Top Kiwi doctor on asthma, cannabis, paracetamol and the 'gravely concerning' US medical landscape

Recently winning the Rutherford Prize for his groundbreaking work on asthma treatment, Richard Beasley has also been investigating whether smoking cannabis increases the risk of lung cancer - yes - and if paracetamol is safe for infants - it seems so.

As United States government health authorities "discount strong scientific evidence" and spread misinformation about the dangers of vaccinations, medical experts are gravely concerned about the impact on disadvantaged communities around the world, Beasley says.

"There's real concern as to where this is heading, and I think that the rest of the world needs to mobilise to ensure that science will rule," he tells Saturday Morning's Susie Ferguson.

As a junior doctor working nights in a hospital, "overloaded with patients coming with severe asthma", Beasley first learned about the scale of the problem in Aotearoa - paricularly for Māori, who have perhaps the highest rate of any ethnic group in the world.

On a fellowship to research treatments in the UK, Beasley developed a 2-in-1 inhaler containing formoterol, a relieving medicine and budesonide, a preventing medicine - "probably the biggest paradigm change in asthma treatment for decades".

"The concept is really simple, and it's been a really major advance."

Asthma is a disease that comes and goes and gets better and gets worse, so it doesn't make sense to give the same dose of inhaled steroid each time.

"We're hoping over the next three or four years, we'll have the depth of evidence to really know exactly how to use this medication in children with different types of asthma and different severities."

To Beasley, it's "really disappointing" that there has not yet been much progress on public health measures to prevent the complex condition that is asthma.

"I think the breakthrough is likely to come, perhaps in an immunological way, a vaccine approach. If [a vaccine] can actually change the way the system is imprinted at an early age, that might be able to avoid the problem."

New Zealand has one of the highest rates of lung cancer in the world, especially amongst Māori, and we now know the risk of developing it is increased by smoking cannabis, Beasley says.

A 2008 study of New Zealanders under 55 who developed lung cancer confirmed this, Beasley says.

Cannabis smoke, which is very similar to tobacco smoke but has higher rates of some carcinogenic compounds, is smoked differently from different smoke and usually without a filter, he says. People take a bigger breath of it and tend to hold it in their lungs for longer.

"If you match a tobacco cigarette in a joint in terms of the same size and smoked in the same way, cannabis results in five times higher levels of carbon monoxide.

"We want to be able to say to a patient, 'This is your lung cancer risk if you smoke cannabis'."

Vaporising cannabis is likely to avoid the lung cancer risk, Beasley says, because it's the products of combustion that cause the problem.

Since taking office last year, US Secretary of Health Robert Kennedy Jr and President Donald Trump have made claims that the use of Tylenol during pregnancy is linked to autism in children.

With paracetamol now a fixture in the kitchen of Kiwi homes, the one-year results of a six-year trial of the effects of paracetamol on nearly 4,000 Auckland infants are "reassuring", he says.

"We were able to show that even if it only caused a modest benefit, actually, it wasn't causing harm.

"The evidence currently available suggests that paracetamol is safe in pregnancy and does not increase the risk of autism.

"All implications to date suggest that it's safe."

Richard Beasley is the founder and director of the Medical Research Institute of New Zealand. He will finish his Tales of the Unexpected lecture tour with a free talk at the Auckland War Memorial Museum on Tuesday 21 October.