Flame retardants are compounds added to manufactured materials, such as plastics and textiles, and surface finishes and coatings that inhibit, suppress, or delay the production of flames to prevent the spread of fire. They may be mixed with the base material (additive flame retardants) or chemically bonded to it (reactive flame retardants). Mineral flame retardants are typically additive while organohalogen and organophosphorus compounds can be either reactive or additive.
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.
- 1 Classes
- 2 Retardation mechanisms
- 3 Use and effectiveness
- 4 Environmental prevalence
- 4.1 Health concerns
- 4.2 Mechanisms of toxicity
- 4.3 Routes of exposure
- 4.4 Disposal
- 4.5 Opposition
- 4.6 TBB
- 4.7 TB117
- 4.8 National Bureau of Standards testing
- 5 See also
- 6 References
- 7 External links
Both Reactive and Additive Flame retardants types, can be further separated into several different classes:
- Minerals such as aluminium hydroxide (ATH), magnesium hydroxide (MDH), huntite and hydromagnesite, various hydrates, red phosphorus, and boron compounds, mostly borates.
- Organohalogen compounds. This class includes organochlorines such as chlorendic acid 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 (TBBPA) and hexabromocyclododecane (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 such as the pentoxide and sodium antimonate are also used.
- Organophosphorus compounds. This class includes organophosphates such as triphenyl phosphate (TPP), resorcinol bis(diphenylphosphate) (RDP), bisphenol A diphenyl phosphate (BADP), and tricresyl phosphate (TCP); phosphonates such as dimethyl methylphosphonate (DMMP); and phosphinates such as aluminum diethyl phosphinate. In one important class of flame retardants, compounds contain both phosphorus and a halogen. Such compounds include tris(2,3-dibromopropyl) phosphate (brominated tris) and chlorinated organophosphates such as tris(1,3-dichloro-2-propyl)phosphate (chlorinated tris or TDCPP) and tetrekis(2-chlorethyl)dichloroisopentyldiphosphate (V6).
The Mineral flame retardants mainly act as additive flame retardants and do not become chemically attached to the surrounding system. Most of the Organohalogen and Organophosphate compounds also do not react permanently attach themselves into their surroundings but further work is now underway to graft further chemical groups onto these materials to enable them to become integrated without losing their retardant efficiency. This also will make these materials non emissive into the environment. Certain new non halogenated products, with these reactive and non emissive characteristics have been coming onto the market since late 2009 but are only being seriously looked at in 2010, because of the public debate about flame retardant emissions. Some of these new Reactive materials have even received EPA approval for their low environmental impacts.
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.
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 and hydromagnesite. 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 additives are often employed; their role is to turn the polymer into a char, which separates the flame from the material and slows the heat transfer to the unburned fuel. Non-halogenated organophosphate flame retardants typically act through this mechanism by generating a polymeric layer of phosphoric acid.
Dilution of gas phase
Inert gases (most often carbon dioxide and water) 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 and hydrogen bromide 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.
Use and effectiveness
Fire safety standards
In 1975, California 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 signed the modified TB117-2013 in November and it became effective in 2014. The modified regulation does not mandate a reduction in flame retardants.
However, these questions of eliminating emissions into the environment from flame retardants can be solved by using a new classification of highly efficient flame retardants, which do not contain halogen compounds, and which can also be keyed permanently into the chemical structure of the foams used in the furniture and bedding industries. The resulting foams have been certified to produce no flame retardant emissions. This new technology is based on entirely newly developed "Green Chemistry" with the final foam containing about one third by weight of natural oils. Use of this technology in the production of California TB 117 foams, would allow continued protection for the consumer against open flame ingition whilst providing the newly recognized and newly needed protection, against chemical emissions into home and office environments. More recent work during 2014 with this "Green Chemistry" has shown that foams containing about fifty percent of natural oils can be made which produce far less smoke when involved in fire situations. The ability of these low emission foams to reduce smoke emissions by up to 80% is an interesting property which will aid escape from fire situations and also lessen the risks for first responders i.e. emergency services in general and fire department personnel in particular.
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.
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.
In 2009, the U.S. National Oceanic and Atmospheric Administration (NOAA) released a report on polybrominated diphenyl ethers (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.
