Risk assessment of chemical substances is always a challenging process. It can be supported by using the potential of the in silico methods such as the read-across approach. Several frameworks and... Show moreRisk assessment of chemical substances is always a challenging process. It can be supported by using the potential of the in silico methods such as the read-across approach. Several frameworks and methodologies can be found, e.g. the Read-across Assessment Framework (RAAF) developed by ECHA, which describes how the analysis is carried out using the read-across approach. However, they are focused on classical chemical substances, not nanomaterials. Thus, our goal was to evaluate publicly available read-across frameworks in the context of ENM. Especially, in view of the recent update of the REACH regulations (Annex VI), which introduced the concept of “nanoform” of the substance. We examined the possibilities as well as the challenges for nanomaterials when applying available frameworks by carrying out readacross case studies for selected nanoforms of nano-SiO2. Structural properties of five ENMs and data related to their ecotoxicity were extracted from the JRC Repository characterization dossier on nanoSiO2 amorphous materials and the corresponding NanoReg2 H2020 project deliverable. From all endpoints available, toxicity results towards the Carp leucocyte cell line were considered as the most appropriate. For the purposes of the case study, we decided to treat one of the nano-SiO2 as a target (NM200) and the four others (NM 201- 204) as source analogues. The analysis consisted of several steps: i) identification and characterization of all nanoforms; ii) development of grouping hypothesis; iii) assignment to groups; iv) data gathering; v) applicability assessment; vi) filling data gaps. After passing through all the stages we were able to estimate the toxicity of target ENM. The formulated hypothesis of the read-across approach for the assessment of ecotoxicity was as follows: SiO2 nanoforms can be separated into two distinct groups based on how the following properties influenced cytotoxicity in fish cells: i) surface area, ii) coating mass, iii) size distribution in stock and media solutions, iv) polydispersity in stock and media solutions. This leads to the follow-up hypothesis of novel SiO2 ENMs with similar physicochemical/structural parameters inducing similar toxicological activities in fish cells. Subsequently, we employed similarity analysis in the space of the mentioned properties. Based on the calculated Euclidean distances, the target nanoform (NM200), has been placed within the group of toxic source analogues (NM201 and 204). Therefore, according to the worst-case approach, one can assume that the target nanoform will be highly toxic to fish cells. The results and lessons learned from this exercise will be discussed further in the context of the work carried out in the PATROLS project. Show less
Zhang, Q.; Zhang, Z.; Lu, T.; Peijnenburg, W.J.G.M.; Gillings, M.; Yang, X.; ... ; Qian, H. 2020
Cyanobacterial blooms are a global ecological problem that directly threatens human health and crop safety. Cyanobacteria have toxic effects on aquatic microorganisms, which could drive the... Show moreCyanobacterial blooms are a global ecological problem that directly threatens human health and crop safety. Cyanobacteria have toxic effects on aquatic microorganisms, which could drive the selection for resistance genes. The effect of cyanobacterial blooms on the dispersal and abundance of antibiotic-resistance genes (ARGs) of concern to human health remains poorly known. We herein investigated the effect of cyanobacterial blooms on ARG composition in Lake Taihu, China. The numbers and relative abundances of total ARGs increased obviously during a Planktothrix bloom. More pathogenic microorganisms were present during this bloom than during a Planktothrix bloom or during the non-bloom period. Microcosmic experiments using additional aquatic ecosystems (an urban river and Lake West) found that a coculture of Microcystis aeruginosa and Planktothrix agardhii increased the richness of the bacterial community, because its phycosphere provided a richer microniche for bacterial colonization and growth. Antibiotic-resistance bacteria were naturally in a rich position, successfully increasing the momentum for the emergence and spread of ARGs. These results demonstrate that cyanobacterial blooms are a crucial driver of ARG diffusion and enrichment in freshwater, thus providing a reference for the ecology and evolution of ARGs and ARBs and for better assessing and managing water quality. Show less
