Cardiovascular Health Effects and Synthetic Cooling Agents in E-Cigarettes Labeled as "Clear" Marketed in Massachusetts After the Tobacco Product Flavoring Ban.

After Massachusetts enacted regulation on flavored tobacco products in 2020, electronic cigarettes (e-cigarettes) labeled "clear" emerged in the state. We studied their acute hemodynamic impact and chemical composition. In participants (age 18-45 years) in the Cardiovascular Injury due to Tobacco Products 2.0 study (Boston, MA), we measured changes in blood pressure and heart rate following a structured use of participants' own e-cigarettes. We compared "clear" e-cigarette users (N=23) with non-"clear" flavored e-cigarette users (N=111) and nonusers (N=73). We used gas chromatograph coupled with mass spectroscopy to characterize and quantify the presence of synthetic cooling agents (WS-3, WS-23), menthol, and nicotine, and other flavorants in 19 "clear" e-cigarettes. All "clear" e-liquids contained the synthetic cooling agents WS-23 and/or WS-3, 18/19 contained menthol, and 12/19 products contained other flavorants. JUUL e-liquids did not contain synthetic coolants. Baseline blood pressure and heart rate measures were similar between "clear" and non-"clear" flavored e-cigarette users. Following acute use, "clear" e-cigarettes resulted in a greater increase in blood pressure and heart rate compared to both non-"clear" flavored e-cigarette use and nonuse, which remained largely consistent in multivariable models. For sensitivity analysis of comparing "clear" users to the subgroup of JUUL non-"clear" flavored users, the directions of associations were similar. The presence of synthetic cooling agents along with traditional flavorants in "clear" e-cigarette products available in the Massachusetts marketplace undermines the efficacy of the flavor ban. The potential that "clear" e-cigarettes induced more pronounced hemodynamic effects necessitates further study of the health impact of these products and synthetic cooling agents. URL: https://www.medrxiv.org/content/10.1101/2024.04.18.24305863v1, medRxiv. 10.1101/2024.04.18.24305863.