New Yorker magazine journalist David Remnick recently wrote a profile of United States President Barack Obama in which he asked the President his views on marijuana, which has been legalised in one US state (Colorado). Obama’s response made global headlines: 

“As has been well documented, I smoked pot as a kid, and I view it as a bad habit and a vice, not very different from the cigarettes that I smoked as a young person up through a big chunk of my adult life. I don’t think it is more dangerous than alcohol.”

Is he right? Is marijuana, illegal in much of the world, no more dangerous than alcohol? We decided to take a look at the dangers and costs of cannabis in Australia, and how that compares with alcohol.

First, the social cost of both. One caveat: the figures are not exactly comparable, as there are many more users of alcohol. A 2004-05 report estimated alcohol had a total social cost of almost $15.3 billion in Australia, whereas illicit drugs had total costs of $8.2 billion. In the breakdown of illicit drugs, cannabis is given the rough cost of about $3 billion (due to 7287 days of lost productivity, and hospital visits). Of all the major substances used in Australia the study identified tobacco as having the highest social cost — almost $31 billion.

The report identified one death attributable to cannabis in 2004-05, while 3494 were attributable to alcohol. But definitions of directly attributable deaths vary, and a separate report from Drug Free Australia found 32 deaths in that same time period to be attributable to cannabis.

However, other reports list no “reported case of death in humans after isolated acute intoxication with cannabis”, which is to say while you can drink yourself to death in one sitting (and die of acute alcohol poisoning), it’s much harder to smoke yourself to death or develop cannabis poisoning.

Of course, direct poisoning is not the only danger posed by mood-altering substances. A 2013 report from the Australian Bureau of Statistics found that between 1995 and 2005, some 813,000 Australians were hospitalised for injuries and diseases attributable to alcohol consumption while 32,700 Australians aged over 15 died as a result of “risky” or “high-risk” drinking. A separate report found 250 deaths between 1995-2005 were attributable to cannabis. By comparison, paracetamol was found to be responsible for 672 deaths.

A 1998 study of 1045 road fatalities found alcohol was present in 36% of cases while cannabis was present in 11%. The study also pointed out that THC, the active ingredient in cannabis, can remain in blood weeks after use, so it is difficult to determine whether the driver had used the drug directly prior to the crash. This study also examined the numbers of deaths throughout Australia attributable to alcohol, tobacco and illicit drug consumption and found that cannabis was attributable to no deaths while alcohol — which was also found to have positive lifetime health outcomes — was responsible for several thousand.

About one-third of Australians admit to having tried marijuana, down from about 39% in 1998. Some 80% of Australians over the age of 14 said they had tried alcohol, according to a 2010 study, with 12% saying they’d never touched it. “Recent” use of cannabis fell from 17.9% in 1998 to 9.1% in 2007, according to the 2010-2015 report.

The health effects of long-term cannabis use, according to the National Cannabis Prevention and Information Centre — run in co-operation with UNSW’s National Drug and Alcohol Research Centre — are:

  • Increased risk of respiratory diseases associated with smoking, including cancer;
  • Decreased memory and learning abilities; and
  • Decreased motivation in areas such as study, work or concentration.

In comparison, the long-term effects of alcohol include:

  • Cancer of the mouth, throat, oesophagus, lips, liver;
  • Brain injury loss of memory, confusion, hallucinations;
  • High blood pressure, irregular pulse, enlarged heart and changes in red blood cells;
  • Weakness and loss of muscle tissue;
  • Sweating, flushing and bruising of the skin;
  • Inflamed stomach lining, bleeding and stomach ulcers;
  • Increased risk of lung infections;
  • Severe swelling of the liver, hepatitis and cirrhosis;
  • Inflamed pancreas;
  • Tingling and loss of sensation in hands and feet;
  • For men, impotence, shrinking of testicles and damaged and reduced sperm; and
  • For women, greater risk of gynaecological problems.
So the evidence is in — we’re judging this one true.

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