Flame retardants are chemicals added or applied to materials to prevent or slow fires. Some flame retardants have been linked to hormone disruption, reduced fertility, decreased intelligence, learning disorders, and cancer.
Since the 1970s, flame retardants have become pervasive in a wide array of industrial and consumer products and in the environment and the human body. They are added during manufacture or applied as treatments to materials such as textiles and plastics. Flame retardants are claimed to decrease the ability of materials to ignite; to stop, delay, or slow fires; limit fire spread; and/or minimize fire damage. There are hundreds of different flame retardants, given that different materials and retardants behave differently during combustion. Some flame retardants are effective on their own; others act synergistically with other flame retardants. Therefore, flame retardants and materials must be appropriately matched. Although many flame retardants have been removed from the U.S. market or are no longer produced, they often have been replaced with chemically similar compounds that may be equally or even more unsafe.
Flame retardants work in one of three ways:
Organohalogen or halogenated flame retardants have bromine or chlorine atoms bonded to carbon atoms (brominated or chlorinated). Brominated compounds are the most abundant flame retardants and are used in a wide range of consumer products and applications to prevent or slow fires. Brominated flame retardants are associated with endocrine (hormone) disruption and other health effects.
Polybrominated diphenyl ethers (PBDEs) do not chemically bind to the materials they are meant to protect. Thus, they are readily released into the air and accumulate in dust, which is a major route of human exposure. High concentrations of PBDEs were first found in breast milk in the late 1990s. Their use was restricted after they were accidentally added to animal feed, resulting in livestock deaths and high levels of human exposure. PBDEs can result in low-birth-weight and low-length newborns and impair neurological development. The PBDE mixture technical grade DE-71 is carcinogenic in rats and mice.
Tetrabromobisphenol A (TBBPA) is widely used in computer circuit boards and other electronics, as well as some textiles and paper and as an additive in other flame retardants. Bisphenol A (BPA) is a known endocrine disrupter.
Hexabromocyclododecane (HBCD) can leach out of polystyrene foam building materials and accumulate in indoor dust. Low levels of HBCD have been found in some food products.
Chlorinated flame retardants act similarly to brominated retardants. Chlorinated tris and tris (2,3-dibromopropyl) phosphate were banned from children's clothing after they were found to be absorbed through the skin and to accumulate in the body. However, they are still used in textiles and other products. In addition to skin absorption, they can bioaccumulate via ingestion or dust inhalation.
Organophosphate flame retardants (OPFRs) have phosphorous atoms bonded to carbon atoms. When heated, they release phosphoric acid, which causes charring and the formation of a thick glassy layer of carbon that stops pyrolysis (high-temperature decomposition) of materials. Some OPFRs have replaced phased-out PBDEs. However, phosphate-ester flame retardants are considered emerging pollutants because of their prevalence and persistence. They are released into the environment from industrial sources and consumer-product disposal. They absorb in soil and can contaminate air and drinking water. Because of their extensive use in plastics, most foods contain trace amounts of phosphate-ester flame retardants, making foods the major source of exposure in the general population.
Nitrogen flame retardants stop pyrolysis and prevent the high-temperature release of flammable gases with inert nitrogen gases that inhibit combustion. They also act synergistically with phosphorous to retard flames.
Inorganic flame retardants contain boron and/or metals, especially hydrated aluminum and magnesium oxides. They slow pyrolysis and release of flammable gases by emitting inert gases and producing a resistant layer on the material surface. Antimony trioxide is a synergist used in flame-retardant systems with bromine, phosphorus, or nitrogen retardants.
Flame retardants came into widespread use in U.S. products beginning in the 1970s. In response to intense lobbying and advertising by the chemical industry, a 1975 California regulation required all polyurethane foam in furniture and children's products to resist open flames for 12 seconds. Other states soon adopted similar regulations. “Playing with Fire,” a 2012 investigation by the Chicago Tribune, revealed that the chemical and tobacco industries used deceptive advertising to promote the use of flame retardants and that the chemicals were ineffective at preventing fires.
Almost all upholstered foam furniture manufactured between the 1970s and 2013 contain flame retardants. A 2014 study reported that 85% of couches in U.S. homes contained toxic or untested flame retardants. Up to 30% by weight of more than half of U.S. sofas consist of flame-retardant chemicals. Flame retardants do not chemically bind to foam or fabric covers, so they are gradually released into the air and settle in dust that can be inhaled or ingested. Of particular concern are baby products such as mattresses, cribs, changing pads, car seats, high chairs, and strollers, as well as children's clothing and toys.
