Helen Callow, Environmental Toxicology and Chemistry
The following is adapted from the introductory article to the special series, Relevant and Realistic Assessments of Microplastics and Nanoplastics in the Environment, and published with permission.
Plastic pollution remains a global, anthropogenic threat because of its universal use in our daily life and ubiquitous presence the environment. Micro- and nanoparticles vary in shape, size and chemical composition, and each parameter may influence the behavior, fate, transport and effects. Add to this variation weathering, additives, absorption or desporption of chemicals and more, the gap between the the traditionally pristine lab studies and the environmental reality of natural exposure continues to grow. Environmental Toxicology and Chemistry (ET&C) has recently published a special series, Relevant and Realistic Assessments of Microplastics and Nanoplastics in the Environment, with guest editors Jana Asselman and Colin Janssen. The manuscripts focus on improving analytical methodologies for complex environmental matrices, accounting for physicochemical properties and environmental interactions in effect assessments of micro- and nanoplastics, and integrating perspectives and analyses on risk assessment.
Julia Moller and co-authors reviewed the limitations of analytical methods for microplastic contamination in soils. They presented a soil purification protocol with a high purification efficiency. Likewise, Christine Knauss and colleagues created a method to create standardized plastic microfibers. Microfibers are one of the most abundant microplastic particle types found in the environment. Samantha Athey and Lisa Erdle identified the understudied compartments and geographic regions of microfibers in their meta-analysis. Source compartments include indoor environments and dust, while key pathways to the environment are storm water, sewage sludge and biosolids. Athey and Erdle also pointed out the need to include both natural and semisynthetic microfibers in future studies to better understand their sources, pathways and effects.
In terms of effect assessment, Kennedy Bucci et al. showed that the impacts of microplastics in fathead minnows are dependent on both polymer type and the presence of sorbed environmental contaminants. They identified both physical and chemical impacts. Overall, the authors concluded that we should treat microplastics as a multiple stressor with both physical and chemical stressors rather than a single contaminant. The complex interactions between microplastics and biota were further observed by Nicholas Buss and co-autors, who observed that polyester microplastic fibers can augment host–parasite interactions at high concentrations in amphibians. Jelena Stanković et al. observed negligible effects of microplastics on community structure in benthic macroinvertebrates but also postulated that long-term presence of microplastics in the sediment may lead to significant changes in community structure driven by sublethal effects.
A specific group within the group of micro- and nanoplastics are fragrance encapsulates, which are a droplet of fragrance oil surrounded by a thin polymeric shell designed to break, allowing slow diffusion of the oil during the washing process. Sebastian Kuehr and colleagues found limited species-specific effects of fragrance encapsulates on aquatic and terrestrial invertebrates. In terms of exposure assessment and risk assessment, Yaping Cai et al. derived both predicted-environmental concentration and predicted-no-effect concentration values and suggested no environmental risk based on the present data.
In terms of general exposure assessment, Lyda Harris and colleagues found a significant breakpoint in the concentrations of microparticles that coincided with the onset of COVID-19 lockdown measures and the decline in air travel. Overall, they observed that the immediate effect of a decrease of tourism on marine microparticle pollution was evident. The study concludes that an improved understanding of how microparticle presence is influenced by seasonality, and both global and regional events may contribute to efficient mitigation and cleanup strategies.
Finally, Gabriela Kalčíková and Mirco Bundschuh discussed the potential interactions between biofilms and micro- and nanoplastics. Their review proposes three strategies to improve science and policy on the fate of microplastics:
- Assess the ability of the biofilm to retain microplastics
- Study the trophic transfer from the substrate-associated biofilms to higher trophic levels
- Study the effects of environmental and anthropogenic stressors on the release dynamics of trapped microplastics
Both SETAC and ET&C are incredibly grateful to both Jana and Colin for organizing this important special series of manuscripts.
Authors’ contact information: hjcallo@umich.edu
