Toxicity Evaluation of Acrylamide on the Early Life Stages of the Zebrafish Embryos (<i>Danio rerio</i>)

Abstract

Acrylamide is a chemical used mainly in industrial applications and the treatment of drinking and wastewater, making it easy to enter aquatic ecosystems. There are few studies known about the toxicity of acrylamide to aquatic organisms which have shown evidence of a number of histopathological effects. To assess the effects of acrylamide to freshwater fish, Zebrafish (Danio rerio) embryos were exposed to serial concentrations of acrylamide (0, 100, 300, and 500 mg/L) to investigate the acute toxicity effects on teleost embryogenesis. Embryos less than 24 hrs old were exposed under static non-renewal conditions for ten days or until hatching. The toxic endpoints evaluated include: egg/embryo viability, hatchability, and morphological/developmental anomalies during organogenesis. The acute toxicity test resulted in a 48 h-LC50 of 585 mg/L for egg viability. Exposure of embryos significantly reduced hatchability and larval survival, in a concentration dependent manner. Dimethyl sulfoxide (DMSO) was used as a solvent carrier to permeate the uptake of acrylamide through the chorion membrane. No significant damages or complications were observed in embryos exposed to DMSO. At 500 mg/L, the highest test concentration, the survival of embryos was greatly reduced within 24 hrs of exposure. The lower test, 100 mg/L, produced a significant number of developmental anomalies to the Zebrafish that included dorsal tail flexure, severe pericardial edema, facial and cranial defects and decreased heartrate (40 bpm). Premature hatching of embryos and developmental arrest was observed in all concentrations. The severity of these anomalies was concentration-dependent and resulted in low survival rate and high frequency of malformations. These results indicate that acrylamide is teratogenic and provide support for sub-lethal toxicity testing using Zebrafish embryos.