Comparative effects of oral exposure to 2, 4, 6-tribromophenol and decabromodiphenyl ether in Nile tilapia

Flame retardants are compounds added to a high diversity of polymers used in electronics and furniture to decrease the risk of combustion. Decabromodiphenyl ether (BDE-209) is a polybrominated diphenyl ether (PBDE) congener still used worldwide, while 2, 4, 6-tribromophenol(TBP) is a PBDE metabolite used as a pesticide and flame retardant for wood conservation. These compounds have lipophilic properties and are easily bioaccumulated in the food chain. In the current study, the acute and chronic toxicity of BDE-209 and TBP was evaluated in O reochromis niloticus through analyses of redox imbalance, neurotoxicity, and histopathological biomarkers after acute (24, 48, 72, and 96 h) and chronic (90 days) exposure to 0.5, 5, and 50 ng/g of the polybrominated compounds. The results showed effects on glutathione S-transferase(GST) activity and damage to biomolecules in both acute and chronic exposures. Liver histopathology and the ultrastructure of hepatocytes revealed alterations and damage in individuals from both experiments, but only BDE-209 led to neurotoxic effects. The current study revealed new endpoints related to polybrominated compounds in fish, highlighting the need to review the risk of exposure to biota. Graphical Abstract