The earliest flame retardants, polychlorinated biphenyls (PCBs), were banned in the U.S. in 1977 when it was discovered that they were toxic. Industries used brominated flame retardants instead, but these are now receiving closer scrutiny. In 2004 and 2008 the EU banned several types of polybrominated diphenyl ethers (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 and Chemtura Corporation, 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.
Nearly all Americans tested have trace levels of flame retardants in their body. Recent research links some of this exposure to dust on television sets, which may have been generated from the heating of the flame retardants in the TV. Careless disposal of TVs and other appliances such as microwaves or old computers may greatly increase the amount of environmental contamination. A recent study conducted by Harley et al. 2010 on pregnant women, living in a low-income, predominantly Mexican-immigrant community in California showed a significant decrease in fecundity associated with PBDE exposure in women.
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, 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 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 skills), 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 to 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, insulation, 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.
A number of recent studies suggest that dietary intake is one of the main routes to human exposure to PBDEs. In recent years, PBDEs have become widespread environmental pollutants, while body burden in the general population has been increasing. The results do show notable coincidences between the China, Europe, Japan, and United States such as dairy products, fish, and seafood being a cause of human exposure to PBDEs due to the environmental pollutant.
A February 2012 study genetically engineered female mice to have mutations in the x-chromosome MECP2 gene, linked to Rett syndrome, a disorder in humans similar to autism. After exposure to BDE-47 (a PDBE) their offspring, who were also exposed, had lower birth weights and survivability and showed sociability and learning deficits.
A January 2013 study of mice showed brain damage from BDP-49, via inhibiting of the mitochondrial ATP production process necessary for brain cells to get energy. Toxicity was at very low levels. The study offers a possible pathway by which PDBEs lead to autism.
Mechanisms of toxicity
Many halogenated flame retardants with aromatic rings, including most brominated flame retardants, are likely thyroid hormone disruptors. The thyroid hormones triiodothyronine (T3) and thyroxine (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 proteins (such as transthyretin) in vitro  and thyroid hormone receptors. A 2009 in vivo animal study conducted by the US Environmental Protection Agency (EPA) demonstrated that deiodination, active transport, sulfation, and glucuronidation 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 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 estrogens, progesterone, and androgens. 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 neurons, as well as neurotransmitter release and uptake at synapses, they interfere with normal neurotransmission. 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.
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, 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 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. 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. However, blood serum levels of PBDEs appear to correlate most highly with levels found in dust in the home. Perhaps 20% to 40% of adult U.S. exposure to PBDEs is through food intake, with the remaining exposure largely due to dust inhalation or ingestion.
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. And, as 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. Young children in the United States tend to carry higher levels of flame retardants per unit body weight than do adults.
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 (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.
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.
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, 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.
The widespread use of flame retardants in the United States evolved after California enacted Technical Bulletin 117 (TB117) in 1975 requiring fillings in furniture such as polyurethane foam to resist an open flame for 12 seconds. In 2013, a Chicago Tribune investigative series alleged that the chemical and tobacco industries mounted a campaign to increase the amount of flame retardants in homes while avoiding the need to manufacture a fire safe cigarette. US Senators asked the EPA to evaluate flame retardants for possible health risks. Firefighters concerned about high cancer rates in their profession have called for stricter regulation of use of flame retardants in homes.
California's furniture flammability standards were changed in 2014. TB117-2013 allows manufacturers to market products that withstand a smolder test in lieu of the open flame test. There are legislative attempts to ban or restrict the use of certain flame retardants.
Flame retardants are effective in reducing the flammability of synthetic materials. The EPA has conducted an assessment of new flame retardants, such as 2,3,4,5-tetrabromo-ethylhexylbenzoate (TBB). However, long-term toxicological investigations into the cumulative effects of chronic TBB exposure were not done as they were outside the scope of the review.
California Technical Bulletin 117 was developed by the California Bureau of Home Furnishings through a consensus standards development process and first implemented in 1975. This regulation was intended to prevent ignition or slow the spread of the flame if the furniture is the first to ignite. When fires do occur, multiple studies show that foams treated with flame retardants burn much slower than untreated foam, giving occupants time to escape.
National Bureau of Standards testing
In a 1988 test program was conducted by the former National Bureau of Standards (NBS), now the National Institute of Standards and Technology (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. 
