Rickard Arvidsson

Challenges in Exposure Modeling of Nanoparticles in Aquatic Environments

ABSTRACT Managing the potential environmental risks of nanoparticles requires methods to link nanoparticle properties with macro-scale risks. This study outlines challenges in exposure modeling of nanoparticles in aquatic environments, such as the role of natural organic matter, natural colloids, fractal dimensions of agglomerates, coatings and doping of particles, and uncertainties regarding nanoparticle emissions to aquatic environments. The pros and cons of the exposure indicators mass concentration, particle number concentration, and surface area are discussed. By applying colloid chemistry kinetic equations describing particle agglomeration and sedimentation for the case of titanium dioxide nanoparticles, a limited exposure assessment including some of the factors mentioned is conducted with particle number concentration as the exposure indicator. The results of the modeling indicate that sedimentation, shear flows, and settling are of less importance with regard to particle number based predicted environmental concentrations. The inflow of nanoparticles to the water compartment had a significant impact in the model, and the collision efficiency (which is affected by natural organic matter) was shown to greatly affect model output. Implications for exposure modeling, regulation, and science are discussed. A broad spectrum of scientific disciplines must be engaged in the development of exposure models where nano-level properties are linked to macro-scale risk.

Prospective Life Cycle Assessment of Graphene Production by Ultrasonication and Chemical Reduction

One promising future bulk application of graphene is as composite additive. Therefore, we compare two production routes for in-solution graphene using a cradle-to-gate lifecycle assessment focusing on potential differences in energy use, blue water footprint, human toxicity, and ecotoxicity. The data used for the assessment is based on information in scientific papers and patents. Considering the prospective nature of this study, environmental impacts from background systems such as energy production were not included. The production routes are either based on ultrasonication or chemical reduction. The results show that the ultrasonication route has lower energy and water use, but higher human and ecotoxicity impacts, compared to the chemical reduction route. However, a sensitivity analysis showed that solvent recovery in the ultrasonication process gives lower impacts for all included impact categories. The sensitivity analysis also showed that solvent recovery is important to lower the blue water footprint of the chemical reduction route as well. The results demonstrate the possibility to conduct a life cycle assessment study based mainly on information from patents and scientific articles, enabling prospective life cycle assessment studies of products at early stages of technological development.

Life Cycle Assessment of Cellulose Nanofibrils Production by Mechanical Treatment and Two Different Pretreatment Processes

Nanocellulose is a bionanomaterial with many promising applications, but high energy use in production has been described as a potential obstacle for future use. In fact, life cycle assessment studies have indicated high life cycle energy use for nanocellulose. In this study, we assess the cradle-to-gate environmental impacts of three production routes for a particular type of nanocellulose called cellulose nanofibrils (CNF) made from wood pulp. The three production routes are (1) the enzymatic production route, which includes an enzymatic pretreatment, (2) the carboxymethylation route, which includes a carboxymethylation pretreatment, and (3) one route without pretreatment, here called the no pretreatment route. The results show that CNF produced via the carboxymethylation route clearly has the highest environmental impacts due to large use of solvents made from crude oil. The enzymatic and no pretreatment routes both have lower environmental impacts, of similar magnitude. A sensitivity analysis showed that the no pretreatment route was sensitive to the electricity mix, and the carboxymethylation route to solvent recovery. When comparing the results to those of other carbon nanomaterials, it was shown that in particular CNF produced via the enzymatic and no pretreatment routes had comparatively low environmental impacts.

Review of Potential Environmental and Health Risks of the Nanomaterial Graphene

ABSTRACT Several future applications have been suggested for the nanomaterial graphene, and its production is increasing dramatically. This study is a review of risk-related information on graphene with the purpose of outlining potential environmental and health risks and guide future risk-related research. Available information is presented regarding emissions, environmental fate, and toxicity of graphene. The results from this study indicate that graphene could exert a considerable toxicity and that considerable emission of graphene from electronic devices and composites are possible in the future. It is also suggested that graphene is both persistent and hydrophobic. Although these results indicate that graphene may cause adverse environmental and health effects, the results foremost show that there are many risk-related knowledge gaps to be filled and that the emissions of graphene, the fate of graphene in the environment, and the toxicity of graphene should be further studied.

Impacts of a Silver-Coated Future Particle Flow Analysis of Silver Nanoparticles

Silver is a compound that is well known for its adverse environmental effects. More recently, silver in the form of silver nanoparticles (Ag NPs) has begun to be produced in increasingly larger amounts for antibacterial purposes in, for instance, textiles, wound dressings, and cosmetics. Several authors have highlighted the potential environmental impact of these NPs. To contribute to a risk assessment of Ag NPs, we apply a suggested method named “particle flow analysis” to estimating current emissions from society to the environment. In addition, we set up explorative scenarios to account for potential technology diffusion of selected Ag NP applications. The results are uncertain and need to be refined, but they indicate that emissions from all applications included may increase significantly in the future. Ag NPs in textiles and electronic circuitry may increase more than in wound dressings due to the limited consumption of wound dressings. Due to the dissipative nature of Ag NPs in textiles, the results indicate that they may cause the highest emissions in the future, thus partly confirming the woes of both scientists and environmental organizations. Gaps in current knowledge are identified. In particular, the fate of Ag NPs during different waste‐handling processes is outlined as an area that requires more research.

