Comparing risks of harm and costs to society
Reprinted from "Cannabis" issue of Visions Journal, 2009, 5 (4), p. 11
When we study the harmful impact of substances in Canada, cannabis, tobacco and alcohol are often the focus. This is because many more people use these drugs than drugs like heroin and ecstasy.
All substance use brings some risk of harm. The harms from substance use can be divided into those related to intoxication, such as car accidents due to drinking and driving, and those related to long-term use, such as lung cancer from lifetime smoking. Some harms are relatively minor, such as missing work due to a hangover, and some are very severe, such as contracting HIV from sharing dirty needles.
There are several major categories of harms, including health harms to individuals, social harms to families, and economic harms to businesses (i.e., lost productivity due to absenteeism, disability or death). And there are even societal harms such as social costs related to providing health care and enforcing laws related to substance use. For example, in 2002 an estimated $1.2 billion was spent treating people with substance use problems in Canada.1 We all pay these costs through our taxes, so they are a form of social harm to society.
The notion of risk relates both to the severity of consequences of substance use and the likelihood that they will occur. Risk of harm from substance use varies according to the type of substance, the amount being used, the ways it is used, where it is used, and so on.
Substance use can be low-risk, moderate-risk or high-risk. For example, low-risk drinking for men is normally defined as no more than two drinks on a single occasion and no more than 14 drinks per week. Use at this level carries few risks of health or social harm. High-risk drinking, on the other hand, is defined as regularly drinking five or more drinks on a single occasion for men. This type of “binge drinking” has been shown to greatly increase the risk of short-term harms due to intoxication.2
In order to compare the harms of various substances across Canadian society, we need to take a number of different factors into account. These include the overall number of users in society, their patterns of use, the environmental and social contexts under which this use occurs, the physical effects of substances, and more. Due to the various factors involved, directly comparing the harmful effects of cannabis, tobacco and alcohol is quite complex.
A look at patterns of use and risk
These 2004 statistics show the percentage of Canadians who used cannabis, tobacco or alcohol at least once in the previous year:2-3
14% used cannabis
20% used tobacco
80% used alcohol
The patterns of use for the three substances also varied greatly, as shown in Figure 1.
Sources: Adlaf et al. 2005; Health Canada n.d.; Davis et al. 2009.2-4
Alcohol is used by a very large number of people with the vast majority of these using in low- or moderate-risk ways. Conversely, cannabis and tobacco are used by far fewer people. The majority of cannabis use is low- and moderate-risk, however, while the majority of tobacco use is high-risk.
Understanding patterns of risk in society is important. A large number of people engaging in low- or moderate-risk use can account for a large share of overall harm.5 This is the situation with alcohol. In Canada, there are many (over 21 million) low- and moderate-risk drinkers. These drinkers account for 40% to 60% of alcohol-related health and social harms.2
The situation with tobacco is very different. (In fact, tobacco use is never considered low risk, thus zero low-risk users). Here we have about four million users who account for a large proportion of the overall harms. In the case of cannabis, we have much fewer people overall using the substance across all levels of risk.
Social costs of substance use
While it is difficult to directly compare the harms of cannabis, alcohol and tobacco, harms can be indirectly compared by measuring the social costs connected to each of the substances (Figure 2).
Cannabis health care costs: $73 M, enforcement costs: $1,167.8 M.
The cannabis-related enforcement costs reported are estimated by assigning 50% of all illicit drug enforcement costs in Canada to cannabis. This figure is reasonable given that around 60% of illicit drug offenses reported by police involve cannabis.
- There are enforcement costs to do with illegally importing and selling tobacco and with enforcing laws against seeling tobacco to minors, but these are likely very minor and weren’t included in the source study
Sources: Health Canada. n.d.; Rehm et al. 2006.
In terms of social costs, the vast majority of the social costs of cannabis are enforcement-related while the vast majority of tobacco costs are health-related. The social costs of alcohol are about evenly distributed between health care and enforcement.
In terms of costs per user: tobacco-related health costs are over $800 per user, alcohol-related health costs are much lower at $165 per user, and cannabis-related health costs are the lowest at $20 per user. On the enforcement side, costs for cannabis are the highest at $328 per user—94% of social costs for cannabis are linked to enforcement. Enforcement costs per user for alcohol are about half those for cannabis ($153), while enforcement costs for tobacco are very low.
The harms, risks and social costs of alcohol, cannabis and tobacco vary greatly. A lot has to do with how the substances are handled legally. Alcohol and tobacco are legal substances, which explain their low enforcement costs relative to cannabis. On the other hand, the health costs per user of tobacco and alcohol are much higher than for cannabis. This may indicate that cannabis use involves fewer health risks than alcohol or tobacco. These variations in risk, harms and costs need to be taken into account as we think about further efforts to deal with the use of these three substances in Canada. Efforts to reduce social costs related to cannabis, for example, will likely involve shifting its legal status by decriminalizing casual use, to reduce the high enforcement costs. Such a shift may be warranted given the apparent lower health risk associated with most cannabis use.
About the author
Gerald is a Senior Policy Analyst with the Centre for Addictions Research of BC (CARBC). He has been with CARBC since May 2007 Chris is a Senior Research Analyst with the Canadian Centre on Substance Abuse and a Professor in Psychology at Carleton University in Ottawa
Rehm, J. Baliunas, S., Brochu, B. et al. (2006). The costs of substance abuse in Canada 2002. Ottawa: Canadian Centre on Substance Abuse. http://ccsa.ca/2003%20and%20earlier%20CCSA%20Documents/ccsa-coststudy-2002.zip
Adlaf, E., Begin, P. & Sawka, E. (Eds.) (2005). Canadian addiction survey (CAS): A national survey of Canadians’ use of alcohol and other drugs: Prevalence of use and related harms: Detailed report. Ottawa: Canadian Centre on Substance Abuse. http://ccsa.ca/2005%20CCSA%20Documents/ccsa-004028-2005.pdf
Health Canada. (n.d.) Canadian Tobacco Use Monitoring Survey (CTUMS) (Results for 2002 and 2004). www.hc-sc.gc.ca/hc-ps/tobac-tabac/research-recherche/stat/ctums-esutc_2002-eng.php. www.hc-sc.gc.ca/hc-ps/tobac-tabac/research-recherche/stat/ctums-esutc_2004-eng.php.
Davis, C., Thomas, G., Jesseman, R. et al. (2009). Drawing the line on risky cannabis use: Assessing problematic use with the ASSIST. Addiction Research and Theory, 17(3), 322-332.
Rose, G., Khaw, K-T. & Marmot, M. (2008). Rose’s strategy of preventative medicine: The complete original text. New York: Oxford University Press.
Dauvergne, M. (2009). Trends in police-reported drug offences in Canada. Juristat 29(2), 5-25. www.statcan.gc.ca/pub/85-002-x/2009002/article/10847-eng.pdf