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The term flame retardants subsumes a diverse group of chemicals that are added to manufactured materials, such as
plastics and
textiles, and surface finishes and
coating
A coating is a covering that is applied to the surface of an object, usually referred to as the substrate. The purpose of applying the coating may be decorative, functional, or both. Coatings may be applied as liquids, gases or solids e.g. Pow ...
s.
[ Flame retardants are activated by the presence of an ]ignition
Ignition may refer to:
Science and technology
* Firelighting, the human act of creating a fire for warmth, cooking and other uses
* Combustion, an exothermic chemical reaction between a fuel and an oxidant
* Fusion ignition, the point at which a ...
source and are intended to prevent or slow the further development of ignition by a variety of different physical and chemical methods. They may be added as a copolymer
In polymer chemistry, a copolymer is a polymer derived from more than one species of monomer. The polymerization of monomers into copolymers is called copolymerization. Copolymers obtained from the copolymerization of two monomer species are some ...
during the polymerisation process, or later added to the polymer at a moulding or extrusion
Extrusion is a process used to create objects of a fixed cross-sectional profile by pushing material through a die of the desired cross-section. Its two main advantages over other manufacturing processes are its ability to create very complex ...
process or (particularly for textiles) applied as a topical finish. Mineral flame retardants are typically additive while organohalogen
Halocarbon compounds are chemicals in which one or more carbon atoms are linked by covalent bonds with one or more halogen atoms (fluorine, chlorine, bromine or iodine – ) resulting in the formation of organofluorine compounds, organochlori ...
and organophosphorus
Organophosphorus compounds are organic compounds containing phosphorus. They are used primarily in pest control as an alternative to chlorinated hydrocarbons that persist in the environment. Some organophosphorus compounds are highly effective in ...
compounds can be either reactive or additive.
Classes
Both Reactive and Additive Flame retardants types, can be further separated into four distinct classes:
* Minerals such as aluminium hydroxide
Aluminium hydroxide, Al(OH)3, is found in nature as the mineral gibbsite (also known as hydrargillite) and its three much rarer polymorphs: bayerite, doyleite, and nordstrandite. Aluminium hydroxide is amphoteric, i.e., it has both basic an ...
(ATH), magnesium hydroxide
Magnesium hydroxide is the inorganic compound with the chemical formula Mg(OH)2. It occurs in nature as the mineral brucite. It is a white solid with low solubility in water (). Magnesium hydroxide is a common component of antacids, such as milk ...
(MDH), huntite
Huntite is a carbonate mineral with the chemical formula Mg3Ca(CO3)4. Huntite crystallizes in the trigonal system and typically occurs as platy crystals and powdery masses. For most of recorded history its main use was as a white pigment. Today ...
and hydromagnesite
Hydromagnesite is a hydrated magnesium carbonate mineral with the formula Mg5(CO3)4(OH)2·4H2O.
It generally occurs associated with the weathering products of magnesium containing minerals such as serpentine or brucite. It occurs as incrustations ...
, various hydrates, red phosphorus
Elemental phosphorus can exist in several allotropes, the most common of which are white and red solids. Solid violet and black allotropes are also known. Gaseous phosphorus exists as diphosphorus and atomic phosphorus.
White phosphorus
White ...
, and boron compounds, mostly borate
A borate is any of several boron oxyanions, negative ions consisting of boron and oxygen, such as orthoborate , metaborate , or tetraborate ; or any salt with such anions, such as sodium metaborate, and disodium tetraborate . The name also re ...
s.
* Organohalogen compounds. This class includes organochlorines
An organochloride, organochlorine compound, chlorocarbon, or chlorinated hydrocarbon is an organic compound containing at least one covalently bonded atom of chlorine. The chloroalkane class (alkanes with one or more hydrogens substituted by chlo ...
such as chlorendic acid
Chlorendic acid, or 1,4,5,6,7,7-hexachlorobicyclo .2.1hept-5-ene-2,3-dicarboxylic acid, is a chlorinated hydrocarbon used in the synthesis of some flame retardants and polymers. It is a common breakdown product of several organochlorine insecticide ...
derivatives and chlorinated paraffins; organobromines such as decabromodiphenyl ether (decaBDE), decabromodiphenyl ethane (a replacement for decaBDE), polymeric brominated compounds such as brominated polystyrenes, brominated carbonate oligomers (BCOs), brominated epoxy oligomers (BEOs), tetrabromophthalic anyhydride, tetrabromobisphenol A
Tetrabromobisphenol A (TBBPA) is a brominated flame retardant. The compound is a white solid (not colorless), although commercial samples appear yellow. It is one of the most common flame retardants.
Production and use
TBBPA is produced by the ...
(TBBPA) and hexabromocyclododecane
Hexabromocyclododecane (HBCD or HBCDD) is a brominated flame retardant. It consists of twelve carbon, eighteen hydrogen, and six bromine atoms tied to the ring. Its primary application is in extruded (XPS) and expanded (EPS) polystyrene foam that ...
(HBCD). Most but not all halogenated flame retardants are used in conjunction with a synergist to enhance their efficiency. Antimony trioxide is widely used but other forms of antimony
Antimony is a chemical element with the symbol Sb (from la, stibium) and atomic number 51. A lustrous gray metalloid, it is found in nature mainly as the sulfide mineral stibnite (Sb2S3). Antimony compounds have been known since ancient t ...
such as the pentoxide and sodium antimonate In chemistry an antimonate is a compound which contains a metallic element, oxygen, and antimony in an oxidation state of +5. These compounds adopt polymeric structures with M-O-Sb linkages. They can be considered to be derivatives of the hypothetic ...
are also used.
* Organophosphorus compounds. This class includes organophosphates such as triphenyl phosphate
Triphenyl phosphate (TPhP) is the chemical compound with the formula OP(OC6H5)3. This colourless solid is the ester (triester) of phosphoric acid and phenol. It is used as a plasticizer and a fire retardant in a wide variety of settings and produc ...
(TPP), resorcinol bis(diphenylphosphate) (RDP), bisphenol A diphenyl phosphate (BADP), and tricresyl phosphate
Tricresyl phosphate (TCP), is a mixture of three isomeric organophosphate compounds most notably used as a flame retardant and as a plasticizer in manufacturing for lacquers and varnishes and vinyl plastics. Pure tricresyl phosphate is a colourles ...