Facing complexity through informed simplifications: a research agenda for aquatic exposure assessment of nanoparticles

Exposure assessment of engineered nanoparticles (ENPs) is a challenging task mainly due to the novel properties of these new materials and the complexity caused by a wide range of particle characteristics, ENP-containing products and possible environmental interactions. We here present a research agenda in which we propose to face the complexity associated with ENP exposure assessment through informed and systematic simplifications. Exposure modelling is presented as a method for addressing complexity by identifying processes dominant for the fate of ENPs in the environment and enabling an iterative learning process by studying different emission and fate scenarios. Furthermore, the use of models is important to highlight most pressing research needs. For this reason, we also strongly encourage improved communication and collaboration between modellers and experimental scientists. Feedback between modellers and experimental scientists is crucial in order to understand the big picture of ENP exposure assessment and to establish common research strategies. Through joint research efforts and projects, the field of ENP exposure assessment can greatly improve and significantly contribute to a comprehensive and systematic risk assessment of ENPs.

Particle flow analysis. Exploring Potential Use Phase Emissions of Titanium Dioxide nanoparticles from Sunscreen, Paint and Cement

Several authors have highlighted the potential risks of nanoparticles (NPs). Still, little is known about the magnitude of emissions of NPs from society. Here, the method of explorative particle flow analysis (PFA), a modification of the more well‐known substance flow analysis (SFA), is suggested. In explorative PFA, particle number instead of mass is used as flow and stock metric and explorative scenarios are used to account for potential technology diffusion and, consequently, potentially higher emissions. The method has been applied in a case study of the use phase of titanium dioxide (TiO) NPs in paint, sunscreen and self‐cleaning cement. The results indicate that the current largest emissions of TiO NPs originate from the use of sunscreen. One scenario implies that, in the future, the largest flows and stocks of TiO NPs could be related to self‐cleaning cement. Gaps in current knowledge are identified and suggestions for future research are given.

A Probabilistic Model for Hydrokinetic Turbine Collision Risks: Exploring Impacts on Fish

A variety of hydrokinetic turbines are currently under development for power generation in rivers, tidal straits and ocean currents. Because some of these turbines are large, with rapidly moving rotor blades, the risk of collision with aquatic animals has been brought to attention. The behavior and fate of animals that approach such large hydrokinetic turbines have not yet been monitored at any detail. In this paper, we conduct a synthesis of the current knowledge and understanding of hydrokinetic turbine collision risks. The outcome is a generic fault tree based probabilistic model suitable for estimating population-level ecological risks. New video-based data on fish behavior in strong currents are provided and models describing fish avoidance behaviors are presented. The findings indicate low risk for small-sized fish. However, at large turbines (≥5 m), bigger fish seem to have high probability of collision, mostly because rotor detection and avoidance is difficult in low visibility. Risks can therefore be substantial for vulnerable populations of large-sized fish, which thrive in strong currents. The suggested collision risk model can be applied to different turbine designs and at a variety of locations as basis for case-specific risk assessments. The structure of the model facilitates successive model validation, refinement and application to other organism groups such as marine mammals.

On the scientific justification of the use of working hours, child labour and property rights in social life cycle assessment: three topical reviews

PurposeWorking hours, child labour and property rights have been suggested as topics to assess in social life cycle assessment (SLCA). The purpose of this study is to investigate the scientific justification of the current use of these topics. The long-term aim is to contribute to the future development of SLCA.MethodsA literature review was conducted for each of the three topics. One thousand scientific articles were analysed for each topic, and relevant articles were selected. The articles were analysed based on whether the topics facilitated or obstructed beneficial social values, and whether they facilitated or obstructed adverse social values.Results and discussionThe results show that the three topics both facilitate and obstruct beneficial social values. They also show that the topics both facilitate and obstruct adverse social values. Considering the complex and ambiguous nature of these topics reported in the scientific literature, the current use of these topics in the SLCA literature is found not to be completely scientifically justified.ConclusionsBased on this study, the current use of working hours, child labour and property rights in SLCA studies should be questioned. We suggest that the fields of social science and economics may be fruitfully considered when seeking scientific justification for topics to assess in SLCA.

Controversy over antibacterial silver: implications for environmental and sustainability assessments

Abstract The potential risks and benefits of using silver, especially nanosilver, as an antibacterial agent in consumer and healthcare products are under debate globally. Using content analysis of texts from newspaper and TV, government agencies, municipalities, government and parliament, non-governmental organizations, and companies, we analyze the argumentation in the Swedish public controversy over antibacterial silver and relate the findings to environmental and sustainability assessments. We conclude that silver is regarded as either beneficial or harmful in relation to four main values: the environment, health, sewage treatment, and product effectiveness. Various arguments are used to support positive and negative evaluations of silver, revealing several contradictory reasons for considering silver beneficial or harmful. Current environmental and sustainability assessments (i.e. substance flow analysis, risk analysis, multi-criteria analysis, and lifecycle assessment) cover many of the concerns raised in the public controversy over antibacterial silver and can therefore inform the debate regarding its toxicity, emissions, and environmental impact. However, not all concerns raised in the public controversy are covered by current environmental and sustainability assessments, most notably, concerns over public health and bacterial resistance issues are not paid full attention. For future environmental and sustainability assessments to make an even more significant societal contribution and to inform consumers and decision-makers about concerns articulated in the public debate, a wider range of issues concerning antibacterial silver needs to be considered through a unified framework.