1,480 research outputs found
Environmental contamination and human exposure to PFASs near a fluorochemical production plant: Review of historic and current PFOA and GenX contamination in the Netherlands
Fluorochemical production plants (FPP) are primary emission sources of per- and polyfluoroalkyl substances (PFASs) to the local environment. An FPP located in the Netherlands has historically used perfluorooctanoic acid (PFOA) for fluoropolymer production and is currently using GenX (HFPO-DA; 2,3,3,3-tetrafluoro-2-(heptafluoropropoxy)propionic acid) as a replacement. This study reviewed existing data from open access reports and peer reviewed publications on the environmental presence of PFOA and GenX in environmental matrices such as surface water, groundwater, soil and vegetation. Published data on human exposure to PFOA and GenX (i.e. via drinking water and food as well as blood monitoring) were reviewed in order to assess the influence of the FPP on contamination of the local population. Concentrations in environmental and human exposure samples were compared to (inter)national quality standards or risk limits. The data showed higher PFOA and GenX concentrations in surface water, groundwater, soil and vegetation samples taken close to point sources, and the highest observed concentrations exceeded these standards and limits (except for PFOA in soil). Drinking water and food also contained higher PFOA and GenX concentrations in samples taken close to point sources compared to samples further away. Tolerable daily intake (TDIs) for both PFASs were exceeded, however, only in a maximum exposure scenario. Blood monitoring of the local population near the FPP, and FPP workers, confirmed high exposure can occur as blood concentrations of several individuals exceeded the safe level. This paper provides a comprehensive overview on PFOA and GenX contamination close to point sources in the Netherlands.</p
Letter to the editor: Comments on ‘A six-weekly dosing schedule for pembrolizumab in patients with cancer based on evaluation using modelling and simulation’
Combatting the rising costs of cancer drugs; interventions from a university hospital’s perspective
Rapid increase in cost continues to have negative impact on patients’ accessibility to life-changing anticancer medications. Moreover, the rising cost does not equate to similar increase in medication effectiveness. We recognise our responsibility as a university hospital to tackle this imbalance and strive to provide high quality, sustainable, affordable and accessible care. An active approach in cost containment of expensive and innovative cancer drugs was adopted in our organisation to safeguard accessibility and improve quality of life for patients. In this article, we described four inverventions: 1) identify right patient and minimise overtreatment, 2) in-house medicine production for selected indications, 3) minimise medicine spillages and 4) effective procurement strategies. We call on other hospitals to take action and, favourably, to collaborate on a European level. Together, we will safeguard the current and future care of our patients.</p
Effects of Concurrent Continuous Visual Feedback on Learning the Lane Keeping Task
This study investigated the training effectiveness of continuous visual feedback in a simulator-based lane keeping task. Two groups of student drivers (total of 30 participants) were instructed to drive as accurately as possible in the center of the right lane in a self-paced driving task during five 8-min sessions. One group received visual feedback using a horizontal compensatory display positioned on the dashboard, which provided an indication of the momentary distance to the lane center during the three training sessions. During two retention sessions (immediate and one day delayed) both groups drove without the augmented feedback. The augmented feedback resulted in improved performance on a measure lane keeping accuracy, but this effect disappeared during retention. Furthermore, the augmented feedback resulted in increased steering wheel activity during all sessions, and increased driver workload in the delayed retention session. These results provide support for the guidance hypothesis and have possible implications for the use of continuous concurrent feedback in simulatorbased driver training
Parikh's Theorem: A simple and direct automaton construction
Parikh's theorem states that the Parikh image of a context-free language is
semilinear or, equivalently, that every context-free language has the same
Parikh image as some regular language. We present a very simple construction
that, given a context-free grammar, produces a finite automaton recognizing
such a regular language.Comment: 12 pages, 3 figure
Legacy and Emerging Persistent Organic Pollutants in Antarctic Benthic Invertebrates near Rothera Point, Western Antarctic Peninsula
