At a glance
| Chemical family | Aryl organophosphate ester (AOPE); flame retardant and plasticizer |
| CAS number | 115-86-6 (TPHP); 838-85-7 (DPHP, urinary metabolite) |
| Classification | Not IARC classified. Identified as an endocrine disruptor in a 2023 SYRINA systematic review on the basis of metabolic and reproductive endpoints. EPA Toxic Substances Control Act prioritized chemical. |
| Where you encounter it | Polyurethane foam mattresses and furniture, electronics casings, PVC products, nail polish, hydraulic fluids, certain textiles, house dust |
| Sleep micro environment relevance | Migrates from foam and electronics into house dust and onto skin surfaces during contact; DPHP urinary metabolite detected in nearly all pregnant women in recent cohorts; documented in mattress emission sampling from current-manufacture polyurethane foam |
| Activated carbon capture | High — log Kow ≈ 4.6, semi-volatile organic compound behavior; aryl OPE class is well within activated carbon's adsorption range |
Regulatory & certification status
Where TPHP (Triphenyl Phosphate) stands across the major regulatory systems and the certifications a bedroom product might carry. Each row links to the governing instrument; where a jurisdiction has no specific measure, that is stated plainly rather than left blank.
| European Union | REACH Substance of Very High Concern: triphenyl phosphate (EC 204-112-2, CAS 115-86-6) was added to the Candidate List on 7 November 2024 as an endocrine disruptor for the environment under Article 57(f) (the Member State Committee reached unanimous agreement in October 2024 after failing to agree in June 2024). It is not on the Authorisation List (Annex XIV) and is not restricted under Annex XVII. There is no harmonised CLP classification: TPHP has no entry (index number) in Annex VI of the CLP Regulation. Regulatory — ECHA |
| United States | Under federal TSCA, EPA designated triphenyl phosphate (phosphoric acid, triphenyl ester; CAS 115-86-6) a High-Priority Substance in December 2019 and it is undergoing a TSCA risk evaluation that is not yet finalized. In June 2023 EPA also proposed a Significant New Use Rule (SNUR) covering certain non-ongoing uses of TPHP (published in the Federal Register on 22 June 2023). It is not listed on California Proposition 65 — neither CAS 115-86-6 (TPHP) nor 838-85-7 (DPHP) appears on the OEHHA list. Regulatory — US EPA · Federal Register |
| Canada | Triphenyl phosphate (on the Domestic Substances List) was assessed in the Flame Retardants Group: the 2021 draft screening assessment proposed it was harmful to the environment but not to human health (and recommended adding it to Schedule 1 on that environmental basis). Since then, new critical human-health effects were identified, prompting a re-examination. On 22 November 2025 Canada published a DRAFT human-health risk characterization (TPHP and TBOEP), with an accompanying Risk Management Scope, proposing that TPHP meets the criteria under paragraph 64(c) of CEPA (danger to human life or health, driven mainly by dermal exposure from consumer products); the 60-day public comment period runs 22 November 2025 to 21 January 2026. This re-assessment is still in consultation and TPHP is not yet on the Schedule 1 List of Toxic Substances. Regulatory — Government of Canada |
| Australia | AICIS completed an environment-focused evaluation of triphenyl phosphate (TPHP, CAS 115-86-6) and its metabolite diphenyl phosphate (DPHP, CAS 838-85-7) on 26 June 2023 (evaluation EVA00108), undertaken because the Evaluation Selection Analysis indicated a potential environmental risk from this organophosphate flame retardant. The output is an evaluation statement with recommendations; no specific import ban or mandatory restriction is identified here. Regulatory — AICIS |
