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'Bong lung' - Cannabis is bad for lungs, but in a different way to tobacco, NZ study finds

May 18, 2020

The bill will be voted on as a referendum at this year’s general election.

As the Government looks at legalising cannabis, an Otago University study has found that smoking the drug is harmful to lungs, but in a different way to tobacco.

Research suggests smoking the drug causes significant respiratory symptoms, including bronchitis, with evidence to suggest it can result in destructive lung disease - sometimes referred to as "bong lung" - in heavy cannabis users.

Cannabis is the second most commonly smoked drug after tobacco and is the most widely used illicit drug in the world. New Zealand, like other nations, is considering making it legal.

Respiratory specialist professor Bob Hancox, from the University of Otago’s Department of Preventive and Social Medicine, said much of the debate about legalising cannabis appears to revolve around the social and mental health effects, but he believe policies around the liberalisation of cannabis should consider the wider health effects of smoking the drug.

"We believe policies around the liberalisation of cannabis should consider the potential impacts on the lungs," he said.

"The potential for adverse effects on respiratory health from smoking cannabis has had much less attention than the social and mental health effects."

Alex Berenson has been brought to New Zealand by Family First.

Waikato Hospital’s Respiratory Department respiratory specialist Dr Kathryn Gracie, who was also a researcher in the study, also said it had been difficult to carry out research on cannabis and its direct impact on the lungs.

"Cannabis may also increase the risk of lung cancer, but there is not enough evidence to be sure of this yet," she said.

"The individuals who are extremely heavy users of cannabis may not be well represented in the existing epidemiological research. Most case reports of cannabis-related destructive lung disease document very heavy cannabis consumption.

"Despite these limitations there is sufficient evidence that cannabis causes respiratory symptoms and has the potential to damage both the airways and the lungs."

The experts said a combination of smoking both cannabis and tobacco is likely to result in poorer health outcomes.

The final version of the legislation bill was released today.

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