Vaping of high concentration causes the same toxic damage to lung cells as traditional cigarettes, a new study has found.
Researchers say the study suggests newer electronic nicotine delivery devices may not be a safer substitute for cigarette smoking.
However, New Zealand experts have slammed the study saying its methods are flawed and contradicts other studies showing vaping is 95 per cent less harmful than traditional cigarettes.
The University of Technology Sydney research -published in ERJ Open Research - tested the effects of new heated tobacco devices with vaping and traditional cigarettes on two types of cells taken from the human airways - epithelial cells and smooth muscle cells.
In healthy lungs, epithelial cells act as the first line of defence to any foreign particles entering the airway while smooth muscle cells maintain the structure of the airway.
However, smoking can lead to difficulty in breathing primarily by hampering the normal functions of these cells.
Dr Pawan Sharma, who led the study, said they found cigarette smoke and heated tobacco vapour were highly toxic to the cells both at lower and higher concentrations.
E-cigarette vapour showed toxicity mainly at higher concentrations, he said.
The new heated tobacco devices, only recently being introduced to New Zealand, heated tobacco leaves at a high temperature without producing any smoke.
Whereas, e-cigarettes (or vaping) vaporised just the nicotine in the tobacco. Commonly, people trying to quit smoking reduced the levels of nicotine slowly until they are just inhaling the vapour.
Sharma said all concentrations tested in the study represented the levels of nicotine found in chronic smokers.
"What came out clearly was that the newer products were in no way less toxic to cells than conventional cigarettes or e-cigarette vaping," Sharma said.
The researcher said the long-term impacts of e-cigarettes and heated tobacco were still unknown but damage to these two types of cells could destroy lung tissue.
"This leads to fatal diseases such as chronic obstructive pulmonary disease, lung cancer and pneumonia, and can increase the risk of developing asthma, so we should not assume that these devices are a safer option," Sharma said.
Sharma said he hoped this study would stimulate more research on heated tobacco devices and vaping - and he planned to continue this work by studying the effects of nicotine devices on more sophisticated models of lung tissue and in mice.
Action on Smoking and Health policy analyst Ben Youdan told the Herald there were many limitations to this research, one being that it was conducted in a lab rather than looking at the "real world impacts."
"Multiple studies in the US, in Europe and the UK have shown improved lung function and respiratory health as a consequence of switching from smoked tobacco to these vaping and heated tobacco devices."
Youdan said the impacts of e-cigarettes on the lungs were also dependent on how people were dosing and the base-line of their lung function before they switched from smoking to vaping or other devices.
"Ultimately e-cigarettes are not risk-free but there are multiple strong-evidence based studies that show they are 95 per cent less harmful...in terms of the impacts of respiratory, the heart and toxicity of the vapour," Youdan said.