Polybrominated diphenyl ethers (PBDEs) are flame retardants used in plastics and textile coatings, with commercial products primarily consisting of penta-, octa-, and decabromodiphenyl ether mixtures. Global PBDE production is about 40,000 tons per year. PBDEs are bioaccumulated and biomagnified in the environment, particularly in aquatic biotopes. Levels in sediments and aquatic biota increased significantly from the mid-1970s to the 1980s, but recent data suggest levels may be at steady state or decreasing. However, PBDE levels in mother's milk increased exponentially from 1973 to 1997. Dietary intake of PBDE in Sweden is estimated to be 0.05 μg per day. Animal studies have shown hepatotoxicity, embryotoxicity, thyroid effects, and maternal toxicity during gestation as characteristic endpoints. Behavioral effects have also been observed in mice exposed to PBDEs during a critical period after birth. The lowest-observed-adverse-effect level (LOAEL) for PBDEs is considered to be 1 mg/kg/day, primarily based on effects of pentaBDEs. While the current dietary intake of PBDEs appears to pose limited health risks, data gaps remain, particularly in carcinogenicity, reproduction, and developmental toxicity, as well as additional exposure routes. The time trend of PBDEs in human breast milk is concerning for the future.Polybrominated diphenyl ethers (PBDEs) are flame retardants used in plastics and textile coatings, with commercial products primarily consisting of penta-, octa-, and decabromodiphenyl ether mixtures. Global PBDE production is about 40,000 tons per year. PBDEs are bioaccumulated and biomagnified in the environment, particularly in aquatic biotopes. Levels in sediments and aquatic biota increased significantly from the mid-1970s to the 1980s, but recent data suggest levels may be at steady state or decreasing. However, PBDE levels in mother's milk increased exponentially from 1973 to 1997. Dietary intake of PBDE in Sweden is estimated to be 0.05 μg per day. Animal studies have shown hepatotoxicity, embryotoxicity, thyroid effects, and maternal toxicity during gestation as characteristic endpoints. Behavioral effects have also been observed in mice exposed to PBDEs during a critical period after birth. The lowest-observed-adverse-effect level (LOAEL) for PBDEs is considered to be 1 mg/kg/day, primarily based on effects of pentaBDEs. While the current dietary intake of PBDEs appears to pose limited health risks, data gaps remain, particularly in carcinogenicity, reproduction, and developmental toxicity, as well as additional exposure routes. The time trend of PBDEs in human breast milk is concerning for the future.