Why is childhood exposure to BFRs relevant to health?
Brominated flame retardants (BFRs) are a class of chemicals that are added to a wide variety of products, including plastics, polyurethane foam, textiles, furniture, and electronics, to reduce the chance of fire and to meet flammability standards.
Polybrominated diphenyl ethers (PBDEs) were once the most widely used BFRs in the United States, until they were phased out between 2004 and 2013. However, many products that contain PBDEs are still in use, allowing PBDEs to escape from these products into the environment. Humans are exposed to PBDEs through diet, contact with flame-retarded products, and contaminated house dust. Young children tend to have higher exposures to PBDEs compared to adults due to frequent contact with floors and other surfaces where dust gathers, as well as frequent hand-to-mouth activity. In addition, children may be particularly vulnerable to the effects of PBDE exposure because they tend to have higher exposures (per kilogram of body weight) than adults and may be exposed during critical periods of development.
Exposure to PBDEs has been associated with disruption of the endocrine system, particularly thyroid hormone regulation. Pregnant women may be especially vulnerable to these effects as thyroid hormones play a key role in healthy pregnancies and fetal development. Reproductive hormones may also be affected, as some studies suggest that PBDE exposure may be linked to decreased fertility in women and changes in male reproductive development. Exposure to PBDEs during in utero and early development has been linked to altered cognitive function and behavior in childhood.
In newly manufactured products, PBDEs have been replaced by a range of “replacement” or “alternative” flame retardants. These include other BFRs such as hexabromocyclododecane (HBCD) and tetrabromobisphenol-A (TBBPA), and a new class of organophosphate, or OP, flame retardants. Although exposure to some of these replacement flame retardants may be widespread, potential health effects related to these exposures are not well understood.
What types of questions can be answered?
Exposure to BFRs can be estimated by measuring the parent chemicals in blood and other biological matrices. Each PBDE congener has a distinct elimination profile, which can vary between individuals. In general, PBDE levels in blood reflect exposure over the past several months or years. However, BDE209 (“Deca-BDE”) has a half-life of only 15 days, so multiple samples or studies to indicate within-person stability over time may be necessary. Many published data exist with which to compare PBDE exposures including general U.S. population data published in CDC’s National Report on Human Exposure to Environmental Chemicals (link is external).
How can exposure to BFRs be measured?
- Analytes: Exposure to PBDEs can be measured by quantifying the parent chemicals in plasma or serum. Because PBDEs concentrate in lipids, concentrations are often normalized according to the lipid content of the sample.
- Methods: Most methods use gas chromatography followed by mass spectrometry.
- Types of biospecimens: Plasma and serum are the most commonly used matrices, although breast milk may also be used. Other matrices such as meconium and placenta are of limited utility.
How does CHEAR ensure the quality of its analyses?
If possible, the inclusion of field “blanks” in a study can help identify any contamination from collection/storage sources. All assays are well validated with respect to accuracy and precision. All assays have embedded positive and negative controls. The positive controls are used to check assay accuracy within each set of samples. The negative controls are generally blanks that are included to assess the possibility of any cross contamination in the assay procedure.
What sample quality and quantity are necessary?
This is highly dependent on the assay to be run, but in general a few milliliters of serum or plasma are required. Less volume usually translates to lower frequency of detection. Multiple freeze-thaw cycles should not be a significant problem for the analysis of these substances.
Centers for Disease Control and Prevention. National Biomonitoring Program Factsheet: Polybrominated Diphenyl Ethers (PBDEs) and Polybrominated Biphenyls (PBBs). http://www.cdc.gov/biomonitoring/PBDEs_FactSheet.html
Fromme H, Becher G, Hilger B, et al. Brominated flame retardants. Exposure and risk assessment for the general population. International Journal of Hygiene and Environmental Health. 2016;219(1):1-23.
Linares V, Bellés M, Domingo JL. Human exposure to PBDE and critical evaluation of health hazards. Archives of Toxicology. 2015;89(3):335-356.
U.S. Environmental Protection Agency. Biomonitoring: Polybrominated Diphenyl Ethers. America’s Children and the Environment. 2013. https://www.epa.gov/sites/production/files/2015-05/documents/biomonitori...