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MARINFORSKHAV-Marine ressurser og miljø - havmiljø

Microplastics: Long-term Effects of plastics and Additive Chemicals on marine organisms

Alternative title: Mikroplast: Langtidseffekter av plast og tilhørende kjemikalier på marine organismer

Awarded: NOK 7.0 mill.

The increasing amount of microplastics resulting from fragmentation and degradation of marine litter are well documented, but the environmental risks of plastic-associated chemicals are emerging as a much lesser understood threat to the marine environment, especially in the long-term. MicroLEACH´s aim is thus to investigate the long-term effects of microplastics and their additives on a selection of marine species found in the Norwegian environment. For this purpose, >50 thermoplastic and elastomer products from domestic and industrial applications, representing different polymers and a broad range of additive chemical profiles were selected and characterized. First, non-target analytical chemical screening was used to identify the number and amount of plastic-associated chemicals in each product. Next, the baseline toxicity of methanol extracts from each product was investigated using the Bacterial Luminescence Toxicity test and the Algal Growth Inhibition test (Skeletonema pseudocostatum). Although the results from both tests showed a broad range of toxicity across the different plastic products, the responses were generally similar, with most leachate extracts inducing significant toxicity. In general, products containing a higher number of chemicals exhibited higher toxicity, with elastomer-based products exhibiting some of the highest additive levels and toxicities. An assessment on the influence of environmental parameters as temperature, turbulence, salinity and time on leaching processes was also conducted on the 50 consumer products. The results demonstrated a complex interplay between the properties of the chemicals, the polymer matrix and the extrinsic environmental parameters. Five consumer products with high baseline toxicity were selected for more comprehensive toxicity testing using carefully prepared aqueous leachates. These included car tire rubber (CTR), balloons (BL), washing gloves (WG), laboratory gloves (LG) and shoe soles (SS). One product with no baseline toxicity (polyethylene terephthalate water bottle, PET) was also selected. Toxicity tests were conducted on early life stages of Atlantic cod Gadus morhua, copepods Tisbe battagliai, Pacific oysters Crassostrea gigas, sea urchins Strongylocentrotus droebachiensis and the polychaete Capitella spp, as well as in primary cells from mussels Mytilus edulis (haemocytes). Overall, leachate exposure showed significant effects on fertilization, hatching success, and larval development, with WG and SS showing the highest effects. As expected, leachates from the PET bottles were the least toxic. A similar trend was detected for mussel haemocytes, where significant toxicity was recorded even at low concentrations. The toxicity of leachates from CTR after 7 and 14 days of leaching was also tested in marine microalgae. Overall, 14 days leachate had a higher effect on algal growth and photosynthetic capacity, with S. pseudocostatum showing the highest sensitivity. The specific toxicity of CTR to S. pseudocostatum was further analyzed, with ROS formation and oxidative stress being the most affected. Finally, the toxicity of SS leachates was investigated on juvenile mussels M. edulis following a 21-day exposure period, after which clearance rate, condition index and oxidative stress parameters were measured. Overall, clearance rate was the most affected parameter, followed by an increase in lipid peroxidation in mussel tissues. Characterization of chemical profiles of leachates used in the toxicity tests is ongoing, but the results obtained so far indicate that the observed toxicity is highly dependent on the chemical profile and leaching potential of associated additives that can result in species specific sensitivity. To distinguishing between the ecotoxicological effects derived from particles from those resulting from associated chemicals, experiments using cod G. morhua early life stages and adult M. edulis were performed to study the effects of three different components of CTR particles: i) only particles without the associated chemicals (particles), ii) only the chemicals leached out from the particles (leachate), and iii) pristine CTR particles including all the associated chemicals. Leachate and CTR exposures led to significantly lower hatching success, increased mortality and developmental alterations compared to the pre-leached particles, which did not have any significant effect. Mussels on the other hand, showed signs of neurotoxicity and oxidative stress in response to CTR and leachates over time. Overall, these results demonstrate that associated chemicals and not the physical particles are the main CTR toxicity drivers for the endpoints studied. Further tests will continue to evaluate the potential effects of these particles and their isolated leachates on other species with ecological and commercial importance. We will also try to understand how these accumulate in organisms and if they are transferred along marine food chains.

Increasing amounts of microplastics (MPs) and associated chemicals, a result from degradation of marine litter, are one of the unknown threats to the marine environment. This project will investigate the long-term effects of MPs to a range of environmentally and commercially relevant marine species from the Norwegian environment and identify the importance of plastic chemical additives to the observable effects. To improve environmental relevance, studies will be conducted with irregular shaped MP particles and fragments generated by cryo-milling post-production and post-consumer MP using realistic and future predicted concentrations. A detailed characterisation of test materials will be conducted using state-of the-art methods in addition to leaching studies of plastic additive chemicals under environmentally relevant conditions (e.g. seawater, synthetic gut fluid). Through innovative approaches, the ecotoxicity studies will attempt to distinguish between long-term effects derived directly from MPs and those resulting from the associated additive chemicals to identify potential risks at the individual and ecosystem level. MicroLEACH will also study MPs uptake, accumulation and elimination routes in test species and determine the associated toxicokinetics to facilitate an improved interpretation of effect data. The project will culminate in a series of trophic transfer-level studies to investigate the potential for bioaccumulation/biomagnification of MPs and associated additives in a Norwegian marine food-web. In a final step, the experimental data will be used to identify test systems for future development of regulatory guidelines for effect assessment of MPs and additive chemicals. MicroLEACH will establish a communication platform towards multiple stakeholders to ensure dissemination of the knowledge generated, with a focus on public engagement, to increase awareness regarding marine litter and ensure a better protection and mitigation of the marine ecosystem.

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MARINFORSKHAV-Marine ressurser og miljø - havmiljø