Muriel Newman: The Danger of Cannabis

As Professor Beasley explains, smoking cannabis is far more harmful to human health than smoking tobacco cigarettes. In terms of cancer risk, smoking one cannabis joint is the equivalent of smoking 20 cigarettes, and in terms of the risk of lung disease, smoking one cannabis joint is the equivalent of smoking up to 5 cigarettes.

Given the significant health and safety risks associated with cannabis use, why don’t our health officials and community leaders speak out more strongly about the dangers of this drug? Is their silence the reason that New Zealand has one of the highest reported rates of cannabis use in the world, with about three-quarters of the population having tried cannabis by the age of 25?

Why don’t the public service advertising campaigns that highlight the risk of lung cancer from smoking cigarettes warn young people of the dangers of smoking cannabis?

Richard Beasley: Cannabis and the lung

New Zealand has one of the highest reported rates of cannabis use, with about three-quarters of New Zealanders having tried cannabis by the age of 25, and nearly 10% cannabis-dependent by this age.

The potential adverse effects such as the dependence syndrome, impaired adolescent psychosocial development and mental health, and increased risk of motor vehicle crashes are well recognised.  

In contrast the potential for habitual cannabis smoking to cause adverse respiratory effects is less well recognised, in part because there has been less research undertaken in this field. In some respects this is surprising, as the usual way to take cannabis is by smoking, and it is known that cannabis smoke contains many of the same constituents as tobacco smoke, including higher levels of some carcinogens.