A cigarette filter, also known as a filter tip, is a component of a
cigarette
A cigarette is a narrow cylinder containing a combustible material, typically tobacco, that is rolled into Rolling paper, thin paper for smoking. The cigarette is ignited at one end, causing it to smolder; the resulting smoke is orally inhale ...
, along with
cigarette paper, capsules and adhesives. Filters were introduced in the early 1950s.
[
Filters may be made from plastic ]cellulose acetate
In biochemistry, cellulose acetate refers to any acetate ester of cellulose, usually cellulose diacetate. It was first prepared in 1865. A bioplastic, cellulose acetate is used as a film base in photography, as a component in some coatings, and ...
fiber, paper
Paper is a thin sheet material produced by mechanically or chemically processing cellulose fibres derived from wood, Textile, rags, poaceae, grasses, Feces#Other uses, herbivore dung, or other vegetable sources in water. Once the water is dra ...
or activated charcoal
"Activated" is a song by English singer Cher Lloyd. It was released on 22 July 2016 through Vixen Records. The song was made available to stream exclusively on ''Rolling Stone'' a day before to release (on 21 July 2016).
Background
In an inter ...
(either as a cavity filter or embedded into the plastic cellulose acetate fibers). Macroporous phenol-formaldehyde resins and asbestos
Asbestos ( ) is a group of naturally occurring, Toxicity, toxic, carcinogenic and fibrous silicate minerals. There are six types, all of which are composed of long and thin fibrous Crystal habit, crystals, each fibre (particulate with length su ...
have also been used. The plastic cellulose acetate filter and paper modify the particulate smoke phase by particle retention (filtration
Filtration is a physical separation process that separates solid matter and fluid from a mixture using a ''filter medium'' that has a complex structure through which only the fluid can pass. Solid particles that cannot pass through the filte ...
), and finely divided carbon
Carbon () is a chemical element; it has chemical symbol, symbol C and atomic number 6. It is nonmetallic and tetravalence, tetravalent—meaning that its atoms are able to form up to four covalent bonds due to its valence shell exhibiting 4 ...
modifies the gaseous phase (adsorption
Adsorption is the adhesion of atoms, ions or molecules from a gas, liquid or dissolved solid to a surface. This process creates a film of the ''adsorbate'' on the surface of the ''adsorbent''. This process differs from absorption, in which a ...
).
Filters are intended to reduce the harm caused by smoking by reducing harmful chemicals inhaled by smokers. While laboratory tests show a reduction of " tar" and 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 cigarette smoke, filters are ineffective at removing gases of low molecular weight, such as carbon monoxide
Carbon monoxide (chemical formula CO) is a poisonous, flammable gas that is colorless, odorless, tasteless, and slightly less dense than air. Carbon monoxide consists of one carbon atom and one oxygen atom connected by a triple bond. It is the si ...
. Most of these measured reductions occur only when the cigarette is smoked on a smoking machine; when smoked by a human, the compounds are delivered into the lungs regardless of whether a filter is used.
Most factory-made cigarettes are equipped with a filter; those who roll their own can buy them from a tobacconist.
History
In 1925, Hungarian inventor Boris Aivaz patented the process of making a cigarette filter from crepe paper.
From 1935, Molins Machine Co Ltd a British company began to develop a machine that made cigarettes incorporating the tipped filter. It was considered a specialty item until 1954, when manufacturers introduced the machine more broadly, following a spate of announcements from doctors and researchers concerning a possible link between lung diseases
Respiratory diseases, or lung diseases, are pathological conditions affecting the organs and tissues that make gas exchange difficult in air-breathing animals. They include conditions of the respiratory tract including the trachea, bronchi, ...
and smoking. Since filtered cigarettes were considered safer, by the 1960s, they dominated the market. Production of filter cigarettes rose from 0.5 percent in 1950 to 87.7 percent by 1975.
Between the 1930s and the 1950s, most cigarettes were long. The modern cigarette market includes mainly filter cigarettes that are .
Cigarettes filters were originally made of cork and used to prevent tobacco flakes from getting on the smoker's tongue. Many are still patterned to look like cork.[
]
Manufacture
Cigarette filters are usually made from plastic cellulose acetate
In biochemistry, cellulose acetate refers to any acetate ester of cellulose, usually cellulose diacetate. It was first prepared in 1865. A bioplastic, cellulose acetate is used as a film base in photography, as a component in some coatings, and ...
fibre
Fiber (spelled fibre in British English; from ) is a natural or artificial substance that is significantly longer than it is wide. Fibers are often used in the manufacture of other materials. The strongest engineering materials often incorp ...
