An assessment of e-liquid label accuracy in Aotearoa New Zealand

E-liquid, also known as vape juice, contains nicotine, flavourings and a base (usually propylene glycol and vegetable glycerin) that can be converted into aerosol for inhalation using a vaping device. The Smokefree Environments and Regulated Products (Vaping) Amendment Act 2020 marked the first attempt to regulate vaping products in Aotearoa New Zealand.¹ However, the statute did not anticipate the rapid growth in vaping product technology, particularly the evolution of nicotine salt products, which typically have higher nicotine concentrations than e-liquids containing freebase nicotine. Disposable nicotine salt vapes appealed to children, and youth vaping rates rose rapidly from 2019, though recent data suggest they have declined slightly since the peak in 2022.^2,3 In response to pressure from parents and health groups,⁴ the Government introduced new product safety requirements in December 2023, including reducing the nicotine concentration limit in single-use vapes to 20mg/ml and to 28.5mg/ml in reusable vaping products containing nicotine salts.

Internationally, researchers have found the accuracy of nicotine concentration labelling highly variable.⁵ A systematic review of 20 cross-sectional studies (published 2011–2019) examined deviations of more than ±10% between the nicotine concentration stated in labels and the concentration found following analysis of e-liquids.⁶ It found nearly half (48.3%) of the 574 samples analysed differed from the reported concentration, with both under-reporting and over-reporting of nicotine content commonplace.

Although the Institute of Environmental Science and Research (ESR) routinely assesses the nicotine concentration of e-liquids, under contract from the Ministry of Health – Manatū Hauora, the findings are not reported publicly. Therefore, people who use vaping products cannot assess the accuracy of product labelling. We obtained data from the ESR testing programme and assessed the accuracy of nicotine concentration labels on e-liquids sold in Aotearoa New Zealand.

Methods

We obtained the data via an Official Information Act (OIA) request to the Ministry of Health – Manatū Hauora seeking the results of ESR’s e-liquid analyses. (Contact the corresponding author for the full OIA response document.) We received test results from 221 vaping products available on the Aotearoa New Zealand market that ESR had selected randomly from the Health Advisory and Regulatory Platform (HARP) database of notified products and tested between June 2023 and June 2024. The categories for product notification, which were also used by ESR, were vaping “devices” (n=32) i.e., prefilled disposable vapes; and “substances” (i.e., e-liquids and prefilled pods), which were subdivided into freebase (n=21) or nicotine salt (n=168).

We analysed differences between the reported and actual nicotine concentrations in mg/ml, and relative percentage differences between the reported and actual nicotine concentrations.

Results

View Table 1.

As shown in Table 1, among 221 samples, 58.4% (129 samples) deviated by ≥10% from their labelled nicotine concentration. Of those, six (4.7% of samples) had a nicotine concentration greater than the stated nicotine concentration (range between 10.4% and 23.3% greater); the average deviation was 13.9%.

Of the samples with a ≥10% deviation in nicotine concentration, 123 out of 129 (95.3%) had less nicotine than the product label stated (average 40.6% less, range between 10.4% and 66.0% less). Some contained substantially less nicotine than stated, with 39 samples (30.2%) containing ≥50% less (average 57.3% less, range between 50.3% to 66.0% less).

When analysed by sample type, vaping devices were more likely than other products tested to fall outside the 10% range (75%) (24/32), followed by nicotine salt e-liquids (58.9%, 99/168) and freebase nicotine e-liquids (28.6%, 6/21).

Discussion

Our findings reveal significant discrepancies in nicotine labelling, emphasising the need for stricter regulatory oversight of Aotearoa New Zealand’s e-liquid market.

Both under- and over-reporting of nicotine concentration pose risks to people who use vaping products. People attempting to quit smoking using vaping products may find the transition from smoking to vaping more difficult if the e-liquids they use contain less nicotine than stated on the label. Furthermore, they may vape more frequently or inhale more deeply to meet their need for nicotine, potentially increasing their exposure to heavy metals and other toxicants. In the worst case, these people may find vaping does not satisfy cravings and revert to smoking.⁷ Conversely, people using nicotine recreationally may face a greater risk of addiction if they unwittingly use products containing more nicotine than described on packaging.

Our findings align with a 2021 systematic review that found nearly half (48.3%) of the 574 samples analysed differed from the reported concentration. However, this review found considerable variability in the direction of the differences reported whereas we found products predominantly had less nicotine than stated on the label.⁶ Ongoing monitoring will be important to assess whether different samples show more variability or if over-reporting continues to be the dominant finding in Aotearoa New Zealand.

While e-liquids are often marketed as a safer alternative to smoking, inaccuracies in labelling may mislead consumers and potentially contribute to unsafe use. This finding is particularly concerning for young people, who may be physiologically more susceptible to nicotine addiction,⁸ and who have been targeted by vaping product manufacturers using appealing flavours and packaging.⁹

Limitations

The sample did not include any e-liquids with a reported 0mg/ml nicotine concentration; however, United States (US) research has found that 91% of US-manufactured e-liquids labelled 0mg/ml contained nicotine.⁵ Nicotine concentration in these samples ranged from 5.7mg/ml to 23.9mg/ml.⁵ The absence of 0mg/ml nicotine samples highlights an opportunity to extend future testing to ensure people using zero nicotine vaping products to stop smoking can feel confident they will not be exposed to nicotine.

Our study focussed solely on nicotine; given the potential for mislabelling of other ingredients, or inclusion of disallowed ingredients in e-liquids, future testing should be more comprehensive. For example, US researchers investigating alcohol concentration in e-liquids found that alcohol was present in 33 of the 35 e-liquid samples labelled as only containing nicotine.¹⁰ Laboratory studies have shown that alcohol significantly impacts e-liquids by altering their physiochemical properties, and increasing aerosol production and the amount of nicotine deposited in the airways, which may heighten their addictive potential.¹¹ In Aotearoa New Zealand, ESR tested ethanol content in a subsample of 30 products, but compliance with alcohol labelling regulations has not been evaluated as far as we are aware. Future research should investigate this question, test for disallowed ingredients (e.g., colourings) and assess whether other regulated substances (e.g., formaldehyde, heavy metals) exceed specified limits.

Finally, we did not examine the cause of any discrepancies, which future research should also explore.

Conclusion

Our findings underscore the urgent need to enforce regulatory standards for e-liquid nicotine concentration, particularly given the government’s reliance on vaping as a means to reduce smoking prevalence.¹² Greater transparency about product testing results and any subsequent regulatory action is needed.