Reviewing the current state of legacy POP-brominated flame retardants in plastic childcare products and toys: a scoping review protocol.

BACKGROUND: Due to their adverse environmental and health impacts, brominated flame retardants (BFRs) are listed in Annex A of the Stockholm Convention for global elimination of production and use. Their health impacts include endocrine disruption, cancer, reproductive effects, and neurobehavioral and developmental disorders in children. Emerging literature suggests that legacy POP-BFRs are increasingly found in consumer products, including those used for and by children. The presence of legacy POP-BFRs in children's products is a big concern. Children are more vulnerable to chemical exposure risks than adults because their bodies are still developing and fragile. The rising problem is contributed to by the global push towards a circular economy that encourages responsible production and consumption by practising the recycling of waste materials. Waste materials such as electronic and electrical equipment plastics often contain POP-BFRs. POP-BFRs in waste materials are transferred into new products through recycling. The recycled products have become a potential source of exposure to legacy POP-BFRs for vulnerable populations, particularly children. Our scoping review aims to map and summarise the emerging literature. This information is needed to inform evidence-based policies to protect children from toxic exposures. METHODS: Our scoping review will follow a methodological framework proposed by Arksey and O'Malley. Peer-reviewed and grey literature on the topic will be retrieved from electronic databases and other relevant sites. Two reviewers will screen titles and abstracts, followed by a full-text review of studies for eligibility based on the established inclusion and exclusion criteria. Data will be extracted, and findings will be mapped in a table according to study settings, types of children's products tested, and concentration of legacy POP-BFRs in contaminated products. A map chart will be created to display how contaminated products are spread globally. DISCUSSION: Because of their unique vulnerabilities, children continue to suffer disproportionate exposures to toxic chemicals compared to adults. Information on potential exposures, particularly for children, is crucial to make evidence-based policies. We intend to map and summarise the emerging literature on legacy POP-BFRs in children's products. Findings will be disseminated to relevant stakeholders through publishing in a peer-reviewed scientific journal and policy briefs. SYSTEMATIC REVIEW REGISTRATION: The protocol is registered with the Open Science Framework ( https://doi.org/10.17605/OSF.IO/7KDE5 ).

Toxicological review of micro- and nano-plastics in aquatic environments: Risks to ecosystems, food web dynamics and human health.

The increase of micro- and nano-plastics (MNPs) in aquatic environments has become a significant concern due to their potential toxicological effects on ecosystems, food web dynamics, and human health. These plastic particles emerge from a range of sources, such as the breakdown of larger plastic waste, consumer products, and industrial outputs. This review provides a detailed report of the transmission and dangers of MNPs in aquatic ecosystems, environmental behavior, and interactions within aquatic food webs, emphasizing their toxic impact on marine life. It explores the relationship between particle size and toxicity, their distribution in different tissues, and the process of trophic transfer through the food web. MNPs, once consumed, can be found in various organs, including the digestive system, gills, and liver. Their consumption by lower trophic level organisms facilitates their progression up the food chain, potentially leading to bioaccumulation and biomagnification, thereby posing substantial risks to the health, reproduction, and behavior of aquatic species. This work also explores how MNPs, through their persistence and bioaccumulation, pose risks to aquatic biodiversity and disrupt trophic relationships. The review also addresses the implications of MNPs for human health, particularly through the consumption of contaminated seafood, highlighting the direct and indirect pathways through which humans are exposed to these pollutants. Furthermore, the review highlights the recommendations for future research directions, emphasizing the integration of ecological, toxicological, and human health studies to inform risk assessments and develop mitigation strategies to address the global challenge of plastic pollution in aquatic environments.

Weathering increases the acute toxicity of plastic pellets leachates to sea-urchin larvae-a case study with environmental samples.

