Research paper
Nicotine levels in electronic cigarette refill solutions: A comparative analysis of products from the US, Korea, and Poland

https://doi.org/10.1016/j.drugpo.2015.01.020Get rights and content

Highlights

  • Nicotine concentrations were measured in 91 e-liquids from US, South Korea, and Poland.

  • We found significant discrepancies in the labelled nicotine concentrations in 19% of products.

  • Traces of nicotine were found in three US products labelled as ‘nicotine free’.

  • A single product labelled as ‘pure nicotine’ contained high concentration of the drug.

  • The study revealed the need for quality standards of the e-liquid products.

Abstract

Background

Electronic cigarettes vaporize nicotine dissolved in glycerine and/or propylene glycol (e-liquid). Due to a lack of regulations, e-liquids may contain inaccurately labelled nicotine levels. Our aim was to test nicotine levels in samples of e-liquids from three countries.

Methods

We measured nicotine concentration in 32, 29 and 30 e-liquids purchased between 2013 and 2014 from locations in the United States (US), South Korea, and Poland, respectively.

Results

Nicotine concentration in the US products varied from 0 to 36.6 mg/mL. Traces of nicotine were found in three US products labelled as ‘nicotine free’. Two-thirds of South Korean products did not contain detectable amounts of nicotine, whereas nicotine concentration in other products varied from 6.4 ± 0.7 to 150.3 ± 7.9 (labelled as ‘pure nicotine’) mg/mL. In products from Poland, nicotine concentration varied from 0 to 24.7 ± 0.1 mg/mL. Overall, we found significant discrepancies (>20%) in the labelled nicotine concentrations in 19% of analysed e-liquids.

Conclusion

Most of the analysed samples had no significant discrepancies in labelled nicotine concentrations and contained low nicotine levels. However some products labelled as ‘nicotine-free’ had detectable levels of the substance, suggesting insufficient manufacturing quality control. We identified a single product labelled as ‘pure nicotine’ which contained significantly higher concentration of the drug, increasing the risk of accidental poisoning. The study reveals the need for quality standards of these new nicotine containing products.

Introduction

Electronic cigarettes (e-cigarettes, ECs) are emerging nicotine delivery devices which operate in an intricate manner. An atomizer within the device allows the nicotine liquid solution (e-liquid) held in a cartridge or reservoir (tank) to be vaporized. The e-liquid consists of a base, typically made from propylene glycol, glycerine, or a mixture of these two substances. When user puffs on the EC, the heating coil inside the device is manually or automatically activated. The e-liquid, when heated, creates the visible vapour which can be inhaled by the user of the device. In addition to producing a smoke-like effect, the base also serves as a solvent for nicotine.

Due to the wide appeal of ECs, they have begun to evolve into a wide range of products to suit the array of customers. The different models of ECs are commonly classified into three main categories based on their functionality and characteristics. The first generation of ECs was built to resemble tobacco cigarettes and thus these products are commonly referred to as ‘cig-a-likes’. They usually contain low-voltage batteries and replaceable e-liquid cartridges, although some devices are disposable. The second generation of ECs has stronger batteries and a larger reservoir for the nicotine solution (tank systems). The latest generations of the product named ‘mods’ or ‘personal vaporizers’ have even stronger batteries, more effective vaporization system, and are often customized. The second and newest generations of the product typically are refillable with e-liquids.

There are relatively few research reports regarding nicotine delivery from ECs; most of the research is based upon first generation devices. Initially, these products were shown to deliver relatively low doses of nicotine compared to tobacco cigarettes, but current devices, which use concentrated nicotine solutions, may deliver nicotine to blood at levels comparable to those derived from tobacco cigarettes (Bullen et al., 2010, Hajek et al., 2015, Vansickel and Eissenberg, 2013, Vansickel et al., 2010). When the efficiency of newer electronic cigarettes is compared to older models, it was reported that there is a 49% increase in nicotine delivery to the bloodstream of the user (Farsalinos et al., 2014). However, it still remains unclear whether various types and models of ECs effectively deliver nicotine to the lungs or the oral mucosa.

ECs emerged onto the international market as an alternative to the traditional tobacco cigarettes. ECs were initially introduced in China in approximately 2003, and quickly gained popularity, spreading across the globe. By the end of first decade of the twenty-first century, the devices had entered the US, European, and Asian markets. The immediate success of ECs serves as a challenge to the current regulatory structure designed for traditional cigarettes, inherently posing some concerns. The new situation may lead to a re-evaluation of the regulation of all products that contain nicotine, including tobacco (Benowitz and Goniewicz, 2013, Etter, 2014, Goniewicz et al., 2014b). Another concern is the lack of mandatory manufacturing standards for ECs on regional and national levels. There are many EC and e-liquid manufacturers, largely in China, Europe and the US, but these products are not manufactured along typical standards imposed on drug delivery devices, and there is a variation in quality control (Benowitz and Goniewicz, 2013, Grana et al., 2014). Therefore, there is no guarantee that the nicotine is of a pure grade, that cartridges are filled according to their label, and that the e-liquids are free of impurities or toxic elements. Other causes of concern may include non-desirable interactions with the packaging material (for example adsorption of nicotine on surfaces inside the bottle, release of chemicals from packaging material into the nicotine solution, or chemical reactions between product ingredients and container material), inadequate handling and storage (Benowitz & Goniewicz, 2013).

