Found 9972 publications. Showing page 231 of 399:
Microfluidic In Vitro Platform for (Nano)Safety and (Nano)Drug Efficiency Screening
Microfluidic technology is a valuable tool for realizing more in vitro models capturing cellular and organ level responses for rapid and animal‐free risk assessment of new chemicals and drugs. Microfluidic cell‐based devices allow high‐throughput screening and flexible automation while lowering costs and reagent consumption due to their miniaturization. There is a growing need for faster and animal‐free approaches for drug development and safety assessment of chemicals (Registration, Evaluation, Authorisation and Restriction of Chemical Substances, REACH). The work presented describes a microfluidic platform for in vivo‐like in vitro cell cultivation. It is equipped with a wafer‐based silicon chip including integrated electrodes and a microcavity. A proof‐of‐concept using different relevant cell models shows its suitability for label‐free assessment of cytotoxic effects. A miniaturized microscope within each module monitors cell morphology and proliferation. Electrodes integrated in the microfluidic channels allow the noninvasive monitoring of barrier integrity followed by a label‐free assessment of cytotoxic effects. Each microfluidic cell cultivation module can be operated individually or be interconnected in a flexible way. The interconnection of the different modules aims at simulation of the whole‐body exposure and response and can contribute to the replacement of animal testing in risk assessment studies in compliance with the 3Rs to replace, reduce, and refine animal experiments.
2021
2009
Micronucleus assay applied to advanced in vitro lung models at ALI for nanotoxicity assessment
Elsevier
2021
Microfibers (MF) are one of the major classes of microplastic found in the marine environment on a global scale. Very little is known about how they move and distribute from point sources such as wastewater effluents into the ocean. We chose Adventfjorden near the settlement of Longyearbyen on the Arctic Svalbard archipelago as a case study to investigate how microfibers emitted with untreated wastewater will distribute in the fjord, both on a spatial and temporal scale. Fiber abundance in the effluent was estimated from wastewater samples taken during two one-week periods in June and September 2017. Large emissions of MFs were detected, similar in scale to a modern WWTP serving 1.3 million people and providing evidence of the importance of untreated wastewater from small settlements as major local sources for MF emissions in the Arctic. Fiber movement and distribution in the fjord mapped using an online-coupled hydrodynamic-drift model (FVCOM-FABM). For parameterizing a wider spectrum of fibers from synthetic to wool, four different density classes of MFs, i.e., buoyant, neutral, sinking, and fast sinking fibers are introduced to the modeling framework. The results clearly show that fiber class has a large impact on the fiber distributions. Light fibers remained in the surface layers and left the fjord quickly with outgoing currents, while heavy fibers mostly sank to the bottom and deposited in the inner parts of the fjord and along the northern shore. A number of accumulation sites were identified within the fjord. The southern shore, in contrast, was much less affected, with low fiber concentrations throughout the modeling period. Fiber distributions were then compared with published pelagic and benthic fauna distributions in different seasons at selected stations around the fjord. The ratios of fibers to organisms showed a very wide range, indicating hot spots of encounter risk for pelagic and benthic biota. This approach, in combination with in-situ ground-truthing, can be instrumental in understanding microplastic pathways and fate in fjord systems and coastal areas and help authorities develop monitoring and mitigation strategies for microfiber and microplastic pollution in their local waters.
2021
2022
2017
Microplastic pellets in Arctic marine sediments: a common source or a common process?
Plastic consumption is increasing, and millions of tonnes of plastic are released into the oceans every year. Plastic materials are accumulating in the marine environment, especially on the seafloor. The Arctic is contaminated with plastics, including microplastics (MPs, <5 mm) but occurrences, concentrations and fate are largely unknown. This study aimed at assessing whether MPs accumulate at greater water depths in the Barents Sea, and close to the Longyearbyen settlement, and at understanding the ubiquity and source of a specific type of collected pellets. Surface sediments were collected at seven stations around Svalbard with a box-corer, and three replicates were taken at each station. MPs were extracted through density separation with saturated saltwater. Many pellets were found, and their composition was assessed by pyrolysis-GC/MS. Procedural blanks were performed using field blanks as samples to assess the overall contamination. The composition of all extracted particles was then analysed by μRaman spectroscopy. On average, 3.61 ± 1.45 MPs/100 g (dw) were found. The sea ice station, after blank correction, was more contaminated and displaying a different profile than the other stations, and the deepest station did not show the highest MP concentrations but rather the opposite. Sediments close to Longyearbyen were not more contaminated than the other stations either. Dark pellets of similar aspect were found at all stations, raising the question about a possible common source or process. These pellets were made of several plastic polymers which varied in proportion for each pellet, suggesting a common process was at the origin of those pellets, potentially marine snow formation.
