Flame resistant clothing is not inherently toxic, but many garments treated with chemical flame retardants do contain compounds that can migrate into the body through the skin, and some of those compounds have well-documented health concerns. The risk depends heavily on which flame retardant chemistry was used, whether the fabric is inherently fire-resistant or was treated with an additive finish, and how the garment is worn and cared for. A notorious case from the 1970s, when a mutagenic flame retardant was absorbed through children’s sleepwear, prompted regulatory bans that reshaped the industry. Yet decades later, researchers are still finding that chemicals in flame resistant fabrics can reach the body through routes most wearers never think about.
How Flame Resistant Fabrics Work
There are two fundamentally different approaches to making a fabric resist fire. The first uses fibers that are inherently flame resistant because of their molecular structure. Fabrics woven from aramid fibers (the family that includes Nomex and Kevlar), modacrylic blends, or polybenzimidazole (PBI) do not need added chemicals to resist ignition. The fire resistance is built into the polymer chain itself. These fabrics are widely used in military, industrial, and firefighter applications. From a toxicity standpoint, they raise fewer chemical-exposure concerns because there is no additive finish that can leach out.
The second approach takes ordinary cotton, polyester, or blended fabric and applies a chemical flame retardant finish. Virtually all common textiles will ignite and burn on their own, so meeting flammability regulations often requires these chemical treatments.1ScienceDirect (Woodhead Publishing). Advances in Fire Retardant Materials – Chapter 8 – Environmentally friendly flame resistant textiles The chemicals used in those finishes are where most toxicity questions center. They fall into broad families: halogenated compounds (containing bromine or chlorine), organophosphate esters, and phosphorus-nitrogen systems, each carrying a different risk profile.
The Tris-BP Sleepwear Scandal
The most dramatic chapter in this story unfolded in the late 1970s. Tris(2,3-dibromopropyl)phosphate, commonly called tris-BP, was widely used to make children’s polyester sleepwear meet new U.S. flammability standards. Researchers at the time discovered that children wearing tris-BP-treated pajamas were absorbing the chemical through their skin. A mutagenic breakdown product, 2,3-dibromopropanol, was found in the urine of ten children who had worn or were wearing treated sleepwear, including eight whose pajamas had been washed many times. Children and adults who had never worn tris-BP garments did not show the metabolite in their urine.2PubMed. Children absorb tris-BP flame retardant from sleepwear: urine contains the mutagenic metabolite, 2,3-dibromopropanol Tris-BP was already known to cause cancer and sterility in laboratory animals. The Consumer Product Safety Commission effectively banned it from children’s clothing in 1977.
That episode is often treated as a closed chapter, but it established a pattern that keeps repeating: a flame retardant chemical enters widespread use, years pass before its health effects are studied in real-world exposure scenarios, and the chemical is eventually restricted or phased out. The same arc has played out with several brominated and chlorinated flame retardants since then.
How Chemicals Get From Fabric Into Your Body
Wearing flame retardant clothing creates a long, close contact between treated fabric and skin. Research using human skin models has confirmed that chlorinated organophosphate flame retardants can pass through skin from fabric at meaningful rates. An in vitro study measuring three common chlorinated phosphorus-based compounds found that between roughly 3.5% and 26% of the chemical dose on the fabric was dermally absorbed over 24 hours, with the specific rate depending on the compound’s properties and the level of skin hydration.3PubMed. Dermal uptake of chlorinated organophosphate flame retardants via contact with furniture fabrics; implications for human exposure A separate study examining ten different flame retardant compounds found that while very little reached the deeper receptor fluid beneath the skin, significant amounts accumulated in the upper skin layers, meaning the skin acts as a depot that slowly releases the chemicals into the body over time.4PubMed. Dermal uptake and percutaneous penetration of ten flame retardants in a human skin ex vivo model
Sweat dramatically amplifies this process. Modeling work on children’s textiles found that the presence of sweat increased chemical absorption by staggering amounts compared to dry contact, up to roughly 3,250-fold for certain PFAS compounds and about 835-fold for organophosphate esters.5PubMed. Sweat-amplified dermal transfer and combined toxicity of per- and polyfluoroalkyl substances and organophosphate esters mixtures in children’s textiles That finding matters because flame resistant clothing is often worn in physically demanding, heat-intensive work environments where the wearer is sweating heavily. The very conditions that make flame resistance necessary also create conditions that maximize chemical migration from fabric to skin.
Clothing also acts as a shuttle for semivolatile organic compounds picked up from indoor air. Chemicals accumulate on fabric fibers during wear and are released when garments are laundered. A study tracking phthalates, brominated flame retardants, and organophosphate esters found that more than 80% of the more water-soluble organophosphate esters were released from cotton and polyester into laundry water, while heavier, greasier brominated compounds were much harder to wash out.6PubMed. From Clothing to Laundry Water: Investigating the Fate of Phthalates, Brominated Flame Retardants, and Organophosphate Esters In practical terms, this means some flame retardant chemicals cling stubbornly to fabric even after repeated washing, maintaining the exposure pathway for the wearer, while others wash off into wastewater.