- U.S. Environmental Protection Agency (2005). Environmental Profiles of Chemical Flame-Retardant Alternatives for Low-Density Polyurethane Foam (Report). EPA 742-R-05-002A. Retrieved 4 April 2013.
- "Market Study Flame Retardants 3rd ed.". Ceresana Research. Retrieved 2015-02-03.
-  Market Study Flame Retardants 2nd ed., Ceresana, 07/11
- Hollingbery, LA; Hull TR (2010). "The Thermal Decomposition of Huntite and Hydromagnesite". Thermochimica Acta 509 (1–2): 1–11. doi:10.1016/j.tca.2010.06.012.
- Hollingbery, LA; Hull TR (2010). "The Fire Retardant Behaviour of Huntite and Hydromagnesite - A Review". Polymer Degradation and Stability 95 (12): 2213–2225. doi:10.1016/j.polymdegradstab.2010.08.019.
- Hollingbery, LA; Hull TR (2012). "The Fire Retardant Effects of Huntite in Natural Mixtures with Hydromagnesite". Polymer Degradation and Stability 97 (4): 504–512. doi:10.1016/j.polymdegradstab.2012.01.024.
- Hollingbery, LA; Hull TR (2012). "The Thermal Decomposition of Natural Mixtures of Huntite and Hydromagnesite". Thermochimica Acta 528: 45–52. doi:10.1016/j.tca.2011.11.002.
- Hull, TR; Witkowski A; Hollingbery LA (2011). "Fire Retardant Action of Mineral Fillers". Polymer Degradation and Stability 96 (8): 1462–1469. doi:10.1016/j.polymdegradstab.2011.05.006.
- van der Veen, I; de Boer, J (2012). "Phosphorus flame retardants: Properties, production, environmental occurrence, toxicity and analysis". Chemosphere 88 (10): 1119–1153. doi:10.1016/j.chemosphere.2012.03.067. PMID 22537891.
- Weil, ED; Levchik, SV (2009). Flame Retardants for Plastics and Textiles: Practical Applications. Munich: Carl Hanser Verlag. p. 97. ISBN 978-1-56990-454-1.
- Shaw, S.; Blum, A.; Weber, R.; Kannan, K.; Rich, D.; Lucas, D.; Koshland, C.; Dobraca, D.; Hanson, S.; Birnbaum, L. (2010). "Halogenated flame retardants: do the fire safety benefits justify the risks?". Reviews on Environmental Health 25 (4): 261–305. doi:10.1515/REVEH.2010.25.4.261. PMID 21268442.
- California Department of Consumer Affairs, Bureau of Home Furnishings (2000). Technical Bulletin 117: Requirements, test procedure and apparatus for testing the flame retardance of resilient filling (PDF) (Report). p. 1-8.
- "Notice of Proposed New Flammability Standards for Upholstered Furniture/Articles Exempt from Flammability Standards". Department of Consumer Affairs, Bureau of Electronic and Appliance Repair, Home Furnishings and Thermal Insulation.
- "Calif. law change sparks debate over use of flame retardants in furniture". PBS Newshour. January 1, 2014. Retrieved November 1, 2014.
- "Low VOC Cal TB 117 Using Bio-Renewable Technologies - Rowlands, J. Polyurethane Foam Association Conference St Petersburg, Florida USA.- May 2013".
- "Future-Proof Natural Foams for the USDA BioPreferred Program - Rowlands, J. Utech Conference and Exhibition, Charlotte USA. June 4th and 5th 2014".
- Guillame, E.; Chivas, C.; Sainrat, E. (2000). Regulatory issues and flame retardant usage in upholstered furniture in Europe (PDF) (Report). Fire Behaviour Division. p. 38-48.
- Greenstreet Berman Ltd., "A statistical report to investigate the effectiveness of the Furniture and Furnishings (Fire) (Safety) Regulations 1988", (December 2009). The study was carried out for the UK Department of Business and Innovation skills (BIS). http://www.bis.gov.uk/files/file54041.pdf
- North American Flame Retardant Alliance. "Do flame retardants work?". Retrieved 12 April 2013.
