Assess flame retardants with care

In their Perspective “Toward fire safety without chemical risk” (19 April, p. [231][1]), J. de Boer and H. M. Stapleton discuss the safety of flame retardants as if they all belong to one class of chemicals. The authors assert that “all substitutes [used to replace older halogenated flame retardants] showed harmful effects.” This generalization does not do justice to improvements in flame retardants or to the variety of chemicals available. Recent flame retardants have been made with properties that render them safer than older alternatives. Polymeric compounds with high molecular weight can now be made with flame-retarding properties ([ 1 ][2], [ 2 ][3]). Contrary to previously used molecules with lower molecular weight, the new versions do not migrate from the polymers to which they are added, such as clothing or upholstery, minimizing the chance of exposure ([ 2 ][3]). Most important, from a toxicology standpoint, these chemicals are essentially not bioavailable, meaning they are unlikely to cross epithelial membranes, enter the body, and cause harm even if exposure occurs ([ 2 ][3]–[ 4 ][4]). For example, the U.S. Environmental Protection Agency (EPA) lists a butadiene styrene brominated copolymer as an alternative to the flame retardant hexabromocyclododecane ([ 2 ][3]). ![][5] As the search for the safest flame retardants continues, accurate assessment is critical. PHOTO: ISTOCK.COM/INHAUSCREATIVE It is inaccurate to generalize flame retardants as if they all have similar effects. At the request of the U.S. Consumer Product Safety Commission, the National Academies of Sciences, Engineering, and Medicine (NASEM) recently investigated whether the safety assessment for organohalogen flame retardants (OFR) can treat all OFRs as a single class ([ 5 ][6]). The committee considered 161 OFRs and attempted grouping based on functional and structural properties as well as known or predicted biological activity. The committee concluded that it is not possible to treat OFRs as a single class for hazard assessment. However, the committee identified 14 subclasses for which this might be feasible. In contrast with the broad statements of de Boer and Stapleton condemning all OFRs as hazardous and posing unacceptable risk, the NASEM report sets the stage for a careful, scientifically robust assessment of the safety of these important substances known to save human lives. 1. [↵][7]1. E. Pearce , Ed., Flame-Retardant Polymeric Materials (Springer Science & Business Media, 2012). 2. [↵][8]U.S. EPA, “Flame retardant alternatives for hexabromocyclododecane (HBCD)” (2014). 3. U.S. EPA, “Interpretive assistance document for assessment of polymers sustainable futures summary assessment: Updated June 2013” (2013). 4. [↵][9]U.S. EPA, “An alternatives assessment for the flame retardant decabromodiphenyl ether” (2014). 5. [↵][10]NASEM, “A class approach to hazard assessment of organohalogen flame retardants” (The National Academies Press, Washington, DC, 2019). This work was supported by the North American Flame Retardant Alliance (NAFRA) of the American Chemistry Council, which provided honoraria to the authors as members of NAFRA's Science Advisory Council. The letter reflects the authors' scientific conclusions, and professional judgments were not subject to the funder's control. [1]: http://www.sciencemag.org/content/364/6437/231 [2]: #ref-1 [3]: #ref-2 [4]: #ref-4 [5]: /embed/graphic-1.gif [6]: #ref-5 [7]: #xref-ref-1-1 View reference 1 in text [8]: #xref-ref-2-1 View reference 2 in text [9]: #xref-ref-4-1 View reference 4 in text [10]: #xref-ref-5-1 View reference 5 in text