Electronic cigarettes (ECs) are battery-powered devices that produce an inhalable aerosol by heating a liquid solution of humectants (usually propylene glycol or glycerol), nicotine, and flavorings (Kalkhoran and Glantz, 2016). ECs entered the United States (U.S.) market in 2007 and began to gain widespread popularity in 2014 (Lichtenberg, 2017). Companies initially marketed ECs as harm reduction substitutes for individuals who use combustible cigarettes (CC) (Bhalerao et al., 2019) as they reduced exposure to toxicants produced through combustion (National Academies of Sciences et al., 2018). Additionally, ECs were seen as a device that could help individuals who use CCs quit. A recent meta-analysis found moderate evidence that ECs with nicotine increased quit rates for at least six months and resulted in higher cessation rates compared to ECs without nicotine and nicotine replacement therapy (Hartmann-Boyce et al., 2021). However, the 2020 Surgeon General’s Report on smoking cessation stated there is inadequate evidence on the efficacy of ECs for smoking cessation among adults and they are not approved by the Federal Drug Administration (FDA) for this purpose (National Center for Chronic Disease P, 2014).

From a harm reduction perspective, complete substitution of ECs for CCs, as reported by the National Academies of Sciences, Engineering, and Medicine, reduces exposure to toxic combustion gases and particles for people who smoke CCs (National Academies of Sciences et al., 2018). Short-term evidence has shown that the levels of toxicants such as formaldehyde, acetaldehyde, acrolein and toluene (Goniewicz et al., 2014) are significantly lower in ECs compared to CCs, supporting the idea that substitution of ECs for CCs may reduce exposure to tobacco-specific toxicants (Hartmann-Boyce et al., 2022). Hence, completely switching from CCs to ECs will likely result in reduced short-term adverse health outcomes (Hartmann-Boyce et al., 2021). A recent randomized clinical trial (RCT) looked at the effect of fourth generation pod-based ECs on carcinogen exposure among Black and Latinx who smoke (Pulvers et al., 2020). This study found that individuals who smoke and were randomized to receive 4th generation ECs (5% nicotine) for 6 weeks were more likely to quit CCs, smoke fewer CCs in the past seven days, and have lower levels of biomarkers of tobacco exposure 4-(methylnitrosamino)− 1-(3-pyridyl)− 1-butanol (NNAL) and carbon monoxide (CO) at 6-week follow-up compared to those randomized to the control condition of continued CC smoking (Pulvers et al., 2020). At week 6 of this study, 28.1% of participants in the EC group exclusively smoked ECs, 57.9% used both ECs and CCs, and 14.0% used CCs exclusively (Pulvers et al., 2020).

One factor that plays a role in switching and product use decision for people who smoke CCs is the initial perception of the harmfulness of ECs compared to CCs. Prior studies suggest low to moderate EC knowledge (Coleman et al., 2016, Sanders-Jackson et al., 2015, Tan et al., 2016, Sutfin et al., 2011) and beliefs that ECs are healthier and more socially acceptable than CCs among predominately White people who smoke CCs and nonsmokers (Coleman et al., 2016). One review found that adult and youth who use ECs, CCs, both ECs and CCs, and those who use neither of these products perceived ECs as healthier, safer, and less addictive than CCs (Romijnders et al., 2018). Additionally, predominantly White adults who use both ECs and CCs who perceive ECs as less harmful were more likely to switch to exclusive EC use (Persoskie et al., 2019). However, EC risk perceptions are changing. While some studies prior to 2014 showed that ECs were perceived as less harmful than CCs, following studies have found ECs are perceived as equally or more harmful than CCs among adults who smoke CCs, individuals who don’t smoke CCs and ECs, and youth who smoke CCs (Romijnders et al., 2018).

There is limited research on EC risk perception by race/ethnicity. One study found that Black and Hispanic participants who smoke were more likely to believe ECs were more harmful than CCs and less likely to begin using ECs in the context of smoking cessation compared to White participants who smoke (Harlow et al., 2019). Similarly, another study found that Black participants had lower EC health risk perceptions (i.e. ECs are less harmful to health than CCs), compared to both White and Hispanic participants who smoke (Webb Hooper and Kolar, 2017). Harm perceptions of ECs have largely been studied in predominately White people who smoke and/or predominately White youth and young adults.

Few studies have examined risk perception differences between racially and ethnically minoritized groups and many are limited in demonstrating switching behaviors. One study looking at primarily White U.S. adults who use both ECs and CCs found that those who deemed ECs as “less harmful” than CCs were more likely to switch to exclusive EC use, more likely to continue smoking both ECs and CCs, and less likely to switch to exclusive CC use one year later compared to individuals who smoke both ECs and CCs who had an EC risk perception of “about the same,” “more harmful,” or “don’t know” (Persoskie et al., 2019). Similar studies should be conducted for Black and Latinx individuals who smoke.

Given the disproportionate burden of smoking-related death and disease among minoritized groups compounded with the low rates of switching from CCs to ECs among these populations, (Harlow et al., 2019, Friedman and Horn, 2019) it is important to study switching patterns among Black and Latinx individuals who smoke CCs. Furthermore, with increases in targeted tobacco advertising in racially and ethnically minoritized neighborhoods, (Baumann et al., 2015) it is important that we gain insight into the current perceptions these populations have about ECs to better tailor public health interventions and research to specific population groups with the ultimate goal of smoking cessation.

The primary objective of this study was 1) to examine whether change in risk perception of ECs predicts the number of cigarettes smoked per week (CPW) at the end of a 6-week RCT. The secondary objectives of this study were 2) to examine how race/ethnicity moderates the relationship between change in risk perception of ECs and CPW, and 3) to compare change in risk perception of EC use between Black and Latinx participants. We hypothesize that 1) people whose risk perception of ECs increases will have higher CPW at week 6 compared to those whose risk perception of ECs decreases, 2) compared to Latinx individuals, Black individuals will be less likely to experience an increase in CPW as EC risk perceptions increase because they are more likely to have overall lower EC risk perception and lower rates of CPW, and 3) given that prior literature showed Black individuals perceived ECs to have less health risks than White and Latinx individuals, (Webb Hooper and Kolar, 2017) we hypothesize that Black individuals who smoke will be more likely to decrease their EC risk perceptions compared to Latinx individuals.