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Even a puff of some flavoured e-cigarettes contain dangerous levels of hazardous chemicals known to cause cancer in humans, a new study has found.
The study confirms that these toxic chemicals are formed not by evaporation, but rather during the chemical breakdown of the flavoured liquid during the rapid heating process (pyrolysis) that occurs inside e-cigarettes or electronic nicotine delivery systems (ENDS).
“How these flavouring compounds in e-cigarette liquids affect the chemical composition and toxicity of the vapour that e-cigarettes produce is practically unknown,” said Andrey Khylstov, from the Desert Research Institute (DRI) in the US.
“Our results show that production of toxic aldehydes is exponentially dependent on the concentration of flavouring compounds,” said Khylstov.
Researchers measured concentrations of 12 aldehydes in aerosols produced by three common e-cigarette devices.
To determine whether the flavouring additives affected aldehyde production during vaping, five flavoured e-liquids were tested in each device. Two unflavoured e-liquids were also tested.
“To determine the specific role of the flavouring compounds we fixed all important parameters that could affect aldehyde production and varied only the type and concentration of flavors,” said Vera Samburova, professor at DRI.
Samburova said that the devices used in the study represented three of the most common types of e-cigarettes – bottom and top coil clearomisers, and a cartomiser.
The study avoided any variation in puff topography (eg puff volume, puff velocity, interval between puffs) by utilising a controlled sampling system that simulated the most common vaping conditions.
E-cigarette vapour was produced from each device by a four-second, 40 ml controlled puff, with 30 second resting periods between puffs.
The e-cigarette devices were manually operated to replicate real-life conditions and all samples were collected in triplicate to verify and confirm results. Specific care was taken to avoid “dry puff” conditions.
To provide further proof that the flavouring compounds, not the carrier e-liquid solvents dominated production of aldehydes during vaping, the researchers performed a series of experiments in which a test flavoured e-liquid was diluted with different amounts of the unflavoured e-liquid.
Liquids with higher flavour content produced larger amounts of aldehydes due to pyrolysis of the flavouring compounds.
In all experiments, the amount of aldehydes produced by the flavoured e-cigarette liquids exceeded the American Conference of Governmental Industrial Hygienists Threshold Limit Values (TLVs) for hazardous chemical exposure.
“One puff of any of the flavoured e-liquids that we tested exposes the smoker to unacceptably dangerous levels of these aldehydes, most of which originates from thermal decomposition of the flavouring compounds,” said Khylstov.
The research was published in the journal Environmental Science and Technology.
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