Cigarette

A cigarette, or cigaret, is a small cylinder of finely cut tobacco leaves rolled in thin paper for smoking. The cigarette is ignited at one end causing the cigarette to smoulder and allowing smoke to be inhaled from the other end, which is held in or to the mouth; in some cases, a cigarette holder may be used, as well. Most modern manufactured cigarettes are filtered, and also include reconstituted tobacco and other additives.^[1]

The term cigarette, as commonly used, refers to a tobacco cigarette, but can apply to similar devices containing other substances, such as cannabis. A cigarette is distinguished from a cigar by its smaller size, use of processed leaf, and paper wrapping, which is normally white, though other colors and flavors are also available. Cigars are typically composed entirely of whole-leaf tobacco.

Rates of cigarette smoking vary widely throughout the world and have changed considerably since cigarettes were first widely used in the mid-19th century. While rates of smoking have over time leveled off or declined in the developed world, they continue to rise in developing nations.^[2][3]

Nicotine, the primary psychoactive chemical in tobacco and therefore cigarettes, is very addictive.^[4] About half of cigarette smokers die of tobacco-related disease^[5] and lose on average 14 years of life.^[4] Cigarette use by pregnant women has also been shown to cause birth defects, including low birth weight, fetal abnormalities, and premature birth.^[6] Second-hand smoke from cigarettes has been shown to be injurious to bystanders,^{[7][8][9][10]} which has led to legislation that has prohibited smoking in many workplaces and public areas. Cigarettes produce an aerosol containing over 4,000 chemical compounds, including nicotine, carbon monoxide, acrolein, and other harmful substances.^[11] Over 50 of these are carcinogenic.^[12] Cigarettes are a frequent source of fires leading to loss of lives in private homes, which prompted both the European Union and the United States to ban cigarettes that are not fire-standard compliant from 2011 onwards.^[13][14]

History

The earliest forms of cigarettes were similar to their predecessor, the cigar. Cigarettes appear to have had antecedents in Mexico and Central America around the 9th century in the form of reeds and smoking tubes. The Maya, and later the Aztecs, smoked tobacco and other psychoactive drugs in religious rituals and frequently depicted priests and deities smoking on pottery and temple engravings. The cigarette and the cigar were the most common methods of smoking in the Caribbean, Mexico, and Central and South America until recent times.^[15]

The North American, Central American, and South American cigarette used various plant wrappers; when it was brought back to Spain, maize wrappers were introduced, and by the 17th century, fine paper. The resulting product was called papelate and is documented in Goya's paintings La Cometa, La Merienda en el Manzanares, and El juego de la pelota a pala (18th century).^[16]

By 1830, the cigarette had crossed into France, where it received the name cigarette; and in 1845, the French state tobacco monopoly began manufacturing them.^[16]

The first patented cigarette machine was by Juan Nepomuceno Adorno of Mexico in 1847.^[17] However, production climbed markedly when another cigarette-making machine was developed in the 1880s by James Albert Bonsack, which vastly increased the productivity of cigarette companies, which went from making about 40,000 hand-rolled cigarettes daily to around 4 million.^[18]

In the English-speaking world, the use of tobacco in cigarette form became increasingly widespread during and after the Crimean War, when British soldiers began emulating their Ottoman Turkish comrades and Russian enemies, who had begun rolling and smoking tobacco in strips of old newspaper for lack of proper cigar-rolling leaf.^[16] This was helped by the development of tobaccos suitable for cigarette use, and by the development of the Egyptian cigarette export industry.

Cigarettes may have been initially used in a manner similar to pipes, cigars, and cigarillos and not inhaled; for evidence, see the Lucky Strike ad campaign asking consumers "Do You Inhale?" from the 1930s. As cigarette tobacco became milder and more acidic, inhaling may have become perceived as more agreeable. However, Moltke noticed in the 1830s (cf. Unter dem Halbmond) that Ottomans (and he himself) inhaled the Turkish tobacco and Latakia from their pipes^[19] (which are both initially sun-cured, acidic leaf varieties).

The widespread smoking of cigarettes in the Western world is largely a 20th-century phenomenon. At the start of the 20th century, the per capita annual consumption in the USA was 54 cigarettes (with less than 0.5% of the population smoking more than 100 cigarettes per year), and consumption there peaked at 4,259 per capita in 1965. At that time, about 50% of men and 33% of women smoked (defined as smoking more than 100 cigarettes per year).^[20] By 2000, consumption had fallen to 2,092 per capita, corresponding to about 30% of men and 22% of women smoking more than 100 cigarettes per year, and by 2006 per capita consumption had declined to 1,691;^[21] implying that about 21% of the population smoked 100 cigarettes or more per year.

German doctors were the first to identify the link between smoking and lung cancer, which led to the first antitobacco movement in Nazi Germany.^[22][23] During World War I and World War II, cigarettes were rationed to soldiers. During the Vietnam War, cigarettes were included with C-ration meals. In 1975, the U.S. government stopped putting cigarettes in military rations. During the second half of the 20th century, the adverse health effects of tobacco smoking started to become widely known and text-only health warnings became common on cigarette packets.

The United States has not implemented graphical cigarette warning labels, which are considered a more effective method to communicate to the public the dangers of cigarette smoking.^[24] Canada, Mexico, Belgium, Denmark, Sweden, Thailand, Malaysia, India, Pakistan, Australia, Argentina, Brazil, Chile, Peru,^[25] Greece, the Netherlands, New Zealand, Norway, Hungary, the United Kingdom, France, Romania, Singapore, Egypt, Nepal and Turkey, however, have both textual warnings and graphic visual images displaying, among other things, the damaging effects tobacco use has on the human body.

