Electronic cigarettes pose potential health risks to users, but these are less than those faced by smokers of tobacco, Otago University at Wellington researchers have concluded.
Professor Nick Wilson and colleagues report on the university's Public Health Expert blog site today that they reviewed studies in which biological markers in "vapers" - e-cigarette users - were compared with those of tobacco smokers.
E-cigarettes are battery-powered devices that vaporise liquid nicotine. Some researchers consider them a useful way to quit or reduce smoking; others fear they may prove a gateway to youth smoking.
Sales of the liquid nicotine are not lawful in New Zealand, the Ministry of Health says. Users can import supplies for personal use. Sales are permitted in the UK, where Public Health England said last year that the best estimate is that e-cigarettes are around 95 per cent less harmful than smoking.
The Wellington researchers say bio-markers, such as certain components of urine and exhaled breath, needed to be assessed to estimate the potential harm of e-cigarettes.
"... past estimates - as per previous reports by Public Health England and the Royal College of Physicians in the UK - largely relied on expert opinion and where evidence was considered it largely focused on studies of vaping aerosol and e-liquid composition with relatively few biomarker studies."
The bloggers say the studies they found suggested diverse results:
• A carbon monoxide risk for vapers that was no more than a few per cent of that faced by smokers;
• A vapers' risk, in a preliminary study, of at least half that of smokers for several other inflammatory markers of likely relevance to cardiovascular and respiratory disease; and
• Vapers' risks of 14 to 23 per cent that of smokers in most studies for cancer-related toxicants.
The cancer-related biomarker findings were "a substantial level of exposure" for vapers. "But it is plausible that some of these toxicants could be due to unreported dual use with smoked tobacco - and even exposure to second-hand smoke."
The Wellington researchers say it seems likely that if smokers shift entirely to vaping, their risk of chronic disease would be expected to decline.
But if they vape long-term they may exposed to some notable levels of toxicants that are hazardous in terms of cancer, cardiovascular disease and possibly long-term respiratory disease.
The safest option for smokers using vaping to reduce their health risk would be to switch to vaping only, as soon as possible, and to aim to quit vaping too - if possible without relapsing to smoking, "which represents the greater risk to health".