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Power
Variable power and voltage devices
Variable devices are variable wattage, variable voltage or both.[ Variable ]power
Power most often refers to:
* Power (physics), meaning "rate of doing work"
** Engine power, the power put out by an engine
** Electric power
* Power (social and political), the ability to influence people or events
** Abusive power
Power may a ...
and/or variable voltage have an electronic chip
An integrated circuit or monolithic integrated circuit (also referred to as an IC, a chip, or a microchip) is a set of electronic circuits on one small flat piece (or "chip") of semiconductor material, usually silicon. Large numbers of tiny ...
allowing the user to adjust the power applied to the heating element.[ The amount of power applied to the coil affects the heat produced, thus changing the vapor output.][ Greater heat from the coil increases vapor production.][ Variable power devices monitor the coil's resistance and automatically adjust the voltage to apply the user-specified level of power to the coil.] Recent devices can go up to 8 V.[
They are often rectangular but can also be cylindrical.][ They usually have a screen to show information such as voltage, power, and resistance of the coil. To adjust the settings, the user presses buttons or rotates a dial to turn the power up or down.][ Some of these devices include additional settings through their menu system such as: atomizer resistance meter, remaining battery voltage, puff counter, and power-off or lock. The power source is the biggest component of an e-cigarette,] which is frequently a rechargeable lithium-ion battery
A lithium-ion or Li-ion battery is a type of rechargeable battery which uses the reversible reduction of lithium ions to store energy. It is the predominant battery type used in portable consumer electronics and electric vehicles. It also se ...
.[ Smaller devices contain smaller batteries and are easier to carry but typically require more repeated recharging.][ Some e-cigarettes use a long lasting ]rechargeable battery
A rechargeable battery, storage battery, or secondary cell (formally a type of Accumulator (energy), energy accumulator), is a type of electrical battery which can be charged, discharged into a load, and recharged many times, as opposed to ...
, a non-rechargeable battery or a replaceable battery that is either rechargeable or non-rechargeable for power.[ Some companies offer portable chargeable cases to recharge e-cigarettes.][ Nickel-cadmium (NiCad), nickel metal-hydride (NiMh), lithium ion (Li-ion), alkaline and lithium polymer (Li-poly), and lithium manganese (LiMn) batteries have been used for the e-cigarettes power source.][
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Temperature control devices
Temperature control
Temperature control is a process in which change of temperature of a space (and objects collectively there within), or of a substance, is measured or otherwise detected, and the passage of heat energy into or out of the space or substance is ad ...
devices allow the user to set the temperature.[ There is a predictable change to the resistance of a coil when it is heated.] The resistance changes are different for different types of wires, and must have a high temperature coefficient
A temperature coefficient describes the relative change of a physical property that is associated with a given change in temperature. For a property ''R'' that changes when the temperature changes by ''dT'', the temperature coefficient α is def ...
of resistance.[ Temperature control is done by detecting that resistance change to estimate the temperature and adjusting the voltage to the coil to match that estimate.]
Nickel
Nickel is a chemical element with symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel is a hard and ductile transition metal. Pure nickel is chemically reactive but large pieces are slow to ...
, titanium
Titanium is a chemical element with the symbol Ti and atomic number 22. Found in nature only as an oxide, it can be reduced to produce a lustrous transition metal with a silver color, low density, and high strength, resistant to corrosion in ...
, NiFe alloys, and certain grades of stainless steel
Stainless steel is an alloy of iron that is resistant to rusting and corrosion. It contains at least 11% chromium and may contain elements such as carbon, other nonmetals and metals to obtain other desired properties. Stainless steel's corros ...
are common materials used for wire in temperature control.[ The most common wire used, kanthal, cannot be used because it has a stable resistance regardless of the coil temperature.][ Nickel was the first wire used because it has the highest coefficient of the common metals.][
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The temperature can be adjusted in Celsius or Fahrenheit. The Evolv's DNA40 and YiHi's SX350J are control boards used in temperature control devices. Temperature control can stop dry wicks from burning, or e-liquid overheating.[
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Mechanical devices
Mechanical PVs or mechanical "mods", often called "mechs", are devices without integrated circuits, electronic battery protection, or voltage regulation.[ They are activated by a switch.][ They rely on the natural voltage output of the battery and the metal that the mod is made of often is used as part of the circuit itself.]
