Spent coffee grounds as a suitable alternative to standard soil in ecotoxicological tests.

Eisenia andrei is considered in OECD and ISO guidelines to be a suitable replacement for Eisenia fetida in ecotoxicological assays. This suggests that other alternative materials and methods could also be used in standard procedures for toxicity testing. The guidelines also favor using less time-consuming procedures and reducing costs and other limitations to ecotoxicological assessments. In recent years, spent coffee grounds (SCG) have been used to produce vermicompost and biochar and as an additive to organic fertilizers. In addition, the physicochemical characteristics of SCG indicate that the material is a suitable substrate for earthworms, with the organisms performing as well as in natural soil. In the present study, a battery of ecotoxicological tests was established with unwashed and washed SCG and a natural reference soil (LUFA 2.2). The test substrates were spiked with different concentrations of silver nitrate. Survival and reproduction of the earthworm E. andrei were assessed under different conditions, along with substrate basal respiration (SBR) as a proxy for microbial activity. Seedling emergence and the germination index of Lepidium sativum were also determined, following standard guidelines. Exposure to silver nitrate had similar effects on earthworm survival and reproduction, as the estimated effective concentrations (EC10 and EC50) in unwashed SCG and LUFA 2.2 overlapped. A hormetic effect was observed for SBR in LUFA 2.2 spiked with 12.8 mg/kg but not in unwashed SCG. Both SBR and root development were inhibited by similar concentrations of silver nitrate in washed SCG. The findings indicate that unwashed SCG could potentially be used as a substrate in E. andrei toxicity tests and support the eventual inclusion of this material in the standard guidelines.

Cytotoxicity Assessment of Nanoplastics and Plasticizers Exposure in In Vitro Lung Cell Culture Systems-A Systematic Review.

Emerging contaminants such as nanoplastics (NPs), as well as manufacturing by-products such as plasticizers, have gained global attention and concern due to their limited biodegradability and their potential impact on human health, in particular the effects on respiratory tissue. In parallel, in vitro cell culture techniques are key to the assessment and characterization of toxic effects and cellular mechanisms in different types of tissues and should provide relevant information to understand the hazardous potential of these emergent contaminants. This systematic review presents the main results on the current knowledge of the effects of NPs and plasticizers on lung cells, as assessed with the use of in vitro cell culture techniques. From the selected studies (n = 10), following the PRISMA approach, it was observed that cell viability was the most frequently assessed endpoint and that most studies focused on epithelial cells and exposures to polystyrene (PS). It was observed that exposure to NPs or plasticizers induces cytotoxicity in a dose-dependent manner, regardless of the size of the NPs. Furthermore, there is evidence that the characteristics of NPs can affect the toxic response by promoting the association with other organic compounds. As such, further in vitro studies focusing on the combination of NPs with plasticizers will be essential for the understanding of mechanisms of NPs toxicity.

Ag Nanoparticles (Ag NM300K) in the Terrestrial Environment: Effects at Population and Cellular Level in Folsomia candida (Collembola).

The effects of nanomaterials have been primarily assessed based on standard ecotoxicity guidelines. However, by adapting alternative measures the information gained could be enhanced considerably, e.g., studies should focus on more mechanistic approaches. Here, the environmental risk posed by the presence of silver nanoparticles (Ag NM300K) in soil was investigated, anchoring population and cellular level effects, i.e., survival, reproduction (28 days) and oxidative stress markers (0, 2, 4, 6, 10 days). The standard species Folsomia candida was used. Measured markers included catalase (CAT), glutathione reductase (GR), glutathione S-transferase (GST), total glutathione (TG), metallothionein (MT) and lipid peroxidation (LPO). Results showed that AgNO3 was more toxic than AgNPs at the population level: reproduction EC20 and EC50 was ca. 2 and 4 times lower, respectively. At the cellular level Correspondence Analysis showed a clear separation between AgNO3 and AgNP throughout time. Results showed differences in the mechanisms, indicating a combined effect of released Ag⁺ (MT and GST) and of AgNPs (CAT, GR, TG, LPO). Hence, clear advantages from mechanistic approaches are shown, but also that time is of importance when measuring such responses.

Senescent bronchial fibroblasts induced to senescence by Cr(VI) promote epithelial-mesenchymal transition when co-cultured with bronchial epithelial cells in the presence of Cr(VI).

Cellular senescence is a physiological process that serves as a powerful barrier for tumorigenesis. However, senescent cells can be deleterious for the tissue microenvironment. Such is the case of senescent fibroblasts that release several pro-tumorigenic factors that promote malignant transformation in the nearby epithelial cells. Occupational exposure to hexavalent chromium [Cr(VI)] compounds is a cause of respiratory cancers. Although Cr(VI) is known to induce senescence in human foreskin fibroblasts, the role of senescent fibroblasts in the Cr(VI)-induced malignant transformation of human bronchial epithelial cells was never assessed. Thus, to study the evolutionary dynamics generated by the interaction between human bronchial epithelial cells and senescent bronchial fibroblasts, the non-tumorigenic human bronchial epithelial BEAS-2B cells were co-cultured with Cr(VI)-induced senescent human bronchial fibroblasts for 4 weeks. Under the pressure of 0.5 µM Cr(VI), senescent fibroblasts promoted the acquisition of mesenchymal features on BEAS-2B cells, e.g. the fusiform shape and increased Vimentin expression, consistent with the occurrence of an epithelial-mesenchymal transition-like process. Features of transformed cells including larger nuclei, as well as nuclei with heterogeneous size, were also observed. Altogether the results obtained demonstrate that besides acting over the epithelium, Cr(VI) also affects bronchial fibroblasts driving them senescent. As a consequence, a paracrine communication loop is established with the above-placed epithelium prompting the epithelial cells for malignant transformation and thus facilitating the initial steps of tumorigenesis.