Effects of Leachates from UV-Weathered Microplastic in Cell-Based Bioassays

Abstract

Standard ecotoxicological testing of microplastic does not provide insight into the influence that environmental weathering by, e.g., UV light has on related effects. In this study, we leached chemicals from plastic into artificial seawater during simulated UV-induced weathering. We tested largely additive-free preproduction polyethylene, polyethylene terephthalate, polypropylene, and polystyrene and two types of plastic obtained from electronic equipment as positive controls. Leachates were concentrated by solid-phase extraction and dosed into cell-based bioassays that cover (i) cytotoxicity; (ii) activation of metabolic enzymes via binding to the arylhydrocarbon receptor (AhR) and the peroxisome proliferator-activated receptor (PPARγ); (iii) specific, receptor-mediated effects (estrogenicity, ERα); and (iv) adaptive response to oxidative stress (AREc32). LC-HRMS analysis was used to identify possible chain-scission products of polymer degradation, which were then tested in AREc32 and PPARγ. Explicit activation of all assays by the positive controls provided proof-of-concept of the experimental setup to demonstrate effects of chemicals liberated during weathering. All plastic leachates activated the oxidative stress response, in most cases with increased induction by UV-treated samples compared to dark controls. For PPARγ, polyethylene-specific effects were partially explained by the detected dicarboxylic acids. Since the preproduction plastic showed low effects often in the range of the blanks future studies should investigate implications of weathering on end consumer products containing additives.

Effects of Polyester Microfibers on Microphytobenthos and Sediment-Dwelling Infauna

“…The results of the univariate and multivariate analyses suggest that light conditions influence the interaction between photosynthesizing MPB, infaunal burrowing, nutrient pools and microfibers in the sediment. UV weathering is an important mechanism by which plastics degrade in the natural environment 111 and previous studies have observed oxidative stress in cell-based bioassays due to the leachates from weathered polyethylene terephthalate (PET) 112 . UV weathering of the plastic fibers can result in the liberation of chemicals from the plastic into the surrounding environment 112 .…”

Variability in Toxicity of Plastic Leachates as a Function of Weathering and Polymer Type: A Screening Study with the Copepod Nitocra spinipes

“…Rochman et al (2014) have previously observed that naturally weathered PE has more endocrine disruptive effects compared to virgin PE. Gewert et al (2018) studied polymer degradation products released to water under UV light exposure, using the same Goodfellow plastic pellets used in this study, and identified mostly oligomeric dicarboxylic acids; but these only partially explained toxicity observed in cell-based bioassays (Rummel et al, 2019). The increased toxicity observed for some old materials in this study might be caused by prior leaching of additives that are UV stabilizers.…”

“…According to the distributor, these pellets contain few additives at low levels. These same pellets have been used in toxicity screening experiments using cell-based bioassays (Rummel et al, 2019). A fraction of these plastic pellets was deployed in floating mesocosms in the Oslo fjord near the town of Drøback for seven months (April-October 2017).…”

From plastics to microplastics and organisms

“…This provides a vector for the transportation of these pollutants by particles floating in seawater over long distances. After the ingestion by different animals, such pollutants can be leached from the particles and enter animal tissues, where they can disrupt normal biochemical processes in the cells [55]. Microplastic particles also represent a source of hormone‐disrupting compounds themselves due to additives that are added during the manufacturing process to achieve particular characteristics.…”