Chapter 3D: Brominated Flame Retardants: Biomarkers and Human Biomonitoring

Several kinds of brominated flame retardants (BFRs) have been used extensively in the past 30–40 years. Some compounds are persistent, bioaccumulative and susceptible to long-range transport and have thus become ubiquitous contaminants, now partly regulated by law or voluntarily withdrawn from the market. Being endocrine disrupters, some BFRs can affect neurodevelopment and have been associated with reproductive impairment, but epidemiological evidence and toxicokinetic information are still sparse. Diet and the indoor environment have been identified as the most important exposure pathways for most BFRs. Exposure estimates vary considerably, depending on concentrations in exposure media and assumptions on accidental dust ingestion, but indicate higher exposure to tri- to hexabrominated diphenyl ethers (PBDEs) for toddlers than for adults and for North Americans than for Europeans, following the application pattern of the technical mixture PentaBDE. Human body burdens show the same geographical pattern, but comparable lipid-normalized concentrations across tissues and matrices. Prenatal exposure to some BFRs has been documented in studies on umbilical cord blood and placental transport, and their presence in breast milk also suggests neonatal exposure. Biomonitoring activities have included temporal trends indicating significant increases, but also recent decreases in PBDE body burdens, as well as identification of susceptible groups or populations. Breast milk and blood have been common matrices for BFR biomonitoring, but hair analysis has given promising results as well. In addition to PBDEs, currently used BFRs and PBDE metabolites are relevant compounds for biomonitoring.