(TCP); phosphonate
In organic chemistry, phosphonates or phosphonic acids are organophosphorus compounds containing groups (where R = alkyl, aryl, or just hydrogen). Phosphonic acids, typically handled as salts, are generally nonvolatile solids that are poorly ...
s such as dimethyl methylphosphonate
Ethane ( , ) is an organic chemical compound with chemical formula . At standard temperature and pressure, ethane is a colorless, odorless gas. Like many hydrocarbons, ethane is isolated on an industrial scale from natural gas and as a petroc ...
(DMMP); and phosphinate
Phosphinates or hypophosphites are a class of phosphorus compounds conceptually based on the structure of hypophosphorous acid. IUPAC prefers the term phosphinate in all cases, however in practice hypophosphite is usually used to describe inorgani ...
s such as aluminium diethyl phosphinate
Aluminium diethyl phosphinate is a chemical compound with formula Al()3. It decomposes above 300 °C.
Applications
In the family of dialkyl phosphinic acid salts, aluminium diethyl phosphinate has been found to be an excellent flame retar ...
. In one important class of flame retardants, compounds contain both phosphorus and a halogen. Such compounds include tris(2,3-dibromopropyl) phosphate
Tris(2,3-dibromopropyl) phosphate ("tris") is a chemical once widely used as a flame retardant in plastics and textiles.
Safety and regulation
Tris is mutagenic and listed as an IARC Group 2A carcinogen. It is one of the chemicals covered by th ...
(brominated tris) and chlorinated organophosphates such as tris(1,3-dichloro-2-propyl)phosphate
Tris(1,3-dichloroisopropyl)phosphate (TDCPP) is a chlorinated organophosphate. Organophosphate chemicals have a wide variety of applications and are used as flame retardants, pesticides, plasticizers, and nerve gases. TDCPP is structurally si ...
(chlorinated tris or TDCPP) and tetrakis(2-chlorethyl)dichloroisopentyldiphosphate (V6).
* Organic compounds such as carboxylic acid and dicarboxylic acid
Retardation mechanisms
The basic mechanisms of flame retardancy vary depending on the specific flame retardant and the substrate. Additive and reactive flame-retardant chemicals can both function in the vapor (gaseous) or condensed (solid) phase.
Endothermic degradation
Some compounds break down endothermically when subjected to high temperatures. Magnesium and aluminium hydroxides are an example, together with various carbonates and hydrates such as mixtures of huntite
Huntite is a carbonate mineral with the chemical formula Mg3Ca(CO3)4. Huntite crystallizes in the trigonal system and typically occurs as platy crystals and powdery masses. For most of recorded history its main use was as a white pigment. Today ...
and hydromagnesite
Hydromagnesite is a hydrated magnesium carbonate mineral with the formula Mg5(CO3)4(OH)2·4H2O.
It generally occurs associated with the weathering products of magnesium containing minerals such as serpentine or brucite. It occurs as incrustations ...
. The reaction removes heat from the substrate, thereby cooling the material. The use of hydroxides and hydrates is limited by their relatively low decomposition temperature, which limits the maximum processing temperature of the polymers (typically used in polyolefins for wire and cable applications).
Thermal shielding (solid phase)
A way to stop spreading of the flame over the material is to create a thermal insulation barrier between the burning and unburned parts. Intumescent
An intumescent is a substance that swells as a result of heat exposure, leading to an increase in volume and decrease in density. Intumescent materials are typically used in passive fire protection and require listing, approval, and compliance in ...
additives are often employed; their role is to turn the polymer surface into a char, which separates the flame from the material and slows the heat transfer to the unburned fuel. Non-halogenated inorganic and organic phosphate flame retardants typically act through this mechanism by generating a polymeric layer of charred phosphoric acid.
Dilution of gas phase
Inert gases (most often carbon dioxide
Carbon dioxide ( chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is trans ...
and water
Water (chemical formula ) is an Inorganic compound, inorganic, transparent, tasteless, odorless, and Color of water, nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living ...
) produced by thermal degradation of some materials act as diluents of the combustible gases, lowering their partial pressures and the partial pressure of oxygen, and slowing the reaction rate.[
]
Gas phase radical quenching
Chlorinated and brominated materials undergo thermal degradation and release hydrogen chloride
The compound hydrogen chloride has the chemical formula and as such is a hydrogen halide. At room temperature, it is a colourless gas, which forms white fumes of hydrochloric acid upon contact with atmospheric water vapor. Hydrogen chloride ga ...
and hydrogen bromide
Hydrogen bromide is the inorganic compound with the formula . It is a hydrogen halide consisting of hydrogen and bromine. A colorless gas, it dissolves in water, forming hydrobromic acid, which is saturated at 68.85% HBr by weight at room tempe ...
or, if used in the presence of a synergist like antimony trioxide, antimony halides. These react with the highly reactive H· and OH· radicals in the flame, resulting in an inactive molecule and a Cl· or Br· radical. The halogen radical is much less reactive compared to H· or OH·, and therefore has much lower potential to propagate the radical oxidation reactions of combustion
Combustion, or burning, is a high-temperature exothermic redox chemical reaction between a fuel (the reductant) and an oxidant, usually atmospheric oxygen, that produces oxidized, often gaseous products, in a mixture termed as smoke. Combus ...
.
Materials
Flame retardant cotton
Flame retardant cotton is cotton
Cotton 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 cellulose, and can contain minor pe ...
that has been treated to prevent or slow ignition by different treatments applied during the manufacturing process. Cotton is typically made flame-resistant by chemical applications of polymeric, nonpolymeric, and polymeric/nonpolymeric hybrids that are composed of one or more of the elements such as nitrogen
Nitrogen is the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at se ...
, sodium
Sodium is a chemical element with the symbol Na (from Latin ''natrium'') and atomic number 11. It is a soft, silvery-white, highly reactive metal. Sodium is an alkali metal, being in group 1 of the periodic table. Its only stable ...
, phosphorus
Phosphorus is a chemical element with the symbol P and atomic number 15. Elemental phosphorus exists in two major forms, white phosphorus and red phosphorus, but because it is highly reactive, phosphorus is never found as a free element on Ear ...
, silicon
Silicon is a chemical element with the symbol Si and atomic number 14. It is a hard, brittle crystalline solid with a blue-grey metallic luster, and is a tetravalent metalloid and semiconductor. It is a member of group 14 in the periodic ta ...
, boron, or chlorine
Chlorine is a chemical element with the symbol Cl and atomic number 17. The second-lightest of the halogens, it appears between fluorine and bromine in the periodic table and its properties are mostly intermediate between them. Chlorine i ...
.
Manufacturing
While non-organic fabrics are typically made flame-resistant by incorporating flame retardants into their matrices
Matrix most commonly refers to:
* ''The Matrix'' (franchise), an American media franchise
** ''The Matrix'', a 1999 science-fiction action film
** "The Matrix", a fictional setting, a virtual reality environment, within ''The Matrix'' (franchis ...
, surface modification is more convenient for organic fabrics like cotton.