- Babrauskas, V.; Harris, R.; Gann, R.; Levin, B.; Lee, B.; Peacock, R.; Paabo, M.; Twilley, W.; Yoklavich, M.; Clark, H. (1988). NBS Special Publication 749: Fire hazard comparison of fire-retarded and non-fire-retarded products (Report). National Bureau of Standards, Center for Fire Research, Fire Measurement and Research Division. p. 1-86.
- Flexible Polyurethane Foams: A Comparative Measurement of Toxic Vapours and Other Toxic Emissions in Controlled Combustion Environments of Foams With and Without Fire Retardants, Matt Blais, Fire Technology Journal, 2013 http://link.springer.com/article/10.1007/s10694-013-0354-5/fulltext.html
- Babrauskas, V. (1983). "Upholstered furniture heat release rates: Measurements and estimation". Journal of Fire Sciences 1: 9–32. doi:10.1177/073490418300100103.
- Schuhmann, J.; Hartzell, G. (1989). "Flaming combustion characteristics of upholstered furniture". Journal of Fire Sciences 7 (6): 386–402. doi:10.1177/073490418900700602.
- Talley, Hugh. "Phase 1, UFAC Open Flame Tests". Polyurethane Foam Association. Retrieved 12 April 2013.
- http://flameretardants.americanchemistry.com/FAQs/The-Need-for-an-Open-Flame-Test.html http://www.sacbee.com/2013/02/28/5223750/state-flammability-rule-change.html
- NOAA. (2009). An Assessment of Polybrominated Diphenyl Ethers (PBDEs) in Sediments and Bivalves of the U.S. Coastal Zone. Free full text[dead link]. Press release.
- ATSDR. (2001). ToxFAQ PCBs— Retrieved 2 September 2013
- New Thinking on Flame Retardants, Environmental Health Perspectives, 116(5), May 2008
- U.S. Environmental Protection Agency. 2010. DecaBDE Phase-out Initiative. Available: EPA.gov
- http://ceh.org/making-news/press-releases/29-eliminating-toxics/615-first-ever-legal-action-targets-cancer-causing-flame-retardant-found-in-childrens-products[dead link]
- Seattle-Times. (2008) Harmful chemical wafts from your TV. Retrieved Sunday, May 11, 2008.
- Harley, KG; Marks, AR; Chevrier, J; Bradman, A; Sjödin, A; Eskenazi, B (2010). "PBDE Concentrations in Women's Serum and Fecundability". Environ Health Perspect 118 (5): 699–704. doi:10.1289/ehp.0901450. PMC 2866688. PMID 20103495.
- Chevrier, J; Harley, KG; Bradman, A; Gharbi, M; Sjödin, A; Eskenazi, B (2010). "Polybrominated Diphenyl Ether (PBDE) Flame Retardants and Thyroid Hormone during Pregnancy". Environ Health Perspect 118 (10): 1444–1449. doi:10.1289/ehp.1001905. PMC 2957927. PMID 20562054.
- Herbstman, JB; Sjödin, A; Kurzon, M; Lederman, SA; Jones, RS; Rauh, V; Needham, LL; Tang, D et al. (2010). "Prenatal Exposure to PBDEs and Neurodevelopment". Environ Health Perspect 118 (5): 712–719. doi:10.1289/ehp.0901340. PMC 2866690. PMID 20056561.
- Roze, E; Meijer, L; Bakker, A; Van Braeckel, KN; Sauer, PJ; Bos, AF (2009). "Prenatal Exposure to Organohalogens, Including Brominated Flame Retardants, Influences Motor, Cognitive, and Behavioral Performance at School Age". Environ Health Perspect 117 (12): 1953–1958. doi:10.1289/ehp.0901015. PMC 2799472. PMID 20049217.
- Rose, M; Bennett, DH; Bergman, A; Fängström, B; Pessah, IN; Hertz-Picciotto, I (2010). "PBDEs in 2- 5-year-old children from California and associations with diet and indoor environment". Environ. Sci. Technol 44 (7): 2648–2653. doi:10.1021/es903240g. PMID 20196589.
- DiGangi, J; Blum, A; Bergman, Å; de Wit, CA; Lucas, D; Mortimer, David; Schecter, Arnold; Scheringer, Martin; Shaw, Susan D.; Webster, Thomas F. (2010). "2010 San Antonio Statement on Brominated and Chlorinated Flame Retardants". Environ Health Perspect 118 (12): 12. doi:10.1289/ehp.1003089. PMC 3002202. PMID 21123135.
