Scenario-based modelling of changes in chemical intake fraction in Sweden and the Baltic Sea under global change.

The climate in Europe is warming twice as fast as it is across the rest of the globe, and in Sweden annual mean temperatures are forecast to increase by up to 3-6 °C by 2100, with increasing frequency and magnitude of floods, heatwaves, and other extreme weather. These climate change-related environmental factors and the response of humans at the individual and collective level will affect the mobilization and transport of and human exposure to chemical pollutants in the environment. We conducted a literature review of possible future impacts of global change in response to a changing climate on chemical pollutants in the environment and human exposure, with a focus on drivers of change in exposure of the Swedish population to chemicals in the indoor and outdoor environment. Based on the literature review, we formulated three alternative exposure scenarios that are inspired by three of the shared socioeconomic pathways (SSPs). We then conducted scenario-based exposure modelling of the >3000 organic chemicals in the USEtox® 2.0 chemical library, and further selected three chemicals (terbuthylazine, benzo[a]pyrene, PCB-155) from the USEtox library that are archetypical pollutants of drinking water and food as illustrative examples. We focus our modelling on changes in the population intake fraction of chemicals, which is calculated as the fraction of a chemical emitted to the environment that is ingested via food uptake or inhaled by the Swedish population. Our results demonstrate that changes of intake fractions of chemicals are possible by up to twofold increases or decreases under different development scenarios. Changes in intake fraction in the most optimistic SSP1 scenario are mostly attributable to a shift by the population towards a more plant-based diet, while changes in the pessimistic SSP5 scenario are driven by environmental changes such as rain fall and runoff rates.

Computational models to confront the complex pollution footprint of plastic in the environment.

The threat posed by plastic in the environment is poorly characterized due to uncertainties and unknowns about sources, transport, transformation and removal processes, and the properties of the plastic pollution itself. Plastic creates a footprint of particulate pollution with a diversity of composition, size and shape, and a halo of chemicals. In this Perspective, we argue that process-based mass-balance models could provide a platform to synthesize knowledge about plastic pollution as a function of its measurable intrinsic properties.

Environmental Degradation of Microplastics: How to Measure Fragmentation Rates to Secondary Micro- and Nanoplastic Fragments and Dissociation into Dissolved Organics.

Understanding the environmental fate of microplastics is essential for their risk assessment. It is essential to differentiate size classes and degradation states. Still, insights into fragmentation and degradation mechanisms of primary and secondary microplastics into micro- and nanoplastic fragments and other degradation products are limited. Here, we present an adapted NanoRelease protocol for a UV-dose-dependent assessment and size-selective quantification of the release of micro- and nanoplastic fragments down to 10 nm and demonstrate its applicability for polyamide and thermoplastic polyurethanes. The tested cryo-milled polymers do not originate from actual consumer products but are handled in industry and are therefore representative of polydisperse microplastics occurring in the environment. The protocol is suitable for various types of microplastic polymers, and the measured rates can serve to parameterize mechanistic fragmentation models. We also found that primary microplastics matched the same ranking of weathering stability as their corresponding macroplastics and that dissolved organics constitute a major rate of microplastic mass loss. The results imply that previously formed micro- and nanoplastic fragments can further degrade into water-soluble organics with measurable rates that enable modeling approaches for all environmental compartments accessible to UV light.