Microplastics, particles under 5 mm, pervade aquatic environments, notably in Tarragona's coastal region (NE Iberian Peninsula), hosting a major plastic production complex. To investigate weathering and yellowness impact on plastic pellets toxicity, sea-urchin embryo tests were conducted with pellets from three locations-near the source and at increasing distances. Strikingly, distant samples showed toxicity to invertebrate early stages, contrasting with innocuous results near the production site. Follow-up experiments highlighted the significance of weathering and yellowing in elevated pellet toxicity, with more weathered and colored pellets exhibiting toxicity. This research underscores the overlooked realm of plastic leachate impact on marine organisms while proposes that prolonged exposure of plastic pellets in the environment may lead to toxicity. Despite shedding light on potential chemical sorption as a toxicity source, further investigations are imperative to comprehend weathering, yellowing, and chemical accumulation in plastic particles.

Unveiling the molecular mechanisms of size-dependent effect of polystyrene micro/nano-plastics on Chlamydomonas reinhardtii through proteomic profiling.

Microplastics have become a prevalent environmental pollutant due to widespread release and production. Algae, as primary producers, play a crucial role in maintaining the ecological balance of freshwater environments. Despite reports on the inhibition of microalgae by microplastics, the size-dependent effects on microalgae and associated molecular mechanism remain poorly understood. This study investigates the impacts of three polystyrene micro/nano-plastics (PS-MNPs) with different sizes (100 nm, 350 nm, and 6 µm) and concentrations (25-200 mg/L) on Chlamydomonas reinhardtii (C. reinhardtii) throughout its growth period. Results reveal size- and concentration-dependent growth inhibition and induction of oxidative stress by PS-MNPs, with microalgae exhibiting increased vulnerability to smaller-sized and higher-concentration PS-MNPs. Proteomics analysis elucidates the size-dependent suppression of proteins involved in the photosynthesis process by PS-MNPs. Photosynthetic activity assays demonstrate that smaller PS-MNPs more significantly reduce chlorophyll content and the maximal photochemical efficiency of photosystem II. Finally, electron microscope and Western blot assays collectively confirm the size effect of PS-MNPs on microalgae growth is attributable to suppressed protein expression rather than shading effects. This study contributes to advancing our understanding of the intricate interactions between micro/nano-plastics and algae at the molecular level, emphasizing the efficacy of proteomics in dissecting the mechanistic aspects of microplastics-induced biological effects on environmental indicator organisms.

Marine degradation and ecotoxicity of conventional, recycled and compostable plastic bags.

Plastic bags are currently a major component of marine litter, causing aesthetical nuisance, and undesirable effects on marine fauna that ingest them or are entangled. Plastic litter also rises concern on the ecotoxicological effects due to the potential toxicity of the chemical additives leached in aquatic environments. Conventional plastic bags are made of polyethylene, either from first use or recycled, but regulations restricting single-use plastics and limiting lightweight carrier bags (<50 µm thickness) have fostered the replacement of thin PE bags by compostable materials advertised as safer for the environment. In this study, we assess the degradation of commercially available plastic bags in marine conditions at two scales: aquariums (60 days) and outdoors flow-through mesocosm (120 days). Strength at break point and other tensile strength parameters were used as ecologically relevant endpoints to track mechanical degradation. Ecotoxicity has been assessed along the incubation period using the sensitive Paracentrotus lividus embryo test. Whereas PE bags did not substantially lose their mechanical properties within the 60 d aquarium exposures, compostable bags showed remarkable weight loss and tensile strength decay, some of them fragmenting in the aquarium after 3-4 weeks. Sediment pore water inoculum promoted a more rapid degradation of compostable bags, while nutrient addition pattern did not affect the degradation rate. Longer-term mesocosms exposures supported these findings, as well as pointed out the influence of the microbial processes on the degradation efficiency of compostable/bioplastic bags. Compostable materials, in contrast toPE, showed moderate toxicity on sea-urchin larvae, partially associated to degradation of these materials, but the environmental implications of these findings remain to be assessed. These methods proved to be useful to classify plastic materials, according to their degradability in marine conditions, in a remarkably shorter time than current standard tests and promote new materials safer for the marine fauna.

