Titanium dioxide nanoparticles induce oxidative stress and DNA-adduct formation but not DNA-breakage in human lung cells

Titanium dioxide (TiO2), also known as titanium (IV) oxide or anatase, is the naturally occurring oxide of titanium. It is also one of the most commercially used form. To date, no parameter has been set for the average ambient air concentration of TiO2 nanoparticles (NP) by any regulatory agency. Previously conducted studies had established these nanoparticles to be mainly non-cyto- and -genotoxic, although they had been found to generate free radicals both acellularly (specially through photocatalytic activity) and intracellularly. The present study determines the role of TiO2-NP (anatase, ∅ < 100 nm) using several parameters such as cyto- and genotoxicity, DNA-adduct formation and generation of free radicals following its uptake by human lung cells in vitro. For comparison, iron containing nanoparticles (hematite, Fe2O3, ∅ < 100 nm) were used. The results of this study showed that both types of NP were located in the cytosol near the nucleus. No particles were found inside the nucleus, in mitochondria or ribosomes. Human lung fibroblasts (IMR-90) were more sensitive regarding cyto- and genotoxic effects caused by the NP than human bronchial epithelial cells (BEAS-2B). In contrast to hematite NP, TiO2-NP did not induce DNA-breakage measured by the Comet-assay in both cell types. Generation of reactive oxygen species (ROS) was measured acellularly (without any photocatalytic activity) as well as intracellularly for both types of particles, however, the iron-containing NP needed special reducing conditions before pronounced radical generation. A high level of DNA adduct formation (8-OHdG) was observed in IMR-90 cells exposed to TiO2-NP, but not in cells exposed to hematite NP. Our study demonstrates different modes of action for TiO2- and Fe2O3-NP. Whereas TiO2-NP were able to generate elevated amounts of free radicals, which induced indirect genotoxicity mainly by DNA-adduct formation, Fe2O3-NP were clastogenic (induction of DNA-breakage) and required reducing conditions for radical formation

ROS-mediated genotoxicity of asbestos-cement in mammalian lung cells in vitro

Asbestos is a known carcinogen and co-carcinogen. It is a persisting risk in our daily life due to its use in building material as asbestos-cement powder. The present study done on V79-cells (Chinese hamster lung cells) demonstrates the cytotoxic and genotoxic potential of asbestos-cement powder (ACP) in comparison with chrysotile asbestos. A co-exposure of chrysotile and ACP was tested using the cell viability test and the micronucleus assay. The kinetochore analysis had been used to analyse the pathway causing such genotoxic effects. Thiobarbituric acid-reactive substances were determined as evidence for the production of reactive oxygen species. Both, asbestos cement as well as chrysotile formed micronuclei and induced loss of cell viability in a concentration- and time- dependent way. Results of TBARS analysis and iron chelator experiments showed induction of free radicals in ACP- and chrysotile exposed cultures. CaSO(4 )appeared to be a negligible entity in enhancing the toxic potential of ACP. The co-exposure of both, ACP and chrysotile, showed an additive effect in enhancing the toxicity. The overall study suggests that asbestos-cement is cytotoxic as well as genotoxic in vitro. In comparison to chrysotile the magnitude of the toxicity was less, but co-exposure increased the toxicity of both

Intracellular Calcium Disturbances Induced by Arsenic and Its Methylated Derivatives in Relation to Genomic Damage and Apoptosis Induction

Arsenic and its methylated derivatives are contaminants of air, water, and food and are known as toxicants and carcinogens. Arsenic compounds are also being used as cancer chemotherapeutic agents. In humans, inorganic arsenic is metabolically methylated to mono-, di-, and trimethylated forms. Recent findings suggest that the methylation reactions represent a toxification rather than a detoxification pathway. In recent years, the correlation between arsenic exposure, cytotoxicity and genotoxicity, mutagenicity, and tumor promotion has been established, as well as the association of arsenic exposure with perturbation of physiologic processes, generation of reactive oxygen species, DNA damage, and apoptosis induction. Trivalent forms of arsenic have been found to induce apoptosis in several cellular systems with involvement of membrane-bound cell death receptors, activation of caspases, release of calcium stores, and changes of the intracellular glutathione level. It is well known that calcium ion deregulation plays a critical role in apoptotic cell death. A calcium increase in the nuclei might lead to toxic effects in the cell. In this review, we highlight the relationship between induced disturbances of calcium homeostasis, genomic damage, and apoptotic cell death caused by arsenic and its organic derivatives

