Organobromine compounds in aquatic environments: Embryotoxicity linked to lipophilicity and molecular structure

Abstract

Organobromine compounds, prevalent in marine environments due to both anthropogenic activities and natural processes, have been shown to exhibit significant toxicity toward aquatic organisms. This study investigates the embryotoxicity and teratogenic effects of six bromophenol compounds using zebrafish (Danio rerio) embryos as a model. The compounds exhibited varying degrees of toxicity, with BP-6 and BP-5 showing the lowest LC₅₀ values. The study identified distinct embryonic malformations, including venous sinus edema, pericardial cysts, and craniofacial malformations. A correlation was observed between the toxicity of the bromophenols and their lipophilicity, with higher lipophilicity compounds demonstrating greater toxicity. Mechanistic insights into the toxicity of bromophenols were further explored through transcriptomic analysis, which identified significant effects on retinol metabolism, modulation of myocardial contraction via Ca²⁺/Na⁺ ion flux, stimulation of nonspecific immune responses, and suppression of primary bile acid synthesis. BP-2 exposure significantly altered calcium signaling and bile acid biosynthesis, indicating a potential mechanism for its enhanced toxicity. These findings underscore the need for further investigation into the environmental and health impacts of bromophenols, particularly as they accumulate in marine ecosystems and the food chain.

Keywords: Acute toxicity; Bromophenols; Lipophilicity; Myocardial contraction; Retinol metabolism.