Polymer aging affects the bioavailability of microplastics-associated contaminants in sea urchin embryos

Are Microfibers a Threat to Marine Invertebrates? A Sea Urchin Toxicity Assessment

The rise of "fast fashion" has driven up the production of low-cost, short-lived clothing, significantly increasing global textile fiber production and, consequently, exacerbating environmental pollution. This study investigated the ecotoxicological effects of different types of anthropogenic microfibers-cotton, polyester, and mixed fibers (50% cotton: 50% polyester)-on marine organisms, specifically sea urchin embryos. All tested fibers exhibited toxicity, with cotton fibers causing notable effects on embryonic development even at environmentally relevant concentrations. The research also simulated a scenario where microfibers were immersed in seawater for 30 days to assess changes in toxicity over time. The results showed that the toxicity of microfibers increased with both concentration and exposure duration, with polyester being the most toxic among the fibers tested. Although synthetic fibers have been the primary focus of previous research, this study highlights that natural fibers like cotton, which are often overlooked, can also be toxic due to the presence of harmful additives. These natural fibers, despite decomposing faster than synthetic ones, can persist in aquatic environments for extended periods. The findings underline the critical need for further research on both natural and synthetic microfibers to understand their environmental impact and potential threats to marine ecosystems and sea urchin populations.

Photoaging of polystyrene-based microplastics amplifies inflammatory response in macrophages

The continuous release of municipal and industrial products into the environment poses a growing concern for public health. Among environmental pollutants, polystyrene (PS) stands out as a primary constituent of environmental plastic waste, given its widespread use and high production rates owing to its durability and user-friendly properties. The detection of polystyrene microparticles (PS-MPs) in various living organisms has been well-documented, posing a serious threat due to their potential passage into the human ecosystem. In this manuscript, we aimed to study the toxicological effects of low concentrations of pristine and photoaged PS-MPs in a murine macrophage cell line. To this purpose, PS-MPs were photoaged by indoor exposure to visible light to simulate environmental weathering due to solar irradiation (PS-MPs3h). Physical characterization revealed that the irradiation treatment results in particle degradation and the possible release of nanoparticles. Monocultures of the RAW264.7 cell line were then exposed to PS-MPs and PS-MPs3h at concentrations comparable to experimental measurements from biological samples, to assess cytotoxicity, intracellular oxidative stress, primary genotoxicity, and inflammatory effects. Significant toxicity-related outcomes were observed in cells treated with both pristine PS-MPs and PS-MPs3h even at low concentrations (0,10 μg/ml and 1 μg/ml). PS-MPs3h exhibited greater adverse effects compared to PS-MPs, including reduced cell viability, increased ROS production, elevated DNA damage, and upregulation of IL-6 and NOS2 gene expression. Therefore, we can conclude that changes induced by environmental aging in the physicochemical composition of PS microplastics play a crucial role in the adverse health outcomes associated with microplastic exposure.

Risk assessment of natural and synthetic fibers in aquatic environment: A critical review

Marine microplastics, categorized as primary and secondary, including synthetic microfibers like polyethylene terephthalate (PET), polypropylene (PP) and acrylic (PC), represent a potential environmental concern. The complex classification of these fibers, originating from diverse sources such as textiles and many others commercial goods, prompts a need for understanding their impact on aquatic organisms. This study assesses the ecological risks associated with both natural and synthetic fibers in aquatic ecosystems, focusing on toxicity data and their effects on taxonomic groups like Mollusca, Arthropoda, Echinodermata, Cnidaria, and Chordata. To carry out species sensitivity distribution (SSD) curves, a comprehensive analysis of scientific literature was conducted, collecting toxicity data related to various fibers. The resulting SSDs provide insights into the relative sensitivity of different taxonomic groups. The potential ecological risks were evaluated by comparing measured concentrations in diverse aquatic environments with Predicted No-Effect Concentration (PNEC) values. The calculation of Risk Quotient (RQ) allowed to indicate areas where fibers abundance poses a potential threat to aquatic organisms. The study reveals that nylon fibers can pose the highest toxicity risk, especially in Atlantic and Pacific Ocean, Arabian Gulf and VietNam river. Mollusca emerged as particularly sensitive to different fiber types, likely due to their body structure facilitating the accumulation of microfibers. The research emphasizes the urgent need for further studies to get data to human health risk analysis and to address comprehensive environmental management strategies to address the global issue of microfiber pollution.

