Prospective nanomaterial mass flows to the environment by life cycle stage from five applications containing CuO, DPP, FeOx, CNT and SiO2

Many new nanoapplications containing engineered nanomaterials (ENM) are introduced to the market every year. Because they have the potential to release ENM to the environment during their life cycle, it is desirable to investigate the amounts of ENM that could be emitted to the environment before they occur. In this research, we created ENM mass consumption scenarios and modelled prospectively the ENM mass flows produced at each life cycle stage of five nano-enhanced applications, using a probabilistic material flow analysis method and a bottom-up approach. The nanoapplications are: (i) wood coating containing CuO; (ii) car bumper with DPP (organic pigment) or (iii) Fe₂O₃ (inorganic pigment); (iv) polymeric car part with CNT; and (v) pancake mixture with SiO₂. The simulated flows were used to (a) describe the potential ENM mass flows in Europe and to determine the distribution of the mass at the end of each LC stage among the technical and environmental compartments analyzed; (b) to compare the flows produced by single applications with the total flows from all existing applications; (c) to estimate the release concentrations in environmental compartments; and (d) to evaluate the origin of the flows by LC stage. The total flows were taken from previously published research or newly modelled in the case of CuO and DPP. The results show that most ENM mass flows from each single application occurred during their end-of-life stage and the main receiving compartments were the landfill (except pancake mixture application) or the agricultural soils and sediments (only pancake mixture). In general, a substantial proportion of the ENMs was either eliminated or transferred to recycling facilities, from where the recovered material fractions containing ENMs could be used as secondary raw materials. The comparison with the total flows shows that only the wood coating would result in a considerable increase of the ENM mass flows to the environment, given the market penetration assumed (1%). The use of the pancake mixture would produce the highest flows into the environment among the different ENMs analyzed, as a consequence of the high direct release during its end-of-life. The assessment by LC stage allowed to stress the role of manufacturing in dominating the flows into the environment for some applications. In general, our assessment shows the potential of the existing material flow modeling methods to investigate prospectively the emissions of ENM mass into the environment from specific applications.