Bioconcentration, metabolism and alterations of thyroid hormones of Tris(1,3-dichloro-2-propyl) phosphate (TDCPP) in Zebrafish

•The bioaccumulation and biotransformation of TDCPP in zebrafish liver was studied.•High levels of TDCPP and its metabolite BDCPP were found in the zebrafish livers.•Genes involved in phase I and II metabolism were upregulated after TDCPP exposure.•Levels of thyroid hormones decreased in female zebrafish after TDCPP exposure.

Tris(1,3-dichloro-2-propyl) phosphate (TDCPP) is an organophosphate widely used as a flame retardant, and has frequently been detected in the environment and biota. The present study investigates the bioconcentration and metabolism of TDCPP in fish. Zebrafish embryos (from 2 h post-fertilization) were exposed to TDCPP (0, 4, 20 and 100 μg/L) for six months. Exposure to TDCPP significantly induced phase I metabolic enzymes 7-ethoxyresorufin O-deethylase (EROD) and 7-methoxyresorufin O-demethylase (MROD) in fish. The mRNA expression of genes related to Phase I and II metabolic enzymes, such as cyp1a1, cyp1b1, cyp1c1 and ugt1ab were also significantly upregulated. Exposure to TDCPP significantly reduced plasma thyroxine (T4) and 3,5,3′-triiodothyronine (T3) levels in females. Chemicals analysis indicated significant levels of TDCPP and its metabolite, bis (1,3-dichloro-2-propyl) phosphate (BDCPP), in the liver. The present study reveals that exposure to low concentrations of TDCPP can cause bioconcentration in fish, and TDCPP can be readily metabolized in liver.