Cause-and-Effect Analysis as a Tool To Improve the Reproducibility of Nanobioassays: Four Case Studies.

One of the challenges in using in vitro data to understand the potential risks of engineered nanomaterials (ENMs) is that results often differ or are even contradictory among studies. While it is recognized that numerous factors can influence results produced by nanobioassays, there has not yet been a consistently used conceptual framework to identify key sources of variability in these assays. In this paper, we use cause-and-effect analysis to systematically describe sources of variability in four key in vitro nanobioassays: the 2',7'-dichlorofluorescein assay, an enzyme-linked immunosorbent assay for measuring interleukin-8, a flow cytometry assay (Annexin V/propidium iodide), and the Comet assay. These assays measure end points that can occur in cells impacted by ENMs through oxidative stress, a principle mechanism for ENM toxicity. The results from this analysis identify control measurements to test for potential artifacts or biases that could occur during conduct of these assays with ENMs. Cause-and-effect analysis also reveals additional measurements that could be performed either in preliminary experiments or each time the assay is run to increase confidence in the assay results and their reproducibility within and among laboratories. The approach applied here with these four assays can be used to support the development of a broad range of nanobioassays.

Comparative Human Health Impact Assessment of Engineered Nanomaterials in the Framework of Life Cycle Assessment.

For safe innovation, knowledge on potential human health impacts is essential. Ideally, these impacts are considered within a larger life-cycle-based context to support sustainable development of new applications and products. A methodological framework that accounts for human health impacts caused by inhalation of engineered nanomaterials (ENMs) in an indoor air environment has been previously developed. The objectives of this study are as follows: (i) evaluate the feasibility of applying the CF framework for NP exposure in the workplace based on currently available data; and (ii) supplement any resulting knowledge gaps with methods and data from the life cycle approach and human risk assessment (LICARA) project to develop a modified case-specific version of the framework that will enable near-term inclusion of NP human health impacts in life cycle assessment (LCA) using a case study involving nanoscale titanium dioxide (nanoTiO2 ). The intent is to enhance typical LCA with elements of regulatory risk assessment, including its more detailed measure of uncertainty. The proof-of-principle demonstration of the framework highlighted the lack of available data for both the workplace emissions and human health effects of ENMs that is needed to calculate generalizable characterization factors using common human health impact assessment practices in LCA. The alternative approach of using intake fractions derived from workplace air concentration measurements and effect factors based on best-available toxicity data supported the current case-by-case approach for assessing the human health life cycle impacts of ENMs. Ultimately, the proposed framework and calculations demonstrate the potential utility of integrating elements of risk assessment with LCA for ENMs once the data are available.

Sameness: The regulatory crux with nanomaterial identity and grouping schemes for hazard assessment.

Regulators and industry need clear rules for identification and grouping of nanomaterials for a streamlined quantitative hazard evaluation. Therefore, we provide convincing reasons for (i) why to introduce pragmatic definition of identities for nanomaterials, (ii) how to combine them into entities, and ultimately (iii) how the entities might be evaluated with testing strategies based on clouds of similar nanomaterials.

Scientific Basis for Regulatory Decision-Making of Nanomaterials Report on the Workshop, 20-21 January 2014, Center of Applied Ecotoxicology, Dübendorf.

The key findings of a workshop jointly organized by the Swiss Centre of Applied Ecotoxicity, the Swiss Centre for Applied Human Toxicology (SCAHT), and the Federal Office of Public Health (FOPH) are summarized and provide a critical analysis of the current regulatory framework for nanomaterials and a snapshot of some hot topics in nanoscience.

Scientific Basis for Regulatory Decision-Making of Nanomaterials Report on the Workshop, 20-21 January 2014, Center of Applied Ecotoxicology, Dübendorf.

The key findings of a workshop jointly organized by the Swiss Centre of Applied Ecotoxicity, the Swiss Centre for Applied Human Toxicology (SCAHT), and the Federal Office of Public Health (FOPH) are summarized and provide a critical analysis of the current regulatory framework for nanomaterials and a snapshot of some hot topics in nanoscience.

Indoor exposure to toluene from printed matter matters: complementary views from life cycle assessment and risk assessment.

A pronounced presence of toluene from rotogravure printed matter has been frequently observed indoors. However, its consequences to human health in the life cycle of magazines are poorly known. Therefore, we quantified human-health risks in indoor environments with Risk Assessment (RA) and impacts relative to the total impact of toxic releases occurring in the life cycle of a magazine with Life Cycle Assessment (LCA). We used a one-box indoor model to estimate toluene concentrations in printing facilities, newsstands, and residences in a best, average, and worst-case scenario. The modeled concentrations are in the range of the values measured in on-site campaigns. Toluene concentrations can be close or even surpass the occupational legal thresholds in printing facilities in realistic worst-case scenarios. The concentrations in homes can surpass the US EPA reference dose (69 µg/kg/day) in worst-case scenarios, but are still at least 1 order of magnitude lower than in press rooms or newsstands. However, toluene inhaled at home becomes the dominant contribution to the total potential human toxicity impacts of toluene from printed matter when assessed with LCA, using the USEtox method complemented with indoor characterization factors for toluene. The significant contribution (44%) of toluene exposure in production, retail, and use in households, to the total life cycle impact of a magazine in the category of human toxicity, demonstrates that the indoor compartment requires particular attention in LCA. While RA works with threshold levels, LCA assumes that every toxic emission causes an incremental change to the total impact. Here, the combination of the two paradigms provides valuable information on the life cycle stages of printed matter.