Down to size: Exploring the influence of plastic particle Dimensions on physiological and nervous responses in early-stage zebrafish.

The chorion is the first protective barrier set to prevent numerous pollutants from damaging the developing embryo. However, depending on their size, some nanoplastics (NPs) can pass through this barrier and reach the embryo, while all microplastics (MPs) remain on the outside. This study brings a straight approach to compare MPs and NPs, and assess their direct and indirect effects on zebrafish embryos and larvae. Zebrafish eggs were exposed before 2 h post fertilization (hpf) to polystyrene MPs (5 µm) and NPs (250 nm) at a concentration of 1000 µg/L until 96 hpf. Physiotoxicity and neurotoxicity were assessed prior and post-hatching through several biomarkers. Response to hypoxia (upregulation of hif-1aa and hif-1ab) were found in embryos exposed to MPs, and partly found in those exposed to NPs. Embryos exposed to NPs showed significant tachycardia, reduced O2 consumption and increased apoptosis in the eyes, whereas MPs affected the expressions of all genes related to the neurodevelopment of embryos (elavl3, pax2a, pax6a, act1b). Post-hatching, physiological responses were muted. MPs and NPs exposures ended by evaluating larval behaviours during dark-and-light cycles. Both sizes of plastic particles negatively affected the visual motor response (VMR) and vibrational startle response (VSR). Thigmotaxis levels were significantly increased by NPs whereas MPs showed anxiolytic properties. This study shows that both MPs and NPs affect the physiology and neurodevelopment of zebrafish at different levels, before and after hatching.

The triple exposure nexus of microplastic particles, plastic-associated chemicals, and environmental pollutants from a human health perspective.

The presence of microplastics (MPs) is increasing at a dramatic rate globally, posing risks for exposure and subsequent potential adverse effects on human health. Apart from being physical objects, MP particles contain thousands of plastic-associated chemicals (i.e., monomers, chemical additives, and non-intentionally added substances) captured within the polymer matrix. These chemicals are often migrating from MPs and can be found in various environmental matrices and human food chains; increasing the risks for exposure and health effects. In addition to the physical and chemical attributes of MPs, plastic surfaces effectively bind exogenous chemicals, including environmental pollutants (e.g., heavy metals, persistent organic pollutants). Therefore, MPs can act as vectors of environmental pollution across air, drinking water, and food, further amplifying health risks posed by MP exposure. Critically, fragmentation of plastics in the environment increases the risk for interactions with cells, increases the presence of available surfaces to leach plastic-associated chemicals, and adsorb and transfer environmental pollutants. Hence, this review proposes the so-called triple exposure nexus approach to comprehensively map existing knowledge on interconnected health effects of MP particles, plastic-associated chemicals, and environmental pollutants. Based on the available data, there is a large knowledge gap in regard to the interactions and cumulative health effects of the triple exposure nexus. Each component of the triple nexus is known to induce genotoxicity, inflammation, and endocrine disruption, but knowledge about long-term and inter-individual health effects is lacking. Furthermore, MPs are not readily excreted from organisms after ingestion and they have been found accumulated in human blood, cardiac tissue, placenta, etc. Even though the number of studies on MPs-associated health impacts is increasing rapidly, this review underscores that there is a pressing necessity to achieve an integrated assessment of MPs' effects on human health in order to address existing and future knowledge gaps.

The combined toxicity of polystyrene nano/micro-plastics and triphenyl phosphate (TPHP) on HepG2 cells.