,[ but sometimes also from ]paper
Paper is a thin sheet material produced by mechanically or chemically processing cellulose fibres derived from wood, Textile, rags, poaceae, grasses, Feces#Other uses, herbivore dung, or other vegetable sources in water. Once the water is dra ...
or activated charcoal
"Activated" is a song by English singer Cher Lloyd. It was released on 22 July 2016 through Vixen Records. The song was made available to stream exclusively on ''Rolling Stone'' a day before to release (on 21 July 2016).
Background
In an inter ...
(either as a cavity filter or embedded into the cellulose acetate).
Cellulose acetate
In biochemistry, cellulose acetate refers to any acetate ester of cellulose, usually cellulose diacetate. It was first prepared in 1865. A bioplastic, cellulose acetate is used as a film base in photography, as a component in some coatings, and ...
is made by ester
In chemistry, an ester is a compound derived from an acid (either organic or inorganic) in which the hydrogen atom (H) of at least one acidic hydroxyl group () of that acid is replaced by an organyl group (R). These compounds contain a distin ...
ifying bleached cotton
Cotton (), first recorded in ancient India, is a soft, fluffy staple fiber that grows in a boll, or protective case, around the seeds of the cotton plants of the genus '' Gossypium'' in the mallow family Malvaceae. The fiber is almost pure ...
or wood pulp
Pulp is a fibrous Lignocellulosic biomass, lignocellulosic material prepared by chemically, semi-chemically, or mechanically isolating the cellulose fiber, cellulosic fibers of wood, fiber crops, Paper recycling, waste paper, or cotton paper, rag ...
with acetic acid
Acetic acid , systematically named ethanoic acid , is an acidic, colourless liquid and organic compound with the chemical formula (also written as , , or ). Vinegar is at least 4% acetic acid by volume, making acetic acid the main compone ...
. Of the three cellulose hydroxy groups available for esterification, between two and three are esterified by controlling the amount of acid (degree of substitution (DS) 2.35-2.55). The ester is spun into fibers and formed into bundles called filter tow. Flavors (menthol
Menthol is an organic compound, specifically a Monoterpene, monoterpenoid, that occurs naturally in the oils of several plants in the Mentha, mint family, such as Mentha arvensis, corn mint and peppermint. It is a white or clear waxy crystallin ...
), sweeteners, softeners ( triacetin), flame retardant
Flame retardants are a diverse group of chemicals that are added to manufactured materials, such as plastics and textiles, and surface finishes and coatings. Flame retardants are activated by the presence of an combustion, ignition source and pr ...
s ( sodium tungstate), breakable capsules releasing flavors on demand, and additives colouring the tobacco smoke may be added to cigarette filters. The five largest manufactures of filter tow are Celanese and Eastman Chemicals in the United States, Cerdia in Germany, Daicel and Mitsubishi Rayon in Japan.
Starch glues or emulsion-based adhesives are used for gluing cigarette seams. Hot-melt and emulsion-based adhesives are used for filter seams. Emulsion-based adhesives are used for bonding the filters to the cigarettes. The tip paper may be coated with polyvinyl alcohol
Polyvinyl alcohol (PVOH, PVA, or PVAl) is a water- soluble synthetic polymer. It has the idealized formula H2CH(OH)sub>''n''. It is used in papermaking, textile warp sizing, as a thickener and emulsion stabilizer in polyvinyl acetate (PVAc) a ...
.
Colour change
The tobacco industry determined that the illusion of filtration was more important than filtration itself. The pH of the cellulose acetate used is modified, so that its colour becomes darker when exposed to smoke (this was invented in 1953 by Claude Teague,[ working for R. J. Reynolds Tobacco Company).] The industry wanted filters to be seen as effective for marketing reasons, despite not making cigarettes any less unhealthy.
Health risks
In the 1970s epidemiologic evidence relative to tobacco-related cancers and data for coronary heart disease indicated a reduced risk among filter smokers for these diseases. Between 1970 and 1980 some studies showed a 20-50% reduction in risk of lung cancer for long-term smokers of filtered cigarettes as compared to smokers of non-filtered cigarettes (IARC, 1986) but later studies indicated a similar risk for lung cancer in smokers of filtered and non-filtered cigarettes. The risk reductions depend on different aspects such as the gender or whether a person is athletic, the study location, the age of the person, and when only studies providing both unadjusted and adjusted estimates were considered. Whether or not relative risk estimates are adjusted for cigarette consumption is not crucial to the conclusion of a clear advantage to filter cigarettes and tar reduction.
Various add-on cigarette filters ("Water Pik", "Venturi", "David Ross") are sold as stop-smoking or tar-reduction devices. The idea is that filters reduce tar and nicotine levels, permitting the smoker to be weaned away from cigarettes.
