Das Buch stellt einen Zugang zu Lernprozessen und -gelegenheiten vor. In Fallanalysen aus dem Politikunterricht wird dieser Ansatz exemplarisch dargestellt und untersucht. In der vorliegenden Arbeit wird ein konstruktivistisch-systemtheoretischer Zugang zu Lernprozessen und -gelegenheiten entwickelt, der theoretisch auf den Arbeiten Piagets und Luhmanns fußt und sich normativ an den Prämissen der Bildungsgangforschung orientiert. In der Fallanalyse einer Interaktionssequenz aus dem Politikunterricht einer achten Gesamtschulklasse findet dieser neue Ansatz seine Anwendung, und verfolgt die fachdidaktische Fragestellung, unter welchen unterrichtlichen Bedingungen die Identitätsarbeit Jugendlicher, die Progression ihrer politischen Urteilskompetenz und die Gewinnung tiefer Einsichten in die Prinzipien, Strukturen und Verfahren einer Demokratie in Einklang gebracht werden können.
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AbstractSynthetic polymers are chemicals of emerging concern for the environment, which is mainly attributed to their persistence in environmental compartments. On the other hand, polymers exist in nature as well. They are regarded of no concern for the environment. The present article focusses on the environmental fate of natural polymers and the implications on the persistence assessment for synthetic polymers. Natural polymers vary widely in structure, function, and properties. Crystallinity, wettability and surface area are important influencing factors on the (bio)degradation kinetics. Chemical and enzymatic hydrolysis is the most important process for the degradation of natural polymers, which for particulate material takes place either by bulk or surface erosion. Some natural polymers are degraded rapidly, but in other cases, degradation of natural polymers takes very long until complete mineralization. These differences in biodegradability are a result of evolution as they have to fulfil specific functions in nature which might require a certain persistency. Consequently, many natural polymers would have to be considered persistent or very persistent (P or vP) based on the available studies using the standard assessment approach. At the same time, they are considered no concern to the environment for good reasons. The analysis emphasizes that mineralization alone is not a resilient persistence endpoint for polymers. This needs to be recognized when assessing synthetic polymers, many of which would fulfil the existing P/vP criteria as well. For such synthetic polymers, it would be important to establish meaningful endpoints and polymer specific criteria to enable an adequate persistence assessment using a weight-of-evidence approach.
Differenz erleben -Gesellschaft gestalten -- Inhalt -- Eine Einleitung in den Band -- Grundkonzepte und Spannungsfelder demokratischer Erziehung in der Schule -- Demokratiepädagogik und interkulturelle Bildung -- Schüler/-innenpartizipation - Kritische Perspektiven -- Schüler/-innenpartizipation in der Grundschule -- Schüler/-innenpartizipation in der Oberstufe -- Schüler/-innenpartizipation in Schulentwicklungsprozessen -- Demokratielernen in Projekten -- Ästhetische Bildung und Demokratiepädagogik -- Partizipative Schulraumgestaltung
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Background Replacing hazardous chemicals with safer alternatives is essential for a toxic-free environment. To avoid regrettable substitution, a comparison of the entire spectrum of potential impacts of the candidate for substitution with those of the available alternatives is required. A particular challenge is to also capture yet unknown long-term impacts of (very) persistent chemicals, including but not limited to PBT and CMR properties.
Results For a flexible and transparent comparative ranking of the impact potential of chemical alternatives, we propose a concern-based scoring scheme (Scoring scheme for Comparative Ranking of chemical Alternatives, SCoRA). The approach accounts for hazards due to ecotoxicity in water/sediment and soil, and effects on human health such as CMR properties and endocrine disruption. This is combined with exposure-related information in terms of expected environmental pollution stock levels. The SCoRA approach is illustrated with case study chemicals of very high concern (15 SVHC, mostly PBT, representing different chemical classes with different modes of bioaccumulation and toxicity). A comparison of PBT substances reveals that SCoRA goes well beyond binary screening criteria (PBT: yes/no), showing that PBT substances are all of very high concern, although their impact profiles can be substantially different. Ordinal scores support a detailed characterisation of their potential for long-term impacts. Furthermore, SCoRA enables a coherent comparative assessment of substances with different primary concerns, for example PBTness and endocrine disruption.