| United Kingdom | TPHP is not currently on the UK (GB) REACH Candidate List, and it was not among the first batch of 15 substances HSE put out for SVHC consultation on 11 March 2026 — that batch was limited to substances that already carry a mandatory GB CLP harmonised CMR or persistence/bioaccumulation classification, which TPHP does not have. Because the EU added TPHP to its Candidate List only in November 2024, after the post-Brexit alignment cut-off, it has not yet been adopted onto the GB list; under the UK's February 2026 approach, post-2021 EU additions are to be reviewed for the GB list where appropriate, so TPHP may be considered in a later batch. Regulatory — HSE · GOV.UK |
| Certifications | CertiPUR-US: not specifically named. The 2025 Slabstock Technical Guidelines prohibit named flame retardants — PBDEs, TDCPP, TCEP, TEPA, TDBPP (the chlorinated/brominated 'Tris' family) and DMMP — but do not list triphenyl phosphate; the emissions criterion is a total-VOC limit of <0.5 mg/m3 (which the guideline notes also corresponds to <0.5 ppm), measured by chamber testing under ISO 16000 (parts 3, 6, 9, 11) with the foam conditioned in the chamber for 72 hours, not a TPHP-specific screen. OEKO-TEX Standard 100: flame retardants are broadly forbidden in certified products except for separately approved substances, but it could not be confirmed that triphenyl phosphate is named as an individually limited substance in the published criteria. GREENGUARD / GREENGUARD Gold: a low-VOC emissions certification that does not specifically screen for a semi-volatile additive like this. Industry — CertiPUR-US · OEKO-TEX |
| The 72-hour test window | Largely missed. Triphenyl phosphate is a semi-volatile organic compound (SVOC) used as a flame retardant and plasticizer; it has a low vapour pressure and migrates into house dust and onto surfaces rather than off-gassing quickly, so a short ~72-hour VOC chamber emissions test does not reliably capture it. Inferred — from the compound's volatility/emission profile versus the VOC focus of short chamber tests |
What it is
TPHP is a solid white crystalline material at room temperature that melts at around 49°C and is added to polyurethane foam, plastics, and electronics during manufacturing to slow ignition and reduce flame spread. Like the other organophosphate flame retardants that replaced PBDEs after 2005, TPHP is added as a non-bound additive rather than chemically incorporated into the polymer matrix — which means it migrates out of the host material over time through abrasion, contact, and partition into adjacent materials.
The shift from PBDEs to TPHP and related aryl OPEs followed the 2005 phase-out of PentaBDE in U.S. manufacturing. Industry needed a replacement that could meet the California flammability standard TB117 and could be used across furniture, electronics, and plastics applications. TPHP and the chlorinated alkyl OPEs (TCPP, TDCPP) divided the market between them, with TPHP and the related aryl phosphates dominating in electronics, PVC, and certain foam categories. The pattern of substitution has been broadly similar to what happened with bisphenols and what is now happening with PFAS: the replacement chemistry was regulated less stringently than the compound it replaced, and the toxicological evidence has been accumulating since.
A 2023 systematic review applying the SYRINA framework to 66 studies of TPHP concluded that TPHP can be identified as an endocrine disruptor based on metabolic disruption and reproductive function endpoints. Peer-reviewed — Bui 2023, Environ Sci Process Impacts
How it gets to the bedroom
From the mattress foam itself
Current-manufacture polyurethane foam mattresses can contain TPHP and related aryl phosphates as flame retardant additives, particularly in product lines that did not move to flame-retardant-free designs after the 2013 revision of TB117. The 2025 Diamond and colleagues study of 25 children's sleeping microenvironments documented organophosphate ester migration from mattresses to the immediate sleep zone, with concentrations higher near the bed than in the bedroom generally. Peer-reviewed — Diamond et al. 2025, PMC12080337 The same study found that the heat and weight of a sleeping child enhances SVOC emissions from foam, which means a body on a mattress is not a passive exposure — body warmth measurably increases the rate at which the foam releases its additives.
