Composition of electronic cigarette aerosol
[1] However, researchers at Johns Hopkins University analyzed the vape clouds of popular brands such as Juul and Vuse, and found "nearly 2,000 chemicals, the vast majority of which are unidentified.
[notes 4][12] The levels of nicotine, tobacco-specific nitrosamines (TSNAs), aldehydes, metals, volatile organic compounds (VOCs), flavors, and tobacco alkaloids in e-cigarette aerosols vary greatly.
[1] The yield of chemicals found in the e-cigarette aerosol varies depending on, several factors, including the e-liquid contents, puffing rate, and the battery voltage.
[23] In 2021, researchers at Johns Hopkins University analyzed the vape aerosols of popular brands such as Juul and Vuse, and found "nearly 2,000 chemicals, the vast majority of which are unidentified.
"[24] E-cigarette vapor contains many of the known harmful toxicants found in traditional cigarette smoke, such as formaldehyde, cadmium, and lead, though usually at a reduced percentage.
[12] Tobacco-specific impurities such as cotinine, nicotine-N'-oxides (cis and trans isomers), and beta-nornicotyrine are believed to be the result of bacterial action or oxidation during the extracting of nicotine from tobacco.
[32] E-cigarette components include a mouthpiece, a cartridge (liquid storage area), a heating element or atomizer, a microprocessor, a battery, and some of them have a LED light at the tip.
[41] For some advanced devices, before inhaling, the user can adjust the heating element temperature, air flow rate or other features.
[45] The evidence indicates that larger capacity tanks, increasing the coil temperature, and dripping configurations seem to be end user modified designs adopted by e-cigarette companies.
[55] Vaping[notes 7] generates particulate matter 2.5 μm or less in diameter (PM2.5), but at notably less concentrations compared to cigarette smoke.
[3] The yield of chemicals found in the e-cigarette vapor varies depending on, several factors, including the e-liquid contents, puffing rate, and the battery voltage.
[14] A 2017 review found that "Adjusting battery wattage or the inhaled airflow modifies the amount of vapor and chemical density in each puff.
[13] Second-generation and third-generation e-cigarettes use more advanced technology; they have atomizers (i.e., heating coils that convert e-liquids into vapor) which improve nicotine dispersal and house high capacity batteries.
[61] Third-generation and fourth-generation devices represent a diverse set of products and, aesthetically, constitute the greatest departure from the traditional cigarette shape, as many are square or rectangular and feature customizable and rebuildable atomizers and batteries.
[62] Cartomizers are similar in design to atomizers; their main difference is a synthetic filler material wrapped around the heating coil.
[61] Clearomizers are now commonly available and similar to cartomizers, but they include a clear tank of a larger volume and no filler material; additionally they have a disposable head containing the coil(s) and wicks.
"[75] A 2015 Public Health England (PHE) report concluded that e-cigarettes "release negligible levels of nicotine into ambient air".
[79] Although several studies have found lower levels of carcinogens in e-cigarette aerosol compared to smoke emitted by traditional cigarettes, the mainstream and second-hand e-cigarette aerosol has been found to contain at least ten chemicals that are on California's Proposition 65 list of chemicals known to cause cancer, birth defects, or other reproductive harm, including acetaldehyde, benzene, cadmium, formaldehyde, isoprene, lead, nickel, nicotine, N-Nitrosonornicotine, and toluene.
[104] A 2020 systematic review found aluminum, antimony, arsenic, cadmium, cobalt, chromium, copper, iron, lead, manganese, nickel, selenium, tin, and zinc, possibly due to coil contact.
[15] Aluminum,[53] antimony,[113] barium,[107] boron,[113] cadmium,[114] chromium,[1] copper,[15] iron,[15] lanthanum,[113] lead,[114] magnesium,[115] manganese,[107] mercury,[116] nickel,[114] potassium,[113] silicate,[15] silver,[15] sodium,[115] strontium,[107] tin,[15] titanium,[107] zinc,[107] and zirconium have been found in e-cigarette vapor.
[81] The metals nickel, chromium, and copper coated with silver have been used to make the normally thin-wired e-cigarette heating elements.
∗The findings are a comparison between e-cigarette daily usage and the regulatory limits of chronic Permissible Daily Exposure from inhalation medications outlined by the US Pharmacopeia for cadmium, chromium, copper, lead and nickel, the Minimal Risk Level outlined by the Agency for Toxic Substances and Disease Registry for manganese and the Recommended Exposure Limit outlined by the National Institute for Occupational Safety and Health for aluminum, barium, iron, tin, titanium, zinc and zirconium,[107] referring to a daily inhalation volume of 20 m3 air and a 10-h volume of 8.3 m3; values are in μg.
[19] In 2015, manufacturers attempted to reduce the formation of formaldehyde and metal substances of the e-cigarette vapor by producing an e-liquid in which propylene glycol is replaced by glycerin.
[32] m-Xylene, p-Xylene, o-Xylene, ethyl acetate, ethanol, methanol, pyridine, acetylpyrazine, 2,3,5-trimethylpyrazine, octamethylcyclotetrasiloxane,[140] catechol, m-Cresol, and o-Cresol have been found in the e-cigarette vapor.
[141] Low levels of isoprene, acetic acid, 2-butanodione, acetone, propanol, and diacetin, and traces of apple oil (3-methylbutyl-3-methylbutanoate) have been found in the e-cigarette vapor.
[145] A 2018 PHE report stated that diacetyl was identified at hundreds of times in lesser amounts than found in cigarette smoke.
[17] E-cigarettes devices using higher voltage batteries can produce carcinogens including formaldehyde at levels comparable to cigarette smoke.
[6] A 2015 study hypothesized from the data that at high voltage (5.0 V), a user, "vaping at a rate of 3 mL/day, would inhale 14.4 ± 3.3 mg of formaldehyde per day in formaldehyde-releasing agents.
"[17] The 2015 study used a puffing machine showed that a third-generation e-cigarette turned on to the maximum setting would create levels of formaldehyde between five and 15 times greater than with cigarette smoke.
[21] But e-cigarette users may "learn" to overcome the unpleasant taste due to elevated aldehyde formation, when the nicotine craving is high enough.
