A team at the University of Toronto measured what a mattress emits while someone lies on it. The result: phthalates, organophosphate flame retardants, and UV filter compounds migrate from foam and fabric into the sleeping environment, and the combination of body heat and body weight accelerates the release above what baseline off-gassing tests capture. The study appeared in Environmental Science & Technology in April 2025 and drew coverage from CNN, CBC, and EWG.
The source. "Are Sleeping Children Exposed to Plasticizers, Flame Retardants, and UV-Filters from Their Mattresses?" by Sara Vaezafshar, Sylvia Wolk, Kayla Simpson, and colleagues at the University of Toronto. Environmental Science & Technology, Vol. 59, No. 16, pp. 7909–7918, April 15, 2025. A companion study on the same cohort appeared in Environmental Science & Technology Letters, Vol. 12, Issue 5, 2025.
What they found
Researchers tested 16 mattresses under three conditions: room temperature, body heat alone (37.5°C), and body heat combined with 7.5 kg of applied weight simulating a child lying down. They identified 21 semi-volatile organic compounds across four classes: phthalates (including DEHP and DiNP), organophosphate esters (TBOEP and TEHP), UV filters, and the flame retardant TCEP.
TCEP (tris(2-chloroethyl) phosphate) is classified as a suspected carcinogen and linked to developmental and reproductive toxicity. Canada prohibited it in polyurethane foam products made for children under three in 2014. One mattress in this study still contained TCEP at 9,000 mg/kg in its foam, more than a decade after the Canadian ban.
The key mechanism: heat pushed higher-volatility compounds off the surface; applied weight compressed the foam and drove lower-volatility compounds out of the material. Together they produced the highest emission rates across all measured chemicals. TBOEP was detected in all 16 mattresses under the combined heat-and-weight condition, compared to only 3 at room temperature.
Where this shows up in the home
You spend roughly a third of your life on a mattress, applying body heat and body weight for hours at a time. The study focused on children because smaller bodies accumulate higher doses per kilogram, they breathe closer to the mattress surface, and developmental windows make endocrine-disrupting compounds like phthalates more consequential. But the heat-and-weight emission mechanism is not unique to children's mattresses.
Flame retardant requirements in both the U.S. and Canada are set for fire performance, not material safety. The researchers found none of the detected flame retardants were necessary for the tested mattresses to meet current flammability standards: they appear to be legacy inputs or manufacturing choices, not functional necessities. The same dynamic applies in the U.S. market. CPSC and EPA do not require pre-market disclosure of mattress chemical content, so buyers have no systematic way to know what is in the foam.
What to do
Short-term options are real but limited. Airing a new mattress outdoors for at least 72 hours before first use reduces initial off-gassing. Most of the peak emissions from foam happen in the first days after manufacture. A tightly-woven organic cotton encasement placed over the mattress creates a physical barrier between the foam and the sleeper, reducing direct emission contact. It does not eliminate the chemical content beneath it.
If you are shopping for a new mattress, the nontoxicnook mattress guide covers picks screened against the criteria that exclude TCEP, organophosphate flame retardants, and phthalates by class, including mattresses that use GOLS-certified natural latex, wool fire barriers, and Greenguard Gold-certified foam.
Cover image: Vecislavas Popa via Pexels (Pexels License) -- source.