Conclusions SCoRA complements existing and established tools such as comparative risk assessment. It is particularly useful, when, for example, only limited data are available or when risk assessment is not feasible, as in the case of persistent chemicals. A strength of SCoRA is that the relative contributions of the impact components determining the concern can be visualised with a heatmap and fingerprints. This facilitates communication among scientists, regulators, risk managers, stakeholders and the public.
Abstract Sprays are used in workplace as well as in consumer environments. Although spraying has several advantages such as uniform distribution of substances on surfaces in a highly efficient manner it is often prone to high inhalation burden which has to be quantified for adequate risk assessments. There are occupational exposure models with different degree of complexity available that are applied for spray applications. In the presentation we report on an effort to create an overall model for estimating inhalation exposure caused by spray applications by re-analyzing, refining and integrating three already existing models into a 2-level tiered approach. The single models used in this context are a 1- and 2-box mass balance model (Tier 1), Spray Expo and a newly developed binary system model (Tier 2). The Tier 1 level models are used for an initial assessment generally designed to deliver conservative results. Only if product safety cannot be derived from these results higher level models are used which are expected to generate results with a lower degree of conservatism. These higher level models are based on the solution of transport equation in space and time for the ingredients, taking into account the complex evaporation kinetics of interacting binary systems and consider the relevant sources in the spraying and post-spraying phase such as evaporation from droplets and treated surfaces. The presentation will contain the description of the overall model, results on plausibility and sensitivity, and the comparison with measured data.
AbstractDisinfectants and preservatives used as biocides may contain or release active substances (a.s.) that can form by-products with the surrounding matrices during their application which may be released into the environment. Over the past 40 years, several hundred of these so-called disinfection by-products (DBPs) have been detected after applications of biocides used for disinfection. Due to intensive research and further development of analytical capabilities, many new DBP classes, such as iodinated DBPs (I-DBPs), halonitromethanes (HNMs), haloacetamides (HaAms), or halomethanesulfonic acids were detected worldwide in various matrices and applications. Due to the possible hazards and risks for humans and the environment, frequently occurring DBP classes, such as trihalomethanes (THM), haloacetic acids (HAA) and nitrosamines (NDMA), have already been included in many legislations and given limit values. In the European Union, biocides are assessed under the Biocidal Products Regulation 528/2012 (BPR) regarding their efficacy, potential hazards, and risks to human health and the environment. However, the available guidance for the environmental risk assessment (ERA) of DBPs remains vague. To identify knowledge gaps and to further develop the assessment scheme for the ERA of DBPs, a literature search on the multiple uses of biocides and their formation potential of DBPs was performed and the existing process for ERA was evaluated. The results show knowledge gaps on the formation of DBP in non-aqueous systems and DBP formation by non-halogen-based biocidal active substances. Based on the literature research on biocides, a possible proposal of grouping a.s. to consider their DBP formation potential is presented to simplify future ERAs. However, this also requires further research. Until then, a pragmatic approach considering the DBPs formation potential of the active substances and the identified knowledge gaps need to be established for the environmental risk assessment of DBPs in the EU. Graphical Abstract
In the first part of the project, a compilation of data on disinfection by-products (DBPs) as well as the biocidal active substances from product types (PTs) 1-5, 11 and 12 that are approved within the EU or within the approval process were compiled. The data on the DBPs resulted from a literature search in which 272 DBPs were identified. In addition to the substance data, the active substances used and the matrix treated were recorded in the tabular summary. A strong bias of the scientific literature on the investigation of highly reactive, especially chlorinating active substances in aqueous solution was determined. The list of biocidal active substances was compiled from the ECHA database (as of July 2019). A categorization of the biocidal active substances was developed and the DBP formation potential of each active ingredient was evaluated on the basis of this categorization. In a modeling approach, the distribution of selected DBPs and biocidal active substances in the water and air compartments for applications in solution and on surfaces and the distribution in water and sewage sludge in a sewage treatment plant was estimated. In most cases, there were significant differences between the distributions of the DBPs and the active ingredients. The formation of approximately 60 DBPs was investigated in laboratory simulations of disinfection applications in solution and on surfaces with different active substances. In addition, samples from real disinfection applications were analyzed. Based on the project results, the current procedure for risk assessment of the DBPs was analyzed in the last project phase and proposals for modifications were discussed, which aim to simplify and harmonize the risk assessment of the DBPs within the EU.