The term "mod" was originally used instead of "modification".[ Users would modify existing hardwares to get better performance, and as an alternative to the e-cigarettes that looked like traditional cigarettes.][ Users would also modify other unrelated items like flashlights as battery compartments to power atomizers.][ The word mod is often used to describe most personal vaporizers.][
Mechanical PVs have no power regulation and are unprotected.][ Because of this ensuring that the battery does not over-discharge and that the resistance of the atomizer requires ]electric current
An electric current is a stream of charged particles, such as electrons or ions, moving through an electrical conductor or space. It is measured as the net rate of flow of electric charge through a surface or into a control volume. The moving pa ...
within the safety limits of the battery is the responsibility of the user.[
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E-cigarette liquid
Composition
E-cigarette liquid, E-Cig liquid,[ e-liquid, juice, vapor juice, vape juice, smoke juice,][ vaping fluid,] vaping juice, e-juice, e-fluid,[ or vape oil] is the mixture used in vapor products including e-cigarettes.[ Since e-cigarettes are not regulated in many countries, the composition of the liquid can change often.] There is a great amount of variability in e-liquid formulations due to fast growth and changes in the manufacturing designs of e-cigarettes.[ The composition of the e-liquid for additives such as nicotine and flavors vary across and within brands.][ E-liquids come in many variations, including different nicotine strengths and many different flavors.] The main ingredients are propylene glycol
Propylene glycol (IUPAC nomenclature, IUPAC name: propane-1,2-diol) is a viscous, colorless liquid, which is nearly odorless but possesses a faintly sweet taste. Its chemical formula is CH3CH(OH)CH2OH.
Containing two Alcohol (chemistry), alcoho ...
, glycerin
Glycerol (), also called glycerine in British English and glycerin in American English, is a simple triol compound. It is a colorless, odorless, viscous liquid that is sweet-tasting and non-toxic. The glycerol backbone is found in lipids known ...
, and flavorings
A flavoring (or flavouring), also known as flavor (or flavour) or flavorant, is a food additive used to improve the taste or smell of food. It changes the perceptual impression of food as determined primarily by the chemoreceptors of the gustat ...
; and most often, nicotine
Nicotine is a natural product, naturally produced alkaloid in the nightshade family of plants (most predominantly in tobacco and ''Duboisia hopwoodii'') and is widely used recreational drug use, recreationally as a stimulant and anxiolytic. As ...
in liquid form. The liquid typically consists of a combined total of 95% propylene glycol and glycerin, and the remaining 5% being flavorings, nicotine, and other additives. The most frequently used e-liquid solvents are propylene glycol and glycerin. Flavorings may contain menthol, sugars, esters, and pyrazine
Pyrazine is a heterocyclic aromatic organic compound with the chemical formula C4H4N2. It is a symmetrical molecule with point group D2h. Pyrazine is less basic than pyridine, pyridazine and pyrimidine. It is a ''"deliquescent crystal or wax-lik ...
s.[ Flavor components include eucalyptol, camphor, methyl salicylate, pulegone, ethyl salicylate, cinnamaldehyde, eugenol, diphenyl ether, coumarin,][ diacetyl, acetoin, 2,3-pentanedione, cyclohexanone, benzaldehyde, cresol, butyraldehyde, and isoamyl acetate.][ Sugars are frequently used in e-liquids to provide a sweet flavor.] Diacetyl, acetoin, and 2,3-pentanedione are used for buttery flavoring.[ Camphor and cyclohexanone are used for minty flavoring.][ Benzaldehyde is used for cherry or almond flavoring.][ Cinnamaldehyde is used for cinnamon flavoring.][ Cresol is used for leathery or medicinal flavoring.][ Butyraldehyde is used for chocolate flavoring.][ Isoamyl acetate is used for banana flavoring.][ E-liquids named coffee, tea, chocolate, or energy drinks, typically contain caffeine at levels considerably less than in comparison with dietary products. E-liquids are also available with vitamins or cannabis flavors.][ In addition, specific e-cigarettes (mods) are available that allow for not only liquids but also herbs, oils, or fruits to be vaped.][ Moreover, dual-function devices handle both concentrates and e-liquids using multiple cartridges.]
