Flame Retardants: Hidden Toxins in Your Home

How Flame Retardants Enter Your Body

The primary route is house dust. Flame retardants slowly volatilize from treated foam and plastics, binding to airborne particles that settle on floors and surfaces. You ingest this dust through normal hand-to-mouth contact and breathing — a route that particularly affects young children who crawl on floors and frequently put hands to mouths [5].

The older class of flame retardants, polybrominated diphenyl ethers (PBDEs), were used in furniture foam from the 1970s until voluntary phase-outs between 2004 and 2013. Despite those phase-outs, PBDE-laden furniture made before 2015 remains in millions of American homes. U.S. body burden levels are 10–40 times higher than European levels, largely because of aggressive U.S. flammability standards — particularly California's TB117 rule, which required foam cushions to withstand an open flame for 12 seconds and drove widespread chemical treatment [5].

Since the PBDE phase-out, manufacturers largely switched to organophosphate flame retardants (OPFRs) such as TDCPP and TCIPP. These replacements are now detectable in the urine of over 90% of U.S. adults.

Where flame retardants accumulate:

• Upholstered sofas, chairs, and mattress foam (the largest residential source)
• Printed circuit boards and plastic casings in electronics
• Car seats, dashboards, and headliners — car dust is among the most concentrated indoor sources
• Children's carpet underlays and some clothing

Why They Disrupt Thyroid Hormones

PBDEs are structurally similar to thyroid hormones T3 and T4. The bromine atoms on their molecular backbone mimic the iodine atoms on thyroid hormone, allowing them to bind to thyroid transport proteins (transthyretin, TBG) and partially displace circulating hormones. They also induce liver enzymes that speed up thyroid hormone breakdown, reducing T4 levels even further [2][3].

A study of 270 pregnant women found that each 10-fold increase in serum PBDE concentration was associated with an 11–19% decrease in TSH, a marker of disrupted thyroid signaling [2]. A 2024 systematic review of 61 studies confirmed the pattern, noting that pregnant women, children, firefighters, and e-waste workers face the highest risk of thyroid-disrupting exposure [3].

This matters enormously during pregnancy: thyroid hormone drives fetal brain development. Even modest maternal thyroid disruption during the first trimester — before the fetal thyroid is functional — can permanently alter neurodevelopment.

Neurodevelopment in Children

The HOME study, a long-running prospective cohort in Cincinnati, measured prenatal PBDE levels in 309 pregnant women and followed their children to age 5. Each 10-fold increase in prenatal BDE-47 (the most common PBDE congener) was associated with a 4.5-point decrease in full-scale IQ and a 3.3-point increase in hyperactivity scores at age 5 [1]. The effects weren't apparent at ages 1–3 but emerged clearly as more complex cognitive functions developed.

For context, lead exposure — the canonical neurodevelopmental toxin — produces roughly 1–5 IQ points of loss per 10 µg/dL blood lead increase. PBDE effects are in a similar range. These are not trivial changes at a population level; a 4-5 point shift in the IQ distribution affects learning capacity, educational attainment, and lifetime earnings across entire birth cohorts.

The New Replacements Are Also Concerning

TDCPP (tris(1,3-dichloro-2-propyl) phosphate), one of the OPFRs that replaced PBDEs in foam furniture, was listed as a probable carcinogen by the State of California. A 2022 laboratory study found TDCPP caused DNA strand breaks, increased oxidative stress, triggered apoptosis, and upregulated 11 cancer-pathway genes in human liver cells — providing a cellular mechanism consistent with animal carcinogenicity data [4].

This is the core problem with flame retardant policy: chemicals are phased out after evidence of harm accumulates, then replaced with structurally different but mechanistically similar compounds, restarting the cycle.

Practical Ways to Reduce Exposure

A behavioral intervention study tested which everyday actions actually reduced OPFR and PBDE metabolites in urine and blood. Within two weeks, the following made a measurable difference [6]:

Most impactful:

• Frequent hand washing, especially before eating — reduced metabolites of some flame retardants by approximately 50% within one week
• HEPA vacuuming and wet mopping floors — reduces dust loading (standard vacuum cleaners can aerosolize fine dust, worsening exposure)

Longer-term reductions:

• Replace pre-2015 upholstered furniture — this is the single largest source in most homes; if replacement isn't feasible, intact furniture with no visible foam degradation is lower-risk than worn or crumbling pieces
• Do not reupholster old foam — cutting and disturbing old foam dramatically releases accumulated chemicals
• Check furniture labels for "TB117-2013" compliance — the 2013 revision of California's standard removed the chemical treatment requirement; furniture labeled with the updated standard may be chemical-free
• Improve ventilation — opening windows regularly dilutes indoor air; flame retardants volatilize slowly from treated materials at room temperature

For children specifically:

• Wash hands frequently and before snacks
• Use a damp cloth to clean floors and play surfaces rather than dry sweeping
• Prefer wooden, cotton-stuffed, or wool-stuffed toys over polyurethane foam toys

See our phthalates page for similar information on another class of hormone-disrupting chemicals found in flexible plastics. See also our mattresses and furniture page for guidance on choosing lower-exposure home furnishings.