Light cigarettes
The tobacco industry has reduced tar and nicotine yields in cigarette smoke since the 1960s. This has been achieved in a variety of ways, including use of selected strains of tobacco plant, changes in agricultural and curing procedures, use of reconstituted sheets (reprocessed tobacco leaf waste), incorporation of tobacco stalks, reduction of the amount of tobacco needed to fill a cigarette by expanding it (like puffed wheat) to increase its "filling power", and by the use of filters and high-porosity wrapping papers. However, just as a drinker tends to drink a larger volume of beer than of wine or spirits, many smokers tend to inversely modify their smoking pattern according to the strength of the cigarette being smoked. In contrast to the standardized puffing of the smoking machines on which the tar and nicotine yields are based, when a smoker switches to a low-tar, low nicotine cigarette, they smoke more cigarettes, take more puffs and inhale more deeply. Conversely, when smoking a high-tar, high-nicotine cigarette there is a tendency to smoke and inhale less.
In spite of the changes in cigarette design and manufacturing over the last fifty years, the use of filters and "light" cigarettes neither decreased the nicotine intake per cigarette, nor lowered the incidence of lung cancer ( NCI, 2001; IARC 83, 2004; U.S. Surgeon General, 2004). The shift over the years from higher- to lower-yield cigarettes may explain the change in the pathology of lung cancer
Lung cancer, also known as lung carcinoma, is a malignant tumor that begins in the lung. Lung cancer is caused by genetic damage to the DNA of cells in the airways, often caused by cigarette smoking or inhaling damaging chemicals. Damaged ...
. That is, the percentage of lung cancers that are adenocarcinoma
Adenocarcinoma (; plural adenocarcinomas or adenocarcinomata ; AC) is a type of cancerous tumor that can occur in several parts of the body. It is defined as neoplasia of epithelial tissue that has glandular origin, glandular characteristics, or ...
s has increased, while the percentage of squamous cell cancers has decreased. The change in tumor type is believed to reflect the higher nitrosamine
Nitrosamines (or more formally ''N''-nitrosamines) are organic compounds produced by industrial processes. The chemical structure is , where R is usually an alkyl group. Nitrosamines have a nitroso group () that are "probable human carcinogens", ...
delivery of lower-yield cigarettes and the increased depth or volume of inhalation of lower-yield cigarettes to compensate for lower level concentrations of nicotine in the smoke.
Safety
Cellulose acetate is non-toxic, odorless, tasteless, and weakly flammable plastic. It is resistant to weak acids and is largely stable to mineral and fatty oils as well as petroleum. Smoked (i.e., used/discarded) cigarette butts contain 5–7 mg (~ 0.08-0.11 gr) of 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 ...
(about 25% of the total cigarette nicotine content). Cellulose acetate is hydrophilic and retains the water-soluble smoke constituents (many of which are irritating, including acids, alkali, aldehydes, and phenols), while letting through the lipophilic aromatic compounds.
Waste
Cigarette butts are the most litter
Litter consists of waste products that have been discarded incorrectly, without consent, at an unsuitable location. The waste is objects, often man-made, such as aluminum cans, paper cups, food wrappers, cardboard boxes or plastic bottles, but ...
ed anthropogenic (man-made) waste item in the world. Approximately 5.6 trillion cigarettes are smoked every year worldwide. Of these, it is estimated that 4.5 trillion cigarette butts become litter every year. The plastic cellulose acetate
In biochemistry, cellulose acetate refers to any acetate ester of cellulose, usually cellulose diacetate. It was first prepared in 1865. A bioplastic, cellulose acetate is used as a film base in photography, as a component in some coatings, and ...
in cigarette butts biodegrades gradually, passing through the stage of microplastics
Microplastics are "synthetic solid particles or polymeric matrices, with regular or irregular shape and with size ranging from 1 μm to 5 mm, of either primary or secondary manufacturing origin, which are insoluble in water." Microplastics a ...
. The breakdown of discarded cigarette butts is highly dependent upon environmental conditions. A 2021 review article cites an experiment where 45-50% of cellulose acetate mass was fully degraded to CO2 after 55 days of controlled composting and another where negligible degradation took place after 12 weeks in pilot-scale compost.
During the act of smoking, plastic cellulose acetate fibers and tipping paper absorb a wide range of chemicals that are present in tobacco smoke. After cigarette butts are discarded, they can leach toxins including nicotine, arsenic, polycyclic aromatic hydrocarbons and heavy metals into the environment. Smoked cigarette butts and cigarette tobacco in butts have been shown to be toxic to water organisms such as the marine topsmelt ('' Atherinops affinis'') and the freshwater fathead minnow ('' Pimephales promelas''). Moreover, cigarette filters enriched in toxic substances that enter environmental waterbodies have been shown to be increasingly colonized by potentially pathogenic bacteria including those displaying antibiotic resistance, as these are particularly well adapted to the adverse conditions on the filters.