Use
Cotton fabrics have been frequently used worldwide because of their advantageous properties with regard to thermal insulation, biocompatibility
Biocompatibility is related to the behavior of biomaterials in various contexts. The term refers to the ability of a material to perform with an appropriate host response in a specific situation. The ambiguity of the term reflects the ongoing de ...
and great moisture absorption and breathability performances. These advantages indicate potential applications of cotton fabrics in protective clothing and human health. However, natural cotton fabric is highly flammable and will rapidly burn out. This fatal drawback reveals a potential danger and limits the use of cotton fabrics. Therefore, treating cotton fabrics to obtain fire-resistant cotton fabrics is important.
Firefighters, or those exposed to flames on a regular basis, rely on flame-retardant cotton for both protection and comfort. Typically, their undergarments beneath the heavier fire-resistant gear are made of flame-retardant cotton or another breathable, organic fabric that's been treated to resist ignition.
Polymers containing nitrogen
Nitrogen is the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at se ...
, sodium
Sodium is a chemical element with the symbol Na (from Latin ''natrium'') and atomic number 11. It is a soft, silvery-white, highly reactive metal. Sodium is an alkali metal, being in group 1 of the periodic table. Its only stable ...
, and phosphorus
Phosphorus is a chemical element with the symbol P and atomic number 15. Elemental phosphorus exists in two major forms, white phosphorus and red phosphorus, but because it is highly reactive, phosphorus is never found as a free element on Ear ...
atoms can work as materials for fire-resistant cellulosic
Cellulose is an organic compound with the formula , a polysaccharide consisting of a linear chain of several hundred to many thousands of β(1→4) linked D-glucose units. Cellulose is an important structural component of the primary cell wa ...
textiles, such as cotton or rayon. Specifically, organic polymers can work as a flame-retardant due to the presence of one or all three types of these elements. These atoms can be in the original polymers, or they can be incorporated by chemical modification.
Use and effectiveness
Fire safety standards
Flame retardants are typically added to industrial and consumer products to meet flammability
A combustible material is something that can burn (i.e., ''combust'') in air. A combustible material is flammable if it ignites easily at ambient temperatures. In other words, a combustible material ignites with some effort and a flammable mat ...
standards for furniture, textiles, electronics, and building products like insulation.
In 1975, California
California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the m ...
began implementing Technical Bulletin 117 (TB 117), which requires that materials such as polyurethane foam used to fill furniture be able to withstand a small open flame, equivalent to a candle, for at least 12 seconds. In polyurethane foam, furniture manufacturers typically meet TB 117 with additive halogenated organic flame retardants. Although no other U.S. states have a similar standard, because California has such a large market many manufacturers meet TB 117 in products that they distribute across the United States. The proliferation of flame retardants, and especially halogenated organic flame retardants, in furniture across the United States is strongly linked to TB 117.
In response to concerns about the health impacts of flame retardants in upholstered furniture, in February 2013 California proposed modifying TB 117 to require that fabric covering upholstered furniture meet a smolder test and to eliminate the foam flammability standards. Gov. Jerry Brown
Edmund Gerald Brown Jr. (born April 7, 1938) is an American lawyer, author, and politician who served as the 34th and 39th governor of California from 1975 to 1983 and 2011 to 2019. A member of the Democratic Party, he was elected Secretary of ...
signed the modified TB117-2013 in November and it became effective in 2014. The modified regulation does not mandate a reduction in flame retardants.
In Europe, flame retardant standards for furnishings vary, and are their most stringent in the UK and Ireland. Generally the ranking of the various common flame retardant tests worldwide for furniture and soft furnishings would indicate that the California test Cal TB117 - 2013 test is the most straightforward to pass, there is increasing difficulty in passing Cal TB117 -1975 followed by the British test BS 5852 and followed by Cal TB133. One of the most demanding flammability tests worldwide is probably the US Federal Aviation Authority test for aircraft seating which involves the use of a kerosene burner which blasts flame at the test piece.
The 2009 Greenstreet Berman study, carried out by the UK government, showed that in the period between 2002 and 2007 the UK Furniture and Furnishings Fire Safety Regulations accounted for 54 fewer deaths per year, 780 fewer non-fatal casualties per year and 1065 fewer fires each year following the introduction of the UK furniture safety regulations in 1988.
Effectiveness
The effectiveness of flame retardant chemicals at reducing the flammability of consumer products in house fires is disputed. Advocates for the flame retardant industry, such as the American Chemistry Council's North American Flame Retardant Alliance, cite a study from the National Bureau of Standards indicating that a room filled with flame-retarded products (a polyurethane foam-padded chair and several other objects, including cabinetry and electronics) offered a 15-fold greater time window for occupants to escape the room than a similar room free of flame retardants. However, critics of this position, including the lead study author, argue that the levels of flame retardant used in the 1988 study, while found commercially, are much higher than the levels required by TB 117 and used broadly in the United States in upholstered furniture.
Another study concluded flame retardants are an effective tool to reduce fire risks without creating toxic emissions.
Several studies in the 1980s tested ignition in whole pieces of furniture with different upholstery and filling types, including different flame retardant formulations. In particular, they looked at maximum heat release and time to maximum heat release, two key indicators of fire danger. These studies found that the type of fabric covering had a large influence on ease of ignition, that cotton fillings were much less flammable than polyurethane foam fillings, and that an interliner material substantially reduced the ease of ignition. They also found that although some flame retardant formulations decreased the ease of ignition, the most basic formulation that met TB 117 had very little effect. In one of the studies, foam fillings that met TB 117 had equivalent ignition times as the same foam fillings without flame retardants. A report from the Proceedings of the Polyurethane Foam Association also showed no benefit in open-flame and cigarette tests with foam cushions treated with flame retardants to meet TB 117. However, other scientists support this open-flame test.
Compared with cotton, flame retardants increase fire toxicity. They have a large effect on bench-scale flammability tests, but a negligible effect on large scale fire tests. Furniture of naturally flame-retardant materials is much safer than foam with fire retardants.
