Physical and Chemical Transformations of Engineered Nanoparticles: Implications for Environmental Fate in Aquatic Environments

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Engineered nanoparticles (ENPs), which have at least one dimension in the range of 1-100 nm, are used in the manufacture of various household and industrial products (e.g. personal care products, paints and coatings) to enable or enhance specific functions. ENPs can be released from these products to aquatic systems with runoff and wastewater effluents. A significant number of these ENPs in their pristine' forms (as ingredients in product formulations) have been shown to be toxic to aquatic and other organisms. Surface and groundwaters are sources of our drinking water as well as important components of our ecosystem, and thus research into the potential environmental and health impacts of increasing releases of ENPs to aquatic environments is an urgent necessity. An important question that will be investigated in this research is whether the environmental behavior and toxicity of ENPs released from products during their lifecycle is similar or different from pristine' ENPs. It is the ENPs released from products that are more likely to cause exposures to environmental receptors than pristine' ENPs, and thus differences in their properties need to be thoroughly examined. Given the high specific surface area and reactivity of ENPs, their exposure to the environment can result in various chemical and physical transformations which may impact the toxicity potential of ENPs. Thus, to better assess the environmental risks of ENP releases, the ENP fate and toxicity in their environmentally relevant states will be investigated. The research will be conducted by 4 PhD, 3 Masters and 5 undergraduate students, who will be an integral part of the applicant's active research program which has other ongoing complementary projects. The research objectives will be investigated through rigorous characterization of a suite of widely used ENPs using cutting edge analytical instruments in the applicant's laboratory. Carefully designed experiments will investigate the aggregation behaviour and chemical interactions with various surface and groundwater components. The toxicity potential of the pristine and product-released ENPs will be assessed in water samples representative of surface and groundwater compositions. Given that ENPs are regulated as new substances' in Canada and elsewhere, there is a need to develop a solid knowledge-base on the fate, and toxicity of ENPs released into the Canadian environment. The emerging field of nanotechnology has tremendous potential to improve our social and economic well-being, but there are still uncertainties about the risks associated with ENPs in the environment. The research proposed will help strengthen the ecological risk assessments of ENPs. The research will be disseminated through publications, conferences, and through ongoing research partnerships with several government and industrial institutions.