Identifying predictors of human exposure to brominated and organophosphate flame retardants in the indoor environments

Thesis (Ph.D.)--Boston UniversityFlame retardants are chemical additives used to meet flammability standards for many materials including high impact polystyrene used in consumer electronics and polyurethane foam used in furniture. To date, research in the U.S. has primarily focused on polybrorninated diphenyl ethers (PBDEs), which have been shown to escape from products over time and accumulate in the dust of indoor environments as well as in our bodies. Due to growing concerns regarding its persistence and toxicity, PBDEs began to be phased out of production in the U.S. in 2005. Since then, other flame retardants such as hexabromocyclododecane (HBCD), tetrabromobisphenol-A (TBBP-A) and tris(1,3-dichloro-2-propyl) phosphate (TDCPP) have potentially increased in use. Therefore, our objectives were to characterize human exposure to these flame retardants and assess predictors of exposure. We investigated exposure to target flame retardants in three potentially susceptible and highly exposed populations: HBCD and TBBP-A in breast milk of first-time mothers, the primary metabolite of TDCPP in urine from office workers, and PBDEs in serum from collegiate gymnasts. The target flame retardants were identified in 100% of samples, with the exception of TBBP-A (35%). Body burdens of HBCD and TBBP-A were similar to reports from other parts of the world. HBCD exposure was positively associated with the number of stereo and video electronics in the home and lower in participants who regularly chose organic foods compared to those who did not. Our measurements of TDCPP metabolite in urine are among the first in the world. Participants who worked in a new office building had urinary concentrations of TDCPP metabolite that were 26% of those who worked in older office buildings. Finally, the geometric mean (GM) concentration of BDE153 in serum from gymnasts was four times higher than in the general U.S. population and similar to the GM concentration measured in foam recyclers and carpet installers. Concentrations of flame retardants in gym air and dust were orders of magnitude higher than previously found in residences. Overall, our results suggest that the indoor environment contributes to flame retardant exposure in our target populations