From electronics in the bedroom
TPHP is used as a flame retardant and plasticizer in electronics casings, printed circuit boards, and television housings. The Stapleton group's house dust studies found TPHP at high concentrations in homes with substantial home electronics, and electronics-rich bedrooms (televisions, gaming consoles, computers) consistently have higher TPHP dust levels than electronics-light bedrooms. Peer-reviewed
From house dust
TPHP and DPHP are detectable in essentially all U.S. house dust samples tested in recent surveys, with bedroom samples often higher than other rooms due to the combined concentration of foam furniture, electronics, and bedding in sleeping areas. Peer-reviewed
From nail polish and personal care
Several studies have documented that nail polish containing TPHP transfers measurable quantities to skin and into urine, with DPHP urinary metabolite rising significantly within hours of nail polish application. The bedroom relevance is indirect — TPHP from personal care products applied during evening routines may transfer to bedding through sweat and skin contact during the night. Peer-reviewed
What the research says
Thyroid disruption
A 2015 study by Kim and colleagues in zebrafish demonstrated that TPHP disrupts the thyroid endocrine system by upregulating genes involved in thyroid hormone synthesis (nis, tpo), metabolism (dio1), and transport (ttr), with significant increases in both T3 and T4 in larval fish. Peer-reviewed — Kim 2015, Aquatic Toxicology A 2017 study by Preston and colleagues in 51 U.S. adults found that high versus low urinary DPHP was associated with a 0.43 µg/dL increase in mean total T3, with the effect substantially stronger in women (0.91 µg/dL increase). Peer-reviewed — Preston 2017, Environment International Hill and colleagues 2018 showed that TPHP and DPHP enhance binding of thyroxine to human transthyretin in vitro, suggesting a novel mechanism for thyroid hormone transport disruption. Peer-reviewed — Hill 2018, Toxicology Letters
A 2025 chemical-proteomics study added a specifically human mechanism: TPHP covalently binds human liver fatty-acid-binding protein (L-FABP) as a predominant, selective target — a protein-adduction route the authors describe as an understudied toxicity pathway for a compound in such wide use. Peer-reviewed — Miller et al. 2025, Environ Sci Process Impacts
Reproductive and endocrine effects
The reproductive toxicity literature on TPHP is unusually deep for a flame retardant. A 2025 study by Ma and colleagues integrated epidemiological and mechanistic approaches to identify TPHP-induced testosterone reduction in adult human males, with disrupted cholesterol metabolism and PPARα-mediated downregulation of the translocator protein TSPO as the proposed mechanism. Peer-reviewed — Ma 2025, J Hazard Mater Ma and colleagues 2021 demonstrated that TPHP delayed pubertal timing and reduced ovarian reserve in female mice as an estrogen receptor antagonist. Peer-reviewed — Ma 2021, Environmental Pollution Wang and colleagues 2023 showed that TPHP induced testicular damage and Leydig cell apoptosis through ROS-mediated mitochondrial fusion inhibition. Peer-reviewed — Wang 2023, Ecotoxicol Environ Saf Witchey and colleagues 2022 in Sprague Dawley rats demonstrated reproductive toxicity beginning at 1000 ppm dietary TPHP exposure, with gestational and lactational transfer to offspring. Peer-reviewed — Witchey 2022, Toxicological Sciences
Placental effects
Hong and colleagues 2022 found that prenatal TPHP accumulated in placenta in mice and impaired pregnancy outcomes through PPARγ-mediated lipid metabolism disruption, endoplasmic reticulum stress, and apoptosis in placental trophoblasts. Peer-reviewed — Hong 2022, Environmental Pollution
Developmental neurotoxicity (general)
The 2024 Shahin review of 48 papers on OPEs concluded that TPHP (metabolized to DPHP) is one of the two most frequently measured, detected, and health-outcome-associated OPEs, with developmental effects spanning thyroid disruption, smaller birthweight, metabolic dysregulation, and impaired cognitive development. Peer-reviewed — Shahin 2024, Environmental Research Ghassabian and colleagues 2025 in 831 ECHO mother-child pairs found that prenatal DPHP was associated with lower cognition scores at age 5.7 years. Peer-reviewed — Ghassabian 2025, Environmental Pollution
Open questions
The TPHP literature does not yet include controlled human chamber studies of mattress-specific emission rates the way the legacy PBDEs and the chlorinated tris compounds do. The mixture interactions with the other OPEs present in the same product (TBOEP, TCPP, TDCPP) have not been fully characterized. Replacement aryl OPEs entering the market — emerging compounds that may be substituted for TPHP under regulatory pressure — have minimal toxicological data, a pattern that has played out repeatedly in this compound class.