Environmental and health issues
The environmental behaviour of flame retardants has been studied since the 1990s. Mainly brominated flame retardant Brominated flame retardants (BFRs) are organobromine compounds that have an inhibitory effect on combustion chemistry and tend to reduce the flammability of products containing them. The brominated variety of commercialized chemical flame retardants ...
s were found in many environmental compartments and organisms including humans, and some individual substances were found to have toxic
Toxicity is the degree to which a chemical substance or a particular mixture of substances can damage an organism. Toxicity can refer to the effect on a whole organism, such as an animal, bacterium, or plant, as well as the effect on a subs ...
properties. Therefore, alternatives have been demanded by authorities, NGOs and equipment manufacturers. The EU-funded collaborative research projec
ENFIRO
(EU research project FP7: 226563, concluded in 2012) started out from the assumption that not enough environmental and health data were known of alternatives to the established brominated flame retardants. In order to make the evaluation fully comprehensive, it was decided to compare also material and fire performance as well as attempt a life-cycle assessment of a reference product containing halogen free versus brominated flame retardants. About a dozen halogen free flame retardants were studied representing a large variety of applications, from engineering plastics, printed circuit board
A printed circuit board (PCB; also printed wiring board or PWB) is a medium used in electrical and electronic engineering to connect electronic components to one another in a controlled manner. It takes the form of a laminated sandwich struc ...
s, encapsulants to textile and intumescent
An intumescent is a substance that swells as a result of heat exposure, leading to an increase in volume and decrease in density. Intumescent materials are typically used in passive fire protection and require listing, approval, and compliance in ...
coatings. A large group of the studied flame retardants were found to have a good environmental and health profile: ammonium polyphosphate
Ammonium polyphosphate is an inorganic salt of polyphosphoric acid and ammonia containing both chains and possibly branching. Its chemical formula is H4 PO3sub>n(OH)2 showing that each monomer consists of an orthophosphate radical of a phosphor ...
(APP), Aluminium diethyl phosphinate
Aluminium diethyl phosphinate is a chemical compound with formula Al()3. It decomposes above 300 °C.
Applications
In the family of dialkyl phosphinic acid salts, aluminium diethyl phosphinate has been found to be an excellent flame retar ...
(Alpi), aluminium hydroxide
Aluminium hydroxide, Al(OH)3, is found in nature as the mineral gibbsite (also known as hydrargillite) and its three much rarer polymorphs: bayerite, doyleite, and nordstrandite. Aluminium hydroxide is amphoteric, i.e., it has both basic an ...
(ATH), magnesium hydroxide (MDH), melamine polyphosphate (MPP), dihydrooxaphosphaphenanthrene (DOPO), zinc stannate (ZS) and zinc hydroxstannate (ZHS). Overall, they were found to have a much lower tendency to bioaccumulate
Bioaccumulation is the gradual accumulation of substances, such as pesticides or other chemicals, in an organism. Bioaccumulation occurs when an organism absorbs a substance at a rate faster than that at which the substance is lost or eliminated ...
in fatty tissue than the studied brominated flame retardants.
The tests on the fire behaviour of materials with different flame retardants revealed that halogen free flame retardants produce less smoke and toxic fire emissions, with the exception of the aryl phosphates RDP and BDP in styrenic polymers. The leaching
Leaching is the loss or extraction of certain materials from a carrier into a liquid (usually, but not always a solvent). and may refer to:
* Leaching (agriculture), the loss of water-soluble plant nutrients from the soil; or applying a small amou ...
experiments showed that the nature of the polymer is a dominating factor and that the leaching behaviour of halogen free and brominated flame retardants is comparable. The more porous or “hydrophilic
A hydrophile is a molecule or other molecular entity that is attracted to water molecules and tends to be dissolved by water.Liddell, H.G. & Scott, R. (1940). ''A Greek-English Lexicon'' Oxford: Clarendon Press.
In contrast, hydrophobes are ...
” a polymers is the more flame retardants can be released. However, moulded plates which represent real world plastic products showed much lower leaching levels than extruded polymer granules. The impact assessment studies reconfirmed that the improper waste
Waste (or wastes) are unwanted or unusable materials. Waste is any substance discarded after primary use, or is worthless, defective and of no use. A by-product, by contrast is a joint product of relatively minor economic value. A waste prod ...
and recycling treatment of electronic products with brominated flame retardants can produce dioxins which is not the case with halogen free alternatives. Furthermore, th
United States Environmental Protection Agency
(US-EPA) has been carrying out a series of projects related to the environmental assessment of alternative flame retardants, the
design for environment
projects on flame retardants for printed wiring boards and alternatives to decabromo diphenylethers and hexabromocyclododecane (HBCD).
In 2009, the U.S. National Oceanic and Atmospheric Administration (NOAA) released a report on polybrominated diphenyl ether
Polybrominated diphenyl ethers or PBDEs, are a class of organobromine compounds that are used as flame retardants. Like other brominated flame retardants, PBDEs have been used in a wide array of products, including building materials, electronics, ...
s (PBDEs) and found that, in contrast to earlier reports, they were found throughout the U.S. coastal zone. This nationwide survey found that New York's Hudson Raritan Estuary had the highest overall concentrations of PBDEs, both in sediments and shellfish. Individual sites with the highest PBDE measurements were found in shellfish taken from Anaheim Bay, California, and four sites in the Hudson Raritan Estuary. Watersheds that include the Southern California Bight, Puget Sound, the central and eastern Gulf of Mexico off the coast of Tampa and St. Petersburg, in Florida, and the waters of Lake Michigan near Chicago and Gary, Indiana, also were found to have high PBDE concentrations.
Health concerns
The earliest flame retardants, polychlorinated biphenyls
Polychlorinated biphenyls (PCBs) are highly carcinogenic chemical compounds, formerly used in industrial and consumer products, whose production was banned in the United States by the Toxic Substances Control Act in 1979 and internationally by ...
(PCBs), were banned in the U.S. in 1977 when it was discovered that they were toxic. Industries used brominated flame retardant Brominated flame retardants (BFRs) are organobromine compounds that have an inhibitory effect on combustion chemistry and tend to reduce the flammability of products containing them. The brominated variety of commercialized chemical flame retardants ...
s instead, but these are now receiving closer scrutiny. In 2004 and 2008 the EU banned several types of polybrominated diphenyl ethers
Polybrominated diphenyl ethers or PBDEs, are a class of organobromine compounds that are used as flame retardants. Like other brominated flame retardants, PBDEs have been used in a wide array of products, including building materials, electronics, ...
(PBDEs). Negotiations between the EPA and the two U.S. producers of DecaBDE (a flame retardant that has been used in electronics, wire and cable insulation, textiles, automobiles and airplanes, and other applications), Albemarle Corporation
Albemarle Corporation is a specialty chemicals manufacturing company based in Charlotte, North Carolina. It operates 3 divisions: lithium (41.0% of 2021 revenues), bromine specialties (33.9% of 2021 revenues) and catalysts (22.9% of 2021 revenu ...
and Chemtura Corporation
Chemtura Corporation was a global corporation headquartered in Philadelphia, Pennsylvania, with its other principal executive office in Middlebury, Connecticut. Merged into Lanxess in 2017, the company focused on specialty chemicals for various i ...
