Persistence, Bioaccumulation, and Toxicity of Halogen-Free Flame Retardants

Abstract

Polymers are synthetic organic materials that have a high carbon and hydrogen content, which renders them readily combustible. When used in buildings, electrical appliances, furniture, textiles, transportation, mining, and in many other applications, polymers have to fulfill flame retardancy regulatory requirements, primarily as mandatory specifications that often differ among countries. To achieve these requirements, chemical additives known as flame retardants (FRs) are incorporated into the polymers. In contrast to most additives, FRs can appreciably impair the material properties of polymers (United Nations Environment Programme (UNEP) 2008). The key challenge is therefore to find a suitable compromise between the performance of the polymers and fulfilling flame retardancy requirements. Brominated flame retardants (BFRs) are rather widely used because they have a low impact on the polymer’s characteristics, are very effective in relatively low amounts compared to other FRs (Alaee et al. 2003), and are relatively cheap (Birnbaum and Staskal 2004). In 2004, BFRs accounted for about 21 % of the total world production of FRs (SRI Consulting (SRIC) 2004). Many BFRs, however, have unintended negative effects on the environment and human health. Some are very persistent (Robrock et al. 2008), some bioaccumulate in aquatic and terrestrial food chains (Boon et al. 2002), and some show serious adverse effects such as endocrine disruption (Meerts et al. 2001). Some BFRs (polybrominated diphenyl ethers (PBDEs), hexabromocyclododecane (HBCD), and tetrabromobisphenol-A (TBBPA), in particular) have been found in increasing concentrations in the human food chain, human tissues, and breast milk (Schantz et al. 2003; Hites 2004; Fängström et al. 2005). In 2000, exponentially increasing PBDE concentrations were measured in Swedish human milk (Norén and Meironyté 2000), and this was later followed by reports of even higher PBDE concentrations in human milk from the USA (Schecter et al. 2008).

Susanne L. Waaijers, Deguo Kong, and Hester S. Hendriks contributed equally to this work.