    Dependence/addiction

    **

    **

    **

    **

    Lasting effects on the foetus

    *

    **

    *

    *

     

    A second tier of assessment was carried out by asking two American experts, Neal Benowitz and Jack Henningfield, to rate the four substance types on five dimensions related to the capacity of each drug to produce addiction and casualties (Hilts, 1995). In Table 16 below, the lower the score, the greater the likelihood comparatively (ie 1 is the most likely to lead to this problem and 4 the least).

    Table 16: Comparative ratings of the dependence potential of cannabis, alcohol, tobacco and heroin (Hall et al, 1999).

     

    Cannabis

    Alcohol

    Tobacco

    Heroin

    Presence and severity of withdrawal symptoms

    4

    1

    3

    2

    Reinforcement: Capacity to get users to use again and again

    4

    2

    3

    1

    Tolerance: How much more needed by a regular user for the same effect

    4

    3

    2

    1

    Dependence: Difficulty quitting and avoiding relapse: perceived need to use

    4

    3

    1

    2

    Intoxication: Impairment of motor abilities, distortion of thinking and mood

    3

    1

    4

    2

    In the table above cannabis is rated as having the lowest ‘addictive’ potential on four of the five criteria identified, with heroin most strongly linked to reinforcement and tolerance, tobacco to dependence and alcohol to intoxication and withdrawal severity.

    Data on drug-related deaths

    Drug related mortality measures one of the more extreme consequences of drug use, but one that seems relatively free from measurement problems. There are however, two problems in considering death data – one that relates to cause and one that relates to attribution. The causal question results from the distance of time between cause and the effect – if an individual’s heart is weakened by chronic heavy drinking and they die from a heart attack, it is not obvious whether or not this is a ‘alcohol-related’ death. This has been the subject of much politicised debate around smoking mortality. A second, related issue, concerns the proximal attribution of the death – thus, in the case of overdose, the death may be recorded as a heroin death in spite of the presence of excessive quantities of alcohol or benzodiazepines. Thus, even death data must be considered in terms of the recording practices employed.

    Box 3: Problems interpreting drug related mortality data.

    • the deceased may be long term addict or occasional recreational user

    • death may be accident, suicide or possibly homicide

    • death may be due to direct, indirect or long term effects of drug use

    • dependent drug use is not always recorded as cause of death in situations such as where drug addict dies in fire, road traffic accident, of viral infection (HIV, hepatitis)

    • drugs involved may be controlled drugs, prescribed substances or a mixture

    • the drug may not be detected at post mortem or recorded on death certificate

    • whether a drug is detected may depend on which part of body sample is taken from

    • whether a drug is detected may depend on how soon after death post mortem is carried out

    • there is much variation between coroners in facilities, resources and workloads

    • what is recorded as verdict/cause of death is at the discretion of coroner (drug use may be omitted for relatives stigma).

    Table 18: Number of deaths where target substance mentioned on death certificate. Source: Office for National Statistics database on drug related deaths.

    SUBSTANCE ANNUAL NUMBER DEATHS 1997
    ALCOHOL 28,000 (over 3000 cases alcohol specified on death certificate)
    AMPHETAMINES 40
    BENZODIAZEPINES temazepam 104; diazepam 122; nitrazepam 14
    CANNABIS 13
    COCAINE HYDROCHLORIDE 38
    FREE BASE COCAINE -
    AMPHETAMINE TYPE (ecstasy) 11
    HALLUCINOGENS 1
    VOLATILE SUBSTANCES 78
    TOBACCO 120,000
    HEROIN 255
    METHADONE 421

     

    An alternative approach to risk: ‘capture rates’

    The issue of the relative impact of prevalence of use on danger is the basis for the capture rate approach. Although it is important to know prevalence, it is just as important to be able to work out how many of those who try a drug will go on to use it regularly or to become dependent on it – the ‘capture rate’ for a drug.

    Much of this information comes from the American National Comorbidity Survey (Anthony, Warner and Kessler, 1994). In a national household survey, they asked about lifetime use and lifetime dependence for a range of psychoactive substances. An estimated 24% of the total sample had developed tobacco dependence at some point in their lives, 14% alcohol dependence and 7% dependence on an illicit drug.

    However, significantly more people had used alcohol or tobacco than had ever used illicit drugs. Therefore, the authors also calculated the proportion of those who had ever used a drug who had gone on to develop dependence (see table 19 below):

    Table 19: Prevalence, dependence & ‘capture’ rates by target substance.

    Drug

    Proportion who have used %

    Proportion who have developed dependence %

    Proportion of dependence among users %

    Tobacco

    75.6

    24.1

    31.9

    Heroin

    1.5

    0.4

    23.1

    Cocaine

    16.2

    2.7

    16.7

    Alcohol

    91.5

    14.1

    15.4

    Cannabis

    46.3

    4.2

    9.1

     

    What this would suggest is that tobacco has the greatest potential for dependence followed by heroin, then cocaine and alcohol. Cannabis has the lowest ‘addictability’ of all the drugs listed above.

    [method problems]

    However, the capture rate approach may be slightly misleading in that it assumes that the people who have ever tried heroin are the same as the people who have ever tried alcohol so that the capture score is a property of the drug and not of the user. Yet we know that being offered drugs in adolescence has been associated with poor neighbourhoods (Crum et al, 1996), with divorced parents (Grady et al, 1986) and with prior use of alcohol or tobacco (Stenbacka et al, 1993). For this reason, the frequency of the shift from experimentation to dependence reflects not only the addictiveness of the drug but the characteristics of those who are willing to experiment with it.