Atmospheric moisture, gastric acid
Gastric acid or stomach acid is the acidic component – hydrochloric acid – of gastric juice, produced by parietal cells in the gastric glands of the stomach lining. In humans, the pH is between one and three, much lower than most other a ...
, light, and enzyme
An enzyme () is a protein that acts as a biological catalyst by accelerating chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the substrates into different mol ...
s hydrolyze cellulose acetate to acetic acid
Acetic acid , systematically named ethanoic acid , is an acidic, colourless liquid and organic compound with the chemical formula (also written as , , or ). Vinegar is at least 4% acetic acid by volume, making acetic acid the main compone ...
and cellulose
Cellulose is an organic compound with the chemical formula, formula , a polysaccharide consisting of a linear chain of several hundred to many thousands of glycosidic bond, β(1→4) linked glucose, D-glucose units. Cellulose is an important s ...
. Cellulose may be further hydrolyzed to cellobiose
Cellobiose is a disaccharide with the formula (C6H7(OH)4O)2O. It is classified as a reducing sugar
- any sugar that possesses the ability or function of a reducing agent. The chemical structure of cellobiose is derived from the condensation of a ...
or glucose
Glucose is a sugar with the Chemical formula#Molecular formula, molecular formula , which is often abbreviated as Glc. It is overall the most abundant monosaccharide, a subcategory of carbohydrates. It is mainly made by plants and most algae d ...
in an acidic medium. Humans cannot digest cellulose and excrete the fibers in feces, because, unlike ruminant animals, rabbit
Rabbits are small mammals in the family Leporidae (which also includes the hares), which is in the order Lagomorpha (which also includes pikas). They are familiar throughout the world as a small herbivore, a prey animal, a domesticated ...
s, rodent
Rodents (from Latin , 'to gnaw') are mammals of the Order (biology), order Rodentia ( ), which are characterized by a single pair of continuously growing incisors in each of the upper and Mandible, lower jaws. About 40% of all mammal specie ...
s, termite
Termites are a group of detritivore, detritophagous Eusociality, eusocial cockroaches which consume a variety of Detritus, decaying plant material, generally in the form of wood, Plant litter, leaf litter, and Humus, soil humus. They are dist ...
s, and some bacteria and fungi, they lack cellulolytic enzymes such as cellulase
Cellulase (; systematic name 4-β-D-glucan 4-glucanohydrolase) is any of several enzymes produced chiefly by fungi, bacteria, and protozoans that catalyze cellulolysis, the decomposition of cellulose and of some related polysaccharides:
: Endo ...
.
Many governments have sanctioned stiff penalties for littering of cigarette filters; for example Washington State imposes a penalty of $1,025 for littering cigarette filters. Another option is developing better biodegradable
Biodegradation is the breakdown of organic matter by microorganisms, such as bacteria and fungi. It is generally assumed to be a natural process, which differentiates it from composting. Composting is a human-driven process in which biodegrada ...
filters. Much of this work relies heavily on the research about the secondary mechanism for photodegradation. However, making a product biodegradable means making it vulnerable to humidity and heat, which does not suit filters made for hot and humid smoke.[ The next option is using cigarette packs with a compartment for discarded cigarette butts, implementing monetary deposits on filters, increasing the availability of cigarette receptacles, and expanding public education. Others have suggested banning the sale of filtered cigarettes altogether on the basis of their adverse environmental impact.][
Recent research has been put into finding ways to use the filter waste in order to develop other products. One research group in South Korea have developed a one-step process that converts the cellulose acetate in discarded cigarette filters into a high-performing supercapacitor electrode material. These materials have demonstrated superior performance as compared to commercially available carbon, ]graphene
Graphene () is a carbon allotrope consisting of a Single-layer materials, single layer of atoms arranged in a hexagonal lattice, honeycomb planar nanostructure. The name "graphene" is derived from "graphite" and the suffix -ene, indicating ...
and carbon nano tubes.
Another group of researchers has proposed adding tablets of food grade acid inside the filters. Once wet enough the tablets would release acid that accelerates degradation to around two weeks, instead of using cellulose triacetate and besides of cigarette smoke being quite acidic.
Activated charcoal filtration
Cigarette filter can incorporate an activated charcoal filtration system. Instead of acetate or cardboard filters, it consists of two ceramic caps on either sides containing activated charcoal, which reduces tar and other toxins in the smoke.
See also
* Cigarette butt
* Cigarette holder
* List of additives in cigarettes
* Nicotine marketing
* Tobacco smoking
Tobacco smoking is the practice of burning tobacco and ingesting the resulting smoke. The smoke may be inhaled, as is done with cigarettes, or released from the mouth, as is generally done with pipes and cigars. The practice is believed to hav ...
References
{{Cigarettes
Cigarettes
Air filters