In the first Australian study of its kind, 559 cannabis-related deaths identified between 2000 and 2018 have been examined by researchers at the National Drug and Alcohol Research Centre (NDARC), UNSW Sydney.

The leading cause of death was accidental injury (30 per cent), followed by suicide (25 per cent), and polysubstance toxicity (17 per cent).

Lead author, Ms Emma Zahra said motor vehicle accidents were the leading cause of accidental injury deaths (75 per cent).

“One in five motor vehicle accident deaths were pedestrians, highlighting that acute cannabis and polysubstance intoxication can affect information processing and perception of risk.”

None of the deaths identified were due to cannabis toxicity alone.

The mean age of death was 35.8 years and more than 80 per cent of cases were male. 62 per cent were aged under 40 years with the highest proportion of cases in the 30-39 age bracket.

“Men were over-represented and were three times more likely to die due to accidental injury than women,” said Ms Zahra.

An overwhelming proportion of cases involved polysubstance use, with the most prominent substance cited alongside cannabis being alcohol (45 per cent).

“Past research has highlighted that polysubstance use is common and increases the risk of harm. When cannabis and alcohol are consumed simultaneously the risk increases considerably,” said Ms Zahra.

Cardiovascular conditions were the most common disease type recorded in cause of death (14 per cent), followed by respiratory conditions (10 per cent).

“Past research has shown regular use of cannabis can lead to chronic bronchitis, and heavy consumption has been associated with serious cardiovascular complications like acute coronary syndrome, vasospasm, and arrhythmias,” said Ms Zahra.

Suicide was the most common manner of death in cannabis only cases, and one quarter of all cannabis-related deaths.

“Those treating people with cannabis dependence should be aware of this elevated risk,

and regular screening for suicidal ideation would appear appropriate, ” said Ms Zahra.

The study calls for accidental injury harm minimisation strategies to remain a priority for both licit and illicit substances.

“Clinicians and the public should be aware of groups that may be vulnerable, such as those with cardiovascular disease or respiratory issues,” said Ms Zahra.

You can read the full report online here.