E-liquid can be made with or without nicotine, with more than 90% of e-liquids containing some level of nicotine. The most regularly used base carrier chemical is propylene glycol with or without glycerin.[ E-liquid containing glycerin and water made without propylene glycol are also sold.] There are e-liquids sold without propylene glycol,[ nicotine,] or flavors. E-liquids containing THC
Tetrahydrocannabinol (THC) is the principal psychoactive constituent of cannabis and one of at least 113 total cannabinoids identified on the plant. Although the chemical formula for THC (C21H30O2) describes multiple isomers, the term ''THC' ...
or other cannabinoid
Cannabinoids () are several structural classes of compounds found in the cannabis plant primarily and most animal organisms (although insects lack such receptors) or as synthetic compounds. The most notable cannabinoid is the phytocannabinoid tet ...
s is also sold. Specific kinds of e-liquids contain a tiny amount of alcohol.[ The amount of alcohol in e-liquids vary, and there are cases where it has not been disclosed as an ingredient.][ It is uncertain whether the nicotine used in e-liquid is manufactured using a ]US Pharmacopeia
The ''United States Pharmacopeia'' (''USP'') is a pharmacopeia (compendium of drug information) for the United States published annually by the United States Pharmacopeial Convention (usually also called the USP), a nonprofit organization that ...
grade nicotine, a tobacco plant or tobacco dust extract, or a synthetic nicotine. Most e-cigarette liquids contain nicotine, but the level of nicotine varies depending on user-preference and manufacturers. Although some e-liquid is nicotine-free, surveys demonstrate that 97% of respondents use products that contain nicotine.[ About 3.5% of users use liquid without nicotine.] An e-cigarette user used approximately three flavors. A 2016 study showed that measurable amounts of arsenic, nickel and other metals were in e-liquids.
Over 80 chemicals such as formaldehyde and metallic nanoparticles have been found in the e-liquid. E-liquids typically contain nicotine, propylene glycol, glycerin, 1,3-butanediol, 1,3-propanediol, ethylene glycol, menthol, safrole, ethyl vanillin, camphor, α-thujone, coumarin, and diethylene glycol, according to a 2017 review. E-liquid can contain a range of toxicants and can contain impurities. A 2013 study found the e-liquids tested had as high as five times the upper threshold permitted levels of impurities.[ E-liquids have been found to contain low levels of some of the toxicants found in tobacco smoke, as well as small concentrations of carcinogens.][ The FDA in 2009 analyzed e-liquid cartridge samples which were found to contain ]tobacco-specific nitrosamines
Tobacco-specific nitrosamines (TSNAs) comprise one of the most important groups of carcinogens in tobacco products, particularly cigarettes (traditional and electronic) and fermented dipping snuff.
Background
These nitrosamine carcinogens are for ...
(TSNAs), diethylene glycol (detected one e-cigarette cartridge), cotinine, anabasine, myosmine, and beta-nicotyrine.[ The TSNAs ''N''-nitrosonornicotine (NNN), 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), N-nitrosoanabasine, and nitrosoanatabine have been detected in five e-liquid cartridge samples from two companies in levels comparable to ]nicotine replacement products
Nicotine replacement therapy (NRT) is a medically approved way to treat people with tobacco use disorder by taking nicotine through means other than tobacco. It is used to help with quitting smoking or stopping chewing tobacco. It increases the ...
