Organophosphate Ester Flame Retardants: Are They a Regrettable Substitution for Polybrominated Diphenyl Ethers?

Abstract

As the use of polybrominated diphenyl ethers (PBDEs), and the entire class of organohalogen flame retardants, is declining, the use of organophosphate esters flame retardants (OPFRs) is increasing. In this paper, we ask whether OPFRs are a better choice than PBDEs. To address this question, we compared OPFRs with PBDEs for a wide range of properties. OPFRs exposure is ubiquitous in people and in outdoor and indoor environments, and are now often found at higher levels compared to PBDE peak exposure levels. Furthermore, data from toxicity testing, epidemiological studies, and risk assessments all suggest that there are health concerns at current exposure levels for both halogenated and non-halogenated OPFRs. Obtaining the scientific evidence needed for regulation of OPFRs can take many years. Given the large number of OPFRs in use, manufacturers can move towards healthier and safer products by developing innovative ways to reduce fire hazard for electronics enclosures, upholstered furniture, building materials and other consumer products without adding flame retardant chemicals.

Figure 1.

Timeline of major regulatory milestones for PBDEs and OPFRs. Policy enactment dates are listed; implementation/ compliance dates are often later (see Table S1 for detailed information).

Figure 2.

Bar chart representing selected median concentrations of total OPFRs and total PBDEs in outdoor air (pg/m³, A), water (ng/L, B), and indoor dust (ng/g, C). Each bar represents data from a different study (see Tables S2–5 for details about the studies included and for a more comprehensive list of locations).

Figure 3.

Flame retardant plasma concentrations measured or estimated from ingestion using data from house dust, breastmilk, and/or handwipe samples (colored bars and circles) are compared to the most potent in vitro concentration per chemical (black dots) and in vivo point-of-departure (POD; triangles). The filled triangles represent rat plasma concentrations based on in vivo POD values (when available), and open triangles represent the Minimum Risk Levels (MRLs). The colored bars represent the range of concentrations and the circles represent the mean, median, or maximum median (see Supporting Information for further details on these calculations).