Background Information

Flame retardants comprise a large group of chemicals applied to carpets, furniture, electronics, and other materials to prevent burning or slow the spread of fire. Most of these chemicals contain bromine or chlorine and are referred to as organohalogen flame retardants. Although they serve a similar commercial function in suppressing fire, these chemicals can differ significantly in their physical, structural, and chemical properties.

Flame retardants are stable chemicals that resist breaking down in the environment. Human exposure is widespread, and many of these chemicals have long half-lives in people. As a result, they are commonly detected in human biological samples. In addition to exposure, there is growing evidence that many flame retardants are associated with human health effects.

Given that there are more than 1,000 organohalogen flame retardants and tens of thousands of structurally related analogs, this group of chemicals has been the focus for methods to evaluate potential health effects of more than one chemical at a time. The National Academies of Sciences, Engineering, and Medicine developed a class approach for hazard assessment of organohalogen flame retardants that proposes 14 subclasses. The framework suggests evaluating health effects evidence for groups of chemicals within each subclass collectively, determining subclasses on both chemical similarity and shared biological mechanisms of effects.

Projects

Researchers in the Division of Translational Toxicology developed two related projects using class-based approaches to identify and assess the scientific evidence that organohalogen flame retardants impact human health:

• Review of organohalogen flame retardants and cancer.
• Comprehensive systematic evidence mapping of health effects research on organohalogen flame retardants.