Toxicity of Unregulated and Regulated Plastic Additives on Early Life Development of Zebrafish (2024)

Abstract

The use of plastic additives has raised environmental concerns owing to their toxic effects on aquatic organisms. N-butyl benzenesulfonamide (NBBS) and triphenyl phosphate (TPHP) are unregulated and on the international watchlist for evaluation. Although certain countries have banned regulated plastic additives such as diethylhexyl phthalate (DEHP) and dibutyl phthalate (DBP), studies on their potential impact on non-target aquatic animals are limited. This study investigated the effects of varying concentrations (0-500 μg/l) of NBBS, TPHP, DEHP, and DBP on zebrafish (Danio rerio) development, locomotion, antioxidant gene expression, and acetylcholinesterase (AChE) activity over four days of embryonic and larval development. The results showed that exposure to plastic additives significantly decreased the survival and hatching rates (≥5 μg/l), while the malformation rates increased (≥0.5 μg/l) significantly depending on the exposure compound. Low environmentally relevant concentrations of 0.5 μg/l NBBS, TPHP, DEHP, and DBP significantly decreased the swimming distance under dark conditions. Furthermore, all four compounds altered the redox response gene expression in tissues. TPHP significantly upregulated the expression of GST, GSR, and GTPx genes, while the latter gene was also upregulated by NBBS and DBP, and Cu/Zn-SOD gene expression was significantly downregulated only at >5 μg/l TPHP. NBBS (≥50 μg/l) and DBP (0.5 and 50 μg/l) significantly upregulated the GTPx gene. p53 expression was significantly upregulated at 500 μg/l DEHP. However, no effect on AChE activity inhibition was observed for the tested compounds. The findings of this study demonstrate that environmentally relevant concentrations of the tested plastic additives can impair parameters related to physiological processes in the early life development of zebrafish, thus emphasising the need for further research.

Keywords

Plastic additives; developmental toxicity; locomotor activity; antioxidant gene expression; zebrafish