Yes, many fire retardants are toxic to humans. The chemicals added to furniture, electronics, and building materials to slow the spread of fire have been linked to hormone disruption, neurodevelopmental problems in children, and increased cancer risk. Aerial wildfire retardants carry a separate set of concerns, primarily from toxic metals. The level of harm depends on which chemicals you’re exposed to, how much, and for how long.
Types of Flame Retardants and Their Risks
Hundreds of flame retardant chemicals are in use, but they fall into a few major groups. Brominated flame retardants are among the most studied and most concerning. They’re found in electronics, furniture, and building materials, and they’ve been linked to endocrine disruption, thyroid dysfunction, immune system changes, and reproductive harm. One common brominated compound, TBBPA, caused cancer in lab animals. Another group, polybrominated diphenyl ethers (PBDEs), was so problematic that manufacturers began phasing them out in 2004, but PBDEs are chemically stable and persist in the environment, homes, and human bodies for years.
Organophosphate flame retardants were introduced as replacements for PBDEs, but they haven’t turned out to be much safer. Research links them to bone and brain health risks, and one specific compound (TDCPP) has been shown to lower thyroid hormone levels in men exposed through household dust. In 2024, the EPA determined that a related chemical, TCEP, poses an unreasonable risk to human health and the environment, and is now developing rules to restrict it.
The pattern is frustrating but consistent: as older flame retardants are phased out due to health concerns, their replacements often turn out to have similar toxic properties.
How You’re Exposed
The primary way most people encounter flame retardants is through household dust. These chemicals don’t bond tightly to the products they’re added to. They migrate out of furniture, curtains, and electronics into the air and onto surfaces, where they settle into dust. Research comparing migration pathways found that flame retardants transfer directly from treated fabric to dust sitting on its surface at rates 71 to 120 times higher than the indirect route of evaporating into the air first. That makes any surface in contact with treated materials a significant source of contamination.
You inhale this dust, ingest it through hand-to-mouth contact, and absorb it through skin. Young children face the highest exposure because they spend more time on floors and put their hands and objects in their mouths frequently. Some flame retardants also enter the food supply, particularly HBCD, which leaches from polystyrene building materials into the environment and accumulates in food chains.
Effects on Children’s Brain Development
The most alarming evidence involves prenatal exposure and children’s cognitive development. A study published in Environmental Health Perspectives tracked children from birth through age six, measuring PBDE levels in umbilical cord blood and then testing the children’s mental and physical development at regular intervals. The results were striking: children in the top 20% of prenatal exposure scored 7 to 11 points lower on developmental tests at age two compared to less-exposed children. By age four, the gap in IQ scores ranged from 5.5 to 8 points. At age six, children with the highest prenatal exposure to certain PBDE compounds scored roughly 4 to 8 points lower on performance IQ tests.
These aren’t subtle differences. A consistent IQ deficit of 5 to 8 points across a population has meaningful consequences for learning, school performance, and long-term outcomes. The effects were dose-dependent, meaning higher prenatal exposure predicted larger deficits, which strengthens the case that the chemicals themselves are responsible rather than some other factor.
Hormone Disruption
Flame retardants interfere with the body’s hormonal systems in several ways. When PBDEs are broken down in the body, they transform into compounds that closely resemble thyroid hormones. These imposters bind to the same proteins that transport and regulate real thyroid hormones, effectively hijacking the system. In animal studies, PBDE exposure reduces circulating levels of key thyroid hormones by speeding up the enzymes that clear them from the blood.
Thyroid disruption matters because these hormones regulate metabolism, energy, and brain development. During pregnancy and early childhood, even small changes in thyroid function can affect how the brain forms and matures, which likely explains the IQ effects seen in exposed children.
Reproductive hormones are also affected. In men, higher concentrations of PBDEs in household dust have been associated with lower levels of free testosterone, luteinizing hormone, and follicle-stimulating hormone. Organophosphate flame retardants similarly interfere with sex hormone production, altering levels of estrogen and testosterone in animal studies.
Cancer Risk
A 2024 meta-analysis pooling data from 15 studies (over 3,400 cancer cases and 4,100 controls) found a significant association between brominated flame retardant exposure and breast cancer, particularly when the chemicals were measured in fat tissue. One specific low-brominated PBDE compound, BDE-28, was linked to a significantly increased risk of endocrine-related cancers overall. The association with thyroid cancer specifically was not confirmed in this analysis, though the broader endocrine cancer link remained.
Animal studies add further concern. TBBPA, widely used in electronics and paints, caused cancer in both rats and mice. The International Agency for Research on Cancer has classified occupational firefighting as a possible carcinogen (Group 2B), partly because of chronic exposure to flame retardant chemicals and their combustion byproducts.
Firefighters Face the Highest Exposure
Firefighters serve as a real-world example of what heavy flame retardant exposure looks like. A study measuring chemical levels before and after controlled residential fires found that firefighters had significantly elevated levels of organophosphate flame retardant byproducts in their urine compared to the general population. Three to six hours after a fire, concentrations of one key metabolite were roughly double the general population average. Even before a fire, baseline levels of another metabolite were more than twice as high as the general public’s, suggesting chronic accumulation from repeated occupational exposure.
Perhaps more concerning, firefighters in the study had elevated pre-fire blood levels of a chlorinated furan compound classified as a known human carcinogen by IARC. This points to long-term buildup from years of exposure to burning flame-retardant materials in structure fires.
Aerial Wildfire Retardants
If your question is about the red slurry dropped from planes during wildfires, that’s a different product with different concerns. Aerial fire retardants are typically based on fertilizer salts like ammonium polyphosphate, which form a protective char layer on vegetation. They’re not the same chemicals found in furniture.
The health concern with aerial retardants centers on toxic metals. A study published in Environmental Science and Technology Letters found that long-term fire retardants contained concentrations of vanadium, chromium, arsenic, cadmium, lead, and other toxic metals at levels 4 to 2,880 times greater than drinking water safety limits. Chromium and cadmium, both known health hazards, were present in especially high concentrations, likely from corrosion inhibitors used to protect aircraft components. Between 2009 and 2021, an estimated 850 kilograms of toxic metals entered surface waters from retardant drops that accidentally hit waterways. Whether these metals remain in soil or reach drinking water sources through runoff is still being studied.
How to Reduce Your Exposure
Dust is your main enemy. Wet-mopping and vacuuming with a HEPA filter regularly reduces the flame retardant load in your home, especially on floors where children play. Washing hands before eating is simple but effective at breaking the hand-to-mouth exposure route.
When buying upholstered furniture, California’s SB-1019 law requires manufacturers to disclose whether flame retardant chemicals were added. Look for labels indicating that no flame retardants were used. Federal labeling under the Consumer Product Safety Commission requires furniture to carry a flammability compliance label, but this label does not disclose chemical composition. It only confirms the product meets flammability standards, which can be achieved without chemical treatments through the use of barrier fabrics and fire-resistant materials.
Replacing old foam furniture from before 2014 can significantly cut exposure, since older pieces are more likely to contain PBDEs that continuously shed into dust. When removing old carpet padding or furniture, ventilate the area well, as disturbing these materials releases concentrated bursts of contaminated particles.