The levels of pollutants in polar regions is gaining progressively more attention from the science community. This is especially so for pollutants that persist in the environment and can reach polar latitudes via a wide range of routes, such as persistent organic pollutants (POPs). In this study samples of Antarctic marine benthic organisms were analysed for legacy and emerging POPs to comprehensively assess the current POPs concentrations in Antarctic benthos and infer the potential sources of the pollutants. Specimens of 5 different benthic invertebrate species were collected in 2 distinct locations near the Rothera Research station (67°35'8"S and 68°7'59"W). Any impact of the nearby Rothera Station as a local source of pollution appeared to be negligible. The most abundant chemicals detected were HCB and BDE-209, reaching the highest concentrations in limpets and urchins, followed by sea stars, ascidians and sea cucumbers. The relative congener patterns of PCBs and PBDEs were almost the same in all species. Some chemicals (e.g. Heptachlor, Oxychlordane and Mirex) were detected in the Antarctic invertebrates for the first time. Statistical methods revealed that the distribution of the POPs is not only driven by the feeding traits of the species, but also by the physico-chemical properties of the individual compounds. Benthic invertebrates are excellent indicators of the contaminant patterns of inshore Antarctic ecosystems
Review of analytical approaches for the identification of non-intentionally added substances in paper and board food contact materials
Background: Food contact materials (FCM) may contain non-intentionally added substances (NIAS) as a result of reaction by-products, oligomers, degradation processes, chemical reactions between packaging materials and foodstuff, or as impurities from the raw materials used for their production. Scope and approach: In this review, current approaches for the detection and identification of NIAS from paper and board FCM are presented. Reviewed are the definition of NIAS, approaches for NIAS identification and quantification, the comprehensive analysis of NIAS and the role of in silico tools and bioassays. Key Findings and Conclusions: NIAS in paper and board are mostly components from printing inks, adhesives, sizing agents and surface coatings. Recycled paper contains overall more NIAS than fresh paper. Targeted analysis is generally performed for predicted NIAS, whereas an untargeted, or full-scan screening method is applied to detect and identify unpredicted NIAS. Sample preparation and contact conditions fall in two categories; migration and extraction. Migration studies are performed with food simulants while extraction studies are Soxhlet or ultrasound assisted solvent extraction. In untargeted analysis in silico tools are gaining importance in the identification of NIAS. Bioassays are used to determine the bioactivity of extracts or fractions in order to assess the potential toxicity of NIAS present in the mixture. A combination of bioassays and chemical analysis is used to direct the identification of unknown bioactive NIAS in complex mixtures like those from paper and board FCM. However, future research is required into the selection of bioassays since these should not only be sensitive enough for detecting all compounds of concern but should also have a relevance with human health.</p
Letter to the editor: Comments on ‘A six-weekly dosing schedule for pembrolizumab in patients with cancer based on evaluation using modelling and simulation’
Perfluoroalkyl and Polyfluoroalkyl Substances in the Environment: Terminology, Classification, and Origins
The primary aim of this article is to provide an overview of perfluoroalkyl and polyfluoroalkyl substances (PFASs) detected in the environment, wildlife, and humans, and recommend clear, specific, and descriptive terminology, names, and acronyms for PFASs. The overarching objective is to unify and harmonize communication on PFASs by offering terminology for use by the global scientific, regulatory, and industrial communities. A particular emphasis is placed on long-chain perfluoroalkyl acids, substances related to the long-chain perfluoroalkyl acids, and substances intended as alternatives to the use of the long-chain perfluoroalkyl acids or their precursors. First, we define PFASs, classify them into various families, and recommend a pragmatic set of common names and acronyms for both the families and their individual members. Terminology related to fluorinated polymers is an important aspect of our classification. Second, we provide a brief description of the 2 main production processes, electrochemical fluorination and telomerization, used for introducing perfluoroalkyl moieties into organic compounds, and we specify the types of byproducts (isomers and homologues) likely to arise in these processes. Third, we show how the principal families of PFASs are interrelated as industrial, environmental, or metabolic precursors or transformation products of one another. We pay particular attention to those PFASs that have the potential to be converted, by abiotic or biotic environmental processes or by human metabolism, into long-chain perfluoroalkyl carboxylic or sulfonic acids, which are currently the focus of regulatory action. The Supplemental Data lists 42 families and subfamilies of PFASs and 268 selected individual compounds, providing recommended names and acronyms, and structural formulas, as well as Chemical Abstracts Service registry numbers. Integr Environ Assess Manag 2011;7:513–541. © 2011 SETA
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