- "Common flame retardant linked to social, behavioral and learning deficits". University of California, Davis. February 16, 2012. Retrieved 2014-01-02.
- "Low levels of common flame-retardant chemical damages brain cells". University of California, Davis. January 16, 2013. Retrieved 2014-01-02.
- Meerts, IA; van Zanden JJ, Luijks EA, van Leeuwen-Bol I, Marsh G, Jakobsson E, Bergman A, Brouwer A. (2000). "Potent competitive interactions of some brominated flame retardants and related compounds with human transthyretin in vitro". Toxicological Sciences 56 (1): 95–104. doi:10.1093/toxsci/56.1.95. PMID 10869457.
- Szabo DT, Richardson VM, Ross DG, Diliberto JJ, Kodavanti PR, Birnbaum LS (January 2009). "Effects of perinatal PBDE exposure on hepatic phase I, phase II, phase III, and deiodinase 1 gene expression involved in thyroid hormone metabolism in male rat pups" Toxicol. Sci 107 (1) 27–39. .doi:10.1093/toxsci/kfn230 PMID 18978342.
- Butt, C; Wang D; Stapleton HM (2011). "Halogenated phenolic contaminants inhibit the in vitro activity of the thyroid-regulating deiodinases in human liver.". Toxicological Sciences 124 (2): 339–47. doi:10.1093/toxsci/kfr117. PMID 21565810.
- Dingemans, MML; van den Berg M; Westerink RHS (2011). "Neurotoxicity of Brominated Flame Retardants: (In)direct Effects of Parent and Hydroxylated Polybrominated Diphenyl Ethers on the (Developing) Nervous System". Environmental Health Perspectives 119 (7): 900–907. doi:10.1289/ehp.1003035. PMC 3223008. PMID 21245014.
- Meerts, IA; Letcher RJ; Hoving S; Marsh G; Bergman A; Lemmen JG; van der Burg B; Brouwer A (2001). "In vitro estrogenicity of polybrominated diphenyl ethers, hydroxylated PDBEs, and polybrominated bisphenol A compounds". Environmental Health Perspectives 109 (4): 399–407. doi:10.1289/ehp.01109399. PMC 1240281. PMID 11335189.
- Rahman, F; Langford, KH; Scrimshaw, MD; Lester, JN (2001). "Polybrominated diphenyl ether (PBDE) flame retardants". Science of the Total Environment 275 (1–3): 1–17. doi:10.1016/S0048-9697(01)00852-X. PMID 11482396.
- Stapleton, H; Alaee, M; Letcher, RJ; Baker, JE (2004). "Debromination of the flame retardant decabromodiphenyl ether by juvenile carp (Cyprinus carpio) following dietary exposure". Environmental Science & Technology 38 (1): 112–119. doi:10.1021/es034746j.
- Stapleton, H; Dodder, N (2008). "Photodegradation of decabromodiphenyl ether in house dust by natural sunlight". Environmental Toxicology & Chemistry 27 (2): 306–312. doi:10.1897/07-301R.1. PMID 18348638.
- Department of Ecology, Washington State; State of Washington Department of Health (2008). Alternatives to Deca-BDE in Televisions and Computers and Residential Upholstered Furniture (Report). 09-07-041.
- McCormick, J; Paiva MS; Häggblom MM; Cooper KR; White LA (2010). "Embryonic exposure to tetrabromobisphenol A and its metabolites, bisphenol A and tetrabromobisphenol A dimethyl ether disrupts normal zebrafish (Danio rerio) development and matrix metalloproteinase expression". Aquatic Toxicology 100 (3): 255–62. doi:10.1016/j.aquatox.2010.07.019. PMID 20728951.
- Lorber, M. (2008). "Exposure of Americans to polybrominated diphenyl ethers.". Journal of Exposure Science & Environmental Epidemiology 18 (1): 2–19. doi:10.1038/sj.jes.7500572. PMID 17426733.
- Johnson-Restrepo, B.; Kannan, K. (2009). "An assessment of sources and pathways of human exposure to polybrominated diphenyl ethers in the United States". Chemosphere 76 (4): 542–548. doi:10.1016/j.chemosphere.2009.02.068. PMID 19349061.
