Tracking relevant nanomaterial transformations, exposure, uptake and effects in freshwater and soil systems

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Nanomaterials (NM) are very small particles much less than the width of a human hair. They are synthesised to provide different properties from larger forms of the same material and they are now used in a wide range of products. The properties that NMs provide include enhanced strength, an ability to reflect light or to react with other chemicals, and efficient electrical conductance. The value of NM is now very widely recognised and many companies are starting to use them in common consumer products, such as sunscreens and cosmetics, plus industry products, such as fabrics and building materials. This means that small quantities of NMs will reach the wider environment from everyday product use.A great deal of recent research has gone into assessing the safety of NMs for humans and the environment. Most of these studies have looked at NMs in their newly-manufactured forms. It is increasingly apparent, however, that once NMs are released into the wider environment, they do not stay in their manufactured state - they change or 'transform'. Transformations can affect NM size, charge, their surface coatings and their ability to bind to other things such as soil particles or other chemicals. Transformations occur both during transfer to the environment (e.g. via sewage works) and once NMs reach the wider environment itself (rivers, sediments and soils). It is of huge importance that we understand the transformation processes and environmental fate(s) of NMs as they can affect their toxicity to humans and the environment. The aim of this project is to study these NM transformations in more detail. We want to better understand whether different types of NMs are transformed in the same or different ways. We will conduct our work with different types of NMs, including those made from silver, titanium dioxide, polystyrene (a type of plastic) and graphene (a type of carbon). We will first use laboratory methods that mimic the ways that NMs are changed during sewage treatment and in natural waters and soils to create the transformed materials that we will then study. We will test how these new and changed NMs affect a range of common aquatic and soil organisms and contrasting their toxicity in their "pristine" state with that after they have been transformed in the environment for different times. During our tests, we will measure how much of each material is taken up by the organisms into different tissues and whether this affects how they grow and reproduce. We will also measure the activity of different genes that are likely to be affected as organisms take up different NMs. We predict that each NM will be transformed in a way that changes its likelihood to cause harmful effects. Each test will be repeated using different soils and waters typically found across the UK, to determine how transformations vary under different conditions.Finally, we will build custom-made, large exposure systems ('mesocosms') designed to mimic the rivers into which sewage works discharged and soils upon which sludge is spread, and populate them with a wide range of common UK native plants, invertebrates and fish (in the waters). By following these mesocosms for several months, we can simulate what may actually be happening in real UK environments in terms of the fate and effects of our transformed NMs. We will use the results to improve models able to predict how our transformed NMs will behave and the effects they will have. Taken together, our results should help us to predict the toxicity of NMs to help assure their safety, supporting the growth of the nanotechnology industry into the future. To this latter end we will run and coordinate a UK Nano-Academics & Regulators Platform, and will also present our results through major European Union (NanoSafety Cluster) and worldwide (Organisation for Economic Cooperation and Discussion) policy working groups, as well as to the public, so reaching as wide an audience as possible.