Are Electronic Cigarettes Safe?

Are Electronic Cigarettes Safe? 1

Many people are worried regarding the safety of using electronic cigarettes, citing that they are as yet untested and an unknown quantity. This, however, is just not true.

Every component of the devices and every ingredient in e-liquids has been extensively tested and used over years, even decades.
Electronic cigarettes do not contain the myriad harmful substances found in the smoke produced by burning tobacco; over 3000 chemicals including benzene, hydrogen cyanide, formaldehyde (a common embalming fluid), chromium (a poisonous metal) and polonium-210 (a highly radioactive metal) to name but a few. None of these things are found in the vapour from e cigarettes.

Electronic cigarettes contain propylene glycol, vegetable glycerine, nicotine and food-grade flavourings. Below is a brief overview of these ingredients:

Propylene Glycol

Propylene glycol or PG, one of the major constituents of most e-liquids, is a clear and colourless liquid that is quite viscous. It has been used in a variety of ways for over half a century; for example, it is used in food, medicines, nebulisers and inhalers, and in personal care products. It has been extensively studied for many years and has been classified as GRAS (Generally Regarded As Safe). Consider the following:

“General Toxicity Observations

Upon reviewing the available toxicity information, the Agency has concluded that there are no endpoints of concern for oral, dermal, or inhalation exposure to propylene glycol and dipropylene glycol. This conclusion is based on the results of toxicity testing of propylene glycol and dipropylene glycol in which dose levels near or above testing limits (as established in the OPPTS 870 series harmonized test guidelines) were employed in experimental animal studies and no significant toxicity observed.

Carcinogenicity Classification

A review of the available data has shown propylene glycol and dipropylene glycol to be negative for carcinogenicity in studies conducted up to the testing limit doses established by the Agency; therefore, no further carcinogenic analysis is required.

Mutagenicity Potential

Propylene glycol and dipropylene glycol were tested for mutagenic or genotoxic potential and found to be negative in a battery of studies”.[i]


“Propylene glycol does not present an acute, chronic, reproductive, or developmental hazard. Acute toxicity is very low, with LD50 values exceeding 19000 mg/kg after ingestion or skin contact. It is not a skin or eye irritant, and does not cause sensitization. The weight of the evidence indicates that it is not genotoxic in vitro or in vivo. Adequate long-term feeding studies are available which indicate that it does not represent a cancer hazard.”[ii]

Vegetable Glycerine (Glycerol)

The other constituent of most base liquids is vegetable glycerine, also called glycerol, which is referred to as VG. It is another clear, colourless liquid but is significantly more viscous than PG. A pure VG base liquid will be noticeably thick and syrupy. VG is also classified as GRAS (Generally Regarded As Safe):

“Glycerol is free from structural alerts, which raise concern for mutagenicity. Glycerol does not induce gene mutations in bacterial strains, chromosomal effects in mammalian cells or primary DNA damage in vitro.”

“The weight of evidence indicates that glycerol is of low toxicity when ingested, inhaled or in contact with the skin.”

“For occupational exposure to glycerol mist, typically an exposure limit is applied based on the low toxicity of the aerosol. This value is 10 mg/m3 as an 8-hour time weighted average. (Belgium, Netherlands, Ireland, USA, UK).”

“It has a calculated half-life for photo-oxidation of ~7 hours and is not susceptible to hydrolysis. The experimental data indicate that glycerol is readily biodegradable under aerobic conditions.”

“No further work is indicated, because of the low hazard potential of this substance.”[iii]


Nicotine is the active ingredient in e-liquid, and in tobacco smoke, and is the drug to which one develops an addiction with use.

It is toxic if swallowed, but the concentrations taken by inhalation are far lower and despite the potential hazards of nicotine itself, the MHRA (Medicines and Healthcare products Regulatory Agency) describes it as “a very safe drug”. With the correct risk and safety phrases, appropriate warning symbols, and child-resistant packaging, it is a much safer chemical than other products that are freely available.

Professor John Britton, who leads the tobacco advisory group for the Royal College of Physicians has said,

“Nicotine itself is not a particularly hazardous drug, it’s something on a par with the effects you get from caffeine.

If all the smokers in Britain stopped smoking cigarettes and started smoking e-cigarettes we would save 5 million deaths in people who are alive today. It’s a massive potential public health prize.”

What does it mean when an e-liquid bottle says 16mg or 1.6% nicotine? Are these concentrations high?

Cartridges and e-liquid for electronic cigarettes often contain 16mg of nicotine per ml of liquid, this is a concentration of 1.6%.

One millilitre is a cubic centimetre (or cm3, which equates to one millionth of a cubic meter, the standard unit for volume) with a mass of around 1g (the exact value depends on the liquid in question). This means that a value in mg per ml is roughly equivalent to milligrams per gram, rather than the milligrams of nicotine per milligrams of liquid that a quick glance would lead you to assume.

This means that for a solution to contain 16% nicotine rather than 16mg, it would need to have 160mg per ml.

Passive Vaping

Passive inhalation of substances like tobacco smoke and e-liquid vapour is monitored by the EU PEL (Permissible Exposure Level); the current standard for nicotione is 0.5mg per cubic metre of air (mg/m3) averaged over 8 hours.

The amount of passive, or ‘side-stream’, vapour produced by an electronic cigarette user is almost negligible in terms of  effects on health of those around them. To meet and exceed the PEL in a 10m2 room, one would need to vapourise 5ml of e-liquid at once. No device currently available can do this, and it’s more than likely no device ever will because that volume of vapour is far beyond what any electronic cigarette user desires.
In fact, because nicotine oxidises (breaks down in air) quickly, one would need to vapourise 5ml continuously, all day, to meet the PEL.
As such, many people regard ‘passive vaping’ as a non-issue.

We here at TABlites are proud to offer a cleaner, safer and cheaper alternative to smoking.

We hope this has been helpful for you.

Happy vaping,
 Team TABlites.

[i] United States Environmental Protection Agency, (2006), Reregistration Eligibility Decision for Propylene Glycol and Dipropylene Glycol, EPA-739-R-06-002

[ii] Hernandez, O., (2001), SIDS Initial Assessment Report on 1,2-Dihydroxypropane, January 2001, UNEP Publications
(Inchem is part of the International Program on Chemical Safety, a co-operative effort between international chemical safety and occupational health bodies.)

[iii] Robertson, S., (2002), SIDS Initial Assessment Report on Glycerol, March 2002, UNEP Publications

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