Assessing risks of nano-enabled products used in restoration of works of art

The development of advanced technologies for artworks preservation has provided conservators with new nanoparticle formulations that represent novel scientific solutions to several issues in restoration and conservation However, the potential human health and environmental impacts that may potentially emerge from these new materials and/or techniques are still unknown. To address these issues, the FP7 Project NANOFORART (Nano materials for the conservation and preservation of movable and immovable artworks) has developed some products based on advanced materials with low environmental impacts. Those include nanoparticle dispersions, micellar solutions, microemulsions and chemical gels used for the consolidation, pH control and cleaning of works of art. We assessed the environmental impacts of a set of nanoparticle dispersions (i.e. four formulations of Ca(OH)2 nanoparticles dispersed in 1-propanol, 2-propanol, ethanol, and two formulations of CaCO3 nanoparticle dispersed in water and in a 2-propanol/water mixture, respectively), along their life-cycle by performing a screening risk assessment. Exposure to both humans and the environment was evaluated by estimating the potential release of the nanoparticles in the manufacturing, preparation, application and post-application stages in order to identify relevant exposure scenarios. Health and environmental hazards were evaluated by self-classifying the investigated formulations according to the "Guidance on the Application of the CLP Criteria" provided by the European Chemicals Agency (ECHA) [3]. This work was supported by tests on nanoparticle dispersions performed according to Human Skin Equivalent Models (HSEM). The results revealed that no relevant exposure and effect are expected for the environmental compartments. For human health, although the self-classification highlighted potential health hazards for some of the proposed dispersions, it was found that the main route of exposure, represented by dermal contact, could lead to adverse toxicological effects only for one system at the highest tested concentration (representative of real application conditions). All the other systems resulted as not irritant for human skin at concentrations representative of real application conditions. However, the use of common personal protective equipment (i.e. gloves, glasses) and prevention measures (i.e. ventilated room), is always recommended in order assure appropriate workers protection. This is one of the first studies addressing environmental impacts of nano-enabled products that can be employed for cultural heritage applications as substitutes of the pure organic solvents and other chemicals with recognized toxicity and environmental impact. The work performed in the NANOFORART project will be further developed and expanded in the frame of the EU Horizon 2020 NANORESTART project in which the ustainability of nanomaterials used for restoration and conservation of contemporary art will be assessed according to environmental, economic, social and technical aspects.