, and the largest U.S. importer, ICL Industrial Products, Inc., resulted in commitments by these companies to phase out decaBDE for most uses in the United States by December 31, 2012, and to end all uses by the end of 2013. The state of California has listed the flame retardant chemical chlorinated Tris (tris(1,3-dichloro-2-propyl) phosphate or TDCPP) as a chemical known to cause cancer. In December 2012, the California nonprofit Center for Environmental Health filed notices of intent to sue several leading retailers and producers of baby products for violating California law for failing to label products containing this cancer-causing flame retardant. While the demand for brominated and chlorinated flame retardants in North America and Western Europe is declining, it is rising in all other regions.
There is a potential association between the exposure to the Phosphorus Flame Retardants (PFR) in residential indoor dust and the development of allergies, asthma and dermatitis. A study was conducted in 2014 by Araki, A. et al. in Japan to assess this relationship. They found a significant association between the Tris (2-chloro-iso-propyl) phosphate (TCIPP) and atopic dermatitis with an odds ratio of 2.43. They also found that the Tributyl phosphate was associated with the development of allergic rhinitis and asthma with an odds ratio of 2.55 & 2.85 respectively.
Another study conducted by Chevrier ''et al.'' 2010 measured the concentration of 10 PBDE congeners, free thyroxine (T4), total T4, and thyroid-stimulating hormone (TSH) in 270 pregnant women around the 27th week of gestation. Associations between PBDEs and free and total T4 were found to be statistically insignificant. However, authors did find a significant association amongst exposure to PBDEs and lower TSH during pregnancy, which may have implications for maternal health and fetal development.
A prospective, longitudinal cohort study initiated after 11 September 2001
The September 11 attacks, commonly known as 9/11, were four coordinated suicide terrorist attacks carried out by al-Qaeda against the United States on Tuesday, September 11, 2001. That morning, nineteen terrorists hijacked four commer ...
, including 329 mothers who delivered in one of three hospitals in lower Manhattan, New York, was conducted by Herbstman ''et al.'' 2010. Authors of this study analyzed 210 cord blood specimens for selected PBDE congeners and assessed neurodevelopmental effects in the children at 12–48 and 72 months of age. Results showed that children who had higher cord blood concentrations of polybrominated diphenyl ethers (PBDEs) scored lower on tests of mental and motor development at 1–4 and 6 years of age. This was the first study to report any such associations in humans.
A similar study was conducted by Roze et al. 2009 in The Netherlands on 62 mothers and children to estimate associations between 12 Organohalogen compounds (OHCs), including polychlorinated biphenyls (PCBs) and brominated diphenyl ether (PBDE) flame retardants, measured in maternal serum during the 35th week of pregnancy and motor performance (coordination, fine motor skill
A motor skill is a function that involves specific movements of the body's muscles to perform a certain task. These tasks could include walking, running, or riding a bike. In order to perform this skill, the body's nervous system, muscles, and br ...
s), cognition (intelligence, visual perception, visuomotor integration, inhibitory control, verbal memory, and attention), and behavior scores at 5–6 years of age. Authors demonstrated for the first time that transplacental transfer of polybrominated flame retardants was associated with the development of children at school age.
Another study was conducted by Rose et al. in 2010 to measure circulating PBDE levels in 100 children between 2 and 5 years of age from California. The PBDE levels according to this study, in 2- to 5-year-old California children was 10 to 1,000 fold higher than European children, 5 times higher than other U.S. children and 2 to 10 times higher than U.S. adults. They also found that diet, indoor environment, and social factors influenced children's body burden levels. Eating poultry and pork contributed to elevated body burdens for nearly all types of flame retardants. Study also found that lower maternal education was independently and significantly associated with higher levels of most flame retardant congeners in the children.
''San Antonio Statement on Brominated and Chlorinated Flame Retardants 2010'': A group of 145 prominent scientists from 22 countries signed the first-ever consensus statement documenting health hazards from flame retardant chemicals found at high levels in home furniture, electronics
The field of electronics is a branch of physics and electrical engineering that deals with the emission, behaviour and effects of electrons using electronic devices. Electronics uses active devices to control electron flow by amplification ...
, insulation
Insulation may refer to:
Thermal
* Thermal insulation, use of materials to reduce rates of heat transfer
** List of insulation materials
** Building insulation, thermal insulation added to buildings for comfort and energy efficiency
*** Insulated ...
, and other products. This statement documents that, with limited fire safety benefit, these flame retardants can cause serious health issues, and, as types of flame retardants are banned, the alternatives should be proven safe before being used. The group also wants to change widespread policies that require use of flame retardants.
Mechanisms of toxicity
Direct exposure
Many halogenated flame retardants with aromatic rings, including most brominated flame retardants, are likely thyroid
The thyroid, or thyroid gland, is an endocrine gland in vertebrates. In humans it is in the neck and consists of two connected lobes. The lower two thirds of the lobes are connected by a thin band of tissue called the thyroid isthmus. The thy ...
hormone disruptor
Endocrine disruptors, sometimes also referred to as hormonally active agents, endocrine disrupting chemicals, or endocrine disrupting compounds are chemicals that can interfere with endocrine (or hormonal) systems. These disruptions can cause ca ...
s. The thyroid hormones triiodothyronine
Triiodothyronine, also known as T3, is a thyroid hormone. It affects almost every physiological process in the body, including growth and development, metabolism, body temperature, and heart rate.
Production of T3 and its prohormone thyroxine ...
(T3) and thyroxine
File:Thyroid_system.svg, upright=1.5, The thyroid system of the thyroid hormones T3 and T4
rect 376 268 820 433 Thyroid-stimulating hormone
rect 411 200 849 266 Thyrotropin-releasing hormone
rect 297 168 502 200 Hypothalamus
rect 66 216 386 25 ...
(T4) carry iodine atoms, another halogen, and are structurally similar to many aromatic halogenated flame retardants, including PCBs, TBBPA, and PBDEs. Such flame retardants therefore appear to compete for binding sites in the thyroid system, interfering with normal function of thyroid transport protein
A transport protein (variously referred to as a transmembrane pump, transporter, escort protein, acid transport protein, cation transport protein, or anion transport protein) is a protein that serves the function of moving other materials within ...
s (such as transthyretin
Transthyretin (TTR or TBPA) is a transport protein in the plasma and cerebrospinal fluid that transports the thyroid hormone thyroxine (T4) and retinol to the liver. This is how transthyretin gained its name: ''transports thyroxine and retinol' ...
