Exposure protocol for ecotoxicity testing of microplastics and nanoplastics

Abstract

Despite the increasing concern about the harmful effects of micro-and nanoplastics (MNPs), there are no harmonized guidelines or protocols yet available for MNP ecotoxicity testing. Current ecotoxicity studies often use commercial spherical particles as models for MNPs, but in nature, MNPs occur in variable shapes, sizes and chemical compositions. Moreover, protocols developed for chemicals that dissolve or form stable dispersions are currently used for assessing the ecotoxicity of MNPs. Plastic particles, however, do not dissolve and also show dynamic behavior in the exposure medium, depending on, for example, MNP physicochemical properties and the medium's conditions such as pH and ionic strength. Here we describe an exposure protocol that considers the particle-specific properties of MNPs and their dynamic behavior in exposure systems. Procedure 1 describes the top-down production of more realistic MNPs as representative of MNPs in nature and particle characterization (e.g., using thermal extraction desorption-gas chromatography/mass spectrometry). Then, we describe exposure system development for short-and long-term toxicity tests for soil (Procedure 2) and aquatic (Procedure 3) organisms. Procedures 2 and 3 explain how to modify existing ecotoxicity guidelines for chemicals to target testing MNPs in selected exposure systems. We show some examples that were used to develop the protocol to test, for example, MNP toxicity in marine rotifers, freshwater mussels, daphnids and earthworms. The present protocol takes between 24 h and 2 months, depending on the test of interest and can be applied by students, academics, environmental risk assessors and industries. Key points• In nature, micro-and nanoplastics (MNPs) occur in various shapes, sizes and chemical compositions. Each of these properties can affect both their dynamic behavior and their toxicology and should be considered when performing ecotoxicology experiments to assess their risk.• Here, MNPs are generated from plastic waste by using either a ball or centrifugal mill. Their physicochemical properties are measured. Ecotoxicology experiments in soil and aquatic systems are described.

The “Microplastome” – A Holistic Perspective to Capture the Real-World Ecology of Microplastics

“…Utilizing these prepared microplastomes for microcosmic experiments facilitates the capture of their real-world ecotoxicological effects. Encouragingly, recent research has started to leverage this idea, striving to reconstruct the ecological impacts of complex microplastics in actual environmental settings. , By adjusting the composition (adjusting the relative proportions of different types of microplastics) with a constant concentration and adjusting the concentration with a constant composition, a concentration-composition-effect model can be developed with machine learning. This model enables us to identify which compositional signatures pose a higher risk and to pinpoint the key microplastic types that dominate the overall ecotoxicological effects.…”

Environmental plastics in the context of UV radiation, climate change, and the Montreal Protocol

“…The environmental accumulation of plastics has led to concerns about the effects of macro‐ (>5 mm), micro‐ (<5 mm), and nano‐ (<0.1 μm) plastics on the health of humans and other organisms. Consequently, there is a need to better understand the environmental fate of plastic debris and especially its degradation and fragmentation into micro‐ and nanoplastics that can be inhaled or ingested (Abdolahpur Monikh et al., 2023).…”