Safer by design sunscreen using titanium dioxide nanoparticles
Résumé
Among cosmetics and personal care products, sunscreen products are of emerging concern regarding both human and environmental health. The fate and impact of mineral nanoparticulate UV-blockers, such as TiO2 nanomaterials, is under consideration from a regulatory perspective due to their potential impact. Here we present the first result of the Eco-SUN research program aimed at developing the eco-design of sunscreens through the minimization of risks associated with nanomaterials incorporated into the formulation. Different stages of the cream lifecycle are considered from its manufacture to its end of life, through its use by the consumer and its impact on the exposed environments. Reducing the potential release and / or toxicity of the nanomaterial from the cream is a decisive criterion for its ecodesign. Different relevant TiO2 UV-blockers have been selected to integrate a typical w/o formulation as case studies. The resulting sunscreens were characterised in terms of nanomaterial localisation, sun protection factor and photo-passivation. The risk for the consumer by dermal exposure will be assessed using skin biopsies, and evaluating inflammation and skin penetration. The risk for the aquatic environment directly exposed will be assessed both in terms of exposure and hazard. The release of nanomaterials from the sunscreen upon normal usage was studied in the laboratory through a simulated aging procedure. Two biological models, sea urchin and coral colonies, were selected as relevant endpoints to assess the marine ecotoxicity of the by-products formed. Finally, the risk related to the end of life of the sunscreen through the removal with cleaning water followed by drainage to sewage treatment plants will be evaluated by considering the scenarios of nanomaterial concentration in sewage sludge later spread as fertilizer in agriculture.