Emerging chemical contaminants (ECCs) have been detected in the environment, but the knowledge on their fate and biological effects is still limited, especially those resulting from mixtures exposure. ECCs are sourced by industrial, domestic and hospital effluents, livestock and aquaculture. Wastewater treatment plants are not designed to eliminate ECCs, which have been found in several aquatic ecosystems. Silver nanoparticles (Ag-NPs) have been incorporated into a wide range of consumer products, mainly because of the antimicrobial effect of Ag+. Moreover, the human population requiring healthcare is escalating, leading to an increase in the quantity and diversity of pharmaceuticals consumed. The cyclophosphamide (CYC) is an anti-cancer drug listed as concern among pharmaceuticals (PHARs). Microplastics are considered global pollutants of high concern, and more knowledge on their biological and ecological effects is urgently needed to improve the environmental risk assessment, as required by national and european regulation (MSFD: 2008/56/EC).
Previously, we assessed the effects of metal NPs (e.g. PTDC/AAC-AMB/121650/2010) and microplastics (JPIOCEANS/0005/2015; PLASTICGLOBAL-PTDC/MARPRO/1851/2014) on marine and freshwater species. The EMERGEMIX project will use environmentally relevant mixtures of AgNPs, nanoplastics and CYC to expand our knowledge on their effects on species and communities from freshwater, estuarine and marine ecosystems, using parameters at different levels of biological organization. This will contribute to identify biomarkers of stress, elucidate the mechanisms of action and interaction between ECCs, and determine toxicity to organisms, populations and communities, ultimately contributing to improve the bases of environmental risk assessment and the safety in the use of ECCs. The selected model organisms, widely used in ecotoxicology, are the mussel Mytillus galloprovincialis and the exotic invasive species Corbicula fluminea, commonly found in estuarine and freshwater tidal areas. Moreover, the impacts of ECCs on aquatic communities and ecosystem processes will be examined on plant litter decomposition driven by microbes and invertebrate shredders in freshwaters and estuaries.
We will investigate the ability of cells to initiate an efficient antioxidant defense system, by measuring responses of antioxidant enzymes, induction of metallothioneins, lipid peroxidation, DNA damage and nuclear morphological alterations in fungi, shredders and bivalves. Proteomics will be carried out in organisms exposed to ECCs, that will allow us to ascertain new biomarkers to ECC exposure and elucidate the mechanisms of toxicity induced by ECCs in mixtures.
Finally, we will use physico-chemical, biological and ecological data to provide multiple lines of evidence with a weight of evidence approach to assess the risks associated with the exposure to mixtures of ECCs in aquatic ecosystems.