What helps reduce exposure
- Tier 1 — Most effective: Ventilate the bedroom during the day, especially when mattresses and electronics are warm. Avoid storing foam-cored furniture and electronics in closed unventilated rooms. Replace TPHP-containing nail polish with brands that disclose flame-retardant-free formulations.
- Tier 2 — Worth considering: Use a mattress with a tight-weave cover that limits direct skin-foam contact and direct dust deposition on the foam. The Embr capture layer is designed to adsorb aryl organophosphate esters including TPHP at the foam-bedding interface; this addresses one component of the cumulative load but does not replace ventilation, source reduction, or foam replacement.
- Tier 3 — Larger interventions: Replace older mattresses (manufactured during the 2005–2013 window when OPE use peaked) with current-manufacture flame-retardant-free alternatives that pass smolder testing without chemical flame retardants. Choose electronics housings labeled halogen-free and OPE-free where available.
What does NOT help
- Air purifiers alone. TPHP is semi-volatile and partitions strongly to surfaces and dust. HEPA filtration captures the dust-bound fraction but does not remove the compound from the foam itself; emission continues.
- "BPA-free" or "PBDE-free" labeling. These claims have no bearing on OPE content. A product can be both BPA-free and TPHP-containing.
- Surface-cleaning the mattress. TPHP migrates from within the foam over time; surface cleaning addresses neither the source nor the ongoing emission.
Open research questions
- The Diamond 2025 sleep microenvironment study quantified OPE migration from mattresses to immediate sleep zone air; specific TPHP emission rates from current-manufacture U.S. mattresses are not yet well characterized.
- The combined effect of TPHP plus other OPEs (TBOEP, TDCPP, TCPP) in the same bedroom on cumulative urinary DPHP, BDCIPP, and BBOEP load has not been fully quantified in residential settings.
- Activated carbon capture efficiency for TPHP specifically — as opposed to the chlorinated tris compounds — has not been independently chamber-tested at realistic sleep environment conditions. This is a gap the Embr foundation arm research direction could address.
Citations
- Bui T et al. 2023. Applying a modified SYRINA framework — TPHP case study. Environ Sci Process Impacts.
- Diamond M et al. 2025. Young Children's Exposure to Chemicals of Concern in Their Sleeping Environment: An In-Home Study. Environmental Science & Technology Letters.
- Kim S et al. 2015. Thyroid disruption by triphenyl phosphate in zebrafish. Aquatic Toxicology.
- Preston EV et al. 2017. Urinary DPHP and thyroid function. Environment International.
- Hill KL et al. 2018. OP triesters enhance T4 binding to transthyretin. Toxicology Letters.
- Ma Y et al. 2025. Cholesterol metabolism, TPHP, testosterone disorder. J Hazard Mater.
- Ma H et al. 2021. TPHP delayed puberty and ovarian reserve decline. Environmental Pollution.
- Wang M et al. 2023. TPHP testicular Leydig cell apoptosis. Ecotoxicol Environ Saf.
- Witchey SK et al. 2022. TPHP and IPP reproductive/developmental toxicity in rats. Toxicol Sci.
- Hong J et al. 2022. Prenatal TPHP activated placental PPARγ. Environmental Pollution.
- Shahin S et al. 2024. OPEs and maternal-child health, 48-paper review. Environmental Research.
- Ghassabian A et al. 2025. Prenatal OPE flame retardants and child cognition. Environmental Pollution.
Related compounds
Embr's capture layer is designed to adsorb organophosphate ester flame retardants including TPHP at the foam-bedding interface. The system reduces a portion of the exposure pathway. It is not a treatment for any condition and does not substitute for source reduction, ventilation, or regulatory action on flame retardant chemistry.
Last reviewed May 2026. If you find an error, contact us.