Infants and toddlers spend much of their day being shuttled from their crib to a changing table to a cushioned car seat, putting them in close contact with products that contain foam. A new study shows for the first time that foam crib mattresses give off significant amounts of volatile organic compounds (VOCs) and that infants are exposed to elevated levels of these potentially harmful chemicals as they sleep (Environ. Sci. Technol. 2014, DOI: 10.1021/es405625q).
In the process of making foam-based consumer products, manufacturers use a variety of resins, catalysts, solvents, and adhesives, many of which can volatilize from the final product. Earlier studies have linked chronic exposure to low concentrations of VOCs to elevated risks of lung infections, allergies, and asthma in infants. And because these children spend 12 to13 hours per day sleeping, an actively emitting crib mattress could be an important source of exposure to VOCs. So Brandon Boor, an environmental engineer at the University of Texas, Austin, decided to measure the amount of VOCs given off by crib mattresses and estimate the dose that an infant might inhale while sleeping.
Boor and his colleagues analyzed 20 new and used crib mattresses made from either polyurethane foam or polyester foam. The researchers placed mattress samples in a chamber and used gas chromatography-mass spectrometry to determine the rate of VOCs released. They also conducted studies in a room-sized chamber using a heated steel cylinder that mimicked the body temperature of a sleeping infant. The team reasoned that the heat from a child would increase the release of VOCs compared to a mattress alone, so the emissions would better match those in real-world conditions. In this experiment, they compared VOC concentrations in an infant’s breathing zone—about 2.5 cm above the mattress—to levels in the room.
The researchers identified more than 30 different VOCs, such as phenol, which the Environmental Protection Agency classifies as an air pollutant, and 2-ethylhexanoic acid, which the European Commission designates as a chemical that can disrupt development. At room temperature, the mattresses released VOCs at an average rate of 56 μg per m2 of mattress per hour—comparable to other indoor materials, such as laminate flooring. On average, new mattresses emitted about four times as much VOCs as the old mattresses.
But the team’s most significant observation was that VOC levels were significantly higher in a sleeping infant’s breathing zone compared to those in bulk room air, which means the children are exposed to twice the VOC concentrations as people standing in the room. Based on average infant sleep times, the researchers estimate that infants inhale approximately 8 μg total VOCs per kg of body weight per day from their mattresses. This amount is similar to infants’ exposure to the VOCs toluene and benzene from indoor air, as measured in an earlier study.
Boor thinks the current results suggest that manufacturers should look for ways to use low-emitting materials when making foam products to mitigate infants’ exposure to VOCs. Also, parents could set aside a new mattress for six months, allowing it to give off most of its VOCs before bringing it in the house, suggests Ying Xu of UT Austin, a study coauthor.
Heather M. Stapleton, an environmental chemist at Duke University, says the study is important because it shows that an infant’s exposure to VOCs is significantly greater than that of an adult standing 10 feet away, “and regulatory agencies don’t take this into consideration.” The work also highlights how critical the sleep environment is when assessing infants’ chemical exposure, she says.