Brominated diphenyl ether (BDE) levels in liver, adipose, and milk from adult and juvenile rats exposed by gavage to the DE-71 technical mixture.

Brominated diphenyl ethers (BDEs) are used as flame retardants in consumer products. Rodent studies indicate that the liver, thyroid, and nervous system of developing animals are targets of BDEs. To explore the relationship between exposure and health in developing animals, BDE accumulation in adult and juvenile rats was examined in conjunction with changes in liver weight and serum thyroxine (T4). Adult (F0) rats received the commercial BDE mixture DE-71 by gavage at doses of 0.5, 5, and 25 mg kg(-1) body weight (bw)/day for 21 weeks. F0 rats were mated and exposure continued throughout breeding, pregnancy, lactation, and postweaning until the pups (F1 generation) reached postnatal day (PND) 42. Milk was collected from lactating dams. Adipose and liver samples were collected from F0 and F1 males and females for BDE congener analysis. Congener prevalence in rat tissues mimicked congener prevalence in wildlife and humans. Tissue concentrations of all congeners except BDE-153 were lower than would be expected based on dose proportionality, confirming that BDE-153 has a high capacity for bioaccumulation. BDEs were transferred from maternal tissues to milk during lactation. Milk congener profiles differed from maternal tissue profiles indicating that degree of bromination and maternal sequestration influenced BDE transfer to milk. Female F1 rats accumulated more BDEs than F1 males, indicating that female rats were less able to metabolize and/or excrete BDEs. Significant effects on liver weight and serum T4 levels were observed in adults and juveniles in the middle and high dose groups, corresponding to BDE levels in the μg g(-1) range. Although it remains to be determined how human liver and thyroid are affected by exposure to much lower BDE levels, the present study confirmed that gender and reproductive status influence BDE accumulation in tissues and BDE transfer to the neonate via milk.