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SRMs track fire retardants in humans and environment

August 20, 2007

If only the flame retardant chemicals routinely added to consumer products from carpets to cell phones just did their job and nothing more. Health officials, however, are concerned that one class of these chemicals called polybrominated diphenylethers (PBDEs), may be doing more than reducing fire-related injuries and property damage.

After several decades of use, PBDEs are widely distributed in the environment as contaminants, and trace levels of these chemicals can be measured in animal tissues and in the food chain (they can be found, for example, in bird eggs and human breast milk). To help scientists evaluate the risks of PBDEs by improving measurements of these pollutants in the environment, the National Institute of Standards and Technology (NIST) has re-evaluated several of its environmental reference materials to report PBDE concentrations in them.

Different commercial PBDE flame retardant formulations have been used, including pentaBDE in furniture foam; decaBDE in plastics for television cabinets, consumer electronics, draperies and upholstery; and octaDBE in plastics for personal computers and small appliances. Although human data on health effects are limited, the U.S. Environmental Protection Agency (EPA) cites animal tests as evidence that PBDEs are neurodevelopmental toxins, disruptors of thyroid functions, and liver toxins. The doses used in animal studies were slightly higher than PBDE levels found in some people in the United States.

U.S. production of pentaBDE and octaBDE formulations ended in 2004. DecaBDE (formulations which do not seem to be easily accumulated in humans, but can degrade to octaBDEs and pentaBDEs) are not banned. Pathways by which PBDEs enter the environment and humans are not yet known. Human exposure might come from food, manufacturing, or even from use of consumer product such as furniture.

To help investigators get a handle on the source and degree of PBDE contamination, NIST measured concentrations of selected PBDEs and other brominated flame retardants including hexabormocyclododecane (HBCD) in seven of the agency's existing Standard Reference Materials (SRMs) that are considered benchmarks for measurements of environmental pollutants.

Concentration values for PBDEs are now available for NIST's reference materials for house dust (SRM 2585), cod liver oil (SRM 1588b) and human blood serum (SRM 1589a). Newly certified values for PBDE concentrations in four other SRMs for whale blubber, mussel tissue and two types of fish tissue are expected to be available soon.

In collaboration with the Centers for Disease Control and Prevention (CDC), NIST also is developing four new SRMs based on human blood and milk. Two of these SRMs will have certified values for current PBDE concentrations to record the level of current human exposure. PBDEs will be added at higher levels for the other two materials to facilitate comparability of measurements among laboratories.

National Institute of Standards and Technology (NIST)