Impact of aged and virgin polyethylene microplastics on multi end-points effects of freshwater fish tissues

The buildup of plastic waste in aquatic environments presents serious threats to the environment, wildlife, and ultimately to humans. Specifically, microplastics (MPs) ingestion by aquatic animals leads to adverse physiological and toxicological effects. In addition, discarded MPs undergo aging and degradation processes which affect their morphological properties and chemical composition, enhancing the absorption of environmental pollutants. Under this prism, the present research was conducted to investigate and compare the impact of 'aged' versus pristine low-density polyethylene microplastics (PE-MPs) on various toxicity endpoints as biochemical and molecular parameters in the muscle tissue and liver of the freshwater fish species Perca fluviatilis. In parallel, the morphological, physicochemical, and structural changes occurred in "aged" PE-MPs, (after being exposed to UV radiation for 120 days) were studied, significantly illustrating signs of oxidation and crack propagation at the surface of the studied MPs. Fish were exposed to artificial diet reached with virgin and "aged" PE-MPs, sized 100-180 μm, at concentrations of 1 mg/g of dry food for a period of 15-days. Thereafter, liver and muscle tissues were analyzed in relation to multi oxidative parameters. Compared to the control group, the observed changes in the examined fish included increased activities of antioxidant enzymes, as superoxide dismutase, catalase and glutathione reductase, enhanced concentrations of malondialdehyde, protein carbonylation, HSP70 levels, elevated MAPK phosphorylation, induction of ubiquitin-proteins, as well as heightened levels of Bax/Bcl-2 proteins, caspases and differentiated levels of LC3 II/I, SQSTM1/p62. From the studied biomarkers, apoptosis, ubiquitin and hsp70 levels, showed a more sensitive response against the ingested MPs, followed by autophagy, p38MAPK levels, antioxidant enzymes, MDA and carbonylation levels. The effect of "aged" PE-MPs was more pronounced compared to that of the virgin ones. When evaluating the response of all oxidative stress biomarkers across the studied tissues, the liver demonstrates the highest response for the majority of the biomarkers against both virgin and "aged" PE-MPs. These findings strongly indicate that "aged" MPs activate the antioxidant defence mechanisms and impact the cellular well-being of the examined fish species.

Role of UV radiation and oxidation on polyethylene micro- and nanoplastics: impacts on cadmium sorption, bioaccumulation, and toxicity in fish intestinal cells

This study investigated the role of ultraviolet (UV) radiation and oxidation in high-density polyethylene microplastics (2-15 μm) and nanoplastics (0.2-9.9 μm) (NMPs) on particle chemistry, morphology, and reactivity with cadmium (Cd). Additionally, toxicity of NMPs alone and with Cd was evaluated using RTgutGC cells, a model of the rainbow trout (Oncorhynchus mykiss) intestine. The role on NMPs on Cd bioaccumulation in RTgutGC cells was also evaluated. Dynamic light scattering indicated that after UV radiation NPs agglomerated size increased from 0.8 to 28 µm, and to 8 µm when Cd was added. Oxidized MPs agglomerated size increased from 11 and 7 to 46 and 27 µm in non-UV- and UV-aged oxidized MPs when adding Cd, respectively. Cd-coated particles exhibited generally significantly higher zeta potential than non-Cd-coated particles, while attenuated total reflectance-Fourier transform infrared spectroscopy showed that the functional chemistry of the particles was oxidized and modified after being exposed to UV radiation. Presence of NMPs resulted in a significant decrease in Cd bioaccumulation in RTgutGC cells (100.5-87.9 ng Cd/mg protein) compared to Cd alone (138.1 ng Cd/mg protein), although this was not quite significant for co-exposures with UV-aged NPs (105.7 ng Cd/mg protein). No toxicity was observed in RTgutGC cells exposed to NMPs alone for 24 h. Moreover, co-exposures with Cd indicated that NMPs reduce the toxicity of Cd. Altogether these results show that UV aging enhances NMP surface reactivity, increasing Cd absorption in solution, which resulted in a reduction in Cd bioavailability and toxicity.

