Brominated flame retardants

The text on this page is taken from an equivalent page of the IEHIAS-project.

There are three major classes of BFRs in Europe:

• tetrabromobisphenol A (TBBPA),
• hexabromocyclododecane (HBCD)
• three commercial mixtures of polybrominated diphenyl ethers (PBDEs), namely deca-BDE, octa-BDE and penta-BDE.

Europe has banned the use of penta- and octa-BDE in electrical and electronic equipment. Deca-BDE is the main PBDE of concern, and consists of a mixture of 97-98% BDE-209.

Brominated flame retardants as a biomarker

Sample collection and storage

Matrix:

BFRs can be determined in blood and adipose tissue, although breast milk is often preferred

Kinetics:

• Major uptake routes include food (fatty fish, milk products), inhalation of dust particles and directly through aerial exposure
• TBBPA and DeBDE have very low uptake rates, with 90-99% of the dose eliminated in feces and gut
• Daily PBDE intake ranges from 0.0001-2.6 µg/kg bw, depending on which congeners considered
• Half-life of Deca-BDE is 11-18 days, and 2 days for TBBPA

Sampling conditions:

Although routine procedures are appropriate for sampling and storing samples, the omnipresence of BFRs is an obvious contamination risk. Samples are stored at -20°C.

Sample measurement

Analytical aspects:

• Methods generally are analyzed using GC-MS, with a wide variety of pretreatment, extraction and clean-up procedures
• LOD in human milk is 0.3-0.7 pg/g milk for PBDEs
• LOQ is < 10 pg/g serum fat or breast milk for TBBPA and 30-1500 pg/g for HBCD and deca-BDE

Performance characteristics:

• Analytical reproducibility imprecision is around 25% for Deca-BDE and HBCF.
• Repeatability is in the range of 5-9% and 1-10% relative standard deviation
• Reliable quantification of Deca-BDE, HBCD and TBBPA remains a problem, with reported CV% of 63% and 53%

Validation:

No uniform, internationally accepted guidelines for BFRs in biological matrices developed yet

Confounding factors:

Occupation (e.g. computer work) and diet may be important confounders

Data interpretation

Concentrations reported in literature:

• BFR concentrations are increasing in the general population, with a doubling of dose every 5 years.
• Concentrations in North America are 10 times higher than in Europe or Japan

Dose-response/effect relationships:

• A general lack of high-quality toxicity data on BFRs
• Acute toxicity is low and no mutagenic potency has been observed.
• Epidemiological studies generally have not shown adverse effects of occupational exposure

Time trend, geographical variation, susceptibel groups:

• An exponential increase in BFRs with a doubling time of 5 years
• Recent data seem to indicate that levels are stabilizing again
• Apart from occupational exposure, no obvious susceptible groups are identified