The cigarette has evolved much since its conception; for example, the thin bands that travel transverse to the "axis of smoking" (thus forming circles along the length of the cigarette) are alternate sections of thin and thick paper to facilitate effective burning when being drawn, and retard burning when at rest. Synthetic particulate filters may remove some of the tar before it reaches the smoker.

The "holy grail" for cigarette companies has been a cancer-free cigarette. On record, the closest historical attempt was produced by scientist James Mold. Under the name project TAME, he produced the XA cigarette. However, in 1978, his project was terminated.^[26][27][28]

Since 1950, the average nicotine and tar content of cigarettes has steadily fallen. The fall in nicotine content has led to smokers inhaling larger volumes per puff.^[29]

Legislational

Smoking restrictions

Many governments impose restrictions on smoking tobacco, especially in public areas. The primary justification has been the negative health effects of second-hand smoke.^[30] Laws vary by country and locality. Bhutan is currently the only country in the world to completely outlaw the cultivation, harvesting, production, and sale of tobacco and tobacco products under the Tobacco Control Act of Bhutan 2010. However, small allowances for personal possession are permitted as long as the possessors can prove that they have paid import duties.^[31] The Pitcairn Islands had previously banned the sale of cigarettes, but it now permits sales from a government-run store. The Pacific island of Niue hopes to become the next country to prohibit the sale of tobacco.^[32] Iceland is also proposing banning tobacco sales from shops, making it prescription-only and therefore dispensable only in pharmacies on doctor's orders.^[33] New Zealand hopes to achieve being tobacco-free by 2025 and Finland by 2040. Singapore and the Australian state of Tasmania have proposed a 'tobacco free millennium generation initiative' by banning the sale of all tobacco products to anyone born in and after the year 2000. In March 2012, Brazil became the world's first country to ban all flavored tobacco including menthols. It also banned the majority of the estimated 600 additives used, permitting only eight. This regulation applies to domestic and imported cigarettes. Tobacco manufacturers have 18 months to remove the noncompliant cigarettes, 24 months to remove the other forms of noncompliant tobacco.^[34][35] Under sharia law, the consumption of cigarettes by Muslims is prohibited.^[36] In the Islamic State of Iraq and the Levant the consumption, and even its possession is illegal.^[37]

Smoking age

Beginning on April 1, 1998, the sale of cigarettes and other tobacco products to people under the state purchase age has been prohibited by law in all 50 states of the United States. The purchasing age in the United States is 18 in 44 of the 50 states — but 19 in Alabama, Alaska, New Jersey, Utah, and Nassau, Suffolk, and Onondaga Counties in New York,^[38][39] and 21 in California, Hawaii, and more than 180 municipalities across the nation. The intended effect of this is to prevent older high school students from purchasing cigarettes for their younger peers. In Massachusetts,^[40] parents and guardians are allowed to give cigarettes to minors, but sales to minors are prohibited.

Similar laws exist in many other countries. In Canada, most of the provinces require smokers to be 19 years of age to purchase cigarettes (except for Quebec and the prairie provinces, where the age is 18). However, the minimum age only concerns the purchase of tobacco, not use. Alberta, however, does have a law which prohibits the possession or use of tobacco products by all persons under 18, punishable by a $100 fine. Australia, New Zealand, Poland, and Pakistan have a nationwide ban on the selling of all tobacco products to people under the age of 18.

Since 1 October 2007, it has been illegal for retailers to sell tobacco in all forms to people under the age of 18 in three of the UK's four constituent countries (England, Wales, Northern Ireland, and Scotland) (rising from 16). It is also illegal to sell lighters, rolling papers, and all other tobacco-associated items to people under 18. It is not illegal for people under 18 to buy or smoke tobacco, just as it was not previously for people under 16; it is only illegal for the said retailer to sell the item. The age increase from 16 to 18 came into force in Northern Ireland on 1 September 2008. In the Republic of Ireland, bans on the sale of the smaller 10-packs and confectionery that resembles tobacco products (candy cigarettes) came into force on May 31, 2007, in a bid to cut underaged smoking.

Most countries in the world have a legal vending age of 18. In Macedonia, Italy, Malta, Austria, Luxembourg, and Belgium, the age for legal vending is 16. Since January 1, 2007, all cigarette machines in public places in Germany must attempt to verify a customer's age by requiring the insertion of a debit card. Turkey, which has one of the highest percentage of smokers in its population,^[41] has a legal age of 18. Japan is one of the highest tobacco-consuming nations, and requires purchasers to be 20 years of age (suffrage in Japan is 20 years old).^[42] Since July 2008, Japan has enforced this age limit at cigarette vending machines through use of the taspo smart card. In other countries, such as Egypt, it is legal to use and purchase tobacco products regardless of age. Germany raised the purchase age from 16 to 18 on the 1 September 2007.

Some police departments in the United States occasionally send an underaged teenager into a store where cigarettes are sold, and have the teen attempt to purchase cigarettes, with their own or no ID. If the vendor then completes the sale, the store is issued a fine.^[43] Similar enforcement practices are regularly performed by Trading Standards officers in the UK, Israel, and the Republic of Ireland.^[44]

Taxation

Cigarettes are a significant source of tax revenue in many localities. This fact has historically been an impediment for health groups seeking to discourage cigarette smoking, since governments seek to maximize tax revenues. Furthermore, some countries have made cigarettes a state monopoly, which has the same effect on the attitude of government officials outside the health field.^[45] In the United States, cigarettes are taxed substantially, but the states are a primary determinant of the total tax rate. Generally, states that rely on tobacco as a significant farm product tend to tax cigarettes at a low rate.^[46] Higher prices for cigarettes discourage smoking. Every 10% increase in the price of cigarettes reduced youth smoking by about 7% and overall cigarette consumption by about 4%.^[47] Thus, increased cigarette taxes are proposed as a means to reduce smoking. Coupled with the federal cigarette tax of $1.01 per pack, total cigarette-specific taxes range from $1.18 per pack in Missouri to $8.00 per pack in Silver Bay. States also charge sizable settlement payments to tobacco companies, and the federal government levies user fees to fund FDA regulatory measures over tobacco. While these charges are not cigarette-specific, tobacco companies are ultimately forced to pass on those costs to their consumers. Lastly, most jurisdictions apply sales tax to the full retail price of cigarettes.

