Nonsmokers around e-cigs absorb nicotine like passive cigarette smokers: Smoke-free should also be ecig-free http://t.co/bOEbADUroA
— Stanton Glantz (@ProfGlantz) October 5, 2014
The study measured nicotine levels in smokers', nonsmokers' and vapers' homes. It also measured cotinine levels in the saliva of the people who live in them. Cotinine is a biomarker for nicotine and is often used as a proxy for tobacco smoke exposure.
Cotinine measurements were taken from people who did not smoke or vape. These were the results study reported:
The [geometric mean averages] of salivary cotinine were 0.38 ng/ml (GSD=2.34) in the smokers’ homes, 0.19 ng/ml (GSD=2.17) in the e-cigarettes users’ homes, and 0.07 ng/ml (GSD=1.79) in the control homes. Salivary cotinine concentrations of the non-smokers exposed to e-cigarette׳s vapour at home (all exposed ≥2 h/day) were statistically significant different that those found in non-smokers exposed to second-hand smoke ≥2 h/day and in non-smokers from control homes.
These results would have to be replicated before they are taken as gospel, but let's say that they are broadly correct.
You would only consider banning the use of e-cigarettes indoors if there was evidence that there was harm being inflicted on bystanders. Glantz assumes—or wants the reader to assume—that a raised level of cotinine/nicotine is indicative of harm. It is not.
Studies like this tend to ignore cotinine in smokers themselves, perhaps because they would provide some useful context. I have written before about the colossal differences in cotinine exposure between smokers and nonsmokers. A systematic review of cotinine readings found that the average smoker has a saliva cotinine reading of 318 ng/ml (and levels seem to be similar in e-cigarette users). This is so far off the scale of what can be found in passive smokers, let alone passive vapers, that it is almost impossible to show on a graph, but let's try anyway.
Smokers produce a thousand times more cotinine than the passive smokers in this new study and two thousand times more than the 'passive vapers'.
Now, we know that the amount of cotinine found in the saliva of smokers is indicative of harm because we know that smoking is bad for health. We know that smoking is bad for health because of epidemiological studies and other evidence, not because of cotinine readings. Cotinine itself is not harmful, nor is nicotine at these kind of levels, and therefore it is only because cotinine readings in smokers can be used as a rough proxy for exposure to the more dangerous chemicals in tobacco smoke that we can associate cotinine with harm.
But this only works if you are dealing with tobacco smoke. If you believe that there is no safe level of tobacco smoke exposure then you can believe that the amount of tobacco smoke absorbed by passive smokers, though orders of magnitude smaller than that absorbed by smokers, poses a degree of risk. Ultimately, that is a question to be settled by epidemiology.
What you can't do, however, is use cotinine as a proxy for dangerous chemicals in tobacco smoke when you are dealing with products that do not contain those chemicals. Glantz has made a basic category error.
Clearly, cotinine readings in the homes of e-cigarette users indicate the presence of nicotine, albeit at an extremely low level. Since nicotine does not cause harm to smokers when they are exposed to it more frequently and in vastly greater concentrations, there is no reason to think that it would cause harm to passive smokers or passive vapers. I'm not aware of any reputable scientist who argues for smoking bans on the basis of nicotine exposure, rather they argue for bans on the basis of exposure to other chemicals that are associated with nicotine in cigarette smoke.
But if you are not dealing with cigarette smoke, cotinine and nicotine are not—and cannot be—used as proxies for other chemicals because those chemicals are not present.
If that seems obvious, it is, but apparently it still needs to be said.