How toxic is foam insulation?

Since industrialisation, chemicals have been rolled out without sufficient testing, resulting in dire consequences for humans, animals and the environment. Well-known examples include DDT (dichlorodiphenyltrichloroethane) and PCBs (polychlorinated biphenyls). 

Now in the spotlight: Polymeric FR (PolyFR), a flame retardant for foam building insulation. Its production has ballooned out to 26,000 tonnes each year with little attention to its health and ecological impacts, according to a team led by Miriam Diamond from the University of Toronto, Canada.

Diamond is the lead author of a scientific opinion piece published in the journal Environmental Science & Technology, in collaboration with members of the Green Science Policy Institute in Berkeley, US, and others.

Heating and cooling buildings produces a substantial amount of greenhouse gas emissions, leading to increased awareness of the need for energy-efficient construction. Polystyrene foams provide good insulation and are light and cost-effective, and flame retardants are typically added to meet building flammability codes – but these don’t have a great track record.

The PBT chemical flame retardant HBCDD (hexabromocyclododecane), used in buildings for decades, is toxic and has been found to accumulate in humans. It has largely been replaced with PolyFR.

Co-author Arlene Blum has long been tracking different types of chemical flame retardants and advocating for proper assessment of their potential for harm, explains Diamond. “I’m the scientist who finally took up her challenge,” she says.

“Given past experiences, we believe that it is no longer acceptable to assume that a chemical is safe,” she adds. “But this chemical, PolyFR, has received very little attention – because it’s a polymer and insufficient testing has assessed its potential to break down.”

Industry claims that PolyFR is safe. It’s assumed that polymers are less risky than monomeric compounds, the authors explain, because they’re larger and less likely to migrate into the environment where they can accumulate. 

But according to Blum and Diamond, research has shown that it does contain or could break down into potentially harmful compounds under certain conditions. 

Notably, PolyFR is made from butadiene and styrene, which are both carcinogens. Bromine is added to make it a flame retardant – and past analysis of such retardants has showed them to be harmful.

Diamond and colleagues outline several opportunities when people and ecosystems can be exposed to potentially toxic breakdown products as it is released into the environment during the foam’s manufacture, installation and disposal.

While stressing the need for “rigorous toxicity and hazard assessments of PolyFR … under realistic scenarios across its lifecycle,” they propose the use of naturally flame-resistant insulation materials such as glass-wool or stone-wool, which don’t need flame retardants. 

“Making buildings more energy-efficient is a key part of tackling the climate crisis,” says Blum. “But we need to be careful not to create new health and environmental problems along the way. A ‘green building’ with potentially hazardous insulation isn’t a green building at all.”