- Stapleton, H.; Sjodin, A.; Jones, R.; Niehuser, S.; Zhang, Y.; Patterson, D. (2008). "Serum levels of polybrominated diphenyl ethers (PBDEs) in foam recyclers and carpet installers working in the United States.". Environmental Science & Technology 42 (9): 3453–3458. doi:10.1021/es7028813. PMID 18522133.
- Costa, L.; Giordano, G. (2007). "Developmental neurotoxicity of polybrominated diphenyl ether (PBDE) flame retardants". NeuroToxicology 28 (6): 1047–1067. doi:10.1016/j.neuro.2007.08.007. PMC 2118052. PMID 17904639.
- EFSA Panel on Contaminants in the Food Chain ‘Scientific Opinion on Hexabromocyclododecanes (HBCDDs) in Food’ 28 July 2011 http://www.efsa.europa.eu/en/efsajournal/doc/2296.pdf and Scientific Opinion on Tetrabromobisphenol A (TBBPA) and its derivatives in food http://www.efsa.europa.eu/en/efsajournal/pub/2477.htm
- Stapleton, H.; Eagle, S.; Sjodin, A.; Webster, T. (2012). "Serum PBDEs in a North Carolina toddler cohort: Associations with handwipes, house dust, and socioeconomic variables". Environmental Health Perspectives 120 (7): 1049–1054. doi:10.1289/ehp.1104802. PMC 3404669. PMID 22763040.
- Watkins, D.; McClean, M.; Fraser, A.; Weinberg, J.; Stapleton, H.; Sjodin, A.; Webster, T. (2012). "Impact of dust from multiple microenvironments and diet on PentaBDE body burden.". Environmental Science & Technology 46 (2): 1192–1200. doi:10.1021/es203314e. PMID 22142368.
- Besis, A.; Samara, C. (2012). "Polybrominated diphenyl ethers (PBDEs) in the indoor and outdoor environments--a review on occurrence and human exposure.". Environmental Pollution 169: 217–229. doi:10.1016/j.envpol.2012.04.009. PMID 22578798.
- U.S. Environmental Protection Agency (2011). Exposure Factors Handbook: 2011 Edition (PDF) (Report). p. 5-5. EPA/600/R-090/052F.
- Sjodin, A.; Wong LY, Jones RS, Park A, Zhang Y, Hodge C, Dipietro E, McClure C, Turner W, Needham LL, Patterson DG Jr. (2008). "Serum concentrations of polybrominated diphenyl ethers (PBDEs) and polybrominated biphenyl (PBB) in the United States population: 2003-2004.". Environmental Science & Technology 42 (4): 1377–1384. doi:10.1021/es702451p. PMID 18351120.
- Lunder, S.; Hovander, L.; Athanassiadis, I.; Bergman, A. (2010). "Significantly higher polybrominated diphenyl ether levels in young U.S. children than in their mothers". Environmental Science & Technology 44 (13): 5256–5262. doi:10.1021/es1009357. PMID 20540541.
- Bi, X.; Thomas, K.; Jones, K.; Qu, W.; Sheng, G.; Martin, F.; Fu, J. (2007). "Exposure of electronics dismantling workers to polybrominated diphenyl ethers, polychlorinated biphenyls, and organochlorine pesticides in South China". Environmental Science & Technology 41 (16): 5647–5653. doi:10.1021/es070346a.
- Thomsen, C.; Lundanes, E.; Becher, G. (2001). "Brominated flame retardants in plasma samples from three different occupational groups in Norway". Journal of Environmental Monitoring 3 (4): 366–370. doi:10.1039/b104304h. PMID 11523435.
- Thuresson, K.; Bergman, K.; Rothenbacher, K.; Hermann, T.; Sjolin, S.; Hagmar, L.; Papke, O.; Jakobsson, K. (2006). "Polybrominated diphenyl ether exposure to electronics recycling workers--a follow up study.". Chemosphere 64 (11): 1855–1861. doi:10.1016/j.chemosphere.2006.01.055. PMID 16524616.
