Life cycle assessment applied to nanomaterials in solid waste management: Focus on human health impact assessment

    Research output: Book/ReportPh.D. thesis

    Abstract

    While the generation of solid waste is globally increasing, much effort is concentrated to minimise the environmental impacts related to their management. With respect to nanoproducts (products containing nanomaterials), a growing amount of ‘nanowaste’ can be expected to enter the waste streams, thus potentially posing problems on human health, e.g. through occupational exposure to engineered nanoparticles. In that setting, through its holistic quantification of environmental impacts, life cycle assessment (LCA) can be a useful decisionsupport tool for managing environmental sustainability of solid waste management systems as well as that of nanoproducts. But how has LCA generally been applied to both fields of solid waste management and nanotechnology until now? In particular, what are the current shortcomings for assessing impacts of released engineered nanoparticles? Is it possible to derive useful preliminary results from currently available data? And, if so, what could be the occupational impacts of engineered nanoparticles taken through the life cycle of nanoproducts including their end-of-life? The answers to these questions form the red thread of the thesis, which is composed by several pieces of work.
    Critical reviews were performed to evaluate the current state of LCA application to solid waste management systems and to nanoproducts. The former revealed that, out of 222 reviewed studies, several limitations were identified in the types of LCA application, with a narrow focus on specific waste types and waste management systems, all primarily reflecting situations in economicallydeveloped countries. At the same time, methodological practice was found in many studies not to be compliant with current reference guidance, such as the ISO standards and the ILCD Handbook. Likewise, in the application of LCA to nanoproducts, important inconsistencies and shortcomings were noted. While some of them could be prevented by a proper application of the LCA methodology, others were strongly related to the data paucity, particularly with regard to the lack of emission data and characterisation factors for assessing engineered nanoparticles.
    To support the impact assessment of engineered nanoparticles in the life cycle of nanoproducts and in solid waste management systems, a comprehensive review of toxicological data for nanosilver and titanium dioxide (TiO2) particles was conducted and it enabled to investigate the influence of some of the physicochemical properties of the particles on their toxic effects. This led to quantify relationships between the primary size and the toxic effects of nanosilver and TiO2 particles that ultimately could be used for deriving consistent, size-dependent no-observed-adverse-effect levels and effect factors applicable in risk assessment and life cycle impact assessment, respectively. The developed effect factors for TiO2 and Ag particles were applied on two simplified LCA case studies, namely the annual consumption of food containing TiO2 nanoparticles in the United Kingdom and a T-shirt embedded with nanosilver. Although highly uncertain because of lack of data, this preliminary assessment suggested that the manufacturing stage may lead to larger occupational impacts from engineered nanoparticles than the disposal stage, and that the occupational exposure to engineered nanoparticles may be negligible when compared to other contributions to human health impacts in the nanoproduct life cycle.
    More than the results themselves, these case studies, along with the developed methodology for investigating the relationships between the physicochemical properties of the particles and their toxic effects, served to pinpoint the data required to perform proper assessment of the impacts of exposure to engineered nanoparticles. In particular, detailed emission data matching the actual processes in both the manufacturing and disposal stages, full characterisations of exposure situations, and the generation of more reliable and relevant toxicological data are highly needed and should urgently be addressed. Integrating these information into LCA practice, for which detailed recommendations are also provided in this thesis, should allow the conduct of consistent LCA studies of waste management systems and nanoproducts, and accurately evaluate the relevance of engineered nanoparticles in the total human health impacts.
    Original languageEnglish
    PublisherDTU Management Engineering
    Number of pages409
    Publication statusPublished - 2014

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