Fire-safe cigarette

According to Simon Chapman, a professor of public health at the University of Sydney, the burning agents in cigarette paper are responsible for fires and reducing them would be a simple and effective means of dramatically reducing the ignition propensity of cigarettes.^[48] Since the 1980s, prominent cigarette manufacturers such as Philip Morris and R.J. Reynolds developed fire-safe cigarettes, but did not market them.

The burn rate of cigarette paper is regulated through the application of different forms of microcrystalline cellulose to the paper.^[49] Cigarette paper has been specially engineered by creating bands of different porosity to create "fire-safe" cigarettes. These cigarettes have a reduced idle burning speed which allows them to self-extinguish.^[50] This fire-safe paper is manufactured by mechanically altering the setting of the paper slurry.^[51]

New York was the first U.S. state to mandate that all cigarettes manufactured or sold within the state comply with a fire-safe standard. Canada has passed a similar nationwide mandate based on the same standard. All U.S. states are gradually passing fire-safe mandates.^[52]

The European Union wishes to ban in 2011 cigarettes that are not fire-safe. According to a study made by the European Union in 16 European countries, 11,000 fires were due to people carelessly handling cigarettes between 2005 and 2007. This caused 520 deaths and 1,600 people injured.^[53]

Cigarette advertising

In many parts of the world, tobacco advertising and sponsorship has been outlawed. The ban on tobacco advertising and sponsorship in the EU in 2005 has prompted Formula One management to look for races in areas that allow the tobacco-sponsored teams to display their livery. In the United States, advertising restrictions took effect on June 22, 2010.

In some jurisdictions, such as the Canadian provinces of British Columbia, Saskatchewan and Alberta, the retail store display of cigarettes is completely prohibited if persons under the legal age of consumption have access to the premises.^[54] In Ontario, Manitoba, Newfoundland and Labrador, and Quebec, Canada and the Australian Capital Territory the display of tobacco is prohibited for everyone, regardless of age, as of 2010. This retail display ban includes noncigarette products such as cigars and blunt wraps.^[55][56]

Warning messages in packages

As a result of tight advertising and marketing prohibitions, tobacco companies look at the pack differently: they view it as a strong component in displaying brand imagery and a creating significant in-store presence at the point of purchase. Market testing shows the influence of this dimension in shifting the consumer’s choice when the same product displays in an alternative package. Studies also show how companies have manipulated a variety of elements in packs designs to communicate the impression of lower in tar or milder cigarettes, whereas the components were the same.^[57]

Some countries require cigarette packs to contain warnings about health hazards. The United States was the first,^[58] later followed by other countries including Canada, most of Europe, Australia,^[59] Pakistan,^[60] India, Hong Kong, and Singapore. In 1985, Iceland became the first country to enforce graphic warnings on cigarette packaging.^[61][62] At the end of December 2010, new regulations from Ottawa increased the size of tobacco warnings to cover three-quarters of the cigarette package in Canada.^[63] As of November 2010, 39 countries have adopted similar legislation.^[58]

In February 2011, the Canadian government passed regulations requiring cigarette packs to contain 12 new images to cover 75% of the outside panel and eight new health messages on the inside panel with full color.^[64]

As of April 2011, Australian regulations require all packs to use a bland olive green, with 75% coverage on the front of the pack and all of the back consisting of graphic health warnings. The only features that differentiate one brand from another are the product name in a standard color, standard position, and standard font size and style.^[65] New Zealand, Canada, and the United Kingdom have considered similar policies. In response to these regulations, Philip Morris International, Japan Tobacco Inc., British American Tobacco Plc., and Imperial Tobacco attempted to sue the Australian government. On August 15, 2012, the High Court of Australia dismissed the suit and made Australia the first country to introduce brand-free plain cigarette packaging with health warnings covering 90 and 70% of back and front packaging, respectively. This took effect on December 1, 2012.^[66]

Construction

Modern commercially manufactured cigarettes are seemingly simple objects consisting mainly of a tobacco blend, paper, PVA glue to bond the outer layer of paper together, and often also a cellulose acetate–based filter.^[67] While the assembly of cigarettes is straightforward, much focus is given to the creation of each of the components, in particular the tobacco blend. A key ingredient that makes cigarettes more addictive is the inclusion of reconstituted tobacco, which has additives to make nicotine more volatile as the cigarette burns.^[1]

Paper

The paper for holding the tobacco blend may vary in porosity to allow ventilation of the burning ember or contain materials that control the burning rate of the cigarette and stability of the produced ash. The papers used in tipping the cigarette (forming the mouthpiece) and surrounding the filter stabilize the mouthpiece from saliva and moderate the burning of the cigarette, as well as the delivery of smoke with the presence of one or two rows of small laser-drilled air holes.^[68]

Tobacco blend

The process of blending gives the end product a consistent taste from batches of tobacco grown in different areas of a country that may change in flavor profile from year to year due to different environmental conditions.^[69]

