Flame Retardant Metabolites in Addled Bald Eagle Eggs from the Great Lakes Region

Organophosphate esters (OPEs) and other alternative flame retardants including 2-ethylhexyl-2,3,4,5-tetrabromobenzoate (EHTBB) and bis­(2-ethylhexyl) tetrabromophthalate (BEHTBP) are ubiquitous in the Great Lakes region, having been detected in air, water, and biota samples. In a recent study, however, we showed that concentrations of six OPEs in eagle eggs were generally low (geometric mean 24 ng/g ww), and the two main Firemaster (FM) components, EHTBB and BEHTBP, were below limits of detection. We therefore hypothesized that the low levels of these compounds in bald eagles may be due to a potential rapid metabolic transformation. We measured metabolites of triaryl and trialkyl phosphates and brominated Firemaster (FM) flame retardants in 21 addled bald eagle (Haliaeetus leucocephalus) eggs from 2000 to 2012 from the Michigan Bald Eagle Biosentinel Program archive. Sampling sites were divided into two groups: inland (IN) and Great Lakes (GL) based on breeding areas. Results suggest that the most abundant metabolites in the eggs are 2,3,4,5-tetrabromobenzoic acid (TBBA) (n.d. – 330 ng/g ww), bis­(2-chloroethyl) phosphate (BCEP) (0.38–26 ng/g ww), and bis­(2,3-dibromopropyl) phosphate (BDBPP) (n.d. – 45 ng/g ww). Detection frequencies ranged from 67% for mono-(2-ethyhexyl) tetrabromophthalate (TBMEHP) to 100% for most of the other compounds. The relative abundances for these parent/metabolite pairs indicate that the majority of the OPEs can be readily metabolized at various rates, depending on the specific compound