Workers who manufacture, use, transport, recycle, or dispose of flame retardants are most at risk for exposure. Firefighters are at particular risk for cancers associated with flame retardants. However, children are most vulnerable to their toxic effects, because children's brains and other organs are still developing. Furthermore, children tend to be close to floors where flame retardants accumulate, and they often put their hands in their mouths.
Flame retardants are dispersed worldwide, but Americans have some of the highest body levels. American babies are born with flame retardants in their blood, and their mothers' breast milk has 75 times the levels of that of mothers in Europe, where some flame retardants are banned. Children have higher concentrations in their bodies than adults, and toddlers have three-to-four-times higher levels than their mothers. A 2014 study reported flame retardants in the blood of every child tested. California children have higher levels than children on the East Coast. Although data on flame-retardant levels in U.S. air, soils, and sediments were unavailable, a 2012 report found that rivers, lakes, and groundwater typically had about 0.5 μg/L (qt.).
In the general population, flame retardants enter the body primarily through contaminated food and water. Inhalation is also a major route of both general-population and workplace exposure, especially for firefighters. Absorption through the skin is a major route of occupational exposure but only a minor route for the general population.
Various factors can increase both exposure to flame retardants and their potential toxicity. For example, ultraviolet rays and heat from the sun accelerate the release of flame retardants from car seats. Furthermore, both photochemical reactions and chemical transformation by microbes can increase the toxicity of flame retardants. This fact has raised questions about the safety of some alternative flame retardants that have replaced PBDEs.
Exposure to flame retardants during fetal development and early childhood can have seriously negative effects. Other health effects tend to be subtle and long term, often not becoming apparent until later in life. The effects of flame-retardant exposure can include:
There are no readily available tests for flame-retardant exposure, nor is it generally possible to directly associate diseases and conditions with flame retardants.
There is no treatment for flame-retardant exposure.
The Stockholm Convention, a treaty signed in 2001 by more than 150 countries for reducing or eliminating the release of POPs, called for a worldwide ban of several organohalogen flame retardants or their byproducts. The Convention banned some PBDEs and, as of 2018, was considering banning others, since PBDEs are structurally similar to other human toxins, such as dioxins and furans, that are banned under the Convention.
In 2010, more than 150 scientists signed the “San Antonio Statement on Brominated and Chlorinated Flame Retardants,” documenting health, environmental, and fire-safety concerns. Both academic and government researchers have reported that the amounts of organohalogens added to household furniture do not effectively protect against fire.
Following years of peer-reviewed research linking flame-retardant exposure to an array of adverse health effects, and in response to a petition by various organizations, including the American Academy of Pediatrics and the International Association of Firefighters, the U.S. Consumer Product Safety Commission took action for the first time in 2017. The commission issued a warning that organohalogen flame retardants “present a serious public health issue” that makes their use in certain products “ill advised,” especially by pregnant women and children. This statement was widely interpreted as a first step toward banning this entire class of flame retardants in at least some products. However, it was unclear whether the industry-friendly, regulation-adverse administration of President Donald Trump would take further action. Moreover, federal agencies rarely ban chemicals without direct orders from Congress.
The U.S. National Institute of Environmental Health Sciences supports research on the health effects of newer flame-retardant alternatives, and, as of 2018, the Environmental Protection Agency (EPA) was evaluating flame retardants for safety and environmental effects. However, it was expected to take more than a decade for the EPA to make its determinations.
As of 2018, flame-retardant use was decreasing, and researchers were searching for safer, so-called green alternatives. For example, scientists have reported that the brain neurotransmitter dopamine can be made into a nontoxic, non-accumulating flame retardant that binds strongly to foam and reduces fire intensity 20% better than retardants currently on the market. Other biomolecules, including proteins and nucleic acids, are being developed as flame retardants for cotton, polyester, and textile blends.
It can be difficult for consumers to determine whether products contain flame retardants. For example, products labeled “PBDE-free” may contain other harmful retardants. Nevertheless, there are some measures for reducing exposure. These include the following:
Firefighters—who have almost three times the cancer risk of the general population—often carry flame-retardant residue on their clothing and skin. Firefighters should:
See also Cancer ; Chemical poisoning .