Lösungsstrategien zur Verminderung von Einträgen von urbanem Plastik in limnische Systeme - PLASTRAT - Synthesebericht

Der Einsatz von Plastik gehört zu den großen Errungenschaften unserer Zeit. Die Nutzung von Plastik in unseren verschiedenen Lebensbereichen ermöglicht uns heute Vieles. Dabei setzen wir Plastik oft ein, ohne dass uns dies bewusst ist. Wieviel „virtuelles Plastik“ war allein notwendig, um diesen Synthesebericht zu erstellen? Wieviel Plastik benötigen Sie gerade, um diesen Synthesebericht zu lesen? Wie so oft, so hat auch der Einsatz von Plastik zwei Seiten: den positiven Errungenschaften stehen negative Auswirkungen gegenüber, vor allem nach der Nutzung von Plastik. Im Fokus stehen hierbei Fragestellungen der Toxikologie sowie der Abfallverwertung. Im Gegensatz zu vielen anderen Stoffen, mit denen wir täglich in Berührung sind, hat Plastik die Eigenschaft, dass sich kleinste Partikel bilden. So ist es nicht verwunderlich, dass sich mittlerweile in allen Umweltmedien Mikroplastikpartikel finden lassen. Die Idee von PLASTRAT war es, in einem interdisziplinären Team Ansätze für die Verminderung von Einträgen von Plastik in Gewässer zu untersuchen. Dabei standen über den Ansatz der systemischen Risikoanalyse die unterschiedlichen Sektoren im Fokus, angefangen von der Erzeugung, über die Nutzung bis hin zu den Eintragspfaden und die toxikologische Bewertung. Der Synthesebericht fasst die Ergebnisse von PLASTRAT zusammen. Vor allem zeigt der Synthesebericht die großen Herausforderungen sowie Lösungsansätze zum Thema Mikroplastik auf. Dabei wird auch deutlich, dass wir bei vielen Fragestellungen zum Umgang mit Plastik erst am Anfang stehen. Die ersten Ideen zu PLASTRAT entstanden 2016. In den vergangenen fünf Jahren stand das Thema Plastik im Fokus von Öffentlichkeit und Presse. In dieser Zeit gab es bereits wichtige Veränderungen beim Einsatz von Plastik bei diversen Produkten, beispielsweise durch die Substitution durch alternative Materialien. Dies zeigt deutlich, dass eine Bewusstseinsveränderung stattgefunden hat, die sich sicherlich in der Zukunft fortsetzten wird. Die Arbeiten und Diskussionen im Projektteam von PLASTRAT waren spannend. In vielen Projektbesprechungen wurde an den Forschungsfragestellungen gearbeitet und nach Lösungen gesucht. Es gab einen intensiven persönlichen Austausch mit allen am Projekt beteiligten Personen, so dass uns die seit 2020 geltenden Einschränkungen durch die Corona-Pandemie nicht immer leichtgefallen sind. Wir möchten uns bei allen bedanken, die bei PLASTRAT mitgewirkt haben. Allen Lesern des Syntheseberichts wünschen wir viele Freude beim Lesen und hoffen, dass wir Ihnen einen Impuls für den zukünftigen Umgang mit (Mikro-)Plastik geben können

Since 2015 the SinoGerman research project SIGN supports water quality improvement in the Taihu region, China

The Taihu (Tai lake) region is one of the most economically prospering areas of China. Due to its location within this district of high anthropogenic activities, Taihu represents a drastic example of water pollution with nutrients (nitrogen, phosphate), organic contaminants and heavy metals. High nutrient levels combined with very shallow water create large eutrophication problems, threatening the drinking water supply of the surrounding cities. Within the international research project SIGN (SinoGerman Water Supply Network, www.water-sign.de), funded by the German Federal Ministry of Education and Research (BMBF), a powerful consortium of fifteen German partners is working on the overall aim of assuring good water quality from the source to the tap by taking the whole water cycle into account: The diverse research topics range from future proof strategies for urban catchment, innovative monitoring and early warning approaches for lake and drinking water, control and use of biological degradation processes, efficient water treatment technologies, adapted water distribution up to promoting sector policy by good governance. The implementation in China is warranted, since the leading Chinese research institutes as well as the most important local stakeholders, e.g. water suppliers, are involved