Flame retardants are chemicals added to everyday materials to slow the spread of fire. They’re found in furniture foam, electronics, building insulation, textiles, and plastics. While they do reduce fire risk, many common flame retardants have come under scrutiny for their effects on human health and the environment, leading to ongoing regulatory action and a push toward safer alternatives.
How Flame Retardants Work
Fire needs three things: fuel, heat, and oxygen. Flame retardants work by disrupting one or more of these factors, using physical mechanisms, chemical mechanisms, or both.
Some flame retardants absorb heat. When temperatures rise, these materials undergo a strong endothermic (heat-absorbing) reaction that pulls energy away from the fire, keeping the surrounding material below its ignition point. Others form a protective char layer on the surface of a burning material. This carbon-rich crust acts as a physical barrier, slowing heat penetration and blocking oxygen from reaching the fuel underneath. A third approach works in the gas phase: certain flame retardants release gases that interfere with the chemical chain reactions that sustain a flame, essentially starving the fire of the reactive molecules it needs to keep burning. Many modern flame retardants combine two or more of these strategies at once.
Main Types of Flame Retardants
Flame retardants fall into several broad chemical families, each with different properties and different risk profiles.
Brominated flame retardants (BFRs) have historically been the most widely used class. Polybrominated diphenyl ethers (PBDEs) were added to furniture foam, electronics casings, and textiles for decades. Tetrabromobisphenol A (TBBPA) is another common brominated compound, used heavily in circuit boards and plastics. Many BFRs have been phased out or restricted because they persist in the environment and accumulate in living organisms, but newer brominated replacements are still in use.
Chlorinated flame retardants include compounds like tris(2-chloroethyl) phosphate (TCEP), once common in insulation, foam seating, and textiles. The EPA has documented that domestic manufacturing and many processing uses of TCEP have been discontinued in the United States, though some industrial applications remain.
Organophosphate flame retardants (OPFRs) emerged as replacements when older brominated and chlorinated chemicals were phased out. Some of these contain halogens themselves, blurring the line between categories. They’re now found in many of the same products their predecessors were used in, from couch cushions to children’s car seats.
Mineral-based flame retardants, such as aluminum hydroxide and magnesium hydroxide, work primarily by absorbing heat and releasing water vapor. They’re generally considered less toxic but require higher concentrations to be effective, which can change the feel and performance of a material.
Where You Encounter Them
The most common point of contact is furniture. Flexible polyurethane foam, the material inside couch cushions, mattresses, and office chairs, has been treated with flame retardants for decades to meet flammability standards. If your foam furniture was purchased before 2005, it may contain pentaBDE, one of the most widely used (and now restricted) brominated flame retardants. Furniture made after that date likely contains replacement chemicals instead.
Beyond furniture, flame retardants appear in electronics (inside TV and computer housings), building insulation, automotive interiors, carpeting, and children’s products. They’re also used in some clothing and industrial textiles.
How People Are Exposed
Flame retardants don’t stay locked inside the products they’re added to. Because many are physically mixed into materials rather than chemically bonded, they gradually escape into indoor air, settle into household dust, and accumulate on surfaces and skin. Since most people spend the majority of their time indoors, this slow release creates ongoing, low-level exposure.
The primary exposure routes are dust ingestion, dermal absorption, and inhalation. For a long time, swallowing contaminated dust (especially relevant for young children who put their hands in their mouths) was considered the dominant pathway. More recent research has shown that dermal absorption, meaning the chemicals passing through your skin from contact with dust and surfaces, accounts for more than 60% of total exposure for most individual flame retardant compounds. Inhalation, by comparison, contributes relatively little. The balance shifts depending on the specific chemical: less volatile compounds are mainly ingested through dust, while more volatile ones are primarily absorbed through skin.
Health Concerns
The health effects of flame retardant exposure have been studied most extensively for PBDEs, the brominated compounds used in foam and electronics through the early 2000s. These chemicals disrupt the endocrine system, particularly thyroid function. In animal studies, PBDE exposure consistently reduces levels of key thyroid hormones (T3 and T4), and human research has linked PBDEs to thyroid dysregulation and clinical thyroid disease.
The organophosphate flame retardants that replaced PBDEs may not be safer. Animal studies suggest some OPFRs exert similar or even more potent endocrine-disrupting effects than the chemicals they were designed to replace. One widely used chlorinated organophosphate significantly reduced thyroid hormone levels in laboratory animals, raising questions about whether the transition to “newer” flame retardants has actually reduced risk.
Effects on Children’s Development
Children face higher exposure relative to their body weight because of their hand-to-mouth behavior and time spent on floors, and their developing brains appear especially vulnerable. Epidemiological studies have linked prenatal PBDE exposure to decreased cognitive ability and increased behavioral problems in children. In one long-running study, a tenfold increase in PBDE levels measured during pregnancy was associated with a 4.7-point drop in IQ scores at age seven. Studies on the newer organophosphate replacements, while less extensive, point in the same direction: suggestive evidence of reduced cognition and more behavioral issues.
Environmental Persistence
Many flame retardants, particularly brominated ones, are persistent organic pollutants. They resist breakdown, accumulate in fatty tissue, and concentrate as they move up the food chain. Aquatic environments are especially affected. Brominated flame retardants build up in fish, shellfish, and marine mammals, with higher-level predators carrying the greatest chemical burden.
The phase-out of older PBDEs did produce results: environmental concentrations of legacy brominated flame retardants peaked between 1970 and 2000 and have gradually declined since. But concentrations of their newer brominated replacements show no decreasing trend. These newer compounds accumulate in the same aquatic organisms and magnify through the same food chains, posing ongoing risk to wildlife and, ultimately, to people who eat seafood.
Regulatory Action in the U.S.
The EPA has been tightening restrictions on several flame retardants under the Toxic Substances Control Act (TSCA). As of 2023, the agency proposed significant new use rules for three flame retardants undergoing risk evaluation: TCEP (a chlorinated compound), TBBPA (a brominated compound), and triphenyl phosphate. These rules would require manufacturers to notify the EPA before resuming discontinued uses of these chemicals, effectively preventing their quiet return to products where they’ve already been removed.
For TCEP specifically, the discontinued uses cover a wide range: building insulation, wood products, fabrics, textiles, and foam seating and bedding products (with narrow exceptions for aerospace applications). California has separately moved to reduce flame retardant requirements in furniture, recognizing that the chemicals in couch cushions may pose more risk than the fires they were meant to prevent.
Safer Alternatives
The push to move away from halogenated flame retardants has driven development of alternatives. One promising direction is bio-based flame retardants made from renewable feedstocks rather than petroleum. Oak Ridge National Laboratory has developed a halogen-free, bio-based flame retardant for building materials that works through a dual mechanism: forming a protective char layer when exposed to fire while simultaneously releasing non-toxic gases that reduce combustion efficiency. Because it contains no halogens, it avoids the toxic chemical release that makes traditional flame retardants so problematic.
Design-based approaches offer another path. Barrier fabrics, which wrap foam in a fire-resistant textile layer, can meet flammability standards without adding any chemicals to the foam itself. Some manufacturers are also switching to materials that are inherently less flammable, such as wool or specially engineered synthetic fibers, reducing or eliminating the need for chemical additives altogether.