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Page 2 of 17 Hammel et al. J Environ Expo Assess 2024;3:8 https://dx.doi.org/10.20517/jeea.2023.51

and shows that internal exposure levels of NBFRs were similar to those of most PBDEs already at the time of PBDE
restrictions.

Keywords: PBDE, NBFR, HBCDD, dechlorane plus, indoor environment, exposure

INTRODUCTION
Brominated flame retardants (BFRs) have been used in consumer products (e.g., home furnishings,
electronics, and building materials) to reduce their flammability and slow down or prevent fires.
Polybrominated diphenyl ethers (PBDEs) were among the first classes of additive flame retardants (FRs)
used worldwide since the 1970s and typically applied in one of three technical mixtures: Penta-, Octa-, and
Deca-BDE . Due to evidence of persistence, bioaccumulation, long-range transport, and toxicity, the Penta-
[1]
[2]
and Octa-BDE mixtures were banned in the EU and phased out in the USA from the mid-2000s , with
their eventual global ban under the Stockholm Convention on Persistent Organic Pollutants (POPs) in
[3]
2009 . The use of DecaBDE in electronic applications has been restricted in the European Union (EU) since
[4]
2008, and DecaBDE was added to the Stockholm Convention in 2017 . In the early 2000s,
hexabromocyclododecane (HBCDD) was the second most prominent BFR on the EU market. It was mainly
used in polystyrene, but also as a replacement for PBDEs . It was banned in the EU and worldwide in 2013
[5]
due to its POP- characteristics. The ban of PBDEs and HBCDD in consumer products led to an increased
demand for alternatives, which include other brominated chemicals often referred to as novel brominated
FRs (NBFRs) and the chlorinated flame retardant dechlorane plus (DP, also known as DDC-CO), which
was recently added to the Stockholm Convention . The use patterns of the different FR classes has varied
[6]
between regions with a notable preference for PentaBDE in North America, HBCDD in Europe, TBBPA in
Asia, and DecaBDE in all three regions . However, there have also been temporal changes in consumption
[7]
of the commercial mixtures of PBDEs, and later export of waste from more to less industrialized countries
has altered the emission patterns . Similar information on use patterns has not been identified for NBFRs.
[8]

Due to their persistence and the long lifetime of many consumer products, PBDEs and HBCDDs are still
detected in the environment, including wildlife and abiotic environmental media such as air, soil, and
indoor dust [9-11] . At the same time, NBFRs have also been widely detected in environmental samples,
consumer products, and food [12,13] . In humans, PBDEs have been measured all over the world in a variety of
matrices, including breast milk, blood, placenta, and adipose tissue, while reports on HBCDDs are less
frequent and only few measurements exist on NBFRs in human matrices [14-18] . NBFRs have also been
detected in upholstered furniture foam and house dust, and a urinary metabolite of 2-ethylhexyl 2,3,4,5-
tetrabromoethylhexylbenzoate (EH-TBB) has been frequently found in both adults and children [19-22] .
However, breast milk measurements of NBFRs have been rare and have only been conducted in the UK,
USA, and China to date [23-26] . Overall, both legacy and current-use BFRs are omnipresent in our
environment, suggesting chronic exposure and consequently concern about potential adverse health
impacts.

PBDE congeners have been associated with a variety of negative health outcomes such as thyroid hormone
disruption and neurodevelopmental deficits in both human and animal studies [27-30] . In particular, prenatal
and early-life PBDE exposure has been linked to various adverse effects on neurobehavioral development in
young children, such as poorer attention, fine motor coordination, and cognition as well as lower IQ [28,31,32] .
Much less is known about the NBFRs and their potential toxicity, but for several of the better-studied
[13]
NBFRs, neurotoxic potential has been shown, possibly linked to endocrine disruption . Specifically,
[33]
components of the Firemaster® 550 mixture, which includes both brominated and organophosphate