Dual users have significantly lower toxicant exposure than exclusive smokers, review

Posted on October 9, 2022 By Colin

A NEW REVIEW has confirmed that toxic chemicals are significantly reduced in dual users (both smoking and vaping) trying to quit, compared to exclusive smoking.

The review analysed 9 studies of smokers trying to quit and 14 harmful toxicants in the saliva, blood and urine of dual users. Levels of 13 of the toxicants were significantly reduced in dual users compared to smokers, with no difference for one chemical.

Reductions were found in nitrosamines, polycyclic aromatic hydrocarbons, mercapturic acids and other known carcinogens.

This analysis debunks the claim by vaping opponents that dual use does not reduce harm and may increase it.

Dual use is more harmful than exclusive vaping and dual users should aim to quit smoking as soon as they can.

What is dual use?

Dual use is a normal, transition phase for many smokers trying to quit, just as it is with nicotine replacement therapy. Some smokers quit smoking soon after they start vaping. Others take longer and smoke and vape for a period while trying to transition to exclusive vaping.

Dual use is less harmful than exclusive smoking because most dual users who are trying to quit substantially reduce their smoking.

Many studies show improvements in health in dual users, such as blood pressure and asthma

This is also occurs with smokers trying to quit with nicotine replacement therapy. When smokers get nicotine from other sources (vaping or NRT) they smoke less.

Dual users are more likely to quit smoking than other smokers, especially if vaping daily. Studies have typically found that 20-45% of dual users quit smoking over the next one to two years

Dual users are a mixed group and some smoke more heavily and vape occasionally and others smoke occasionally and vape regularly.

Dual users are more nicotine-dependent than exclusive smokers and some will take longer to quit smoking altogether. Many will not be able to quit smoking in a given attempt.

How common is dual use?

At any one time, less than half the people vaping are dual users: in Australia 54%, Great Britain 35% and in the United States 35-39%. Studies show that the rate of dual use has declined over time as more dual users switch to exclusive vaping.


Hartmann-Boyce J et al. Biomarkers of potential harm in people switching from smoking tobacco to exclusive ecigarette use, dual use, or abstinence: Secondary analysis of Cochrane systematic review of trials of e-cigarettes for smoking cessation. Addiction 2022

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