- Exposure to Flame Retardants in Electronics Recycling Sites , Rosenberg, Christina; Haemeilae, Mervi; Tornaeus, Jarkko; Saekkinen, Kirsi; Puttonen, Katriina; Korpi, Anne; Kiilunen, Mirja; Linnainmaa, Markku; Hesso, Antti, Annals of Occupational Hygiene (2011), 55(6), 658-665
- Wang, C.; Lin, Z., Dong, Q., Lin, Z., Lin, K., Wang, J., Huang, J., Huang, X., He, Y., Huang, C., Yang, D., Huang, C. (2012). "Polybrominated diphenyl ethers (PBDEs) in human serum from Southeast China.". Ecotoxicology and Environmental Safety 78 (1): 206–211. doi:10.1016/j.ecoenv.2011.11.016. PMID 22142821.
- Shaw, S.; Berger, M.; Harris, J.; Yun, S. H.; Wu, Q.; Liao, C.; Blum, A.; Stefani, A.; Kannan, K. (2013). "Persistent organic pollutants including polychlorinated and polybrominated dibenzo-p-dioxins and dibenzofurans in firefighters from Northern California.". Chemosphere 91 (10): 1386–94. doi:10.1016/j.chemosphere.2012.12.070. PMID 23395527.
- Wong, M.; Wu, S C; Deng, W J; Yu, X Z; Luo, Q; Leung, A O W; Wong, C S C; Luksemburg, W J; Wong, A S (2007). "Export of toxic chemicals - a review of the case of uncontrolled electronic-waste recycling.". Environmental Pollution 149 (2): 131–140. doi:10.1016/j.envpol.2007.01.044. PMID 17412468.
- Rodil, R.; Quintana, J.; Concha-Graña, E.; López-Mahía, P.; Muniategui-Lorenzo, S.; Prada-Rodríguez, D. (2012). "Emerging pollutants in sewage, surface and drinking water in Galicia (NW Spain).". Chemosphere 86 (10): 1040–1049. doi:10.1016/j.chemosphere.2011.11.053. PMID 22189380.
- Marklund, A.; Andersson, B.; Haglund, P. (2005). "Organophosphorus flame retardants and plasticizers in Swedish sewage treatment plants.". Environmental Science & Technology 39 (10): 7423–7429. doi:10.1021/es051013l. PMID 16245811.
- Guidelines for safe recycling BFR containing plastic developed by Stena recycling plant (Sweden) and BSEF, Autumn 1999. http://stenatechnoworld.com
- "Chemical companies, Big Tobacco and the toxic products in your home". Chicago Tribune. Retrieved 4 May 2013.
- "Durbin urges action on hazardous flame retardants". Chicago Tribune. Retrieved 4 May 2013.
- "Senate sees stalemate on flame-retardant furniture safety regs". The Hill. Retrieved 4 May 2013.
- "Senators call for closer look at flame retardants". Philadelphia Inquirer. Retrieved 4 May 2013.
- Lynne Peeples (March 27, 2014). "Firefighters Sound Alarm on Toxic Chemicals". Huffington Post. Retrieved November 2, 2014.
- California TB117-2013
- Sen. Schumer's proposal to regulate flame retardants, Sept. 15, 2014 
- Daniel Moraine, Chemical Industry Insider Comes Out, Sacramento Bee, Sacramento, California, Jan 26 2014.
- This article incorporates public domain material from websites or documents of the United States Government. Senate subcommittee: Superfund, Toxics and Environmental Health (24 July 2012). "Written Testimony of Mr. Marshall Moore (Director of Technology, Advocacy and Marketing at Chemtura)" (FREE PDF DOWNLOAD). Oversight of EPA Authorities and Actions to Control Exposures to Toxic Chemicals. United States Senate. Retrieved 30 May 2014.
- This article incorporates public domain material from websites or documents of the National Institute of Standards and Technology. Babrauskas, V.; Harris, R. H; Gann, R. G; et al. (July 1989), "Fire Hazard Comparison of Fire-Retarded and Non-Fire-Retarded Products" (FREE PDF DOWNLOAD AVAILABLE), NBS Special Publication 749 (U.S. Commerce Dept. National Bureau of Standards (NBS)), retrieved 30 May 2014
- FlameRetardants-Online from Clariant Produkte (Deutschland) GmbH
- Phosphorus, Inorganic and Nitrogen Flame Retardants Association
- European Flame Retardants Association (EFRA)