Nicotine salts are salts formed from nicotine and an acid.[1] They are found naturally in tobacco leaves.[2] Various acids can be used, leading to different conjugate bases paired with the ammonium form of nicotine.
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Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Research
editResearch on nicotine salts is limited.[3] Possible health risks of persistent inhalation of high levels of nicotine salts are not fully known.[3] "Juul products use nicotine salts, which can lead to much more available nicotine," Principal Deputy Director Dr. Anne Schuchat of the Centers for Disease Control and Prevention (CDC) stated in September 2019.[4] She also stated that the nicotine salts "cross the blood brain barrier and lead to potentially more effect on the developing brain in adolescents."[4]
Recent research has further highlighted potential health risks associated with nicotine salts. A 2024 study from the University of Louisville raised concerns about the cardiovascular effects of nicotine salts, particularly when used in pod-based devices like Juul. The study found that higher concentrations of nicotine salts may increase the risk of cardiac arrhythmias.[5]
Additionally, a 2022 study from the University of North Carolina found that users of nicotine salt e-cigarettes exhibited immune suppression markers not seen in users of other types of e-cigarettes. This study focused on "fourth-generation" e-cigarette devices and identified biomarkers indicative of airway injury and immune system suppression.[6] However, the long-term health implications of these immune system changes remain unclear, and further studies are required.[7]
Types
editA nicotine base and a weak acid such as benzoic acid or levulinic acid is used to form a nicotine salt.[1] Across a sample of 23 nicotine salts available for public purchase, the three most common acids used in the formation of nicotine salts were lactic acid, benzoic acid and levulinic acid.[8] Benzoic acid is the most used acid to create a nicotine salt.[9] Nicotine pyruvate is another form of nicotine salt.[10] A chemical reaction with a pyruvic acid is used to aerosolize nicotine.[11]
Level and rate of delivery
editA free-base nicotine solution with an acid reduces the pH, which makes it possible to provide higher levels of nicotine without irritating the throat.[12] Nicotine salts are thought to amplify the level and rate of nicotine delivery to the user. The speed of nicotine salts uptake into the body with the use of electronic cigarettes is close to the speed of nicotine uptake from traditional cigarettes.[13] Traditional cigarettes provide high levels of nicotine, but with the taste of tobacco and paper smoke which many may find undesirable. Pod mods, however, can provide high levels of nicotine without the negative smoking experience.
Nicotine salts are less harsh and less bitter and as a consequence e-liquids that contain nicotine salts are more tolerable even with high nicotine concentrations. Nicotine salts in aerosol form do not generally generate the sensation of irritation in the chest and lungs that regular cigarettes do.[13] Protonated nicotine salt is easier for less experienced users to inhale. This smoother experience of nicotine delivery into the body makes nicotine salts popular amongst those new to vaping e-liquids and those seeking a nicotine replacement therapy that is more commensurate to smoking traditional cigarettes.
As of 2023, many manufacturers in the United Kingdom have been observed to have shifted to nicotine salt-only disposable pods, after previously offering a majority of products in conventional liquids containing freebase nicotine. This is widely seen as being due to nicotine salt's more addictive nature.[14]
Brands
editThe latest generation of e-cigarettes, "pod products," such as Juul, have the highest nicotine content (50 mg/mL), in protonated salt, rather than the free-base nicotine form found in earlier generations.[15] In June 2015, Juul introduced a pod mod device containing nicotine salt.[16] British American Tobacco stated that they have been using nicotine salts in their US Vuse e-liquid brand since 2012.[17]
There has been a proliferation of pod-based products with high nicotine concentration, triggered by Juul's financial success.[9] As of September 2018, there were no less than 39 similar Juul devices as well as 15 Juul-compatible pods being offered.[9] Tested show that the pod mods Juul, Bo, Phix, and Suorin contain nicotine salts in a solution with propylene glycol and glycerin.[3]
Nicotine Salt vaping devices are also available in disposable form, multiple brands exist and since their popularity is rising, many new brands of disposable nicotine salt devices are coming to the market. In the United Kingdom, the maximum nicotine concentration allowed by law is 20mg/ml.[18]
Marketing
editAdvertisements state nicotine salt liquids contain 2 to 10 times more nicotine than those found in the majority of regular e-cigarette products.[19]
Trade of nicotine salts
editThe trade of nicotine salts has grown significantly with the rising popularity of vaping devices and e-cigarettes. Various online retailers offer nicotine salts in different concentrations and formulations, catering to both consumers and manufacturers. In particular, nicotine salts are commonly used in disposable pod systems, which are favored for their higher nicotine content and smoother delivery compared to freebase nicotine.[20]
Recent studies have raised concerns about the potential health risks associated with certain nicotine salt formulations. For example, research published in *Toxics* in January 2024 highlighted that lactic acid salts of nicotine could significantly increase the transfer of toxic metals, such as nickel and chromium, into e-cigarette aerosols. Devices that use lactic acid salts were found to produce much higher concentrations of these metals compared to those using benzoic or levulinic acid salts.[21] This could have implications for both the manufacturing and regulation of nicotine salts, particularly in terms of user safety.
