Nanomaterials (NMs) are multipurpose substances used in almost all industries and product categories. Titanium dioxide (TiO2) is one of the most versatile NMs, especially E171, which is used as an additive in food products. The aim of this master's thesis was to investigate its potential negative effects on zebrafish (Danio rerio) embryo development. Blastula stage embryos were exposed to different concentrations of TiO2 E171 (1 mg/l, 10 mg/l and 100 mg/l) for 48 hours and development was monitored until hatching (72 hours). Embryos were examined at 24-hour intervals and assessed for lethal (embryo coagulation, heart rate, muscle contraction, and detachment of the tail from the RV) and sublethal effects (hatching and developmental abnormalities). At the highest TiO2 concentration, mortality was 15 %, and lethal effects were mainly manifested in embryo coagulation, which was more pronounced in the first 24 hours of development. TiO2 promoted early hatching of embryos from the chorionic membrane by 16 ̶ 24 % after 48 hours of development, while the effect on body length was negligible. At the highest TiO2 concentration, at least one developmental abnormality occurred in 29 % of embryos. The results of our research suggest that sublethal effects should be considered and developmental abnormalities should be monitored when assessing toxicity, otherwise the toxicity of nanoparticles may be underestimated.
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