    [method advantages]

    Yet the capture rate approach is a particularly promising method for those who wish to study the longitudinal dangers associated with a range of substances. Thus, there is no reason why this approach should be restricted to the relationship between experimenters and dependent users. An entire capture risk chain could be, in principle, calculated in which the start point is the first time the drug is offered to an individual, followed by first use, then regular use, then dependent use, and so on. Similarly, a capture equation could be made for first use to particular forms of morbidity and mortality. This method would permit an actuarial approach in which ‘hit rates’ could be calculated for substance effects according to the requirements of the policy makers.

    General developmental issues & danger

    [Variables, adolescence & independence-assertion]

    The developmental approach assumes that, across populations, there are predictable patterns of deviant careers in which most people will flirt with delinquent behaviours (such as drug use) during adolescence, but will ‘grow out’ of these in early adulthood. This will be true for all but around 5% of young delinquents, who will develop long-term and serious problems associated with their adolescent delinquency. In contrast, most adolescents will go through a brief spell of independence-assertion, called ‘adolescent-limited delinquency’, during which they will reject the value system of their parents. This will lead to a period in which deviance is valued, petty crime committed, where excessive drinking is commonplace and where recreational drug use occurs. In general, early adulthood signals the end of this period, with employment and marriage the most frequent catalysts.

    [Variables, expectations]

    Thus, there is a danger period for two aspects of substance use – initiation and escalation that are not independent of each other. The developmental approach has generally involved a consideration of ‘risk’ factors as the key determinants of harm or danger. These include background characteristics such as parental drug use and family income, anti-social personality, low intelligence and other factors that may increase the risk of all kinds of lifetime problems. On the other hand, there are also contemporary-contextual factors that influence the decisions made here and now about whether to use a drug. These may include availability, opportunity, peer influence and expectancies about what the drug will do. This distinction allows us to incorporate both general factors that will shape risk-taking behaviour across the life course with factors that will determine the outcome of a particular risk situation.

    General discussion

    [context, social expectations]

    The first point to make here is that the dangerousness of an individual substance is difficult to abstract from the context of its use – a context that is likely to include the individual taking the drug, their expectations and beliefs about the drug, the society that defines these beliefs and the likelihood of sanctions and the state of the individual at the time of consuming the drug. This state will reflect not only predisposition (biological and psychological) but other forms of substance use that have been engaged in before or at the same time as the target drug.

    The dangerousness of a drug cannot be generalised across all situations – the criterion specified and the method of calculating both the likelihood of and the extent of the negative outcome [must be?] clarified so that it is consistent with the objectives of the policymaker initiating the assessment of danger.

    This is why the capture rate approach offers such a potentially useful method of calculation. As it requires the clear specification of the outcome (e.g. mortality rate) and the delineation of the calculation criteria (e.g. as a proportion of all problem users or lifetime users), the comparability between populations and between substances is less evidently skewed.

    Similarly, for the policy-maker attempting to assess the adequacy of the statistical information available, it permits a clear delineation of the gaps in the data necessary to make this form of calculation.

    A further point this raises is about the temporal aspect of measurement. If it is accepted that the dangerousness of a drug is not exclusively a function of the pharmacological properties of the substance, then there are likely to be ephemeral factors (such as availability and purity) that will influence the likelihood of particular negative outcomes. The ability to measure shifts in these danger outcomes is also crucial to understanding shifting risk patterns, the efficacy of public health interventions and changing patterns of drug use. To this end it is critical not only that measures of dangerousness are maximised, it is also crucial that they are obtained consistently across time.

    Implications

    [Variables]

    there are some intrinsic logical issues that prevent clear delineation of risks by substance use:

    a. factors related to the substance – in particular, the quantity and purity of the drug consumed.

    b. how this relates to factors in the consumer – their physiological frame and state, their history of consumption and consequences for tolerance, and psychological factors including expectations and psycho-adaptation to the drug. Individual factors will also be mediated by ‘career’ variables including age and developmental state as well as other use forms.

    c. combination use – the concurrent or consecutive use of several drugs both within and across drug classes provides an enormous confounding effect on the prediction of effects.

    d. route of administration – while it is generally acknowledged that use by injection carries the most immediate risk it should not be assumed that other routes – smoking and swallowing in particular – are without hazards.

    [social context, beliefs, law]

    What this implies is that the actuarial calculation of risk associated with any given substance is a multi-faceted assessment embedded within the typical use patterns and circumstances commonly undertaken in particular societies.

    This is partly a reflection on both societal and sub-cultural beliefs and preferences, but will also be impacted upon by the legal framework within which use occurs. Thus, there is a fundamental dysjunction between the risks associated with readily available legal drugs such as tobacco and alcohol, and the illicit drugs, for which a criminal justice component is inherent in the profiling of dangers. Thus, while swallowing cocaine may be generally less harmful than its injection, this is not the case for the cocaine dealer who swallows a package to avoid criminal detection.

    [perceived benefits of drug use]

    the current project does not attempt to enumerate the positive effects that may be associated with substance use, although it readily acknowledges that part of the risk relates to this reinforcing quality and the ‘functionality’ of much substance use.