Modern cigarettes produced after the 1950s, although composed mainly of shredded tobacco leaf, use a significant quantity of tobacco processing byproducts in the blend. Each cigarette's tobacco blend is made mainly from the leaves of flue-cured brightleaf, burley tobacco, and oriental tobacco. These leaves are selected, processed, and aged prior to blending and filling. The processing of brightleaf and burley tobaccos for tobacco leaf "strips" produces several byproducts such as leaf stems, tobacco dust, and tobacco leaf pieces ("small laminate").^[69] To improve the economics of producing cigarettes, these byproducts are processed separately into forms where they can then be added back into the cigarette blend without an apparent or marked change in the cigarette's quality. The most common tobacco byproducts include:

• Blended leaf (BL) sheet: a thin, dry sheet cast from a paste made with tobacco dust collected from tobacco stemming, finely milled burley-leaf stem, and pectin.^[70]
• Reconstituted leaf (RL) sheet: a paper-like material made from recycled tobacco fines, tobacco stems and "class tobacco", which consists of tobacco particles less than 30 mesh in size (about 0.6 mm) that are collected at any stage of tobacco processing:^[71] RL is made by extracting the soluble chemicals in the tobacco byproducts, processing the leftover tobacco fibers from the extraction into a paper, and then reapplying the extracted materials in concentrated form onto the paper in a fashion similar to what is done in paper sizing. At this stage, ammonium additives are applied to make reconstituted tobacco an effective nicotine delivery system.^[1]
• Expanded (ES) or improved stem (IS): ES is rolled, flattened, and shredded leaf stems that are expanded by being soaked in water and rapidly heated. Improved stem follows the same process, but is simply steamed after shredding. Both products are then dried. These products look similar in appearance, but are different in taste.^[69]

In recent years, the manufacturers' pursuit of maximum profits has led to the practice of using not just the leaves, but also recycled tobacco offal^[1] and the plant stem.^[72] The stem is first crushed and cut to resemble the leaf before being merged or blended into the cut leaf.^[73] According to data from the World Health Organization,^[74] the amount of tobacco per 1000 cigarettes fell from 2.28 pounds in 1960 to 0.91 pounds in 1999, largely as a result of reconstituting tobacco, fluffing, and additives.

A recipe-specified combination of brightleaf, burley-leaf, and oriental-leaf tobacco is mixed with various additives to improve its flavors.

Additives

Various additives are combined into the shredded tobacco product mixtures, with humectants such as propylene glycol or glycerol, as well as flavoring products and enhancers such as cocoa solids, licorice, tobacco extracts, and various sugars, which are known collectively as "casings". The leaf tobacco is then shredded, along with a specified amount of small laminate, expanded tobacco, BL, RL, ES, and IS. A perfume-like flavor/fragrance, called the "topping" or "toppings", which is most often formulated by flavor companies, is then blended into the tobacco mixture to improve the consistency in flavor and taste of the cigarettes associated with a certain brand name.^[69] Additionally, they replace lost flavors due to the repeated wetting and drying used in processing the tobacco. Finally, the tobacco mixture is filled into cigarette tubes and packaged.

A list of 599 cigarette additives, created by five major American cigarette companies, was approved by the Department of Health and Human Services in April 1994. None of these additives is listed as an ingredient on the cigarette pack(s). Chemicals are added for organoleptic purposes and many boost the addictive properties of cigarettes, especially when burned.

One of the classes of chemicals on the list, ammonia salts, convert bound nicotine molecules in tobacco smoke into free nicotine molecules. This process, known as freebasing, could potentially increase the effect of nicotine on the smoker, but experimental data suggests that absorption is, in practice, unaffected.^[75]

Cigarette tube

Cigarette tubes are prerolled cigarette paper usually with an acetate or paper filter at the end. They have an appearance similar to a finished cigarette, but are without any tobacco or smoking material inside. The length varies from what is known as King Size (84 mm) to 100s (100 mm).^[76]

Filling a cigarette tube is usually done with a cigarette injector (also known as a shooter). Cone-shaped cigarette tubes, known as cones, can be filled using a packing stick or straw because of their shape. Cone smoking is popular because as the cigarette burns, it tends to get stronger and stronger. A cone allows more tobacco to be burned at the beginning than the end, allowing for an even flavor^[77]

The United States Tobacco Taxation Bureau defines a cigarette tube as "Cigarette paper made into a hollow cylinder for use in making cigarettes."^[78]

Cigarette filter

Cigarette butt

The common name for the remains of a cigarette after smoking is a cigarette butt. The butt is typically about 30% of the cigarette's original length. It consists of a tissue tube which holds a filter and some remains of tobacco mixed with ash. They are the most numerically frequent litter in the world.^[79] Cigarette butts accumulate outside buildings, on parking lots, and streets where they can be transported through storm drains to streams, rivers, and beaches.^[80] It is also called a fag-end or dog-end.^[81]

In a recent trial the city of Vancouver, British Columbia, partnered with TerraCycle to create a system for recycling of cigarette butts. A reward of 1¢ per collected butt was offered to determine the effectiveness of a deposit system similar to that of beverage containers.^[82][83]

Environmental impact

Cigarette filters are made up of thousands of polymer chains of cellulose acetate, which has the chemical structure shown to the right. Once discarded into the environment, the filters create a large waste problem. Cigarette filters are the most common form of litter in the world, as approximately 5.6 trillion cigarettes are smoked every year worldwide.^[84] Of those, an estimated 4.5 trillion cigarette filters become litter every year.^[85] To develop an idea of the waste weight amount produced a year the table below was created.

Estimated waste produced from filters

Number of filters	weight
1 pack (20)	0.12 ounces (3.4 g)
sold daily (15 billion)	5,625,000 pounds (2,551,000 kg)
sold yearly (5.6 trillion)	2,100,000,000 pounds (950,000,000 kg)
estimated trash (4.5 trillion)	1,687,500,000 pounds (765,400,000 kg)

Discarded cigarette filters usually end up in the water system through drainage ditches and are transported by rivers and other waterways to the ocean.

