Friday, August 09, 2013

Review of Laboratory Studies on Electronic Cigarettes Concludes that They Pose Few Health Risks and that Secondhand Vapor is Unlikely to Be Hazardous

A new study which reviews approximately 40 laboratory studies of the chemical constituents of electronic cigarette vapor concludes that these products pose few health risks and that secondhand vapor is unlikely to pose any significant health hazard.

(See: Burstyn I. Peering through the mist: What does the chemistry of contaminants in electronic cigarettes tell us about health risks. Philadelphia, PA: Drexel University School of Public Health, 2013.)

The major conclusion of the report is that vaping poses few health concerns and that "passive vaping" is unlikely to pose any health concerns.

What are the few health concerns potentially associated with vaping? The study confirms that the concerns are as I have outlined them previously:

1. Concern about potential respiratory effects of long-term inhalation of propylene glycol; and
2. Concern about long-term exposure to low, but measurable levels of formaldehyde and acrolein.

Diethylene glycol (i.e., anti-freeze) is not a health concern, despite the continuing warnings from the FDA. Neither are the presence of tobacco-specific nitrosamines, again despite the continuing warnings from the FDA. Metals also do not appear to be a major concern.

The report concludes that "secondhand vaping" is unlikely to have any significant health risks.

The Rest of the Story

This study appears to confirm my assessments of the health risks of vaping and passive vaping, which I have shared over the past several months. The issues that the FDA should focus on are:

1. Study of potential long-term respiratory effects of propylene glycol inhalation; and
2. Methods to reduce the formation of formaldehyde in electronic cigarettes.

The study demonstrates that anti-smoking advocates and groups which continue to argue that we know nothing about the potential health effects of electronic cigarettes are wrong. For example, the American Lung Association recently stated that: "Until the Obama administration and the Food and Drug Administration assert their authority to regulate e-cigarettes and force manufacturers to disclose what ingredients are in them, their safety or harm cannot be assessed."

This statement is simply untrue. We actually have a very good understanding of the ingredients in electronic cigarettes (which are nicotine, propylene glycol, glycerin, and flavorings). We also have a good understanding of the constituents in e-cigarette vapor. Moreover, the safety or harm of these products can most certainly be assessed.

While further research is necessary to assess potential long-term respiratory effects of vaping and to figure out ways to minimize exposure to certain volatile organic compounds (especially formaldehyde), there is strong evidence that:

1. Vaping is much safer than smoking;
2. Potential health risks associated with vaping are relatively small; and
3. It is unlikely that passive vaping has any significant health effects.

UPDATE (August 9th, 2013 - 9:00 a.m.) -- Stan Glantz has just released a criticism of this report, in which he argues that the TLV's (threshold limit values) are not the appropriate standard to be used in judging long-term exposures such as vaping. On this basis, he discounts the report.

I actually agree with Stan's argument. However, I disagree that the report should be discounted or that its ultimate conclusions are incorrect.

Stan is correct that the TLV's are not the appropriate standard to use for long-term, daily exposures such as vaping. These standards are for use with acute occupational exposures. They are designed for the occupational setting only. In fact, if you apply TLV's to secondhand smoke, you'll find that many of the TLV's are not reached. This doesn't mean that secondhand smoke isn't harmful.

However here's the problem: Although the report errs by comparing the exposures to TLV's, it nevertheless does provide the actual levels of exposures to each of the constituents. We can still make judgments about the magnitude of these exposures based on their absolute levels, without using any TLV threshold. Based on the observed levels of these exposures, they are unlikely to be of great concern. For example, it would take many years of exposure to formaldehyde at the exposure level observed to pose any carcinogenic risk, and that risk would be quite small. The same is true for the observed levels of metals as well as tobacco-specific nitrosamines. Most of these chemicals are present at levels that are similar in nicotine inhalers.

So I agree with Stan that the TLV limits are irrelevant, but I don't agree that the report can be thrown in the trash. We can still evaluate the absolute exposure levels observed, and those are quite small.

Once again, I think the main issues of concern are whether there are potential respiratory effects of long-term propylene glycol inhalation and whether there are ways to reduce the presence of the few volatile organic compounds, especially formaldehyde and acrolein.

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