Prospective environmental life cycle assessment of nanosilver T-shirts.

A cradle-to-grave life cycle assessment (LCA) is performed to compare nanosilver T-shirts with conventional T-shirts with and without biocidal treatment. For nanosilver production and textile incorporation, we investigate two processes: flame spray pyrolysis (FSP) and plasma polymerization with silver co-sputtering (PlaSpu). Prospective environmental impacts due to increased nanosilver T-shirt commercialization are estimated with six scenarios. Results show significant differences in environmental burdens between nanoparticle production technologies: The "cradle-to-gate" climate footprint of the production of a nanosilver T-shirt is 2.70 kg of CO(2)-equiv (FSP) and 7.67-166 kg of CO(2)-equiv (PlaSpu, varying maturity stages). Production of conventional T-shirts with and without the biocide triclosan has emissions of 2.55 kg of CO(2)-equiv (contribution from triclosan insignificant). Consumer behavior considerably affects the environmental impacts during the use phase. Lower washing frequencies can compensate for the increased climate footprint of FSP nanosilver T-shirt production. The toxic releases from washing and disposal in the life cycle of T-shirts appear to be of minor relevance. By contrast, the production phase may be rather significant due to toxic silver emissions at the mining site if high silver quantities are required.

Life cycle assessment of engineered nanomaterials: state of the art and strategies to overcome existing gaps.

The use of engineered nanomaterials offers advantages as well as disadvantages from a sustainability perspective. It is important to identify such points as early as possible in order to be able to build on existing strengths, while counteracting disadvantages. Life Cycle Assessment (LCA) is a suitable method to assess the environmental performance of a product or process. But so far studies applying LCA to the area of nanotechnology have been scarce. One reason might be that the LCA framework has a whole list of issues that need further precision in order to be applicable to nanotechnologies: system boundaries and a functional unit have to be chosen in a way that allows one to do a comparison of equal functionalities; adequate and comprehensive life cycle inventory data for engineered nanomaterials are the key on the level of inventory analysis; and the impact assessment step requires a clear definition of the degree of detail on the level of nanoparticle emissions. The LCA studies existing thus far in the area of nanotechnology have barely begun to cover all these aspects. Thus, in order to improve the current situation, the authors propose to go ahead in each of the LCA stages as far as scientific advances allow. For the inventory modelling this means e.g. that comprehensive, transparently documented and quality ensured data of the most important engineered nanomaterials should be collected and made available in a widely-accepted format. Concerning nanoparticle emissions, as many parameters as possible have to be collected pertaining to the production, use, and the disposal phase of these engineered nanomaterials. Furthermore, on the level of impact assessment, relevant physical characteristics have to be identified for a toxicity assessment of nanoparticles and a consensus has to be found for a limited but sufficient number of independent parameters influencing toxicity to be collected.

Exposure to engineered nanoparticles: Model and measurements for accident situations in laboratories.

In the life cycle of engineered nanoparticles (ENP), their manufacturing requires particular attention because of unwanted potential ENP emissions to workplaces. We simulated three scenarios of equipment failure during gas phase production of nanoparticles in a laboratory. The emission plume of nanoparticles was tracked with high spatial and temporal resolution by 10 measurement devices. While under normal production conditions, no elevated ENP concentrations were observed, worst case scenarios led to homogeneous indoor ENP concentrations of up to 10(6)cm(-3) in a 300m(3) production room after only 60s. The fast dispersal in the room was followed by an exponential decrease in number concentration after the emission event. Under conditions like those observed - rapid dispersal and good mixing - a single measurement device alone can provide valuable information for an ENP exposure assessment. A one-box model adequately reflected measured number concentrations (r(2)>0.99). The ENP emission rates to the workplace were estimated between 2.5·10(11) and 6·10(12)s(-1) for the three emission scenarios. The worst case emission rate at the production zone was also estimated at 2·10(13)s(-1) with a stoichiometric calculation based on the precursor input, density and particle size. ENP intake fractions were 3.8-5.1·10(-4) inhaled ENP per produced ENP in the investigated setting. These could only be substantially lowered by leaving the production room within a few minutes after the emission event.

Persistence of engineered nanoparticles in a municipal solid-waste incineration plant.

More than 100 million tonnes of municipal solid waste are incinerated worldwide every year. However, little is known about the fate of nanomaterials during incineration, even though the presence of engineered nanoparticles in waste is expected to grow. Here, we show that cerium oxide nanoparticles introduced into a full-scale waste incineration plant bind loosely to solid residues from the combustion process and can be efficiently removed from flue gas using current filter technology. The nanoparticles were introduced either directly onto the waste before incineration or into the gas stream exiting the furnace of an incinerator that processes 200,000 tonnes of waste per year. Nanoparticles that attached to the surface of the solid residues did not become a fixed part of the residues and did not demonstrate any physical or chemical changes. Our observations show that although it is possible to incinerate waste without releasing nanoparticles into the atmosphere, the residues to which they bind eventually end up in landfills or recovered raw materials, confirming that there is a clear environmental need to develop degradable nanoparticles.