2025
2018
Microplastics and nanoplastics in the marine-atmosphere environment
The discovery of atmospheric micro(nano)plastic transport and ocean–atmosphere exchange points to a highly complex marine plastic cycle, with negative implications for human and ecosystem health. Yet, observations are currently limited. In this Perspective, we quantify the processes and fluxes of the marine-atmospheric micro(nano)plastic cycle, with the aim of highlighting the remaining unknowns in atmospheric micro(nano)plastic transport. Between 0.013 and 25 million metric tons per year of micro(nano)plastics are potentially being transported within the marine atmosphere and deposited in the oceans. However, the high uncertainty in these marine-atmospheric fluxes is related to data limitations and a lack of study intercomparability. To address the uncertainties and remaining knowledge gaps in the marine-atmospheric micro(nano)plastic cycle, we propose a future global marine-atmospheric micro(nano)plastic observation strategy, incorporating novel sampling methods and the creation of a comparable, harmonized and global data set. Together with long-term observations and intensive investigations, this strategy will help to define the trends in marine-atmospheric pollution and any responses to future policy and management actions.
2022
2020
Microplastics in Norwegian coastal areas, rivers, lakes and air (MIKRONOR1)
The Norwegian Environment Agency (Miljødirektoratet, NEA) tasked the Norwegian Institute for Water Research (NIVA) to initiate Norway’s National microplastic monitoring program. The program “Microplastics in Norwegian coastal areas, rivers, lakes and air (MIKRONOR)”, was designed to target the multitude of environments in the Norwegian coastal, freshwater and terrestrial ecosystems. The primary aim is to provide information on levels and types of microplastics in aquatic environments as well as in air and build on the baseline data already generated for a number of these environments on previous assignments by NEA.
This report contains the first results of coastal sites, open marine waters, lakes, rivers and air including high-volume water samples (freshwater and marine, n=48), Ferrybox samples (marine, n=20), blue mussels (marine, n=71), vertical plankton net samples (marine, n=29) and 24 air samples (precipitation n= 12 and active air sampling n = 12).
Norsk institutt for vannforskning
2022
Microplastics in Norwegian coastal areas, rivers, lakes and air (MIKRONOR1)
Norsk institutt for vannforskning
2022
2022
The atmosphere and cryosphere have recently garnered considerable attention due to their role in transporting microplastics to and within the Arctic, and between freshwater, marine, and terrestrial environments. While investigating either in isolation provides valuable insight on the fate of microplastics in the Arctic, monitoring both provides a more holistic view. Nonetheless, despite the recent scientific interest, fundamental knowledge on microplastic abundance and consistent monitoring efforts are lacking for these compartments. Here, we build upon the work of the Arctic Monitoring and Assessment Programme's Monitoring Guidelines for Litter and Microplastic to provide a roadmap for multicompartment monitoring of the atmosphere and cryosphere to support our understanding of the sources, pathways, and sinks of plastic pollution across the Arctic. Overall, we recommend the use of existing standard techniques for ice and atmospheric sampling and to build upon existing monitoring efforts in the Arctic to obtain a more comprehensive pan-Arctic view of microplastic pollution in these two compartments.
2022
Migration analysis of chemical additives from indoor consumer plastic products
NILU has, on behalf of the Norwegian Environment Agency, performed chemical analyses of a selection of chemical additives in indoor consumer plastic products. The goal was to identify content and migration of the chemical additives in and from the products to particles and surfaces of the products at room temperature. The plastic products included; furniture wrap, wall papers, table cloths, shower curtains, floor tiles, mattresses, pillows, carpet underlays and a bathtub mat. Targeted chemicals were organophosphorous flame retardants (OPFRs), brominated flame retardants (BFRs) including tetrabromobisphenol A (TBBPA), chlorinated paraffins (CPs) and dechloranes. MCCPs and SCCPs were found in ‰ to % levels in PVC containing products. Four of the OPFRs were found in up to ‰ levels in adhesive foils to be put on furniture or floor/walls and mattresses. None of the targeted brominated compounds nor melamine were detected in the product samples.
NILU
2023