Effects of exposure to nanoplastics on the gill of mussels Mytilus galloprovincialis: An integrated perspective from multiple biomarkers

Environmental and Sublethal Concentrations of Polystyrene Nanoplastics Induced Antioxidant System, Transcriptomic Responses, and Disturbed Gut Microbiota in Oyster Magallana Hongkongensis

Nanoplastics (NPs) are emerging contaminants having persistent nature, diverse ecological impacts, and potential food safety risks. Here, we examined the ecotoxicity of 80 nm polystyrene nanoplastics (PS-NPs) at environmentally relevant concentrations (ERCs, 10 and 100 μg/L), and sublethal concentrations (SLCs, 500 and 2500 μg/L) in Magallana hongkongensis. Results showed that SLCs significantly (p < 0.05) increased superoxide dismutase (SOD), catalase (CAT), and alkaline phosphatase (AKP) activities and altered tnfα, cat, gst, sod, and se-gpx genetic expressions. Further, PS-NP exposure at both levels reduced beneficial bacteria and increased potentially pathogenic bacteria in the gut. In transcriptomic analysis, 5118 and 4180 differentially expressed genes (DEGs) were identified at ERCs, while 5665 and 4817 DEGs were found at SLCs, respectively. Upregulated DEGs enriched lysosomes, ABC transporters, and apoptosis pathways, while downregulated DEGs enriched ribosomal pathways. Overall, ERCs significantly altered gut microbiota and transcriptomic responses, while SLCs, in addition, also impacted the antioxidant and immune systems.

An overview on dispersion procedures and testing methods for the ecotoxicity testing of nanomaterials in the marine environment

Considerable efforts have been devoted to develop or adapt existing guidelines and protocols, to obtain robust and reproducible results from (eco)toxicological assays on engineered nanomaterials (NMs). However, while many studies investigated adverse effects of NMs on freshwater species, less attention was posed to the marine environment, a major sink for these contaminants. This review discusses the procedures used to assess the ecotoxicity of NMs in the marine environment, focusing on the use of protocols and methods for preparing NMs dispersions and on the NMs physicochemical characterization in exposure media. To this purpose, a critical analysis of the literature since 2010 was carried out, based on the publication of the first NMs dispersion protocols. Among the 89 selected studies, only <5 % followed a standardized dispersion protocol combined with NMs characterization in ecotoxicological media, while more than half used a non-standardized dispersion method but performed NMs characterization. In the remaining studies, only partial or no information on dispersion procedures or on physicochemical characterization was provided. This literature review also highlighted that metal oxides NMs were the most studied (42 %), but with an increasing interest in last years towards nanoplastics (14 %) and multicomponent nanomaterials (MCNMs, 7 %), in line with the growing attention on these emerging contaminants. For all these NMs, primary producers as algae and bacteria were the most studied groups of marine species, in addition to mollusca, while organisms at higher trophic levels were less represented, likely due to challenges in evaluating adverse effects on more complex organisms. Thus, despite the wide use of NMs in different applications, standard dispersion protocols are not often used for ecotoxicity testing with marine species. However, the efforts to characterize NMs in ecotoxicological media recognize the importance of following conditions that are as standardized as possible to support the ecological hazard assessment of NMs.