Combined toxicity is a critical concern during the risk assessment of environmental pollutants. Due to the characteristics of strong hydrophobicity and large specific surface area, microplastics (MPs) and nanoplastics (NPs) have become potential carriers of organic pollutants that may pose a health risk to humans. The co-occurrence of organic pollutants and MPs would cause adverse effects on aquatic organism, while the information about combined toxicity induced by organophosphorus flame retardants and MPs on human cells was limited. This study aimed to reveal the toxicity effects of co-exposure to triphenyl phosphate (TPHP) and polystyrene (PS) particles with micron-size/nano-size on HepG2 cell line. The adsorption behaviors of TPHP on PS particles was observed, with the PS-NP exhibiting a higher adsorption capacity. The reactive oxygen species generation, mitochondrial membrane potential depolarization, lactate dehydrogenase release and cell apoptosis proved that PS-NPs/MPs exacerbated TPHP-induced cytotoxicity. The particle size of PS would affect the toxicity to HepG2 cells that PS-NP (0.07 µm) exhibited more pronounced combined toxicity than PS-MP (1 µm) with equivalent concentrations of TPHP. This study provides fundamental insights into the co-toxicity of TPHP and PS micro/nanoplastics in HepG2 cells, which is crucial for validating the potential risk of combined toxicity in humans.

Comparing the impact of microplastics derived from a biodegradable and a conventional plastic mulch on plant performance.

Agricultural lands have been identified as plastic sinks. One source is plastic mulches, which are a source of micro- and nano-sized plastics in agricultural soils. Because of their persistence, there is now a push towards developing biodegradable plastics, which are designed to undergo (partial) breakdown after entering the environment. Yet, limited research has investigated the impacts of both conventional and biodegradable plastics on distinct plants. Moreover, comparisons among studies are difficult due to differences in experimental design. This study directly compares the effects of artificially weathered conventional polyethylene (PE) and starch-based biodegradable polybutylene adipate terephthalate (PBAT) on four food crops, including two monocots (barley, Hordeum vulgare, and wheat, Triticum aestivum L.) and two dicots (carrot, Daucus carota, and lettuce, Lactuca sativa L.). We investigated the effects of environmentally relevant low, medium, and high (0.01 %, 0.1 %, 1 % w/w) concentrations of PE and starch-PBAT blend on seed germination (acute toxicity), and subsequently on plant growth and chlorophyll through a pot-plant experiment (chronic toxicity). Germination of all species was not affected by both plastics. However, root length was reduced for lettuce and wheat seedlings. No other effects were recorded on monocots. We observed a reduction in shoot length and bud wet weight of carrot seedlings for the highest concentration of PE and starch-PBAT blend. Chronic exposure resulted in a significant decrease in shoot biomass of barley and lettuce. Additionally, a positive increase in the number of leaves of lettuce was observed for both plastics. Chlorophyll content was increased in lettuce when exposed to PE and starch-PBAT blend. Overall, adverse effects in dicots were more abundant than in monocots. Importantly, we found that the biodegradable plastic caused more commonly adverse effects on plants compared to conventional plastic, which was confirmed by a mini-review of studies directly comparing the impact of conventional and biodegradable microplastics.

Ecotoxicity evaluation using the avoidance response of the oribatid mite Oppia nitens (Acari: Oribatida) in bioplastics, microplastics, and contaminated Superfund field sites.

Bioplastics are considered sustainable alternatives to conventional microplastics which are recognized as a threat to terrestrial ecosystems. However, little is known about the potential ecotoxicological effects of bioplastics on soil fauna and ecosystems. The present study assessed the toxicity of microplastics [Polystyrene (PS), Polyethylene (PE)] and bioplastics [Polyvinyl alcohol (PVA), Sodium polyacrylate (NaPa) on a key soil fauna Oppia nitens, a soil oribatid mite, and investigated the ecological relevance of O. nitens avoidance response as a valuable tool for the risk assessment of contaminated soils such as the Superfund sites. Findings showed that the mites' net response indicated avoidance behavior such that in most cases as concentrations of micro- and bioplastics increased, so did the avoidance responses. The avoidance EC50 endpoints showed PS < PE < PVA < NaPa, indicating higher deleterious effects of microplastics. High toxicity of PS in soils to O. nitens at EC50 of 165 (±25) mg/kg compared to bioplastics and other known contaminants poses an enormous threat to soil. For bioplastics in this study, there were no significant avoidances at concentrations up to 16,200 mg/kg compared to PS and PE which showed avoidance responses at 300 and 9000 mg/kg respectively, implying that bioplastics might be relatively safer to soil mites compared to conventional microplastics. Also, results indicated that long-term heavy metal pollution such as in contaminated Superfund sites decreased microbial biomass; a useful bioindicator of soil pollution. Furthermore, O. nitens avoidance of heavy metals contaminated sites demonstrated the ecological relevance of avoidance response test when assessing the habitat integrity of contaminated soil. The present study further supports the inclusion of the oribatid mite, O. nitens in the ecological risk assessment of contaminants in soil.

