Reviewed by Lexie CornerJan 28 2025
Researchers from the Green Science Policy Institute warn that flame retardants commonly used in electronic enclosures are linked to cancer and other health concerns. These chemicals can migrate into recycled products such as children's toys and food containers. A study published in Environmental Science & Technology finds no evidence that these flame retardants provide any fire safety benefit for plastic battery casings.
Image Source: https://doi.org/10.1021/acs.est.4c10630
The use of flame retardants in plastic battery enclosures has no demonstrated benefit and poses threats that can last generations. For example, toxic flame retardants migrate out of plastics into the air and drop into house dust, which we inadvertently breathe and ingest. When those flame-retarded plastics are recycled years later, additional people will be exposed from products made with the recycled plastic.
Lydia Jahl, Study Lead Author and Scientist, Green Science Policy Institute
E-bikes, electric cars, and a growing number of portable devices like smartphones and earbuds are powered by lithium-ion batteries. As their use grows, standards are being adopted to reduce their significant fire risks. One common approach is adding chemical flame retardants to plastic enclosures to meet widely recognized "flame rating" standards.
However, no publicly available research shows that flame retardants in plastics effectively reduce battery fires in real-world conditions. When lithium-ion batteries experience thermal runaway, flame retardants are unlikely to slow or extinguish the resulting intense fires.
Trying to stop thermal runaway fires by adding flame retardants to plastic is like adding a screen door to a submarine. It's a futile effort against an overwhelming force.
Dr. Vyto Babrauskas, Distinguished Fire Scientist, Green Science Policy Institute
Organohalogens and organophosphates, commonly used flame retardants for this purpose, are associated with cancer as well as neurological, reproductive, and immune system damage, with pregnant women and young children being particularly vulnerable. The study outlines multiple exposure pathways, including battery production, use of products like earbuds or e-bikes, disposal, recycling, and recycled products, such as black plastic spatulas or sushi trays.
This issue recalls earlier problems with flame retardants in furniture. For decades, California's furniture flammability standard mandated the use of flame retardants, yet failed to reduce fire fatalities. Meanwhile, the chemicals were linked to a 300 % increase in cancer deaths and a loss of three to five IQ points in children in the U.S. When the standard was revised 10 years ago to meet flammability requirements without flame retardants, furniture fire rates remained low or declined.
The best solution for both public health and fire safety is to prevent battery fires from occurring in the first place. Strategies like improving battery management systems and stopping the use of faulty batteries can prevent dangerous thermal runaway fires. This would save lives both from fires as well as from cancer and the many other health harms linked to flame retardants.
Arlene Blum, Study Co-Author and Executive Director, Green Science Policy Institute
Journal Reference:
Arlene, B., et al. (2025) High Potential Harm, Questionable Fire-Safety Benefit: Why Are Flame Retardants in Lithium-Ion Battery Enclosures? Environmental Science & Technology. doi.org/10.1021/acs.est.4c10630