Effects of e-liquid flavor, nicotine content, and puff duration on metal emissions from electronic cigarettes


Vaping is taking in and exhaling aerosols emitted by electronic cigarettes. The aerosols can contain varying amounts of harmful chemicals, such as metals. This study aimed to determine the elements that influence the concentration of metals, including the nicotine content and flavor in the e-liquid as well as the duration of puffs. Aerosols were gathered from the closed-system (cartridge-based) or open-system e-cigarettes, using liquids with various flavors (fruit tobacco, tobacco, and menthol) as well as nicotine levels (0 6, 24 as well as 59 mg/mL) and various puff durations (1 2, 3, and 4 seconds). The inductively-coupled plasma mass spectroscopy determined the levels of 14 different metals in the collected aerosols. The concentrations in As, Fe, and Mn aerosols varied considerably between tobacco, fruit, and menthol flavors in both open-system and closed-system devices. The attention for Al, Fe, Sn, and U was significantly higher in menthol or tobacco-flavored aerosols when compared with fruit flavors found in closed-system devices. Levels of aerosol W were considerably higher in the tobacco-flavored aerosols than in fruit flavors found on open-system devices. Amounts in As, Fe, and Mn were more significant in the aerosols that had a tobacco flavor when compared with menthol flavors on both kinds of devices. Median Pb concentration fell substantially between 15.8 to 0.88 mg/kg as nicotine levels increased from 0 mg/mL to 59 mg/mL. Median Ni concentrations were 9.60 times greater in aerosols containing 59 mg/mL of nicotine than the 24 mg/mL (11.9 and 1.24 mg/kg) for closed-system devices. There were no significant differences in the concentrations of metals in aerosols for different puff durations. Metal concentrations in aerosols varied among different flavors and nicotine content but not based on the length of the breath. The flavor and nicotine content of the e-liquid might be sources of metal emissions. Certain elements had higher concentrations in certain conditions, highlighting the need for developing strict product guidelines, specifically regarding the composition of e-liquids and nicotine content, to inform users of the risk of exposure to metals through vaping.


Metal components of electronic cigarette (e-cigarette) cartridges as well as devices could expose e-cigarette users to a range of metals such as (but not only) chrome (Cr) as well as lead (Pb) as well as nickel (Ni), and tin (Sn) and all of which are found in electronic cigarettes’ hardware, including the heating elements and solder joint (Aherrera and co. 2017, Goniewicz as well. 2014; Hess et al. 2017, 2017; Mikheev et al. in 2016; Zhao et al., 2020). In the study of 64 electronic cigarettes customers, Cr and Ni levels in urine and saliva were significantly associated with the stories of metals present in the aerosols from e-cigarettes (Aherrera et al., 2017), which raises concerns about the health-related effects that could be a result of metals, which include respiratory disease, cardiovascular disease, and lung cancer (IARC 2012a, 2012b; Jaishankar et al., 2014; Navas-Acien, et the. in 2020). In addition, Studies have demonstrated that smoking e-cigarettes can lead to over-reaching MRLs (MRL) for Mn and Ni (Zhao et al.., 2019). There is substantial variability in metal content in e-cigarette aerosols and e-liquids (Na et al., 2019; Gaur et al., 2019; Fowles et al., 2020). Therefore, it is crucial to determine how various environments can impact the metal concentrations in aerosols ingested by users.

The flavors in e-liquids significantly influence the use of e-cigarettes by youth. In the 13,651 US adolescents aged 12-17, 81% of people who use e-cigarettes said they began vaping due to the availability of flavor-infused products (Ambrose & Co., 2015). In January 2020, the US Food and Drug Administration (FDA) announced the removal of sweet-flavored e-liquids from the market of cartridge-based electronic cigarettes (closed-system) that are appealing to youngsters. The flavors currently not allowed include dessert, fruit, and mint. However, tobacco and menthol-flavored products are still widely available and can also be attractive to young people (FDA, 2020). A study found higher exposure to benzaldehyde for consumers of e-liquids with cherry flavor in comparison to users of nicotine-containing sweet, tobacco mint, mint, and different flavors (5.1-141.2 and. 0.03-10.3 mg per 30 puffs) (Kosmider and colleagues. (2016)). The impact that flavors could have on tobacco or menthol products and on the aerosol levels of metals has yet to be discovered and warrants more research.