) in vitro and thyroid hormone receptor
A hormone receptor is a receptor molecule that binds to a specific chemical messenger . Hormone receptors are a wide family of proteins made up of receptors for thyroid and steroid hormones, retinoids and Vitamin D, and a variety of other recepto ...
s. A 2009 ''in vivo'' animal study conducted by the US Environmental Protection Agency (EPA) demonstrated that deiodination, active transport, sulfation
Sulfation is the chemical reaction that entails the addition of SO3 group. In principle, many sulfations would involve reactions of sulfur trioxide (SO3). In practice, most sulfations are effected less directly. Regardless of the mechanism, the ...
, and glucuronidation
Glucuronidation is often involved in drug metabolism of substances such as drugs, pollutants, bilirubin, androgens, estrogens, mineralocorticoids, glucocorticoids, fatty acid derivatives, retinoids, and bile acids. These linkages involve gl ...
may be involved in disruption of thyroid homeostasis after perinatal exposure to PBDEs during critical developmental time points in utero and shortly after birth. Disruption of deiodinase
Deiodinase (or "Monodeiodinase") is a peroxidase enzyme that is involved in the activation or deactivation of thyroid hormones.
Types
Types of deiodinases include:
Iodothyronine deiodinases catalyze release of iodine directly from the thyro ...
as reported in the Szabo et al., 2009 ''in vivo'' study was supported in a follow-up ''in vitro'' study. The adverse effects on hepatic mechanism of thyroid hormone disruption during development have been shown to persist into adulthood. The EPA noted that PBDEs are particularly toxic to the developing brains of animals. Peer-reviewed studies have shown that even a single dose administered to mice during development of the brain can cause permanent changes in behavior, including hyperactivity.
Based on ''in vitro'' laboratory studies, several flame retardants, including PBDEs, TBBPA, and BADP, likely also mimic other hormones, including estrogen
Estrogen or oestrogen is a category of sex hormone responsible for the development and regulation of the female reproductive system and secondary sex characteristics. There are three major endogenous estrogens that have estrogenic hormonal ac ...
s, progesterone, and androgen
An androgen (from Greek ''andr-'', the stem of the word meaning "man") is any natural or synthetic steroid hormone that regulates the development and maintenance of male characteristics in vertebrates by binding to androgen receptors. This in ...
s. Bisphenol A compounds with lower degrees of bromination seem to exhibit greater estrogenicity. Some halogenated flame retardants, including the less-brominated PBDEs, can be direct neurotoxicants in ''in vitro'' cell culture studies: By altering calcium homeostasis and signalling in neuron
A neuron, neurone, or nerve cell is an electrically excitable cell that communicates with other cells via specialized connections called synapses. The neuron is the main component of nervous tissue in all animals except sponges and placozoa. ...
s, as well as neurotransmitter release and uptake at synapses, they interfere with normal neurotransmission
Neurotransmission (Latin: ''transmissio'' "passage, crossing" from ''transmittere'' "send, let through") is the process by which signaling molecules called neurotransmitters are released by the axon terminal of a neuron (the presynaptic neuron), ...
. Mitochondria may be particularly vulnerable to PBDE toxicity due to their influence on oxidative stress and calcium activity in mitochondria. Exposure to PBDEs can also alter neural cell differentiation and migration during development.
Degradation products
Many flame retardants degrade into compounds that are also toxic, and in some cases the degradation products may be the primary toxic agent:
* Halogenated compounds with aromatic rings can degrade into dioxins and dioxin-like compounds
Dioxins and dioxin-like compounds (DLCs) are a group of chemical compounds that are persistent organic pollutants (POPs) in the environment. They are mostly by-products of burning or various industrial processes - or, in case of dioxin-like PCBs ...
, particularly when heated, such as during production, a fire, recycling, or exposure to sun. Chlorinated dioxins are among the highly toxic compounds listed by the Stockholm Convention on Persistent Organic Pollutants.
* Polybrominated diphenyl ethers with higher numbers of bromine atoms, such as decaBDE, are less toxic than PBDEs with lower numbers of bromine atoms, such as pentaBDE. However, as the higher-order PBDEs degrade biotically or abiotically, bromine atoms are removed, resulting in more toxic PBDE congeners.
* When some halogenated flame retardants such as PBDEs are metabolized, they form hydroxylated
In chemistry, hydroxylation can refer to:
*(i) most commonly, hydroxylation describes a chemistry, chemical process that introduces a hydroxyl group () into an organic compound.
*(ii) the ''degree of hydroxylation'' refers to the number of OH gr ...
metabolites that can be more toxic than the parent compound. These hydroxylated metabolites, for example, may compete more strongly to bind with transthyretin or other components of the thyroid system, can be more potent estrogen mimics than the parent compound, and can more strongly affect neurotransmitter receptor activity.
* Bisphenol-A diphenyl phosphate (BADP) and tetrabromobisphenol A (TBBPA) likely degrade to bisphenol A (BPA), an endocrine disruptor of concern.
Routes of exposure
People can be exposed to flame retardants through several routes, including diet; consumer products in the home, vehicle, or workplace; occupation; or environmental contamination near their home or workplace. Residents in North America tend to have substantially higher body levels of flame retardants than people who live in many other developed areas, and around the world human body levels of flame retardants have increased over the last 30 years.
Exposure to PBDEs has been studied the most widely. As PBDEs have been phased out of use due to health concerns, organophosphorus flame retardants, including halogenated organophosphate flame retardants, have frequently been used to replace them. In some studies, indoor air concentrations of phosphorus flame retardants has been found to be greater than indoor air concentrations of PBDEs. The European Food Safety Authority (EFSA) issued in 2011 scientific opinions on the exposure to HBCD and TBBPA and its derivates in food and concluded that current dietary exposure in the European Union does not raise a health concern.
