Babies and young children might be breathing in harmful chemicals while they sleep, according to new research from the University of Toronto.
Two studies, published Tuesday in the journal Environmental Science & Technology, found that common children’s mattresses release toxic substances like phthalates and flame retardants — chemicals linked to hormone disruption, asthma, lower IQ scores, behaviour issues and even cancer.
“Sleep is vital for brain development, particularly for infants and toddlers. However, our research suggests that many mattresses contain chemicals that can harm kids’ brains,” said Miriam Diamond, senior author of the two studies and a professor in the University of Toronto’s department of earth sciences and school of the environment.
“Kids can spend up to 18 hours a day on their mattresses, and kids are more susceptible to exposure and more vulnerable to the effects of exposure,” she said.
The studies didn’t disclose brand names, but Diamond said the mattresses were ordered online from major Canadian retailers and typically cost between $50 and $150. Many were made with materials from other countries, like the United States and Mexico.
Infant mattresses are often made with different materials, such as waterproof covers, plastic layers and firmer foam, which can contain more chemical additives and treatments than those made for older children or adults, Diamond explained.
That’s part of the reason she and her team wanted to study the potential chemical exposure in these products.
Health Canada told Global News in an email that it is aware of the studies and is carefully reviewing the findings and other available information to identify any risks to human health or non-compliance with legislative or regulatory requirements.
“The Department will take appropriate action to protect people in Canada,” a spokesperson said Tuesday. “The Canada Consumer Product Safety Act (CCPSA) prohibits the manufacture, import, advertisement or sale of any consumer product that is a ‘danger to human health or safety.’”
In the first study, researchers looked at the air quality in 25 bedrooms of children between six months and four years old, located in Toronto and Ottawa between 2022 and 2023.
In total, they found 28 different chemicals in the bedroom air, 31 in the sleeping area and 30 coming off the mattresses. The chemicals include phthalates, flame retardants and UV filters, with the highest concentrations right around the beds.
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Phthalates are added to make plastics more flexible, flame retardants help slow the spread of fire, and UV filters protect materials from sun damage.
But Health Canada has linked these chemicals to reproductive and developmental issues and has even restricted their use in the soft vinyl used in children’s toys.
Flame retardants have been linked to hormone disruption, reproductive issues and even cancer, according to Health Canada.
But under Canada’s safety standards, they aren’t required to meet flammability rules. Mattresses only need to pass a “smouldering cigarette test” — something that can be done without using these chemicals, the study said.
In a follow-up study, the researchers tested 16 brand-new children’s mattresses purchased from well-known retailers in 2024.
The study found that one particular mattress exceeded Canada’s 0.1 per cent regulatory limit for the chemical Dnbp, which is a type of phthalate.
“We were particularly surprised that one mattress exceeded the regulatory limit in Canada. It’s a particular plasticizer that Health Canada has said it should not be above the 0.1 per cent limit,” Diamond said. “And one of the mattresses had that at 0.22, so twice the regulatory limit.”
One of the mattresses had high levels of a flame retardant called TCEP — a chemical that’s been banned in Canada since 2014 because of health concerns, such as causing cancer and reproductive effects.
On top of that, five of the mattresses had between one to three per cent of other similar chemicals known as organophosphate esters, flame retardants and plasticizers, which are also linked to health concerns.
Five of the mattresses also had phthalates — including DiBP, DnOP and DiNP — which are banned in kids’ toys but not in mattresses.
The researchers also wanted to understand how chemical emissions changed when a child was using the mattress, with body weight and warmth.
When they simulated a child’s body heat and pressure, the amount of chemicals released increased significantly — in some cases, several times higher than at room temperature.
Karl Jobst, an associate professor of chemistry at Memorial University of Newfoundland, said this study represents “yet more evidence that there are some potentially harmful chemicals being added to consumer products that don’t actually need to be.”
“The study makes a good point that there are certain flame retardants that are present in high concentrations in a mattress, yet are not needed,” he said. “There have to be more logical solutions to protect a kid from fire rather than having them breathe that in for a large fraction of the day.”
What makes all these chemicals in mattresses especially concerning is how vulnerable young children are, Diamond said.
Their bodies are still developing, they breathe much faster than adults (about 10 times more) and they’re constantly putting things in their mouths, she said.
Their skin is also thinner and more absorbent, with a lot more surface area compared to their body weight, which means they can absorb more of whatever’s around them, including harmful chemicals.
“Then they’re sleeping on a mattress and right against it … so the skin is right against a mattress,” she said.
Also, the chemicals found in the study are known carcinogens and also known to cause behavioural issues, she said.
“So effects like ADHD, difficulties with social circumstances, lowering IQ, there’s a whole range of behavioural outcomes,” Diamond said. “So that’s why we were concerned, and that’s why we were looking at these chemicals.”
“And some of the phthalates have been known endocrine disruptors. Some of them are related to abnormal development of the male reproductive system, but also have implications for the female reproductive system,” she added.
At the end of the study, the researchers call on manufacturers to do better when it comes to testing for harmful chemicals in kids’ mattresses.
They also say it’s time for stronger regulations, especially around flame retardants and plasticizers. In Canada, they recommend expanding existing bans on certain chemicals in toys to include mattresses and bedding, since several mattresses still contain banned or restricted substances.
In the meantime, Diamond said there are actions parents can take to reduce their children’s exposure.
She recommends decluttering your child’s sleeping area by reducing the number of pillows, blankets and toys. She also advises washing and refreshing your child’s bedding and bed clothing frequently, since these act as a protective barrier to reduce exposure.
An effective way to add a layer of protection between the sheet and the mattress is by using a terry cloth towel or a wool blanket — both can help absorb some of the chemical emissions, she said.
“Terry cloth is very clever … it increases the effectiveness of the towel sucking up both water and chemicals,” she explained.
Finally, Diamond said that undyed or neutral colour fabrics are likely safer to use since keeping strong colours requires the addition of UV-filters and other additives that may be harmful.
