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Technical Report 
Current and future predicted environmental exposure to engineered nanoparticles 
Boxall, A; Chaudhry, Q; Sinclair, C; Jones, A; Aitken, R; Jefferson, B; Watts, C 
Central Science Laboratory 
York, UK 
t is inevitable that during their manufacture and use, engineered nanoparticles (ENPs) will be released to the environment. This study was therefore performed to 1) identify the potential releases of ENPs to the environment; 2) review the fate of ENPs in environmental systems and 3) to assess the potential current and future environmental exposures. Whilst ENPs may be emitted during the manufacturing process, the route of input to the environment will primarily depend on the end use of the ENP-containing product. In many of the applications, nanoparticles are in a fixed or bound form, and hence pose minimal risk to the environment. Applications that contain free engineered nanoparticles, and/or those that are likely to give rise to a greater likelihood and extent of exposure to the environment (e.g. airborne nanoparticles, or those products likely to be disposed of in wastewaters) include cosmetics, paints & coatings, catalysts & lubricants, water treatment and bioremediation products, food & food packaging, human and veterinary medicines and plant protection products. A number of products that contain ENPs have been identified that are currently on the UK market. However, due to a lack of published data, it is not currently possible to estimate the UK market penetration for these products. Moreover, whilst some data are available on the concentrations of ENPs in selected products, for some products this is totally lacking. Available data indicate that, following release to water and air, nanoparticles will aggregate to some degree and that the behaviour of the resulting aggregates will be very different from the free nanoparticle The degree of aggregation and the size range of the aggregates is dependent on the characteristics of the particle, the concentration of the particles and the characteristics of the environmental system. ENPs will exhibit differing mobilities in the soils and waterbodies and in water treatment processes compared to their corresponding parent form. The behaviour of nanoparticles in environmental systems is therefore highly complex and appears to be dependent on not only the particle type but also the particle size and the nature of the receiving environments. As a result of the lack of data on usage and environmental fate, a framework of simplistic models and algorithms for estimating concentrations in water, soil and air has been developed and applied to a range of ENPs. This modelling framework was applied to estimate the likely concentrations of ENPs in water and soil for a range of usage scenarios. For the 10% market penetration scenario, which probably overestimates current exposure levels, concentrations of silver, aluminium and fullerene C60 concentrations were predicted to be in the ng/l, whereas, titanium dioxide, zinc oxide, nanolatex and hydroxyapatite are predicted to be in the mg/l range (Table E.1). Predicted concentrations in soil ranged from <0.01 (cerium dioxide) to around 4.3 mg/kg (nanolatex). Predictions were also obtained for concentrations of selected ENPs in the air compartment. If, in the future, all of the product types investigated contained engineered nanoparticles, then concentrations in water could range from < 1 ng/l (cerium dioxide) to 1 mg/l (nanolatex). The exposure data developed in this study provide a benchmark to a) inform the development of new analytical methodologies for environmental system, b) inform 8 the design of environmental fate studies; and c) interpret the significance of existing ecotoxicology data on ENPs. A comparison of the results of the exposure estimations with the available ecotoxicological data (Table E.1) is reassuring and indicates that even the conservative exposure concentrations generated in this study are many orders of magnitude lower than concentrations likely to cause acute effects in invertebrates, fish algae or sublethal effects on fish, invertebrates or bacteria. Whilst this study has identified the potential environmental exposure arising from a range of key ENP types, the assessment has been limited by the availability of data and knowledge. Work in the future should therefore focus on 1) establishing a detailed knowledge of the content and use of products containing ENPs in the UK; 2) developing an understanding of the factors and processes affecting the fate and transport of ENPs in the environment; 3) the development and evaluation of more complex exposure assessment models; and 4) the development of a better understanding of the ecotoxicity of ENPs under environmentally-relevant exposure situations.