First measure of flame retardants in dust from U.K. daycares shows surprisingly high levels.

Jul 06, 2010

Harrad, S, E Goosey, J Dexborough, MA-E Abdallah, L Roosens and A Covaci. 2010. Dust from U.K. primary school classrooms and daycare centers: The significance of dust as a pathway of exposure of young U.K. children to brominated flame retardants and polychlorinated biphenyls. Environmental Science and Technology

Synopsis by Heather Stapleton

Children are likely receiving significant exposure to toxic flame retardant chemicals and polychlorinated biphenyls (PCBs) in daycare centers and schoolrooms in the United Kingdom, finds a study that documents higher than expected exposures and raises health concerns.

A first attempt at measuring flame retardants and PCBs in dust from daycare centers and classrooms in the United Kingdom shows these facilities to be an important source of exposure for toddlers and young children, with a small group of them experiencing very high exposures. Researchers may be underestimating the impact from these facilities, as levels of certain chemical types were higher than those from house dust or car dust.

While chemical levels in dust from U.K. homes and cars are known, this is the first study to measure and evaluate exposures in early childhood classrooms – another place where children spend time. These results aid in understanding sources of exposures and increase the concern over indoor exposures and their affects on children’s health.

Furthermore, this study demonstrates that computer models used to estmate exposure levels may need to be modified to account for the increased exposure while children are in daycare and schoolrooms.

One concern is with a flame retardant known as HBCD. The high levels of HBCD detected in the classrooms were more than levels measured in homes and offices in previous studies. This raises red flags about childrens' exposure to this chemical. 

The use of HBCDs is not currently restricted in the United Kingdom, Europe, the United States or globally. However, due to its persistence and bioaccumulation potential, it is currently under consideration for listing under the Stockholm Convention. Furthermore, the European Chemicals Agency identified HBCD as a substance of very high concern under the REACH regulation program. Animal studies have demonstrated endocrine disrupting effects from exposure to HBCD.

Generally, the largest chemical exposures occur through breathing contaminated air and food, and from inadvertent dust ingestion. Children may have higher exposures than adults because of their small bodies, the  time they spend crawling around on floors and their increased hand-to-mouth behaviors.

Flame retardants are used in almost all consumer products to slow burning if they catch on fire. Furniture, fabrics, carpets, computers, other electronics and many other household consumer products contain some type of chemical flame retardant. During product use, the chemicals can be released and may end up clinging to nearby dust particles. The health effects of long term exposures are not well understood or documented, although some types have been shown to affect reproduction and the nervous system.

In this study, researchers measured a suite of brominated flame retardants and several PCBs in about 40 samples of dust collected from classrooms at 43 schools and daycare centers in the United Kingdom. Children between 1- and 6-years-old use these facilities.

The authors examined seven PCBs and three main classes of flame retardants – hexabromocyclododecanes (HBCDs), polybrominated diphenyl ethers (PBDEs) and tetrabromobisphenol-A (TBBP-A).  The authors used a computer model that combined these newly measured levels with data gathered from prior studies to estimate and compare the young childrens' exposures from ingesting the contaminated dust from classrooms, homes and cars.

The large volume use flame retardant HBCD was detected in every sample. The concentrations were significantly higher than levels measured in dust collected from homes and offices. Inadvertent exposure to dust may be an important source of exposure in young children, relative to their diet.

PBDEs are a well known class of brominated flame retardants that have been phased out from use due to their persistence, bioaccumulation potential and toxicity. Even though, they were measured and detected in all samples. Dust exposure to two particular types – BDE-99 and BDE-209 – may be a concern for some British children. PBDE levels in the daycare centers and classrooms were similar to levels previously measured in U.K. homes and offices.

TBBPA and PCBs were also measured in all dust samples from the schools and daycare centers with similar concentrations to those reported in U.K. homes. In the United Kingdom, dust ingestion of PCBs may not be a major source of exposure. However,in contrast, current data suggest that PCB levels are higher in U.S. daycare centers, and thus children's exposures to PCBs present in daycare/school dust may be higher than in the United Kingdom. PCBs were used in sealers and other contruction materials and can be released into the indoors as these materials decay.

Using the levels of these contaminants measured in dust, dietary intakes for these chemicals were caculated with dust exposure computer models. Median concentrations of the contaminants measured in the dust equated to daily intakes of the flame retardants and PCBs of approximately 34 nanograms per kilogram of body weight per day (ng/kg bw/day). However, a "high dust" exposure model – using the highest concentrations of each contaminant – resulted in exposure intakes of approximately 13,300 ng/kg bw/day. This suggests that very high exposures are occurring for a small population of U.K. children. In addition, exposure to BDE 209 in this "high dust" exposure model was significantly higher than the U.S. Environmental Protection Agency’s IRIS Reference Oral dose.