Biodegradation of Polystyrene by Plastic-Eating Tenebrionidae Larvae

Polystyrene (PS) is an extremely stable polymer with a relatively high molecular weight and a strong hydrophobic character that makes it highly resistant to biodegradation. In this study, PS was subjected to biodegradation tests by Tenebrio Molitor (T. Molitor) and Zophobas Morio (Z. Morio) larvae. Specifically, six different experimental diets were compared: (i) T. Molitor fed with bran; (ii) T. Molitor fed only PS; (iii) T. Molitor fed only PS treated with H2O2; (iv) Z. Morio fed with bran; (v) Z. Morio fed only PS; and (vi) Z. Morio fed only PS treated with H2O2. Therefore, the mass change of the larvae and the survival rate were measured periodically, while the frass collected after 15 and 30 days was analyzed by different analyses, such as spectroscopy (FTIR), spectrometry (molecular weight and polydispersity), thermal analysis (TGA) and microscopy (scanning electron microscopy observations). The obtained results suggest that in the case of T. Molitor larvae, larvae feeding on bran showed the highest survival rate of ~94% at 30 days, while in the case of the Z. Morio larvae, the highest survival rate was exhibited by larvae eating PS-H2O2. Although not strongly pronounced, the Mw and Mn of PS in the frass of both T. Molitor and Z. Morio larvae decreased over 30 days, suggesting PS biodegradation. Finally, the morphological analysis shows that PS samples isolated from the frass of T. Molitor and Z. Morio larvae showed completely different, rough and irregularly carved surface structures, in comparison to PS before biodegradation.

Effect of Polymer Aging on Uptake/Release Kinetics of Metal Ions and Organic Molecules by Micro- and Nanoplastics: Implications for the Bioavailability of the Associated Compounds

The main driver of the potential toxicity of micro- and nanoplastics toward biota is often the release of compounds initially present in the plastic, i.e., polymer additives, as well as environmentally acquired metals and/or organic contaminants. Plastic particles degrade in the environment via various mechanisms and at different rates depending on the particle size/geometry, polymer type, and the prevailing physical and chemical conditions. The rate and extent of polymer degradation have obvious consequences for the uptake/release kinetics and, thus, the bioavailability of compounds associated with plastic particles. Herein, we develop a theoretical framework to describe the uptake and release kinetics of metal ions and organic compounds by plastic particles and apply it to the analysis of experimental data for pristine and aged micro- and nanoplastics. In particular, we elucidate the contribution of transient processes to the overall kinetics of plastic reactivity toward aquatic contaminants and demonstrate the paramount importance of intraparticulate contaminant diffusion.

Eco-toxicity assessment of industrial by-product-based alkali-activated binders using the sea urchin embryogenesis bioassay

New cement-based materials such as alkali-activated binders (AABs) or geopolymers allow the incorporation of waste or industrial by-products in their formulation, resulting an interesting valorization technique. Therefore, it is essential to inquire about the potential environmental and health impacts throughout their life cycle. In the European context, a minimum aquatic toxicity tests battery has been recommended for construction products, but their potential biological effects on marine ecosystems have not been considered. In this study, three industrial by-products, PAVAL® (PV) aluminum oxide, weathered bottom ash (WBA) resulting from incinerator bottom ash and glass cullet recycling waste (CSP), were evaluated as precursors in the AAB formulation from an environmental point of view. To determine the potential effects on marine environment caused by the leaching of contaminants from these materials into seawater, the leaching test EN-12457-2 and an ecotoxicity test using the model organism sea urchin Paracentrotus lividus were conducted. The percentage of abnormal larval development was selected as endpoint of the toxicity test. Based on the results obtained from the toxicity tests, AABs have less damaging impact (EC₅₀ values: 49.2%-51.9%) on the marine environment in general than raw materials. The results highlight the need to stablish a specific battery of toxicity tests for the environmental assessment of construction products on marine ecosystem.