An estimated 22,000 people in Ireland have a cannabis dependency with hospital data (2020) identifying more than 1,000 admissions to both medical and psychiatric hospitals with cannabis-related diagnoses in that year. 

Despite this, public perceptions of the risks of cannabis use continue to decline, further driving up use.

With insistent pressure in the public and social media for the legalisation of cannabis, public messaging from the State around the risks of cannabis use is almost entirely absent. 

As the roll-out of the SPHE senior cycle programme on substance use in schools lumbers slowly forward, the fallout from cannabis use increasingly presents in every town and city in Ireland.

As the lobbying to legalise cannabis gains pace, the evidence that legalisation is an abject failure is stark. 

In locations where cannabis use is legal, a staggering 10-12% of young adults use cannabis daily while the black market continues to thrive.

Evidence from Canada shows that after regulation of sale, almost half (45%) of cannabis users admitted to buying cannabis from the black market and the emergence of cannabis corporations has benefitted greatly from investment from the tobacco and alcohol market industry. 

Cannabis lobbyists meet government and policymakers across the globe, influencing government policy to expand the hugely profitable cannabis market while the plight of individuals and families is ignored.

What's the alternative?

If legalisation is failing what is the alternative? 

There needs to be clarity on the lead State authority responsible for primary prevention of cannabis and other harmful drug use and it needs to be robustly resourced.

The State needs to promote a strong public health campaign on the health effects of cannabis use that targets reducing the numbers of young adults experimenting with cannabis use as well as the frequency of use, particularly of high potency products. 

Health impacts on adolescents and women who are pregnant or breastfeeding need to be highlighted. The lack of knowledge of the dangers of cannabis use among youth must be addressed.

Following the introduction of the ‘Planet Youth’ model in Iceland, over two decades from 1997-2017, the percentage of 15 and 16-year-olds who had been drunk in the previous month plummeted from almost half (42%) in 1998 to one in 20 (5%) in 2016.

Cannabis use dropped from 17% to 7% and cigarette smoking fell from almost a quarter (23%) to 3%.

The turnaround was both radical and evidence-based. The combination of legislation banning the sale of alcohol under the age of 20 and tobacco under the age of 18 and a ban on advertising of both tobacco and alcohol was combined with campaigns to encourage parents to spend time with their children, know who their friends are and keep them off the streets at night. Parents were encouraged not to allow unsupervised parties and not to buy alcohol for minors. State funding for organised sport, music, art and dance was significantly increased with priority for low-income groups.

The evidence was immediate and comprehensive. Annual surveys found the number of kids spending time with their parents doubled (from 23% to 46%) while sports participation increased from 24% to 42% and use of cigarette smoking, drinking and cannabis use plummeted.

The research clearly shows an evidence-based programme that works to cut the rates of smoking, drinking and cannabis use while bringing families closer and helping young people of all incomes to become healthier in all kinds of ways.

Why is this programme not being considered in an Irish context?

Healthcare professionals, including consultants and general practitioners, need formal education in cannabis use and public health.

The use of legislation as a critical public health intervention to protect and improve health needs to be acknowledged and maximised. 

Legal intervention has consistently been shown to benefit public health in terms of the workplace, smoking ban, road safety as well as alcohol and tobacco control. The role of legislation is terms of preventing harms of cannabis use is no less important. A review paper in the BMJ (2017) confirmed that local and national public health interventions are highly cost saving.

“Cuts to public health budgets in high income countries represents a false economy and are likely to generate billions of pounds of additional costs to health services and the wider economy,” the authors concluded.

The public health effects of cannabis use are all too apparent. Evidence published in the Lancet (2021) reported worryingly high risks, particularly among young people. Cannabis use among Europeans aged 15-24 years increased from 13% in 2010 to 16% in 2019.

“Cannabis dependency is a risk among frequent users and adolescents in particular have a significant risk of developing psychosis and schizophrenia with prolonged use.”

No less than 10 different peer-reviewed studies have shown strong correlation between the degree of cannabis exposure in earlier life and the risk of schizophrenia in later life. The risk among regular cannabis users rises by about 300%. Some have reported a nearly 700% increased risk.

Showing that two things are correlated does not necessarily prove that one causes the other (cannabis proponents will emphasise this point).

The only way to definitively prove that regular cannabis use does (or does not) cause schizophrenia would be to round up about 10,000 people who have never used cannabis and randomly assign half to regularly use cannabis and half to use a placebo. And then count the new cases of persistent psychosis over the next 10 years. 

Obviously, the definitive experiment can never be done. Incidentally, the definitive study was never done to establish the causal link between earlier-life cigarette use and later-life cancer either.

Is this what we want for our young people and are they even aware of these risks?

Cannabis is also reported to have effects on cardiovascular health, increased risk for depression, anxiety and suicidal behaviours and worsens outcomes in those with mental disorders.

In addition to direct health effects, experts also warn of the risk of cannabis-related traumatic injuries and deaths; data from a US study suggested an increase in lethal traffic accidents after cannabis legislation.

Legalisation in Canada and some states in the US has resulted in a booming industry worth CA$2.6bn in Canada and $US18bn in the US according to an editorial in The Lancet in 2021.

The editorial warned that such economic benefits and the potential for tax revenues are major factors in the political motivation to legalise cannabis.

"But these financial incentives should be weighed against the public health implications of legislation," the Lancet editorial warned.

It is imperative that there should be a formal declaration of conflict of interest on any submission accepted for consideration by the Citizens' Assembly.

The Citizens’ Assembly is an opportunity to widen the debate from repeated discussions around legalisation, to identify and prioritise the critical and evidence-based interventions supporting prevention and treatment in an Irish setting.

Dr Catherine Conlon is a public health doctor in Cork and former director of human health and nutrition, Safefood