The effect factor for nano TiO2: preliminary toxicity tests on Daphnia magna and future developments

Nanotechnologies are being developed for application in a large variety of sectors, from food industry to environmental remediation technology. However, numerous uncertainties exist regarding their possible impacts on the environment and human health. The Life Cycle Assessment (LCA) methodology could be a tool to evaluate, analyze and manage the environmental and health effects for the emerging technologies. The evaluation of the environmental performance of nanotechnologies trough LCA is not always possible due to the lack of data regarding the environmental pathway of NPs. The focus of the present research is to evaluate the freshwater ecotoxicological Effect Factor (EF) for TiO2 nanoparticles (which are widely used in different applications as sunscreens, solar cells, ecc.), following the framework of the USEtox model. This model is used for the Life Cycle Impact Assessment (LCIA) phase and is aimed to provide the Characterization Factor (CF) for the ecotoxicity impact category. The CF is quantified trough the evaluation of the Fate Factor (FF) and Effect Factor (EF). The latter is based on chronic or acute toxicity value as EC50. In order to establish the acute EC50 for nano TiO2, two preliminary toxicity tests on Daphnia magna (72h) have been performed. The particles were prepared following two different treatments. In the first case the nano TiO2 suspensions were stirred for 24 h only before the test; in the second case the particles were maintained in agitation also for the whole duration of the bioassay. No adverse effects have been observed for the concentration applied, this contrasts with the findings of other studies that reported effects of nano TiO2 on D. magna. The future developments of our research are to conduct other toxicity tests on D. magna, following different treatments of the sample (example: irradiation with UV-A, filtration etc), and to conduct toxicity test on different trophic level (algae, crustaceans, fish) as suggested by USEtox framework. The research is intended to identify suitable treatments for nanoparticles to be used in toxicity test, taking into account their tendency to aggregate and precipitate and that this could influence the results of the tests. The suitable treatment should also reproduce the actual exposure modality of the organisms in the field.