PFAS in Firefighter Turnout Gear
Firefighter protective equipment deserves special attention because it layers multiple chemistries together. The outer shell provides flame resistance, the middle layer acts as a moisture barrier, and the inner thermal liner insulates against heat. An analysis of new turnout gear found that the moisture barrier layers, made of a PTFE film (a member of the PFAS family), contained the highest concentrations of both total fluorine and individual per- and polyfluoroalkyl substances. The moisture barrier layer contained total fluorine concentrations of about 122,000 milligrams per kilogram, along with volatile PFAS concentrations of roughly 20.7 milligrams of fluorine per kilogram.7Environmental Science & Technology. Disposition of Fluorine on New Firefighter Turnout Gear The study’s authors concluded that new turnout gear should be examined as a potential source of occupational PFAS exposure for firefighters.
The dermal exposure question for PFAS specifically is nuanced. Recent in vitro work on human skin found that short-chain PFAS compounds showed measurable penetration rates over 24 hours, with one compound (FBSA) reaching about 7% permeation when tested individually. Long-chain PFAS, by contrast, did not penetrate the skin within the same period.8PubMed. Dermal permeation of perfluoroalkyl substances in human skin – An in-vitro study PFAS exposure in firefighters likely comes from a combination of routes: the gear itself, fireground contamination, and aqueous film-forming foam. Isolating exactly how much comes from clothing versus other sources remains an active area of research.
Antimony Trioxide and Aging Textiles
Antimony trioxide is widely used as a synergist in brominated flame retardant formulations. It does not retard fire on its own but boosts the effectiveness of the bromine compounds it is paired with. This has led to concern about antimony exposure, particularly for firefighters who wear these fabrics for years.
A health evaluation that measured urine antimony levels in firefighters from two departments found reassuring results under normal wearing conditions. All 20 firefighters from one department and 41 of 42 from the other had antimony concentrations below or within the national reference range. The study concluded that wearing antimony-containing uniforms does not pose a risk for antimony toxicity under typical use.9PubMed. A health hazard evaluation of antimony exposure in fire fighters
The picture changes when those same textiles age. Research subjecting antimony trioxide and decabromodiphenyl ether (BDE-209) back-coated textiles to combined heat and ultraviolet light found that the presence of antimony trioxide increased BDE-209 release rates by 40% to 80%. After sequential aging and abrasion, the dominant release pathway shifted to inhalable sub-100 nanometer particles, with total particle numbers jumping roughly 3.5-fold.10ChemistrySelect. Combined Thermal‐UV Stress Induces Synergistic Release and Inhalable Nanoparticle Formation of BDE‐209 and Antimony Trioxide From Ageing Flame‐Retardant Textiles Old, sun-exposed, or heat-worn flame retardant textiles release more of their chemical load than new ones, and the particles are small enough to be breathed deep into the lungs. This suggests that the safety picture for a brand-new garment does not necessarily extend to the same garment after months or years of field use.
What Happens When Flame Resistant Clothing Gets Hot
Flame resistant clothing is designed to protect the wearer in fire conditions, but exposing the fabric to high temperatures also triggers chemical changes. A review on firefighter protective garments noted that thermal degradation of flame retardant compounds in textile materials can lead to volatilization, releasing chemical vapors during or after fire exposure.11Journal of Fire Sciences. A review on volatilization of flame retarding compounds from polymeric textile materials used in firefighter protective garment An older study comparing treated and untreated fabrics found that flame retardant treatments altered the mix of gases produced during burning, with tested fabrics releasing carbon monoxide, carbon dioxide, nitrogen oxides, hydrogen cyanide, hydrogen sulfide, and sulfur dioxide.12Fire and Materials. Toxic gaseous products of thermal decomposition and combustion of natural and synthetic fabrics with and without flame retardant These gases are mainly a concern for firefighters and industrial workers who may breathe them during active fire suppression, rather than for everyday wear. But they underscore that flame retardant chemicals are not inert passengers on the fabric; they are reactive compounds whose behavior changes in heat.
Skin Reactions and a Possible Link to Skin Lymphoma
Beyond systemic absorption, flame retardant fabrics can cause direct skin problems. Contact dermatitis from a flame retardant textile finish has been documented. One reported case involved a painter who developed eczema on his forehead at the points where a treated cotton cap contacted his skin. Patch testing confirmed sensitivity to the flame retardant chemical itself, not to formaldehyde, which is sometimes released by certain phosphorus-based finishes.13PubMed. Contact dermatitis from a textile flame retardant
A more alarming observation comes from a retrospective analysis that identified eight patients with mycosis fungoides, a type of cutaneous T-cell lymphoma, who had occupational exposure to flame retardant clothing. All eight were male, ranging from 31 to 64 years old, with most wearing flame retardant clothing for two to four years before lesions appeared. Three patients who stopped wearing the clothing went into remission, and one who added a cotton undershirt barrier also improved, while a patient who continued wearing flame retardant garments saw the disease persist.14PubMed Central. Association of Flame-Retardant Clothing With Mycosis Fungoides: A Retrospective Analysis Eight patients is a very small series, and the study cannot prove causation. But the pattern of improvement upon discontinuation is suggestive enough that the authors flagged it as a concern for occupational health screening.
