title: Probabilistic modeling of the flows and environmental risks of nano-silica.
abstract: Nano-silica, the engineered nanomaterial with one of the largest production volumes, has a wide range of applications in consumer products and industry. This study aimed to quantify the exposure of nano-silica to the environment and to assess its risk to surface waters. Concentrations were calculated for four environmental (air, soil, surface water, sediments) and two technical compartments (wastewater, solid waste) for the EU and Switzerland using probabilistic material flow modeling. The corresponding median concentration in surface water is predicted to be 0.12 μg/l in the EU (0.053-3.3 μg/l, 15/85% quantiles). The concentrations in sediments in the complete sedimentation scenario were found to be the largest among all environmental compartments, with a median annual increase of 0.43 mg/kg · y in the EU (0.19-12 mg/kg · y, 15/85% quantiles). Moreover, probabilistic species sensitivity distributions (PSSD) were computed and the risk of nano-silica in surface waters was quantified by comparing the predicted environmental concentration (PEC) with the predicted no-effect concentration (PNEC) distribution, which was derived from the cumulative PSSD. This assessment suggests that nano-silica currently poses no risk to aquatic organisms in surface waters. Further investigations are needed to assess the risk of nano-silica in other environmental compartments, which is currently not possible due to a lack of ecotoxicological data.
authors.affiliation: Empa, Swiss Federal Laboratories for Materials Science and Technology, CH-9014 St. Gallen, Switzerland.
authors.forename: Yan
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Empa, Swiss Federal Laboratories for Materials Science and Technology, CH-9014 St. Gallen, Switzerland.
authors.forename: Anna
authors.initials: A
authors.lastname: Kalinina
authors.affiliation: Empa, Swiss Federal Laboratories for Materials Science and Technology, CH-9014 St. Gallen, Switzerland.
authors.forename: Tianyin
authors.initials: T
authors.lastname: Sun
authors.affiliation: Empa, Swiss Federal Laboratories for Materials Science and Technology, CH-9014 St. Gallen, Switzerland. Electronic address: nowack@empa.ch.
authors.forename: Bernd
authors.initials: B
authors.lastname: Nowack
mesh_terms: D004784:Environmental Monitoring / Q000379:methods*; D004785:Environmental Pollutants / Q000032:analysis*; D004787:Environmental Pollution / Q000706:statistics & numerical data*; D015233:Models, Statistical; D049329:Nanostructures / Q000032:analysis*; D018570:Risk Assessment; D012822:Silicon Dioxide / Q000032:analysis*; D013557:Switzerland; D014866:Waste Products / Q000706:statistics & numerical data
chemical_list: D004785:Environmental Pollutants; D014866:Waste Products; D012822:Silicon Dioxide
keywords: Engineered nanomaterial; Nanosilica; Predicted environmental concentration; Probabilistic species sensitivity; Risk assessment; Silicon dioxide