Aquatic life health concerns

In the 2006 International Coastal Cleanup, cigarettes and cigarette butts constituted 24.7% of the total collected pieces of garbage, over twice as many as any other category, which is not surprising seeing the numbers in the table above of waste produced each year.^[86] Cigarette filters contain the chemicals filtered from cigarettes and can leach into waterways and water supplies.^[87] The toxicity of used cigarette filters depends on the specific tobacco blend and additives used by the cigarette companies. After a cigarette is smoked, the filter retains some of the chemicals, and some of which are considered carcinogenic.^[79] When studying the environmental impact of cigarette filters, the various chemicals that can be found in cigarette filters are not studied individually, due to its complexity. Researchers instead focus on the whole cigarette filter and its LD₅₀. LD₅₀ is defined as the lethal dose that kills 50% of a sample population. This allows for a simpler study of the toxicity of cigarettes filters. One recent study has looked at the toxicity of smoked cigarette filters (smoked filter + tobacco), smoked cigarette filters (no tobacco), and unsmoked cigarette filters (no tobacco). The results of the study showed that for the LD₅₀of both marine topsmelt (Atherinops affinis) and freshwater fathead minnow (Pimephales promelas), smoked cigarette filters + tobacco are more toxic than smoked cigarette filters, but both are severely more toxic than unsmoked cigarette filters.^[88]

LD₅₀ of cigarette filters to marine life (cigarette per liter)

Cigarette type	Marine topsmelt	Fathead minnow
Smoked cigarette filter (smoked filter + tobacco)	1.0	1.0
Smoked cigarette filters (no tobacco)	1.8	4.3
Unsmoked cigarette filters (no tobacco)	5.1	13.5

Other health concerns

Toxic chemicals are not the only human health concern to take into considerations; the others are cellulose acetate and carbon particles that are breathed in while smoking. These particles are suspected of causing lung damage.^[89] The next health concern is that of plants. Under certain growing conditions, plants on average grow taller and have longer roots than those exposed to cigarette filters in the soil. A connection exists between cigarette filters introduced to soil and the depletion of some soil nutrients over a period time. Another health concern to the environment is not only the toxic carcinogens that are harmful to the wildlife, but also the filters themselves pose an ingestion risk to wildlife that may presume filter litter as food.^[90] The last major health concern to make note of for marine life is the toxicity that deep marine topsmelt and fathead minnow pose to their predators. This could lead to toxin build-up (bioaccumulation) in the food chain and have long reaching negative effects. Smoldering cigarette filters have also been blamed for triggering fires from residential areas^[91] to major wildfires and bushfires which has caused major property damage and also death^[92][93][94] as well as disruption to services by triggering alarms and warning systems.^[95]

Degradation

Once in the environment, cellulose acetate can go through biodegradation and photodegradation.^[96][97][98] Several factors go into determining the rate of both degradation process. This variance in rate and resistance to biodegradation in many conditions is a factor in littering^[99] and environmental damage.^[100]

Biodegradation

The first step in the biodegradation of cellulose acetate is the deactylation of the acetate from the polymer chain (which is the opposite of acetylation). An acetate is a negative ion with the chemical formula of C₂H₃O₂⁻. Deacetylation can be performed by either chemical hydrolysis or acetylesterase. Chemical hydrolysis is the cleavage of a chemical bond by addition of water. In the reaction, water (H₂O) reacts with the acetic ester functional group attached the cellulose polymer chain and forms an alcohol and acetate. The alcohol is simply the cellulose polymer chain with the acetate replaced with an alcohol group. The second reaction is exactly the same as chemical hydrolysis with the exception of the use of an acetylesterase enzyme. The enzyme, found in most plants, catalyzes the chemical reaction shown below.^[101]

acetic ester + H₂O ⇌ alcohol + acetate

In the case of the enzymatic reaction, the two substrates (reactants) are again acetic ester and H₂O, the two products of the reaction are alcohol and acetate. This reaction is exactly the same as the chemical hydrolysis. Both of these products are perfectly fine in the environment. Once the acetate group is removed from the cellulose chain, the polymer can be readily degraded by cellulase, which is another enzyme found in fungi, bacteria, and protozoans. Cellulases break down the cellulose molecule into monosaccharides ("simple sugars") such as beta-glucose, or shorter polysaccharides and oligosaccharides.

These simple sugars are not harmful to the environment and are in fact are a useful product for many plants and animals. The breakdown of cellulose is of interest in the field of biofuel.^[102] Due to the conditions that affect the process, large variation in the degradation time of cellulose acetate occurs.

Factors in biodegradation

The duration of the biodegradation process is cited as taking as little as one month^[96] to as long as 15 years or more, depending on the environmental conditions. The major factor that affects the biodegradation duration is the availability of acetylesterase and cellulase enzymes. Without these enzymes, biodegradation only occurs through chemical hydrolysis and stops there. Temperature is another major factor, if the organisms that contain the enzymes are too cold to grow, then biodegradation is severely hindered. Availability of oxygen in the environment also affects the degradation. Cellulose acetate is degraded within 2–3 weeks under aerobic assay systems of in vitro enrichment cultivation techniques and an activated sludge wastewater treatment system.^[103] It is degraded within 14 weeks under anaerobic conditions of incubation with special cultures of fungi.^[104] Ideal conditions were used for the degradation (i.e. right temperature, and available organisms to provide the enzymes). Thus, filters last longer in places with low oxygen concentration (ex. swamps and bogs). Overall, the biodegraditon process of cellulose acetate is not an instantaneous process.

