Exposure of juvenile Danio rerio to aged TiO_2 nanomaterial from sunscreen

摘要

The toxicity of dietary exposure to artificially aged TiO_2 nanomaterial (T-Lite?) used in sunscreen cream was studied on Danio rerio. Embryolarval assays were conducted to assess the effects of TiO_2 residues of nanomaterial (RNM) on fish early life stages. Juvenile fishes were exposed by the trophic route in two experiments. During the first experiment, juvenile fishes were exposed to TiO_2 RNM for 14 days by adding RNM to commercial fish food. The second one consisted in producing a trophic food chain. Pseudokirchneriella subcapitata algae, previously contaminated with TiO_2 RNM in growth medium, was used to feed Daphnia magna neonates over a 48-h period. Daphnia were used next to feed juvenile fishes for 7 days. Accumulation of Ti, life traits (survival and growth) and biochemical parameters such as energy reserves, digestive (trypsin, esterase, cellulose and amylase) and antioxidant (superoxide dismutase and catalase) enzyme activity were measured at the end of exposures. As expected in the receiving aquatic system, TiO_2 RNM at low concentrations caused a low impact on juvenile zebrafish. A slight impact on the early life stage of zebrafish with premature hatching was observed, and this effect appeared mainly indirect, due to possible embryo hypoxia. When juvenile fish are exposed to contaminated food, digestive enzyme activity indicated a negative effect of TiO_2 RNM. Digestive physiology was altered after 14 days of exposure and seemed to be an indirect target of TiO_2 RNM when provided by food.