Early life exposure of zebrafish (Danio rerio) to synthetic pyrethroids and their metabolites: a comparison of phenotypic and behavioral indicators and gene expression involved in the HPT axis and innate immune system

Ecotoxicological studies have revealed the association between synthetic pyrethroid (SP) exposure and aquatic toxicity in fish; however, research on the toxic effects of SP metabolites is still limited. In this study, the toxicity of two SPs (permethrin (PM) and beta-cypermethrin (beta-CP)) and their three metabolites (3-phenoxybenzoic alcohol (PBCOH), 3-phenoxybenzaldehyde (PBCHO), and 3-phenoxybenzoic acid (PBCOOH)) towards zebrafish embryos and larvae was evaluated. Both SPs and their metabolites exhibited significant developmental toxicities, caused abnormal vascular development, and changed locomotor activities in larvae. The alteration of gene expression involved in the thyroid system and the innate immune system indicated that SPs and their three metabolites have the potency to induce thyroid disruption and trigger an immune response. The results from the present study suggest that SP metabolites could induce multiple toxic responses similar to parent compounds, and their toxicity should be considered for improving the understanding of environmental risks of SPs.