Photodegradation

The other process of degradation is photodegradation, which is when a molecular bond is broken by the absorption of photon radiation (i.e. light). Due to cellulose acetate carbonyl groups, the molecule naturally absorbs light at 260 nm,^[105] but it contains some impurities which can absorb light. These impurities are known to absorb light in the far UV light region (< 280 nm).^[106] The atmosphere filters radiation from the sun and allows radiation of > 300 nm only to reach the surface. Thus, the primary photodegradation of cellulose acetate is considered insignificant to the total degradation process, since cellulose acetate and its impurities absorb light at shorter wavelengths. Research is focused on the secondary mechanisms of photodegradation of cellulose acetate to help make up for some of the limitations of biodegradation. The secondary mechanisms would be the addition of a compound to the filters that would be able to absorb natural light and use it to start the degradation process. The main two areas of research are in photocatalytic oxidation^[107] and photosensitized degradation.^[108] Photocatalytic oxidation uses a species that absorbs radiation and creates hydroxyl radicals that react with the filters and start the breakdown. Photosensitized degradation, though, uses a species that absorbs radiation and transfers the energy to the cellulose acetate to start the degradation process. Both processes use other species that absorbed light > 300 nm to start the degradation of cellulose acetate.

Solution and remediation projects

Several options are available to help reduce the environmental impact of cigarette butts. Proper disposal into receptacles leads to decreased numbers found in the environment and their effect on the environment. Another method is making fines and penalties for littering filters; many governments have sanctioned stiff penalties for littering of cigarette filters; for example, Washington imposes a penalty of $1,025 for littering cigarette filters.^[109] Another option is developing better biodegradable filters; much of this work relies heavily on the research in the secondary mechanism for photodegradation as stated above, but a new research group has developed an acid tablet that goes inside the filters, and once wet enough, releases acid that speeds up the degradation to around two weeks.^[110] The research is still only in test phase and the hope is soon it will go into production. The next option is using cigarette packs with a compartment in which to discard cigarette butts, implementing monetary deposits on filters, increasing the availability of butt receptacles, and expanding public education. It may even be possible to ban the sale of filtered cigarettes altogether on the basis of their adverse environmental impact.^[111] Recent research has been put into finding ways to use the filter waste to develop a desired product. One research group in South Korea has developed a simple one-step process that converts the cellulose acetate in discarded cigarette filters into a high-performing material that could be integrated into computers, handheld devices, electrical vehicles, and wind turbines to store energy. These materials have demonstrated superior performance as compared to commercially available carbon, grapheme, and carbon nanotubes. The product is showing high promise as a green alternative for the waste problem.^[112]

Consumption

As of 2002, about 5.5 trillion cigarettes were produced globally, and were smoked by over 1.1 billion people, or greater than one-seventh of the world population. While smoking rates have leveled off or declined in developed nations, they continue to rise in developing parts of the world. Smoking rates in the United States have dropped by half from 1965 to 2006, falling from 42% to 20.8% of adults.^[2] In the developing world, tobacco consumption is rising by 3.4% per year.^[3] Smoking rates in Australia have dropped 4.9% in the year that ended in March 2014. Consumption of cigarettes and tobacco dropped 7.6% in the first quarter in Australia, and 0.1% of the nation’s gross domestic product was clipped from the cut in household consumption of cigarettes. Australia is cutting their overall smoking consumption faster than most of the developed world, in part due to landmark legislation passed banning logos on cigarette cartons, and instead replacing labels with graphic images of sick or dying cigarette smokers and dire health warnings in front of the images. This legislation, passed in 2011, is called Australia’s Plain Packaging Act, and was fought in the country’s High Court by manufacturers of tobacco products. The legislation has significantly reduced consumption in Australia, and could serve as precedent for many other governments currently expanding restrictive legislation on cigarette and tobacco use. An independent review made by one of Britain’s most prominent doctors, Cyril Chantler, may be one of the first steps for Britain to follow Australia in cutting its overall household consumption. In his report, he notes that “standardized packaging would serve to reduce the rate of children taking up smoking.” Ireland’s health minister, James Reilly, has said the government has passed a draft bill in 2014 on plain packaging. In New Zealand, a bill has been presented to parliament in which the government’s associate health minister said “takes away the last means of promoting tobacco as a desirable product.”^[114]

Smoking prevalence by sex (2000)

	Percent smoking
Region	Men	Women
Africa	29%	4%
United States	35%	22%
Eastern Mediterranean	35%	4%
Europe	46%	26%
Southeast Asia	44%	4%
Western Pacific	60%	8%

Source: World Health Organization estimates, 2000

Leading consumers of cigarettes (1998)^[115]

Country	Population (millions)	Cigarettes consumed (billions)	Cigarettes consumed (per capita)
China	1,248	1,643	1,320
USA	270	451	1,670
Japan	126	328	2,600
Russia	146	258	1,760
Indonesia	200	215	1,070

Smoking prevalence in the U.S. (2006)^[116]

Rank	State	%	Rank	State	%	Rank	State	%	Rank	State	%
1	KY	28.6	14	SC	22.3	27	KS	20.0	40	AZ	18.1
2	WV	25.7	15	NV	22.2	28	GA	20.0	41	VT	18.0
3	OK	25.7	16	NC	22.1	29	ND	19.6	42	DC	17.9
4	MS	25.1	17	DE	21.7	30	VA	19.3	43	CO	17.9
5	AK	24.2	18	WY	21.6	31	RI	19.3	44	MA	17.8
6	IN	24.1	19	PA	21.5	32	MT	19.0	45	MD	17.8
7	AR	23.7	20	IA	21.5	33	NH	18.7	46	HI	17.5
8	LA	23.4	21	FL	21.0	34	NE	18.6	47	WA	17.1
9	MO	23.3	22	ME	20.9	35	OR	18.5	48	CT	17.0
10	AL	23.3	23	WI	20.8	36	NY	18.3	49	ID	16.8
11	TN	22.6	24	IL	20.5	37	MN	18.3	50	CA	14.9
12	OH	22.5	25	SD	20.4	38	TX	18.1	51	UT	9.8
13	MI	22.4	26	NM	20.2	39	NJ	18.1

