Relative Toxicity of Organophosphate Flame Retardants in Embryonic Zebrafish

Organophosphate flame retardants (OPFRs) delay ignition of commercial products manufactured in the textile and furniture industries. In the current study, embryonic zebrafish (Danio rerio) were exposed to varying concentrations of seven selected OPFRs at 6 hours post fertilization (hpf) and evaluated daily for morbidity and mortality. Glutathione S-transferase (GST) activity was assessed in zebrafish at 120 hpf following OPFR exposure in order to probe oxidative stress as a mode of action, and acetylcholinesterase (AChE) activity was evaluated as an indicator of neurotoxicity. Our study found that OPFRs elicited a variety of effects, with triphenyl phosphate, tributyl phosphate, tris-(2-butoxyethyl) phosphate and tris-(1,3-dichloro-2-propyl) phosphate inducing mortality in a concentration dependent manner. Furthermore, several of the selected OPFRs impacted spontaneous movement and AChE activity. Due to the rising production volumes of OPFRs, these results underscore concerns regarding human exposure and adverse health effects.