, according to the results of the FDA's analysis. TSNAs were found in a broad range of levels. TSNAs present in tobacco smoke, were also found in e-liquids, at different levels, in trace amounts. Studies in 2013 of other e-liquids had not detected diethylene glycol. The majority of the e-liquids analyzed contained NNN from 0.34 to 60.08 μg/L and contained NNK from 0.22 to 9.84 μg/L.[ The FDA issued warnings to several e-cigarette companies for selling e-cartridges and refill solutions containing active pharmaceutical ingredients such as rimonabant (Zimulti) for the purpose of losing weight and reducing smoking addiction, and tadalafil (the active ingredient in Cialis) for the purpose of increasing sexual capacity.][ FDA analyses of these e-cartridges and solutions showed the presence of amino-tadalafil and not tadalafil, and the presence of an oxidative product of rimonabant, as well as rimonabant.]
The e-liquid often contain other substances unknown and/or undisclosed to the user. The specific origin of the e-liquid ingredients is often unclear. When content information is given on the packaging, it is usually incomplete.[ Contamination with various compounds in e-liquids is a result of poor quality control.][ Some nicotine and TSNAs have been found in e-liquids labelled as 'no nicotine'.][ Nicotine content information on labels for some e-liquid companies may be vague, inaccurate or absent.][ E-liquid were found to contain low levels of anthracene, phenanthrene, 1-methyl phenanthrene and pyren.] Diethylene glycol, ethylene glycol, hydrocarbons, ethanol, terpenic compounds and aldehydes, particularly formaldehyde and acrolein were found in the e-liquid. Diethylene glycol is a potential byproduct of propylene glycol.[ A 2014 study showed that e-liquids from a specific manufacturer contained greater amounts of ethylene glycol than glycerin or propylene glycol, which was likely a result of improper manufacturing methods.] Some liquids contained residual solvents such as 1,3-butadiene, cyclohexane, and acetone.[ Some e-liquids contain tobacco alkaloids such as nornicotine, anabasine, or anatabine, and TSNAs, such as ''N''-nitrosonornicotine (NNN), 4-(methylnitrosamine)-1-(3-pyridyl)-1-butanone (NNK),][ nitrates, and phenol.][ Tobacco alkaloids that were identified in some e-liquids were not found on the ingredient list.][ Small quantities of volatile organic compounds (VOCs) such as benzene, toluene, xylene, and styrene have been found in the e-liquid.][ Diethyl phthalate and diethylhexyl phthalate have been found in e-liquids. Some e-liquids contain tin "whiskers," microscopic crystals that originate from tin in the ]solder joint
Soldering (; ) is a process in which two or more items are joined by melting and putting a filler metal (solder) into the joint, the filler metal having a lower melting point than the adjoining metal. Unlike welding, soldering does not involv ...
s.[
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Levels of aldehydes in e-liquid
∗A 2013 analysis tested a total of 42 bottles of e-liquids.
Contents
The e-liquid is sold in bottles, pre-filled disposable cartridges, or as a kit for consumers to make their own e-liquids. E-liquids are made with various tobacco, fruit, and other flavors,[ as well as variable nicotine concentrations (including nicotine-free versions).][ The standard notation "mg/ml" is often used on labels to denote nicotine concentration, and is sometimes shortened to "mg".] Some flavors are created to resemble the flavors used in traditional cigarettes such as tobacco and menthol-tobacco. Adults in general also preferred sweet flavors (though smokers like tobacco flavor the most) and disliked flavors that elicit bitterness or harshness.[ Young adults overall preferred sweet, menthol, and cherry flavors, while non-smokers in particular preferred coffee and menthol flavors.] In surveys of regular e-cigarette users, the most popular e-liquids had a nicotine content of 18 mg/ml, and the preferred flavors were largely tobacco, mint and fruit.[ Men tend to favor flavors with tobacco, while women tend to favor chocolate or sweet flavors.][ The most favorite flavors among regular e-cigarette users reported in a 2017 UK survey were fruit, tobacco, and menthol/mint. The survey also found 2.6% regular e-cigarette users used no flavors. A 2013 study examined 33 countries and found that only 1% of the adult smokers exclusively used non-nicotine e-cigarettes.][ A cartridge may contain 0 to 20 mg of nicotine.][ Refill liquids are often sold in the size range from 15 to 30 ml.] E-liquids are frequently sold in dropper bottles. One cartridge may typically last as long as one pack of cigarettes. A refill bottle can contain up to 100 mg/ml of nicotine, which is meant to be diluted before use. Some users, probably due to financial reasons and the willingness to experiment, are opting to make homemade e-liquids. A small percentage of liquids without flavoring is also sold. The flavorings may be natural or artificial.[ ]Certified organic
Organic certification is a certification process for producers of organic food and other organic agricultural products, in the European Union more commonly known as ecological or biological products.Labelling, article 30 o''Regulation (EU) 2018/ ...