Lights

Cigarettes labeled as “Lights”, “Milds”, or “Low-tar” are considered to have a “lighter”, less pronounced flavor than regular cigarettes. These cigarette brands may also contain lower levels of tar, nicotine, or other chemicals inhaled by the smoker.^[117] The filter design is one of the main differences between light and regular cigarettes, although not all cigarettes contain perforated holes in the filter anymore. In some light cigarettes, the filter is perforated with small holes that theoretically diffuse the tobacco smoke with clean air. In regular cigarettes, the filter does not include these perforations. In ultralight cigarettes, the filter’s perforations are larger, and in theory, these larger holes produce an even smaller smoke-to-air ratio.

The majority of major cigarette manufacturers offer a light, low-tar, and/or mild cigarette brand. Due to recent U.S. legislation prohibiting the use of these descriptors, tobacco manufacturers are turning to color-coding to allow consumers to differentiate between regular and light brands.^[118]

The scientific evidence is that switching from regular to light or low-tar cigarettes does not reduce the health risks of smoking or lower the smoker’s exposure to the nicotine, tar, and carcinogens present in cigarette smoke.^{[119][120][121]}

Notable cigarette brands

Health effects

Smokers

Nicotine, the primary psychoactive chemical in cigarettes, is highly addictive.^[122] The resulting use of tobacco is the single greatest cause of preventable death globally.^[123] Smoking leads most commonly to diseases affecting the heart, liver, and lungs, being a major risk factor for heart attacks, strokes, chronic obstructive pulmonary disease (COPD) (including emphysema and chronic bronchitis), and cancer (particularly lung cancer, cancers of the larynx and mouth, and pancreatic cancer). It also causes peripheral vascular disease and hypertension. On average, each cigarette smoked is estimated to shorten life by 11 minutes.^{[4][124][125]} Starting smoking earlier in life and smoking cigarettes higher in tar increases the risk of these diseases. The World Health Organization estimates that tobacco caused 5.4 million deaths in 2004^[126] and 100 million deaths over the course of the 20th century.^[127] Cigarettes produce an aerosol containing over 4,000 chemical compounds, including nicotine, carbon monoxide, acrolein, and oxidant substances.^[11] Over 50 of these are carcinogens.^[12]

The most important chemical compounds causing cancer are those that produce DNA damage since such damage appears to be the primary underlying cause of cancer.^[128][129] Cunningham et al.^[130] combined the microgram weight of the compound in the smoke of one cigarette with the known genotoxic effect per microgram to identify the most carcinogenic compounds in cigarette smoke. The seven most important carcinogens in tobacco smoke are shown in the table, along with DNA alterations they cause.

The most genotoxic cancer causing chemicals in cigarette smoke

Compound	Micrograms per cigarette	Effect on DNA	Ref.
Acrolein	122.4	Reacts with deoxyguanine and forms DNA crosslinks, DNA-protein crosslinks and DNA adducts	[131]
Formaldehyde	60.5	DNA-protein crosslinks causing chromosome deletions and re-arrangements	[132]
Acrylonitrile	29.3	Oxidative stress causing increased 8-oxo-2'-deoxyguanosine	[133]
1,3-butadiene	105.0	Global loss of DNA methylation (an epigenetic effect) as well as DNA adducts	[134]
Acetaldehyde	1448.0	Reacts with deoxyguanine to form DNA adducts	[135]
Ethylene oxide	7.0	Hydroxyethyl DNA adducts with adenine and guanine	[136]
Isoprene	952.0	Single and double strand breaks in DNA	[137]

"Ulcerative colitis is a condition of nonsmokers in which nicotine is of therapeutic benefit."^[138] A recent review of the available scientific literature concluded that the apparent decrease in Alzheimer disease risk may be simply because smokers tend to die before reaching the age at which it normally occurs. "Differential mortality is always likely to be a problem where there is a need to investigate the effects of smoking in a disorder with very low incidence rates before age 75 years, which is the case of Alzheimer's disease", it stated, noting that smokers are only half as likely as nonsmokers to survive to the age of 80.^[139]

Second-hand smoke

Second-hand smoke is a mixture of smoke from the burning end of a cigarette, and the smoke exhaled from the lungs of smokers. It is involuntarily inhaled, lingers in the air hours after cigarettes have been extinguished, and can cause a wide range of adverse health effects, including cancer, respiratory infections, and asthma.^[140] Nonsmokers who are exposed to second-hand smoke at home or work increase their heart disease risk by 25–30% and their lung cancer risk by 20–30%. Second-hand smoke has been estimated to cause 38,000 deaths per year, of which 3,400 are deaths from lung cancer in nonsmokers.^[141] Sudden infant death syndrome, ear infections, respiratory infections, and asthma attacks can occur in children who are exposed to second-hand smoke.^{[142][143][144]} Scientific evidence shows no level of exposure to second-hand smoke is safe.^[142][143]

Smoking cessation

Smoking cessation (quitting smoking) is the process of discontinuing the practice of inhaling a smoked substance.^[145]

Smoking cessation can be achieved with or without assistance from healthcare professionals or the use of medications.^[146] Methods that have been found to be effective include interventions directed at or through health care providers and health care systems; medications including nicotine replacement therapy (NRT) and varenicline; individual and group counselling; and web-based or stand-alone computer programs. Although stopping smoking can cause short-term side effects such as reversible weight gain, smoking cessation services and activities are cost-effective because of the positive health benefits.

