Three commercial sunscreen formulations, organic (A), mineral (B), and hybrid (C), containing UV filters and cosmetic additives, were evaluated for developmental toxicity in zebrafish, Danio rerio (Hamilton, 1822) embryos. The bioassay was conducted for 120 hours on post-fertilization stages. A broad concentration range of 1 to 1,000 mg L-1 was tested for effects on mortality, coagulation, and morphology. Each tested sunscreen displayed distinct toxicity profiles. Sunscreen A caused mostly sublethal effects, leading to developmental changes, whereas the mineral sunscreen B displayed the highest acute toxicity, reaching ~40% mortality at 1,000 mg L-1. However, the mineral sunscreen C exhibited non-monotonic toxicity, with the strongest effects observed at the lowest concentrations tested. In contrast, organic sunscreen A caused mild changes in shape and behavior at high concentrations and exhibited very low toxicity. Threshold values for effect (NOEC, LOEC) for all tested effects were determined, and mortality proved to be the most sensitive effect. Despite a non-linear toxicity profile for the chemical Sunscreen C, significant risks to aquatic ecosystems at environmentally relevant exposure levels are expected, attributable to endocrine effects on sexual characteristics. The increased toxicity at lower concentrations indicates that high-dose toxicity testing may grossly underestimate the potential effects of such chemicals on ecosystems. Evaluating whole commercial formulations rather than individual ingredients and assessing environmental hazards of sunscreen pollution from the perspective of the final formulated product (FP) rather than individual chemicals can better predict ecological risks. An evaluation of the potential ecological risks to aquatic and terrestrial ecosystems from the human use of sunscreens, along with consideration of mixture toxicity effects and non-monotonic dose-response relationships, may be warranted. The possible consequences of sunscreen pollution are discussed to inform the development of greener alternatives and formulations that pose lower environmental hazards and are safer for the environment than current products.