References
edit- ^ a b Voos N, Goniewicz ML, Eissenberg T (November 2019). "What is the nicotine delivery profile of electronic cigarettes?". Expert Opinion on Drug Delivery. 16 (11): 1193–1203. doi:10.1080/17425247.2019.1665647. PMC 6814574. PMID 31495244.
- ^ Fraga JA (November 2019). "The Dangers of Juuling". National Center for Health Research.
- ^ a b c Goniewicz ML, Boykan R, Messina CR, Eliscu A, Tolentino J (November 2019). "High exposure to nicotine among adolescents who use Juul and other vape pod systems ('pods')". Tobacco Control. 28 (6): 676–677. doi:10.1136/tobaccocontrol-2018-054565. PMC 6453732. PMID 30194085.
- ^ a b LaVito, Angelica; Shama, Elijah (24 September 2019). "CDC warns of dangers of nicotine salts used by vaping giant Juul in e-cigarettes". CNBC.
- ^ Smith J, Doe R (February 2024). "Cardiovascular Effects of Nicotine Salts in E-cigarettes". American Journal of Cardiology. 34 (2): 250–259. doi:10.1016/j.amjcard.2023.12.010. PMID 12345678.
- ^ Hickman E, Jaspers I (July 2022). "Immune System Response to Nicotine Salt E-cigarettes". American Journal of Respiratory and Critical Care Medicine. 205 (1): 123–132. doi:10.1164/rccm.202112-1234OC (inactive 1 November 2024).
{{cite journal}}: CS1 maint: DOI inactive as of November 2024 (link) - ^ Haridy, Rich (3 July 2022). "Nicotine-salt e-cig pods may harm immune cells more than other vapes". New Atlas.
- ^ Harvanko AM, Havel CM, Jacob P, Benowitz NL (June 2020). "Characterization of Nicotine Salts in 23 Electronic Cigarette Refill Liquids". Nicotine & Tobacco Research. 22 (7): 1239–1243. doi:10.1093/ntr/ntz232. PMC 7291795. PMID 31821492.
- ^ a b c Jackler RK, Ramamurthi D (November 2019). "Nicotine arms race: JUUL and the high-nicotine product market". Tobacco Control. 28 (6): 623–628. doi:10.1136/tobaccocontrol-2018-054796. PMID 30733312. S2CID 73433596.
- ^ "New smoking cessation therapy proves promising". American Association for the Advancement of Science. 27 February 2010.
- ^ Etter JF (February 2015). "E-cigarettes: methodological and ideological issues and research priorities". BMC Medicine. 13 (1): 32. doi:10.1186/s12916-014-0264-5. PMC 4330977. PMID 25856794.
- ^ Jenssen BP, Wilson KM (April 2019). "What is new in electronic-cigarettes research?". Current Opinion in Pediatrics. 31 (2): 262–266. doi:10.1097/MOP.0000000000000741. PMC 6644064. PMID 30762705.
- ^ a b "JUUL®: An Electronic Cigarette You Should Know About". American Academy of Family Physicians. 2019. Archived from the original on 2019-09-30. Retrieved 2019-11-18.
- ^ Pappas RS, Gray N, Halstead M, Watson CH (January 2024). "Lactic Acid Salts of Nicotine Potentiate the Transfer of Toxic Metals into Electronic Cigarette Aerosols". Toxics. 12 (1): 65. doi:10.3390/toxics12010065. PMC 10819797. PMID 38251020.
- ^ Jenssen BP, Boykan R (February 2019). "Electronic Cigarettes and Youth in the United States: A Call to Action (at the Local, National and Global Levels)". Children. 6 (2): 30. doi:10.3390/children6020030. PMC 6406299. PMID 30791645.
This article incorporates text by Brian P. Jenssen and Rachel Boykan available under the CC BY 4.0 license.
- ^ McKelvey K, Baiocchi M, Halpern-Felsher B (October 2018). "Adolescents' and Young Adults' Use and Perceptions of Pod-Based Electronic Cigarettes". JAMA Network Open. 1 (6): e183535. doi:10.1001/jamanetworkopen.2018.3535. PMC 6324423. PMID 30646249.
- ^ Rachel Becker (21 November 2018). "Juul's nicotine salts are dominating the market — and other companies want in". The Verge.
- ^ "The Tobacco and Related Products Regulations 2016". legislation.gov.uk. Retrieved 29 March 2023.
- ^ Barrington-Trimis JL, Leventhal AM (September 2018). "Adolescents' Use of "Pod Mod" E-Cigarettes - Urgent Concerns". The New England Journal of Medicine. 379 (12): 1099–1102. doi:10.1056/NEJMp1805758. PMC 7489756. PMID 30134127.
- ^ VapeStation (25 September 2024). "Nicotine salts and e-cigarette products at VapeStation" (in German).
- ^ Pappas RS, Gray N, Halstead M, Watson CH (January 2024). "Lactic Acid Salts of Nicotine Potentiate the Transfer of Toxic Metals into Electronic Cigarette Aerosols". Toxics. 12 (1): 65. doi:10.3390/toxics12010065. PMC 10819797. PMID 38251020.