Cordner, Alissa. Toxic Safety: Flame Retardants, Chemical Controversies, and Environmental Health. New York: Columbia University Press, 2016.
Hassan, Areej. Everyday Environmental Toxins: Children's Exposure Risks. Waretown, NJ: Apple Academic, 2015.
Abel, David. “Ban Sought on Flame Retardants: Firefighters Say Chemicals in Furniture Pose too Great a Cancer Risk, Do Little to Slow Down Fires.” Boston Globe April 25, 2016: B1.
Bauers, Sandy. “Toxic Chemicals in Car Seats Pose Risk.” Philadelphia Inquirer June 21, 2015: G3.
Chen, Da, Robert C. Hale, and Robert J. Letcher. “Photochemical and Microbial Transformation of Emerging Flame Retardants: Cause for Concern?” Environmental Toxicology and Chemistry 34, no. 4 (April 2015): 687.
Hawthorne, Michael. “Federal Panel Votes to Warn Publicabout Flame Retardants in Baby Products, Furniture.” Chicago Tribune September 20, 2017. http://www.chicagotribune.com/news/watchdog/ct-flame-retardants-banned-cpsc-met-20170920-story.html (accessed April 4, 2018).
Malucelli, Giulio. “Biomacromolecules as Effective Green Flame Retardants for Textiles: An Overview.” International Journal of Energy, Environment and Economics 23, nos. 4–5 (2015): 663–83.
Tao, Fang, Mohame Abou-Elwafa Abdallah, and Stuart Harrad. “Emerging and Legacy Flame Retardants in UK Indoor Air and Dust: Evidence for Replacement of PBDEs by Emerging Flame Retardants?” Environmental Science & Technology 50, no. 23 (December 6, 2016): 13052.
American Chemistry Council. “Flame Retardant Basics.” https://flameretardants.americanchemistry.com/Flame-Retardant-Basics (accessed March 25, 2018).
Environmental Protection Agency. “Fact Sheet: Assessing Risks from Flame Retardants.” https://www.epa.gov/assessing-and-managing-chemicals-under-tsca/factsheet-assessing-risks-flame-retardants (accessed March 25, 2018).
Environmental Protection Agency. “Reducing Your Child's Exposure to Flame Retardant Chemicals.” https://www.epa.gov/sites/production/files/2016-05/documents/flame_retardant_fact_sheet_3-22-16.pdf (accessed March 25, 2018).
Green Science Policy Institute. “Flame Retardants.” http://greensciencepolicy.org/topics/flame-retardants (accessed March 25, 2018).
National Institute of Environmental Health Sciences. “Flame Retardants.” https://www.niehs.nih.gov/health/topics/agents/flame_retardants/index.cfm (accessed March 25, 2018).
Zissu, Alexandra. “The Fight Against Flame Retardants.” Natural Resources Defense Council. https://www.nrdc.org/stories/fight-against-flame-retardants (accessed March 25, 2018).
American Chemistry Council, 700 2nd St. NE, Washington, DC, 20002, (202) 249-7000, Fax: (202) 249-6100, https://www.americanchemistry.com .
Environmental Protection Agency, 1200 Pennsylvania Ave. NW, Washington, DC, 20460, https://www.epa.gov .
Green Science Policy Institute, PO Box 9127, Berkeley, CA, 94709, (510) 898-1739, email@example.com, http://greensciencepolicy.org .
Learning Disabilities Association of America, 4156 Library Rd., Pittsburgh, PA, 15234-1349, (412) 341-1515, Fax: (412) 344-0224, firstname.lastname@example.org, https://ldaamerica.org .
National Institute of Environmental Health Sciences, PO Box 12233, MD K3-16, Research Triangle Park, NC, 27709-2233, (919) 541-3345, Fax: (301) 480-2978, web email@example.com, https://www.niehs.nih.gov .
Natural Resources Defense Council, 40 W. 20th St., 11th Fl., New York, NY, 10011, (212) 727-2700, nrdcinfo@nrdc. org, https://www.nrdc.org .
U.S. Consumer Product Safety Commission, 4330 East-West Hwy., Bethesda, MD, 20814, (301) 504-7923, Fax: (301) 504-0124, 504-0025, (800) 638-2772, https://www.cpsc.gov .
Margaret Alic, PhD