Engineered nanomaterials release from nano-enabled products

Abstract

The increased presence of nano-enabled products in multiple applications has raised concerns about its potential risks to human health and the environment. Therefore, there is a need for a responsible and coordinated approach to ensure that potential safety issues are being addressed at the same time as the technology is developing. The research presented in this PhD Thesis has the objective to contribute to the understanding of the potential human and environmental risks associated with engineered nanomaterials and nano-enabled products by generating relevant data on engineered nanomaterials released from nano-enabled products along their life cycle.

The objective has been tackled from three different perspectives: Firstly, by upgrading and refining material flow models that allow the prediction of engineered nanomaterials concentration in the environment; secondly, by generating release data from experimental simulations with multiple nano-enabled products; and thirdly, by evaluating the current research performed in Nanosafety Projects funded by the European Commission and suggesting where future research on release studies should focus.

The material flow model refinement is presented in the form of one peer-reviewed publication. In this study, a country-specific assessment of the flows to the environment from production to end-of-life of nano-Ag, -TiO2 and -ZnO within Europe is described. The MF model provided insights on potential exposure to the environment. The outcomes from the model were ENM concentrations (tonnes/km2) in different environmental compartments due to release. From these data, via realistic fate and exposure assessment, the data could be used to determine the potential risk that nano-TiO2, -ZnO and -Ag releases could pose to the environment.

The release data generation from experiments is presented by two peer-reviewed publications and five unpublished results. In the first publication, the release from a fluorescent ink containing CdTe quantum dots during inkjet printing is evaluated. In the second publication, the release mechanisms of Polyamide 6 nanocomposites under weathering conditions are assessed. Nanocomposites containing nano-SiO2, -TiO2, -ZnO, multiwalled carbon nanotubes and two nano-organoclays were included in the study. Regarding the five unpublished studies, three of them are related to the use phase: household washing of curtains containing nano-TiO2, weathering and abrasion of an asphalt coating containing nano-TiO2 and household washing of a textile incorporating nano-Ag in different forms (nanoparticles and two nanowires of different lengths). The other two unpublished studies are related to the end-of-life, both of them considering the potential leaching that occurs in landfills. One study evaluates a camping tent

containing nano-Ag and the other a printed circuit for electronics with conductive ink containing nano-Ag. . An exhaustive characterisation was done in all the cases on both starting materials (engineered nanomaterials before being incorporated in the product), in the nano-enabled products before and after the respective experiments, and also on the released materials. The main outcomes were release rates and release forms, which were included in publically accessible databases to be used by the entire nanosafety community.

The evaluation of the current research performed in Nanosafety Projects funded by the European Commission and the suggestions where future research on release studies should focus is presented in the form of one peer-reviewed publication. The purpose of analysing the nanosafety research was to provide an overview of the products studied compared to what can realistically be found in the market (i.e. the exposure relevant materials that workers, consumers and the environment may be exposed to). In addition, the inventory also provided a rich source of information from which readers with different data needs can extract their own conclusions, providing relevant insights for the nanosafety community

The combination of key information and analyses deriving from the different studies allowed the extraction of conclusions and recommendations to contribute to the understanding of the potential human and environmental risks associated with engineered nanomaterials and nano- enabled products, which is described in the discussions and conclusions section.

La major presència de productes amb nanomaterials en múltiples aplicacions ha suscitat preocupacions sobre els seus possibles riscos per a la salut humana i el medi ambient. Per tant, cal un enfocament responsable i coordinat per garantir que s'aborden els possibles problemes de seguretat a el mateix temps que es desenvolupa la tecnologia. La investigació presentada en aquesta tesi doctoral té com a objectiu contribuir a la comprensió dels possibles riscos humans i ambientals associats amb els nanomaterials i els productes que en continguin, mitjançant la generació de dades rellevants sobre el seu alliberament al llarg del seu cicle de vida.

L'objectiu s'ha abordat des de tres perspectives diferents: en primer lloc, mitjançant l'actualització i perfeccionament dels models de flux de materials,; en segon lloc, generant dades d'alliberament a partir d'experiments amb múltiples productes que contenen nanomaterials; i en tercer lloc, avaluant la investigació realitzada en Projectes de Nanoseguretat finançats per la Comissió Europea.

El perfeccionament del model de flux de materials es presenta mitjançant una publicació científica. En aquest estudi, es descriu una avaluació específica per a cada país Europeu dels fluxos a l'entorn, des de la producció fins al final de la vida útil de nano-Ag, -TiO2 i -ZnO.

La generació de dades d'alliberament a partir d'experiments es presenta mitjançant dues publicacions científiques i cinc resultats no publicats. Per a tots els experiments es van determinar les velocitats d'alliberament i les formes d'alliberament.

Mitjançant l'avaluació de la recerca realitzada en Projectes de Nanoseguretat finançats per la Comissió Europea s’han generat suggeriments sobre en qué hauria de centrar-se la investigació futura sobre estudis d'alliberament, el qual es presenta també mitjançant una publicació científica.

La combinació de la informació generada i l'anàlisi derivat dels diferents estudis permet l'extracció de conclusions i recomanacions que contribueixen a la comprensió dels possibles riscos humans i ambientals associats als nanomaterials i els productes que en continguin, el que es descriu a la secció de discussions i conclusions.