Many users of electronic cigarettes consider nicotine content was deemed to be the third important aspect, following price and flavor in deciding on e-cigarettes or liquids derived from e-cigarettes (Laverty & Co., 2016). Nicotine content differs among e-cigarette brands; sure electronic cigarettes permit the use of e-liquids with different nicotine content, including no nicotine, whereas others, like JUUL, offered just one high nicotine content in 2017. (Cameron and al., 2014; Kavuluru et al., 2019). 2014; Kavuluru et al. 2019). One study, which looked at primarily cigalikes, revealed that As Cr, As Ni Sb, Sn, and Zn levels varied significantly between aerosols containing and without nicotine (Mikheev et al. (2016)). Cigalike devices are generally first-generation devices and do not represent E-cigarettes currently available. The effect of the amount of nicotine consumed on metal levels from mod and tank devices that allow users to refill their atomizers with e-liquids that differ in nicotine level remains unknown.

Puff topography, precisely puff duration, is an established aspect that can influence how toxic traditional cigarettes are (Maziak and al., 2011; Reilly et al., 2017). (2011); Reilly et al. 2017) may also affect the emissions of e-cigarettes to metal. The duration of a puff varies greatly for e-cigarette users (range: 1.9-8.3 s) as well as an average of that is 4 seconds (Farsalinos al., 2013a; Farsalinos et al., 2013a, Hua and. (2013)). Most studies on e-cigarette emissions’ elements have employed four seconds. It has been suggested that the excess concentrations of metals in the aerosols were related to the duration of puffs (Williams and Co., 2019). The evaluation of vaping topography, particularly the length of time a breath lasts, is essential to evaluate the possible variations in the concentrations of metals in the aerosols inhaled by users.

In a prior study, we observed that the device type and power settings are the main factors determining metal concentrations in the aerosol produced by electronic cigarettes (Zhao and al. 2019, 2019). The present study analyzed the effect of the flavor of e-liquid and nicotine content, as and the duration of puffs, on the emission of metals from aerosols.

Section Snippets

E-cigarettes and the characteristics of e-liquid

Four electronic cigarettes from the commercial market comprising two closed-system units (CD) and both pods and two devices that are open system (OD) and both mods were examined. These devices, the CDs BLU and JUUL, are classified as CD1 and CD2, respectively. In addition, the ODs Istick Pico 25 and SMOK Alien 220 are identified as OD1 and OD2.

An array of sixteen different e-liquids in taste and nicotine content were tested during this investigation (Table 1.). In each gadget, e-liquids from three flavors were bought, such as tobacco, fruit, and

Aerosol concentrations of metals in E-liquid flavor

For closed-system devices, we observed statistically significant variations among As, Fe, Mn Pb Sb, Sn, and U concentrations between tobacco, fruit, and menthol-flavored aerosols (Table 2; Figure. 1). When comparing tobacco and fruit flavors, the median Al, Fe, Sn, and U aerosol concentrations were 2.71, 1.65, 1.38 and 1.5 times more for tobacco flavors as well as it was found that the mean Pb level was 2.6 times less. In comparing menthol and fruits flavors, the Mn levels were lower (0.53 against. 1.39 mg/kg)


Concentrations of the metals in aerosols were influenced by the flavor of the e-cigarette and nicotine content but not by the length of the puff. The concentrations for As, Fe, and Mn differed significantly between tobacco, fruit, and menthol flavors on both open-system and closed-system devices. In closed-system devices, the attention of Al, Fe, Sn, and U was substantially higher for menthol or tobacco flavorings than for fruit flavors. In open-system devices, the concentrations of aerosol W are considerably greater for flavors of tobacco.


In general, e-cigarettes can be sources of exposure to various poisonous metals. Tobacco and menthol-flavored aerosols are available on the US market and may cause greater exposure to Al, Fe, Sn U, W, and Al than other flavors. Metal levels differ widely between different nicotine content, even though no apparent changes in the emission of metals were observed with increased nicotine levels. Our results do not suggest an impact significant of the time between puffs on the level of metals in aerosols.

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