Micro- and nanoplastics concepts for particle and fibre toxicologists.

Micro- and nanoplastic particles (MNP) are omnipresent as either pollution or intentionally used in consumer products, released from packaging or even food. There is an exponential increase in the production of plastics. With the realization of bioaccumulation in humans, toxicity research is quickly expanding. There is a rapid increase in the number of papers published on the potential implications of exposure to MNP which necessitates a call for quality criteria to be applied when doing the research. At present, most papers on MNP describe the effects of commercially available polymer (mostly polystyrene) beads that are typically not the MNP of greatest concern. This is not a fault of the research community, necessarily, as the MNPs to which humans are exposed are usually not available in the quantities needed for toxicological research and innovations are needed to supply environmentally-relevant MNP models. In addition, like we have learned from decades of research with particulate matter and engineered nanomaterials, sample physicochemical characteristics and preparation can have major impacts on the biological responses and interpretation of the research findings. Lastly, MNP dosimetry may pose challenges as (1) we are seeing early evidence that plastics are already in the human body at quite high levels that may be difficult to achieve in acute in vitro studies and (2) plastics are already in the diets fed to preclinical models. This commentary highlights the pitfalls and recommendations for particle and fibre toxicologists that should be considered when performing and disseminating the research.

Developmental toxicity of pre-production plastic pellets affects a large swathe of invertebrate taxa.

Microplastics pose risks to marine organisms through ingestion, entanglement, and as carriers of toxic additives and environmental pollutants. Plastic pre-production pellet leachates have been shown to affect the development of sea urchins and, to some extent, mussels. The extent of those developmental effects on other animal phyla remains unknown. Here, we test the toxicity of environmental mixed nurdle samples and new PVC pellets for the embryonic development or asexual reproduction by regeneration of animals from all the major animal superphyla (Lophotrochozoa, Ecdysozoa, Deuterostomia and Cnidaria). Our results show diverse, concentration-dependent impacts in all the species sampled for new pellets, and for molluscs and deuterostomes for environmental samples. Embryo axial formation, cell specification and, specially, morphogenesis seem to be the main processes affected by plastic leachate exposure. Our study serves as a proof of principle for the potentially catastrophic effects that increasing plastic concentrations in the oceans and other ecosystems can have across animal populations from all major animal superphyla.

White tides: The plastic nurdles problem.

The proliferation of plastic pollution, particularly from nurdles (small plastic pellets used in manufacturing), poses significant environmental and ecological risks. Originating with the invention of Bakelite in 1907 and escalating post-World War II with advanced petrochemical technologies, nurdles are the second largest source of primary microplastic pollution globally. Each year an estimated 445,970 tonnes of nurdles enter the environment worldwide. Nurdle spills, such as those along Spain's Galician coast and other global incidents, underline the need for improved spill response, preventive measures, and international regulatory coordination. The environmental impact of nurdles, compared to more visible oil spills, is insidious and long-lasting due to their persistence and widespread dispersion. Current regulations, like the International Maritime Organization's (IMO) guidelines, reveal gaps in enforcement and fail to fully address the long-term consequences of spills. Recent technological innovations and policy interventions aim to mitigate risks, but there's an urgent need for coordinated global action, stricter controls, and investment in biodegradable alternatives to safeguard marine environments and ensure ecological sustainability.