Exposure in the general population
The body burden of PBDEs in Americans correlates well with the level of PBDEs measured in swabs of their hands, likely picked up from dust. /sup>">5/sup> /sup>">6/sup> Dust exposure may occur in the home, car, or workplace. Levels of PBDEs can be as much as 20 times higher in vehicle dust as in household dust, and heating of the vehicle interior on hot summer days can break down flame retardants into more toxic degradation products. /sup>">7/sup> However, blood serum levels of PBDEs appear to correlate most highly with levels found in dust in the home. /sup>">6/sup> 60-80% of exposures are due to dust inhalation or ingestion. /sup>">0/sup> /sup>">1/sup>. In addition to this, 20% to 40% of adult U.S. exposure to PBDEs is through food intake as PBDEs bioaccumulate in the food chain. High concentration can be found in meat, dairy and fish with the remaining exposure largely due to dust inhalation or ingestion /sup>">0/sup> /sup>">1/sup>. Individuals can also be exposed through electronic and electrical devices. Young children in the United States tend to carry higher levels of flame retardants per unit body weight than do adults. /sup>">9/sup> /sup>">0/sup> Infants and toddlers are particularly exposed to halogenated flame retardants found in breast milk and dust. Because many halogenated flame retardants are fat-soluble, they accumulate in fatty areas such as breast tissue and are mobilized into breast milk, delivering high levels of flame retardants to breast-feeding infants. /sup>">1/sup> PBDEs also cross the placenta, meaning infants are exposed in utero. Mothers thyroid hormone (T4) level can be disrupted and exposure in utero in rat studies has been demonstrated to alter motor control, delay sensory development and puberty.
Another reason for high levels of exposure in young children are due to aging consumer products age, small particles of material become dust particles in the air and land on surfaces around the home, including the floor. Young children crawling and playing on the floor frequently bring their hands to their mouths, ingesting about twice as much house dust as adults per day in the United States. /sup>">8/sup> Children also have a higher food intake per kilogram of bodyweight compared to adults. Young children are also exposed to flame retardants through their clothing, car seats and toys. The introduction of these chemicals came about after the tragic death of children wearing brushed rayon fabric that would ignite easily. The U.S enacted the Flammable Fabrics Act passed in 1953 after which, flame retardants were mandated to be added to many children's items, including pajamas. While flame retardants are shown to decrease the risk of burn injuries in children, the risks of thyroid disruption as well as physical and cognitive developmental delays, are not outweighed.
A study was conducted by Carignan in 2013, C. et al. found that gymnasts are exposed to some flame-retardant products such as PentaBDE and TBB more than the general population in the United States. After testing hand-wipe samples before and after the exercise, they found that the BDE-153 concentration was four to over six times greater among gymnasts than the United States population. Also, the PentaBDE concentration was higher up to three times after exercise compared to the level before; indicating a higher level of the flame-retardants on the training equipment. Moreover, they also found several flame-retardant products with different concentrations in the air and dust that were higher in the gym than residencies. However, the study was performed on a small sample size; and further studies are recommended to assess the association.
Occupational exposure
Some occupations expose workers to higher levels of halogenated flame retardants and their degradation products. A small study of U.S. foam recyclers and carpet installers, who handle padding often made from recycled polyurethane foam, showed elevated levels of flame retardants in their tissues. Workers in electronics recycling plants around the world also have elevated body levels of flame retardants relative to the general population. Environmental controls can substantially reduce this exposure, whereas workers in areas with little oversight can take in very high levels of flame retardants. Electronics recyclers in Guiyu, China, have some of the highest human body levels of PBDEs in the world. A study conducted in Finland determined the occupational exposure of workers to brominated flame retardants and chlorinated flame retardants (TBBPA, PBDEs, DBDPE, HBCD, Hexabromobenzene and Dechlorane plus). In 4 recycling sites of waste electrical and electronic equipment
Electronic waste or e-waste describes discarded electrical or electronic devices. Used electronics which are destined for refurbishment, reuse, resale, salvage recycling through material recovery, or disposal are also considered e-waste. Informa ...
(WEEE), the study concluded that control measures implemented on site significantly reduced the exposure. Workers making products that contain flame retardants (such as vehicles, electronics, and baby products) may be similarly exposed. U.S. firefighters can have elevated levels of PBDEs and high levels of brominated furans, toxic degradation products of brominated flame retardants.
Environmental exposure
Flame retardants manufactured for use in consumer products have been released into environments around the world. The flame retardant industry has developed a voluntary initiative to reduce emissions to the environment (VECAP) by promoting best practices during the manufacturing process. Communities near electronics factories and disposal facilities, especially areas with little environmental oversight or control, develop high levels of flame retardants in air, soil, water, vegetation, and people.
Organophosphorus flame retardants have been detected in wastewater
Wastewater is water generated after the use of freshwater, raw water, drinking water or saline water in a variety of deliberate applications or processes. Another definition of wastewater is "Used water from any combination of domestic, industrial ...
in Spain and Sweden, and some compounds do not appear to be removed thoroughly during water treatment. Organophosphorus flame-retardants were also found in tap and bottled drinking water in China. Likewise in the Elbe river in Germany.[Wolschke, H., Suhring, R., Xie, Z., & Ebinghaus, R. (2015). Organophosphorus flame retardants and plasticizers in the aquatic environment: A case study of the Elbe River, Germany. Environ Pollut, 206, 488-493. doi:10.1016/j.envpol.2015.08.002]
Disposal
When products with flame retardants reach the end of their usable life, they are typically recycled, incinerated, or landfilled.
Recycling can contaminate workers and communities near recycling plants, as well as new materials, with halogenated flame retardants and their breakdown products. Electronic waste
Electronic waste or e-waste describes discarded electrical or electronic devices. Used electronics which are destined for refurbishment, reuse, resale, salvage recycling through material recovery, or disposal are also considered e-waste. Inform ...
, vehicles, and other products are often melted to recycle their metal components, and such heating can generate toxic dioxins and furans. When wearing Personal Protection Equipment (PPE) and when a ventilation system is installed, exposure of workers to dust can be significantly reduced, as shown in the work conducted by the recycling plant Stena-Technoworld AB in Sweden. Brominated flame retardants may also change the physical properties of plastics, resulting in inferior performance in recycled products and in “downcycling” of the materials. It appears that plastics with brominated flame retardants are mingling with flame-retardant-free plastics in the recycling stream and such downcycling is taking place.
Poor-quality incineration similarly generates and releases high quantities of toxic degradation products. Controlled incineration of materials with halogenated flame retardants, while costly, substantially reduces release of toxic byproducts.
Many products containing halogenated flame retardants are sent to landfills. Additive, as opposed to reactive, flame retardants are not chemically bonded to the base material and leach out more easily. Brominated flame retardants, including PBDEs, have been observed leaching out of landfills in industrial countries, including Canada and South Africa. Some landfill designs allow for leachate capture, which would need to be treated. These designs also degrade with time.