Formaldehyde and Legacy Chemical Finishes
Some older phosphorus-based flame retardant finishes for cotton present a separate issue. Tetrakis(hydroxymethyl)phosphonium chloride (THPC), once widely used in children’s sleepwear and other cotton garments, degrades to yield hydrochloric acid and formaldehyde under heat or certain chemical conditions. Testing of a commercial THPC sample found it contained 4% to 14% free formaldehyde depending on pH.15PubMed. Evaluation of chemical flame retardants for carcinogenic potential Formaldehyde is a known skin sensitizer and a recognized carcinogen at high chronic exposure levels. Modern flame retardant formulations have largely moved away from THPC, but variations of phosphorus-based cross-linking finishes remain in use, and formaldehyde release from treated textiles is still a relevant concern for garments produced in regions with less stringent chemical regulations.
Effects Beyond the Skin
When flame retardant chemicals enter the body, the story does not end at the skin. Animal research has begun documenting effects on internal systems. In one study, indirect exposure to triphenyl phosphate during early development disrupted the gut microbiota of offspring, with male animals showing the most pronounced changes. Affected males had altered gut bacteria populations, disturbed gene expression along the gut-liver signaling axis, and increased lipid accumulation in the liver along with raised blood levels of triglycerides and cholesterol.16PubMed. Gestation and lactation triphenyl phosphate exposure disturbs offspring gut microbiota in a sex-dependent pathway Separately, work using a simulated human intestinal system showed that another organophosphate flame retardant, diethyl ethylphosphonate, shifted the balance of gut bacteria and altered levels of short-chain fatty acids at higher doses.17PubMed. Diethyl ethylphosphonate retardants disturbed the gut microbiome and metabolite SCFAs in vitro based on simulator of the human intestinal microbial ecosystem These are early-stage findings and translating them directly to humans wearing flame retardant work clothes would be a stretch. But they point to a broader biological footprint for these chemicals than just the skin or lungs.
The Shift Toward Bio-Based Alternatives
Growing awareness of the health and environmental costs of halogenated flame retardants has accelerated a shift in the industry. Research and development have increasingly focused on phosphorus-nitrogen intumescent systems (which char and swell to form a protective barrier), mineral additives, and bio-derived retardants made from materials like chitosan, lignin, starch, and phytic acid.18Chemical Review and Letters. Development of eco-friendly flame-retardant textile materials: Global trends, bio-based flame retardants, and advanced modification technologies These alternatives aim to avoid the bioaccumulation and persistence problems of older chemistries. Whether they perform as well in durability and wash resistance remains an active challenge, but the trajectory is clearly away from halogenated compounds.
For firefighter gear specifically, some manufacturers are beginning to offer PFAS-free moisture barriers, responding to growing regulatory pressure and internal advocacy from firefighter unions. Several U.S. states have passed or proposed legislation restricting PFAS in turnout gear. The transition is slow because replacement materials must meet the same stringent thermal and water-penetration standards, and testing takes years.
Practical Steps for People Who Wear Flame Resistant Clothing
If you wear flame resistant clothing for work, a few evidence-informed habits can reduce your chemical exposure. Wearing a cotton base layer underneath treated garments creates a physical barrier that limits direct skin contact. The mycosis fungoides case series noted above found that even a simple cotton undershirt appeared to reduce exposure enough to improve one patient’s condition. Laundering flame resistant garments separately from household laundry, and washing them regularly, helps remove accumulated surface chemicals, though stubborn brominated compounds resist washing more than organophosphate esters do.
Replacing aging, UV-degraded, or heavily heat-exposed garments on schedule matters more than many wearers realize, because chemical release rates increase substantially as fabric ages. Avoid storing gear in hot vehicles or direct sunlight when possible. And if you develop unexplained skin rashes in areas where treated fabric contacts your body, raise the possibility of contact sensitivity with a dermatologist, since flame retardant allergy is real but underdiagnosed.
Why Consumer Awareness Remains Low
A survey of 1,500 U.S. consumers conducted after the early wave of flammability regulations found that most people had limited understanding of which textile products contained flame retardants and how to care for them safely, leading the researchers to call for extensive consumer education on textile flammability.19Journal of Consumer Studies & Home Economics. CONSUMER AWARENESS AND ACCEPTANCE OF FLAME RETARDANT TEXTILE PRODUCTS AND FLAMMABILITY LEGISLATION That study is decades old, but the knowledge gap has arguably widened since. Today’s flame resistant garments are used across oil and gas, electrical utility, military, and emergency services industries, and many workers receive them as employer-issued uniforms without detailed information about what chemicals are on the fabric. Garment labels typically identify a fabric as “FR” without specifying which flame retardant system was used, making it difficult for the wearer to make an informed judgment about exposure risk. Clothing-mediated chemical exposures can be substantial in certain circumstances and may have health consequences, yet they remain poorly characterized compared to dietary or inhalation exposure routes.20PubMed Central. Clothing-Mediated Exposures to Chemicals and Particles Until labeling standards catch up with the chemistry, workers are largely relying on their employers and manufacturers to have made safe choices on their behalf.