Regulations of ECs vary widely across countries, ranging from complete prohibition to unregulated marketing. Manufacturers and distributors of e-liquids are not adequately controlled by the agencies that otherwise control medications and tobacco products, because of the varying policies of each country. This new market has largely developed outside an appropriate regulatory framework, allowing for some manufacturers and vendors to develop, lacking adequate knowledge about product safety (Barboza, 2014). This is particularly concerning when most of these companies do not disclose information regarding their products and manufacturing processes.

In the US, the devices were first popularized by celebrity sponsors and the active advertisement campaign around 2007–2008. The devices were quickly taken under the Food and Drugs Administration's (FDA) jurisdiction as medical devices. However, in 2011 due to the Sottera Inc. vs. FDA case (http://www.gpo.gov/fdsys/pkg/USCOURTS-caDC-10-05032), it was ruled that the FDA could not regulate ECs as medical devices unless the devices themselves were marketed for therapeutic purposes. The FDA is poised to deem ECs as a tobacco product, based on the fact that these products contain nicotine derived from tobacco. In doing so, the FDA would be granted the authority to require EC manufacturer registration and disclosure, to regulate product characteristics, and to regulate the industry's marketing. The current regulation of tobacco products by the FDA requires the consideration of both scientific evidence on the risk and benefits posed by the devices to the individual smokers as well as to the population as a whole. Recently, some US-based companies formed the American E-liquid Manufacturing Standards Association (AEMSA), which has developed the guidelines for nicotine labelling in EC products. According to these guidelines nicotine concentration in e-liquids should be within ±10% of the labelled value (American E-liquid Manufacturing Standards Association, 2014).

ECs made their way to South Korea in 2008 and have since been heavily marketed as an alternative to the conventional tobacco cigarette. The authority to regulate the products is split between the Korean Food and Drug Administration (KFDA) and the Ministry of Finance (MoF). The KFDA has the authority to regulate all products sold without nicotine while the MoF regulates all products containing nicotine. Currently, the legislation in South Korea does not restrict the sale or use of the devices; however the Korean government has heavily taxed the sale of the products. Moreover, the open sales of the products, is coupled with the adolescent-focused advertising. A survey among Korean adolescents conducted in 2011 found that 9.4% have ever used ECs and 4.7% were current EC users with a vast majority of users being tobacco smokers (Lee, Grana, & Glantz, 2014).

In Poland, the consumption of ECs is rising rapidly. It has been estimated that one out of ten Polish have already tried ECs, which in total amounts to about 1.2 million users (Goniewicz et al., 2014c, Prokurat, 2014). Marketing data shows that around 5% percent of ECs bought by Poles comes from local factories, whereas the rest is imported (90% from China, Prokurat, 2014). Since 2010 there has been a dynamic growth of the ECs distribution network with kiosks and stands appearing across the country. Current Polish laws do not yet regulate the ways in which ECs can be sold and used, thus studies have shown an increasing popularity of the devices amongst the Polish youth (Goniewicz and Zielinska-Danch, 2012, Goniewicz et al., 2014a). Even though Polish laws do not regulate this sector, recently, the European Parliament voted to regulate ECs and refill solutions under the Tobacco Product Directive unless they are produced as medicinal devices (European Parliament & the Council, 2014). Beginning in mid-2016, advertising for ECs will be banned in the 28 nations of the European Union, including Poland, which currently serves as the status quo for conventional tobacco products. Containers must be childproof. Lastly, the concentration of nicotine will be limited to 20 mg/mL (European Parliament & the Council, 2014).

The purpose of this international study was to measure nicotine concentration in a sample of popular nicotine refill solutions from three countries: US, South Korea, and Poland. We estimated the accuracy of labelled nicotine concentrations of analysed e-liquids by comparing detected amounts with amounts declared on product packaging.

Section snippets

Products

This study examined popular brands of e-liquids available in the US, South Korean, and Polish markets. Since the Internet remains an important distribution channel for these products, we browsed web search engines, price comparison websites, online marketplaces, and Internet discussion forums for EC users and identified popular brands of e-liquids specific to each country. The products were purchased between July 2013 and August 2014, either online or from regional venues. We purchased a total

Results

The comparison of labelled and determined nicotine concentrations in all e-liquids analysed in the study is presented in Table 1. Nicotine concentration in 32 samples from the United States varied from below limits of quantitation (BLQ; US-28) to 36.6 ± 1.0 (US-21) mg/mL. The differences between labelled and detected nicotine concentrations varied from −92.4% (US-12) to +103.7% (US-30). Nine out of 32 (28%) US products tested in the study showed differences between labelled and detected nicotine

Discussion

The present study looked at the nicotine levels in samples of EC refill solutions from three countries: US, South Korea, and Poland. We found a high diversity in nicotine concentrations of products within each country. In addition, there were some differences in nicotine concentrations across the three countries. For example, a significant proportion (66%) of South Korean products was labelled as ‘nicotine-free’ and did not contain detectable amounts nicotine. In South Korea, these types of

Funding

This study was supported by NIH grant 1R01DA037446-01.

Acknowledgments

The authors thank Noel Leigh for editorial help.
Conflicts of interest

MLG reports a grant from Pfizer (2011 Global Research Award for Nicotine Dependence), a manufacturer of smoking cessation drugs, outside the submitted work; AS reports personal fees from eSmoking Institute, Poznan, Poland, and nonfinancial support from Chic Group LTD, a manufacturer of electronic cigarettes in Poland, outside the submitted work. The other authors have nothing to disclose.

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