At the University of Buffalo, researchers found out that fruit and vegetable consumption can help a smoker cut down or even quit smoking^[147]

• A growing number of countries have more ex-smokers than smokers.^[148]
• Early "failure" is a normal part of trying to stop, and more than one attempt at stopping smoking prior to longer-term success is common.^[146]
• NRT, other prescribed pharmaceuticals, and professional counselling or support also help many smokers.^[146]
• However, up to three-quarters of ex-smokers report having quit without assistance ("cold turkey" or cut down then quit), and cessation without professional support or medication may be the most common method used by ex-smokers.^[146]

Tobacco contains nicotine. Smoking cigarettes can lead to nicotine addiction.^{[149]:2300–2301} The addiction begins when nicotine acts on nicotinic acetylcholine receptors to release neurotransmitters such as dopamine, glutamate, and gamma-aminobutyric acid.^[149]:2296 Cessation of smoking leads to symptoms of nicotine withdrawal such as anxiety and irritability.^[149]:2298 Professional smoking cessation support methods generally endeavour to address both nicotine addiction and nicotine withdrawal symptoms.

The number of nicotinic receptors in the brain returns to the level of a nonsmoker between 6 and 12 weeks after quitting.^[150]

Replacement

Electronic cigarettes are battery-powered vaporizers that simulate the feeling of smoking, but without tobacco.^[151] Their use is commonly called "vaping".^[152] The user activates the e-cigarette by taking a puff or pressing a button.^[152][153] Some look like traditional cigarettes, but they come in many variations.^[154][155] Most are reusable but there are also disposable versions called first generation cigalikes.^[156] There are also second, third, and fourth generation devices.^{[157][158][159]} Instead of cigarette smoke, the user inhales an aerosol, commonly called vapor.^[160] E-cigarettes typically have a heating element that atomizes a liquid solution known as e-liquid.^[161] E-liquids usually contain propylene glycol, glycerin, nicotine, and flavorings.^{[162][163][164][165]}

The benefits and the health risks of e-cigarettes are uncertain.^[166][167]>^[168] There is tentative evidence that they can help people quit smoking,^[165] but they have not been proven better than regulated medication.^[168] Their usefulness in tobacco harm reduction is unclear,^[169] but they could form part of future strategies to decrease tobacco related death and disease.^[163][170] Their safety risk to users is similar to that of smokeless tobacco.^[170] Regulated nicotine replacement products are safer than e-cigarettes,^[169] but e-cigarettes are probably safer than smoking.^[171]

Non-smokers who use e-cigarettes risk nicotine addiction^[172] The e-liquid has a low level of toxicity, and contamination with various chemicals has been identified in the product.^[173] E-cigarette vapor contains fewer toxic substances,^[154] and lower concentrations of potential toxic substances than cigarette smoke.^[174] Metal parts of e-cigarettes in contact with the e-liquid can contaminate it with metals.^[175] Normal usage of e-cigarettes generates very low levels of formaldehyde.^[176] A 2015 review found that later-generation e-cigarettes set at higher power may generate equal or higher levels of formaldehyde compared to smoking.^[177] A 2015 review found that these levels were the result of overheating under test conditions that bear little resemblance to common usage.^[176] No serious adverse effects from e-cigarettes have been reported in trials.^[165] Less serious adverse effects include throat and mouth inflammation, vomiting, nausea, and cough.^[154] The long-term effects of e-cigarette use are unknown.^[152][153]

Insufficient data are available to determine the impact on public health from e-cigarettes.^[178] The potential harm to bystanders from e-cigarettes is unknown.^[179] No long-term data are available.^[180] A white paper published in 2014 by the American Industrial Hygiene Association concluded e-cigarettes emit airborne contaminants that may be inhaled by the user and those nearby.^[181] Due to this possible risk, they urged restriction of their use indoors, similar to smoking bans, until research has shown the aerosol does not significantly harm others in the area.^[181] A 2014 review indicated that the levels of inhaled contaminants from the e-cigarette vapor are not of significant health concern for human exposures by the standards used in workplaces to ensure safety.^[182] The British Medical Association reported in 2013 that "concerns [exist] that the use of e-cigarettes could threaten the norm of not smoking in public places and workplaces."^[183] The use of e-cigarettes in a smoke-free area could expose nonusers to toxins.^[184] The effect on bystanders would likely be much less harmful than traditional cigarettes.^[180]

See also

References

Further reading

• Bogden JD, Kemp FW, Buse M, et al. (January 1981). "Composition of tobaccos from countries with high and low incidences of lung cancer. I. Selenium, polonium-210, Alternaria, tar, and nicotine". J. Natl. Cancer Inst. 66 (1): 27–31. PMID 6935462. doi:10.1093/jnci/66.1.27. 
• Hecht SS (July 1999). "Tobacco smoke carcinogens and lung cancer". J. Natl. Cancer Inst. 91 (14): 1194–210. PMID 10413421. doi:10.1093/jnci/91.14.1194. 
• Zhou, Xun Yu; Gilman, Sander L. (2004). Smoke: a global history of smoking. London: Reaktion Books. ISBN 978-1-86189-200-3. 
• Matuszko, Jan (November 2006). "Tobacco Products Processing Detailed Study" (PDF). www.epa.gov. U.S. Environmental Protection Agency. Retrieved 29 March 2017. 

External links

Wikimedia Commons has media related to Cigarette.

• US Center for Disease Control - Smoking and Health Database
• GLOBALink
• National Clearinghouse on Tobacco and Health - Canada
• Society for Research on Nicotine and Tobacco
• Bibliography on History of Cigarette Smoking