The epidemiology of cannabis use and cannabis‐related harm in Australia 1993–2007

Aims To examine trends in patterns of cannabis use and related harm in the Australian population between 1993 and 2007. Design Analysis of prospectively collected data from: (1) the National Drug Strategy Household Survey (NDSHS) and Australian Secondary Student Alcohol and Drug Survey (ASSADS); (2) the National Hospital Morbidity Database (NHMD); and (3) the Alcohol and Other Drug Treatment Services National Minimum Dataset (AODTS‐NMDS). Participants Australians aged 14 years and over from the general population; students aged 12–17 years; public and private hospital in‐patients; public and private in‐patients and out‐patients attending for drug treatment. Measurement Prevalence of 12‐month cannabis use among the general population and secondary students. Proportions in the general population by age group reporting: daily cannabis use; difficulties in controlling cannabis use; and heavy cannabis use on each occasion. Number of hospital and treatment presentations for cannabis‐related problems. Findings Prevalence of past‐year cannabis use has declined in the Australian population since the late 1990s. Among those reporting past‐year use, daily use is prevalent among 40–49‐year‐olds, while heavy patterns of use are prevalent among 14–19‐year‐olds. Hospital presentations for cannabis‐related problems reflect similar trends. Past‐year cannabis use has decreased among the 10–19‐year age group, but those who are daily users in this age group report using large quantities of cannabis. Conclusions Despite declines in the prevalence of cannabis use, continued public health campaigns warning of the harms associated with cannabis use are essential, aimed particularly at users who are already experiencing problems. The increasing demand for treatment for cannabis problems in Australia suggests the need for more accessible and more effective interventions for cannabis use disorders.     

Cannabis potency and contamination: a review of the literature

AIMS: Increased potency and contamination of cannabis have been linked in the public domain to adverse mental health outcomes. This paper reviews the available international evidence on patterns of cannabis potency and contamination and potential associated harms, and discusses their implications for prevention and harm reduction measures. METHODS: A systematic literature search on cannabis potency and contamination was conducted. RESULTS: Cannabis samples tested in the United States, the Netherlands, United Kingdom and Italy have shown increases in potency over the last 10 years. Some countries have not shown significant increases in potency, while other countries have not monitored potency over time. While there are some grounds to be concerned about potential contaminants in cannabis, there has been no systematic monitoring. CONCLUSION: Increased potency has been observed in some countries, but there is enormous variation between samples, meaning that cannabis users may be exposed to greater variation in a single year than over years or decades. Claims made in the public domain about a 20- or 30-fold increase in cannabis potency and about the adverse mental health effects of cannabis contamination are not supported currently by the evidence. Systematic scientific testing of cannabis is needed to monitor current and ongoing trends in cannabis potency, and to determine whether cannabis is contaminated. Additionally, more research is needed to determine whether increased potency and contamination translates to harm for users, who need to be provided with accurate and credible information to prevent and reduce harms associated with cannabis use.     

Design considerations for legalizing cannabis: lessons inspired by analysis of California's Proposition 19

Aims No modern jurisdiction has ever legalized commercial production, distribution and possession of cannabis for recreational purposes. This paper presents insights about the effect of legalization on production costs and consumption and highlights important design choices. Methods Insights were uncovered through our analysis of recent legalization proposals in California. The effect on the cost of producing cannabis is largely based on existing estimates of current wholesale prices, current costs of producing cannabis and other legal agricultural goods, and the type(s) of production that will be permitted. The effect on consumption is based on production costs, regulatory regime, tax rate, price elasticity of demand, shape of the demand curve and non‐price effects (e.g. change in stigma). Results Removing prohibitions on producing and distributing cannabis will dramatically reduce wholesale prices. The effect on consumption and tax revenues will depend on many design choices, including: the tax level, whether there is an incentive for a continued black market, whether to tax and/or regulate cannabinoid levels, whether there are allowances for home cultivation, whether advertising is restricted, and how the regulatory system is designed and adjusted. Conclusions The legal production costs of cannabis will be dramatically below current wholesale prices, enough so that taxes and regulation will be insufficient to raise retail price to prohibition levels. We expect legalization will increase consumption substantially, but the size of the increase is uncertain since it depends on design choices and the unknown shape of the cannabis demand curve.     

Testing for cannabis in the work‐place: a review of the evidence

Background Urinalysis testing in the work‐place has been adopted widely by employers in the United States to deter employee drug use and promote ‘drug‐free’ work‐places. In other countries, such as Canada, testing is focused more narrowly on identifying employees whose drug use puts the safety of others at risk. Aims We review 20 years of published literature on questions relevant to the objectives of work‐place drug testing (WPDT), with a special emphasis on cannabis, the most commonly detected drug. Results We conclude (i) that the acute effects of smoking cannabis impair performance for a period of about 4 hours; (ii) long‐term heavy use of cannabis can impair cognitive ability, but it is not clear that heavy cannabis users represent a meaningful job safety risk unless using before work or on the job; (iii) urine tests have poor validity and low sensitivity to detect employees who represent a safety risk; (iv) drug testing is related to reductions in the prevalence of cannabis positive tests among employees, but this might not translate into fewer cannabis users; and (v) urinalysis has not been shown to have a meaningful impact on job injury/accident rates. Conclusions Urinalysis testing is not recommended as a diagnostic tool to identify employees who represent a job safety risk from cannabis use. Blood testing for active tetrahydrocannabinol (THC) can be considered by employers who wish to identify employees whose performance may be impaired by their cannabis use.