The Common Targeted Organ in Zebrafish Embryos Exposed to Eight Toxic Chemicals

Zebrafish (Danio rerio) embryos are widely used in toxicity tests, especially in investigations on chlorinated or brominated flame retardants (BFRs) and metals. A key challenge in environmental risk assessment (ERA) is how to clarify the same or different sites of toxic action in a species after exposure to the individual chemicals or chemical mixtures and further provide the common toxic sites or organs for risk assessment of chemical mixtures. In this study, zebrafish embryo was used to evaluate the sublethal toxicity (gas bladder damage) of tris(2,3-dibromopropyl) isocyanurate (TBC), Chlorinated paraffins (CPs), hexabromocyclododecane (HBCD), and Cu, Cd, Pb, Ag, Zn, and corresponding sublethal molecular levels (and inflammation-related enzymes [deiodinase (DIO) enzymes]) in fish through optical microscopy methods. The tested chemicals all caused failed inflation of the gas bladder, as indicated by activity inhibition of type 2 iodothyroxine deiodinase enzyme. We put up with the common targeted sites or organs for further studying the toxic mechanisms underlying the chemical mixtures.