Regulatory opposition
Shortly after California amended TB117 in 2013 to require only flame-resistant furniture coverings (without restriction on the interior components), furniture manufacturers across the US heard increased demands for flame-retardant-free furniture. Of note, smolder-resistant fabrics used in flame-resistant coverings do not contain PBDEs, organophosphates, or other chemicals historically associated with adverse effects on human health. A number of decision-makers in the health sector - which accounts for nearly 18% of the US GDP - are committed to purchasing such materials and furniture. Early adopters of this policy included Kaiser Permanente, Advocate Health Care, Hackensack University Hospital, and University Hospitals. All together, furniture purchasing power of these hospitals totalled $50 million.[Westervelt, Amy. California law sparks nationwide demand for flame-retardant-free furniture. The Guardian. September 20, 2104.] All of these hospitals and hospital systems ascribe to the Healthier Hospitals Initiative, which has over 1300 member hospitals, and promotes environmental sustainability and community health within the healthcare industry.
Further legislation in California has served to educate the public about flame retardants in their homes, in effect reducing consumer demand for products containing these chemicals. According to a law (Senate Bill, 1019) signed by Governor Jerry Brown in 2014, all furniture manufactured after January 1, 2015 must contain a consumer warning label stating whether it does or does not contain flame retardant chemicals
As of September 2017, the topic reached federal regulatory attention in the Consumer Product Safety Commission, which voted to put together a Chronic Hazard Advisory Panel focused on describing certain risks of various consumer products, specifically baby and childcare products (including bedding and toys), upholstered home furniture, mattresses and mattresses and mattress pads, and plastic casings surrounding electronics. This advisory panel is charged specifically to address the risks of additive, non-polymeric organohalogen flame retardants (OFRs). Although these chemicals have not been banned, this ruling sets in motion an in-depth consumer safety investigation which could eventually lead to complete removal of these substances from consumer manufacturing.
Pursuant with the Toxic Substances Control Act of 1976, the Environmental Protection Agency is also actively evaluating the safety of various flame retardants, including chlorinated phosphate esters, tetrabromobisphenol A, cyclic aliphatic bromides, and brominated phthalates. Further regulations depend on EPA findings from this analysis, though any regulatory processes could take several years.
National Bureau of Standards testing
In a 1988 test program, conducted by the former National Bureau of Standards
The National Institute of Standards and Technology (NIST) is an agency of the United States Department of Commerce whose mission is to promote American innovation and industrial competitiveness. NIST's activities are organized into physical sci ...
(NBS), now the National Institute of Standards and Technology
The National Institute of Standards and Technology (NIST) is an agency of the United States Department of Commerce whose mission is to promote American innovation and industrial competitiveness. NIST's activities are organized into physical s ...
(NIST), to quantify the effects of fire retardant chemicals on total fire hazard. Five different types of products, each made from a different type of plastic were used. The products were made up in analogous fire-retardant (FR) and non-retarded variants (NFR).[
The impact of FR (flame retardant) materials on the survivability of the building occupants was assessed in two ways:
First, comparing the time until a domestic space is not fit for occupation in the burning room, known as "untenability"; this is applicable to the occupants of the burning room. Second, comparing the total production of heat, toxic gases, and smoke from the fire; this is applicable to occupants of the building remote from the room of fire origin.][
The time to untenability is judged by the time that is available to the occupants before either (a) room flashover occurs, or (b) untenability due to toxic gas production occurs. For the FR tests, the average available escape time was more than 15-fold greater than for the occupants of the room without fire retardants.
Hence, with regard to the production of combustion products,][
* The amount of material consumed in the fire for the fire retardant (FR) tests was less than half the amount lost in the non-fire retardant (NFR) tests.
* The FR tests indicated an amount of heat released from the fire which was 1/4 that released by the NFR tests.
* The total quantities of toxic gases produced in the room fire tests, expressed in "CO equivalents," were 1/3 for the FR products, compared to the NFR ones.
* The production of smoke was not significantly different between the room fire tests using NFR products and those with FR products.
Thus, in these tests, the fire retardant additives decreased the overall fire hazard.][
]
Global demand
In 2013, the world consumption of flame retardants was more than 2 million tonnes. The commercially most import application area is the construction sector. It needs flame retardants for instance for pipes and cables made of plastics. In 2008 the United States, Europe and Asia consumed 1.8 million tonnes, worth US$4.20-4.25 billion. According to Ceresana, the market for flame retardants is increasing due to rising safety standards worldwide and the increased use of flame retardants. It is expected that the global flame retardant market will generate US$5.8 billion. In 2010, Asia-Pacific was the largest market for flame retardants, accounting for approximately 41% of global demand, followed by North America, and Western Europe.Market Study Flame Retardants 2nd ed.
Ceresana, 07/11
See also
* Brominated flame retardant Brominated flame retardants (BFRs) are organobromine compounds that have an inhibitory effect on combustion chemistry and tend to reduce the flammability of products containing them. The brominated variety of commercialized chemical flame retardants ...
* Cotton
Cotton 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 cellulose, and can contain minor pe ...
* Fire glass
Fire glass (also fire pit glass, fire rocks, fire beads or lava glass) is a type of tempered glass, chunks of which are used decoratively on fireplaces. Pieces of the glass are heaped around jets of burning gas, or around liquid ethanol, in order ...
* Fire retardant
A fire retardant is a substance that is used to slow down or stop the spread of fire or reduce its intensity. This is commonly accomplished by chemical reactions that reduce the flammability of fuels or delay their combustion. Fire retardants m ...
* Flammability
A combustible material is something that can burn (i.e., ''combust'') in air. A combustible material is flammable if it ignites easily at ambient temperatures. In other words, a combustible material ignites with some effort and a flammable mat ...
* NEMA FR-2
FR-2 (Flame Resistant 2) is a NEMA designation for synthetic resin bonded paper, a composite material made of paper impregnated with a plasticized phenol formaldehyde resin, used in the manufacture of printed circuit boards. Its main properties a ...
* NEMA FR-4
* Polymer
A polymer (; Greek '' poly-'', "many" + ''-mer'', "part")
is a substance or material consisting of very large molecules called macromolecules, composed of many repeating subunits. Due to their broad spectrum of properties, both synthetic a ...
References
Further reading
*
The Dangers of Brominated Fire Retardants
', by Nick Gromicko, International Association of Certified Home Inspectors, Inc, viewed January 2018.
*
Fire Resistant and Fire Retardant Cables
', by Steven McFadyen, myElectrical Engineering, July 4, 2013.
*
External links
FlameRetardants-Online
from Clariant Produkte (Deutschland) GmbH
Phosphorus, Inorganic and Nitrogen Flame Retardants Association
{{DEFAULTSORT:Flame Retardant
Flame retardants
The term flame retardants subsumes 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 ignition source and ...
Flame retardant fabrics
Cotton