e-liquid is also sold. About 8,000 flavors existed in 2014. More than 15,500 flavors existed in 2018. A user does not normally consume a whole cartridge in a single session.[ Most e-liquids are produced by a few manufacturers in China, the US, and Europe.][ An e-cigarette user will usually obtain 300 to 500 puffs per ml of e-liquid.][ A 2017 survey found that 62.2% of everyday e-cigarette users stated using lower than 4 ml daily and 1.5% used higher than 10 ml daily. 18.1% of everyday e-cigarette users were not aware of the amount of e-liquid they use.
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Manufacturing
E-liquids are manufactured by many producers, both in the US and across the world.[ First tier manufacturers use lab suits, gloves, hair covers, inside of certified clean rooms with air filtration similar to pharmaceutical-grade production areas.]
Standards
E-liquid manufacturing requirements under the US Food and Drug Administration
The United States Food and Drug Administration (FDA or US FDA) is a List of United States federal agencies, federal agency of the United States Department of Health and Human Services, Department of Health and Human Services. The FDA is respon ...
(FDA) rules include report user fee information, pay user fees, register their establishment and submit list of products, including labeling and advertisements, submit health documents, submit ingredient listing, include required warning statements on packages and advertisements, submit quantities of harmful and potentially harmful constituents, and submit a modified risk tobacco product application.[ The revision to the EU ]Tobacco Products Directive
The Tobacco Products Directive (TPD) or European Tobacco Products Directive (EUTPD) (2014/40/EU) is a directive of the European Union which places limits on the sale and merchandising of tobacco and tobacco related products in the EU. The TPD aim ...
has some standards for e-liquids.[
Standards for e-liquid manufacturing have been created by American E-liquid Manufacturing Standards Association (AEMSA), which is trade association dedicated to creating responsible and sustainable standards for the safe manufacturing of e-liquids used in vapor products. AEMSA has published a comprehensive list standards and best known methods, which are openly available for use by any manufacturer of e-Liquids.][ The AEMSA standards cover nicotine, ingredients, sanitary manufacturing rooms, safety packaging, age restrictions, and labeling.] AEMSA guidelines recommend that the nicotine levels in e-liquids be within the amount of ±10% from the levels stated on the label.
Regulation
Effective August 8, 2016, under the FDA rules, a company that mixes or prepares e-liquids is regulated as a tobacco product manufacturer.[ Under the same regulation, a company that sells e-liquids is regulated as a tobacco retailer.] Companies who import or try to sell for import into the US must conform to the Federal Food, Drug, and Cosmetic Act
The United States Federal Food, Drug, and Cosmetic Act (abbreviated as FFDCA, FDCA, or FD&C) is a set of laws passed by the United States Congress in 1938 giving authority to the U.S. Food and Drug Administration (FDA) to oversee the safety of f ...
. The 2016 FDA ruling did not incorporate regulation concerning flavoring of e-cigarettes. Industry standards have been created and published by the American E-liquid Manufacturing Standards Association (AEMSA).[ The FDA authority to regulate e-liquids was announced in May 2016.] The FDA has sought to regulate e-liquid in 2014 through use of the Family Smoking Prevention and Tobacco Control Act
Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Ideall ...