'Real-world' compensatory behaviour with low nicotine concentration e-liquid: subjective effects and nicotine, acrolein and formaldehyde exposure

Addiction. 2018 Oct;113(10):1874-1882. doi: 10.1111/add.14271. Epub 2018 Jun 19.


Aims: To compare the effects of (i) high versus low nicotine concentration e-liquid, (ii) fixed versus adjustable power and (iii) the interaction between the two on: (a) vaping behaviour, (b) subjective effects, (c) nicotine intake and (d) exposure to acrolein and formaldehyde in e-cigarette users vaping in their everyday setting.

Design: Counterbalanced, repeated measures with four conditions: (i) low nicotine (6 mg/ml)/fixed power; (ii) low nicotine/adjustable power; (iii) high nicotine (18 mg/ml)/fixed power; and (iv) high nicotine/adjustable power.

Setting: London and the South East, England.

Participants: Twenty experienced e-cigarette users (recruited between September 2016 and February 2017) vaped ad libitum using an eVic Supreme™ with a 'Nautilus Aspire' tank over 4 weeks (1 week per condition).

Measurements: Puffing patterns [daily puff number (PN), puff duration (PD), interpuff interval (IPI)], ml of e-liquid consumed, changes to power (where permitted) and subjective effects (urge to vape, nicotine withdrawal symptoms) were measured in each condition. Nicotine intake was measured via salivary cotinine. 3-Hydroxypropylmercapturic acid (3-HPMA), a metabolite of the toxicant acrolein, and formate, a metabolite of the carcinogen formaldehyde, were measured in urine.

Findings: There was a significant nicotine concentration × power interaction for PD (P < 0.01). PD was longer with low nicotine/fixed power compared with (i) high nicotine/fixed power (P < 0.001) and (ii) low nicotine/adjustable power (P < 0.01). PN and liquid consumed were higher in the low versus high nicotine condition (main effect of nicotine, P < 0.05). Urge to vape and withdrawal symptoms were lower, and nicotine intake was higher, in the high nicotine condition (main effects of nicotine: P < 0.01). While acrolein levels did not differ, there was a significant nicotine × power interaction for formaldehyde (P < 0.05).

Conclusions: Use of a lower nicotine concentration e-liquid may be associated with compensatory behaviour (e.g. higher number and duration of puffs) and increases in negative affect, urge to vape and formaldehyde exposure.

Keywords: Acrolein; E-cigarette; compensatory behaviour; formaldehyde; nicotine; puffing patterns; subjective effects.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Acetylcysteine / analogs & derivatives
  • Acetylcysteine / urine
  • Acrolein
  • Adult
  • Cotinine / analysis
  • Craving
  • England
  • Female
  • Formaldehyde
  • Formates / urine
  • Humans
  • Inhalation Exposure / statistics & numerical data
  • Male
  • Middle Aged
  • Nicotine / administration & dosage*
  • Nicotine / adverse effects
  • Nicotinic Agonists / administration & dosage*
  • Nicotinic Agonists / adverse effects
  • Saliva / chemistry
  • Substance Withdrawal Syndrome / etiology
  • Vaping*
  • Young Adult


  • Formates
  • Nicotinic Agonists
  • formic acid
  • Formaldehyde
  • Nicotine
  • Acrolein
  • S-(3-hydroxypropyl)cysteine N-acetate
  • Cotinine
  • Acetylcysteine