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Developmental Exposure to Organophosphate Flame Retardants Elicits Overt Toxicity and Alters Behavior in Zebrafish (Danio rerio)
Citation:
Dishaw, L., D. Hunter, B. Padnos, S. Padilla, AND H. Stapleton. Developmental Exposure to Organophosphate Flame Retardants Elicits Overt Toxicity and Alters Behavior in Zebrafish (Danio rerio). TOXICOLOGICAL SCIENCES. Society of Toxicology, RESTON, VA, 142(2):445-454, (2014).
Impact/Purpose:
This work compares the overt toxicity, developmental neurotoxicity and bioaccumulation of four organophosphate flame retardants. Their over toxicity is directly related to their bioaccumulation, and all chemicals preturb locomotive behavior in the larval zebrafish.
Description:
Organophosphate flame retardants (OPFRs) are common replacements for the phased-out polybrominated diphenyl ethers (PBDEs) and have been detected at high concentrations in environmental samples. OPFRs are structurally similar to organophosphate pesticides and may adversely affect the developing nervous system. This study evaluated the overt toxicity, uptake and neurobehavioral effects of tris (1,3-dichloro-2-propyl) phosphate (TDCPP), tris (2-chloroethyl) phosphate (TCEP), tris (1-chloropropyl) phosphate (TCPP), and tris (1,3-dibromopropyl) phosphate (TDBPP) in early-life stage zebrafish. Chlorpyrifos was used as a positive control.For overt toxicity and neurobehavioral assessments, zebrafish were exposed from 0-5 days post fertilization (dpf). Hatching, death, or malformations were evaluated daily. Teratogenic effects were scored by visual examination on 6 dpf. To evaluate uptake and metabolism, zebrafish were exposed to 1 µM of each OP flame retardant and collected on 1 and 5 dpf to monitor accumulation. Larval swimming activity was measured in 6 dpf larvae to evaluate neurobehavioral effects of exposures below the acute toxicity threshold. TDBPP elicited the greatest toxicity at >1 µM. TDCPP and chlorpyrifos were overtly toxic at concentrations ≥10 µM, TCEP and TCPP were not overtly toxic at the doses tested. Tissue concentrations increased with increasing hydrophobicity of the parent chemical after 24 h exposures. TDCPP and TDBPP and their respective metabolites were detected in embryos on 5dpf. For all chemicals tested, developmental exposures that were not overtly toxic significantly altered larval swimming activity. These data indicate that OPFRs adversely affect development of early-life stage zebrafish. Key words: flame retardant, organophosphate, TDCPP, zebrafish, development, neurotoxicity
