1,721,088 research outputs found
Framework for human health characterization factor calculation of tio2 nanoparticles
No full textThe widespread use of engineered nanoparticles (ENPs) in various industrial applications is leading inevitably to releases of these materials into the environment, increasing like this human and environmental exposure to these substances, and is getting consequently more and more a concern regarding their potential adverse effects on both, the environment and the human health. In this context, Life Cycle Assessment (LCA) is recognized as one of the key methods for the assessment of the environmental performance of products containing such ENPs. However, so far, factors to assess releases of ENPs into the environment have been still completely missing, making all LCA studies of such materials incomplete. For this, a clear toxicological characterization of the effects is a prerequisite in order to establish trustworthy characterization factor (CFs) for release of nanoparticles into the environment. Humans could potentially be exposed to ENPs releases along the whole life cycle (i.e. during manufacture, handling, use and disposal treatment of ENPs). Therefore, this work aims to provide a methodological framework for establishing human health CFs for releases of ENPs, using titanium dioxide nanoparticles (TiO2-NPs) as an exemplary example. Starting point for this is USEtox, the internationally recognized consensus model for the assessment of toxicity within LCA studies. USEtox calculates the impact on human toxicity as product of emission, intake fractions (iF) and effect factors (EF). The intake fraction is originally defined as ratio of the mass intake by an individual over the mass released to the environment. The effect factor on the other hand contemplates the change in life time disease probability due to change in life time intake of a pollutant. Both effects, i.e. carcinogens and non-carcinogens, are taken into account in the calculation of the actual EF:
• the EF for carcinogens effects is determined based on a benchmark dose used by the National Institute for Occupational Safety and Health (NIOSH) to determinate the recommended occupational exposure limit (REL) for TiO2-NPs;
• the EF for non-carcinogens effects is calculated based on NOAEL (no-observed adverse effect level) and LOAEL (lowest observed adverse effect level) values.
Limiting the examinations here on releases to air as only investigated compartment, a one-box model using steady-state conditions and direct human exposure can be applied for the calculation of the intake fractions. Here, intake fractions for indoor and outdoor conditions have been calculated for TiO2-NPs. While indoor iF, a complete mixing for the volume and the indoor volume per workers for the Chemical industry in Switzerland have been evaluated. For the outdoor iF, the fate factor matrix has been calculated by applying the SimpleBox4Nano (SB4N) multimedia modelling developed by Meesters and co-author. Thanks to this model it is possible to obtain transport and removal rates constants for ENPs in and across air, rain, surface water, soil and sediment compartments, taking into account various input parameters (i.e. radius, mass density, aggregation and attachement efficiency of TiO2-NPs) and systemic dimensions (area, height and volume for each compartments). Again, based on the study by Mueller and Nowack, the scenario is focusing on Switzerland as geographical area
Life Cycle Assessment of building nanomaterials: indoor and outdoor issues
No full textNanomaterials are currently being considered for using in modern technology, with a vast range of applications, such as in medicine, electronics, building materials, commercial products and energy production. On the other hand, there is a serious lack of information concerning the toxicity and environmental impact of nanomaterials. Nanotitania is widely used in building sector since it is well known its photocatalytic properties, which decomposes air pollutants as nitrogen oxides (NOx) and volatile organic compounds (VOCs). LCA is an established method to assess potential impacts to the natural environment and on human health, along the whole life cycle [1]. Moreover, LCA has been recognized as a key tool for assessing the environmental performance of nanoproducts [2]. Four LCA case studies on building materials functionalized with nanoTiO2 (resin, glass, glaze and tile) have been conducted in order to identify the life cycle steps where the nanoparticle release mainly occurs. Outdoor installations have been considered for all building materials excluding resin case study, where indoor application has been assessed. A preliminary evaluation of the potential damage on human health and environment caused by released nanoTiO2, during the life cycle stages, has been calculated. The outcomes showed that the phases mainly affected by nanoTiO2 releases are: nanocoating application, maintenance operations and end of life steps. In collaboration with Empa, Swiss Federal Laboratories for Materials Science and Technology, a framework to evaluate the characterization factor for human indoor exposure using USEtox modelling has been develope
Human health characterization factors of nano-TiO2 for indoor and outdoor environments
No full textThe increasing use of engineered nanomaterials (ENMs) in industrial applications and consumer products is leading to an inevitable release of these materials into the environment. This makes it necessary to assess the potential risks that these new materials pose to human health and the environment. Life cycle assessment (LCA) methodology has been recognized as a key tool for assessing the environmental performance of nanoproducts. Until now, the impacts of ENMs could not be included in LCA studies due to a lack of characterization factors (CFs). This paper provides a methodological framework for identifying human health CFs for ENMs. Methods: The USEtoxTM model was used to identify CFs for assessing the potential carcinogenic and non-carcinogenic effects on human health caused by ENM emissions in both indoor (occupational settings) and outdoor environments. Nano-titanium dioxide (nano-TiO2) was selected for defining the CFs in this study, as it is one of the most commonly used ENMs. For the carcinogenic effect assessment, a conservative approach was adopted; indeed, a critical dose estimate for pulmonary inflammation was assumed. Results and discussion: We propose CFs for nano-TiO2 from 5.5E−09 to 1.43E−02 cases/kgemitted for both indoor and outdoor environments and for carcinogenic and non-carcinogenic effects. Conclusions: These human health CFs for nano-TiO2 are an important step toward the comprehensive application of LCA methodology in the field of nanomaterial technology
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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