Insights into the potential effects of released engineered nanomaterials from polymer nanocomposites: environmental issues and future activities for risk assessment and management

The use, production, and disposal of engineered nanomaterials (ENMs) raise concerns about their environmental impact at all stages of the life cycle, considering that nanostructured materials can be released to the air, soil, or water in common industrial processes and/or accidental events, and ultimately accumulate in the soil, water, or biota, endangering the health of living organisms and ecosystems. Within this context, the present study is focused on the analysis of the potential effects of common polymeric composites incorporating ENMs in relevant organisms from soil and aquatic compartments. To this end, a set of polymeric materials, including PET, PLA, and PP, were compounded with a list of ENMs to produce PP_Ag, PET_Ag, PET_ZnO, and PLA_SiO2 films that were aged in a weathering chamber using UV radiation to simulate the degradation effects of sunlight and other relevant environmental factors. Weathered samples were micronized to conduct ecotoxicity studies following adapted OECD protocols on the aquatic invertebrates Daphnia magna and Brachionus plicatilis, the green alga Pseudokirchneriella subcapitata, and the soil invertebrate Eisenia foetida. The results showed a low level of toxicity for the nanocomposites studied, except in the case of the silver (Ag)-based nanocomposite (PP_Ag), where a high toxicity was found for the aquatic invertebrate Daphnia magna due probably to the effect of silver ions. The aging process of the polymer nanocomposites promotes the release of ENMs, with potential adverse effects expected in natural environments.