Chronic, dietary polybrominated diphenyl ether exposure affects survival, growth, and development of Rana pipiens tadpoles

Abstract

Levels of polybrominated diphenyl ethers (PBDEs) in the environment have been increasing rapidly over the past two decades; however, the toxicology of these compounds to aquatic organisms is poorly understood. Because amphibians play a role in both aquatic and terrestrial food webs, and are currently undergoing worldwide population declines, it is of interest to determine how PBDEs may affect amphibian health. This is the first study that reports chronic, dietary effects of environmentally relevant levels (7-277 ng/g wet food) of PBDEs in amphibians throughout larval development. Beginning at the free-swimming stage (Gosner Stage [GS] 25), Rana pipiens tadpoles were orally exposed to a technical pentabromodiphenyl ether mixture (DE-71) through metamorphic climax (GS 42). On exposure day 43, a subset of tadpoles was removed for body residue analysis. Sum PBDEs in whole-body tissue correlated linearly to dietary concentrations with BDE-99 represented as the highest contributing congener in both diet and tissue. Survival among all treatments compared to the control was decreased by DE-71 exposure. Further, growth and development were delayed in all but the highest treatment, perhaps indicating greater PBDE tolerance among those individuals that survived the highest treatment. Time to metamorphic climax was delayed, on average, 22 to 36 d in DE-71-treated tadpoles compared to control tadpoles. Additionally, size at metamorphosis was smaller in the highest treatment, suggesting that individuals that survived and metamorphosed similarly to the controls did so with a trade-off in size. At environmentally relevant levels, PBDEs induced mortality as well as sublethal effects on developing tadpoles through dietary exposure.