Nrf2-mediated ferroptosis of spermatogenic cells involved in male reproductive toxicity induced by polystyrene nanoplastics in mice. / Nrf2ä»‹å¯¼çš„ç”Ÿç²¾ç»†èƒžé“æ­»äº¡å‚ä¸Žäº†èšè‹¯ä¹™çƒ¯çº³ç±³å¡‘æ–™å¯¼è‡´çš„å°é¼ é›„æ€§ç”Ÿæ®–æ¯’æ€§.

Microplastics (MPs) and nanoplastics (NPs) have become hazardous materials due to the massive amount of plastic waste and disposable masks, but their specific health effects remain uncertain. In this study, fluorescence-labeled polystyrene NPs (PS-NPs) were injected into the circulatory systems of mice to determine the distribution and potential toxic effects of NPs in vivo. Interestingly, whole-body imaging found that PS-NPs accumulated in the testes of mice. Therefore, the toxic effects of PS-NPs on the reproduction systems and the spermatocytes cell line of male mice, and their mechanisms, were investigated. After oral exposure to PS-NPs, their spermatogenesis was affected and the spermatogenic cells were damaged. The spermatocyte cell line GC-2 was exposed to PS-NPs and analyzed using RNA sequencing (RNA-seq) to determine the toxic mechanisms; a ferroptosis pathway was found after PS-NP exposure. The phenomena and indicators of ferroptosis were then determined and verified by ferroptosis inhibitor ferrostatin-1 (Fer-1), and it was also found that nuclear factor erythroid 2-related factor 2 (Nrf2) played an important role in spermatogenic cell ferroptosis induced by PS-NPs. Finally, it was confirmed in vivo that this mechanism of Nrf2 played a protective role in PS-NPs-induced male reproductive toxicity. This study demonstrated that PS-NPs induce male reproductive dysfunction in mice by causing spermatogenic cell ferroptosis dependent on Nrf2.

Polyethylene, whose surface has been modified by UV irradiation, induces cytotoxicity: A comparison with microplastics found in beaches.

Microplastics, plastic particles 5 mm or less in size, are abundant in the environment; hence, the exposure of humans to microplastics is a great concern. Usually, the surface of microplastics found in the environment has undergone degradation by external factors such as ultraviolet rays and water waves. One of the characteristics of changes caused by surface degradation of microplastics is the introduction of oxygen-containing functional groups. Surface degradation alters the physicochemical properties of plastics, suggesting that the biological effects of environmentally degraded plastics may differ from those of pure plastics. However, the biological effects of plastics introduced with oxygen-containing functional groups through degradation are poorly elucidated owing to the lack of a plastic sample that imitates the degradation state of plastics found in the environment. In this study, we investigated the degradation state of microplastics collected from a beach. Next, we degraded a commercially available polyethylene (PE) particles via vacuum ultraviolet (VUV) irradiation and showed that chemical surface state of PE imitates that of microplastics in the environment. We evaluated the cytotoxic effects of degraded PE samples on immune and epithelial cell lines. We found that VUV irradiation was effective in degrading PE within a short period, and concentration-dependent cytotoxicity was induced by degraded PE in all cell lines. Our results indicate that the cytotoxic effect of PE on different cell types depends on the degree of microplastic degradation, which contributes to our understanding of the effects of PE microplastics on humans.

Temperature fluctuation in soil alters the nanoplastic sensitivity in wheat.

Despite the wide acknowledgment that plastic pollution and global warming have become serious agricultural concerns, their combined impact on crop growth remains poorly understood. Given the unabated megatrend, a simulated soil warming (SWT, +4 °C) microcosm experiment was carried out to provide a better understanding of the effects of temperature fluctuations on wheat seedlings exposed to nanoplastics (NPs, 1 g L-1 61.71 ± 0.31 nm polystyrene). It was documented that SWT induced oxidative stress in wheat seedlings grown in NPs-contaminated soil, with an 85.56 % increase in root activity, while decreasing plant height, fresh weight, and leaf area by 8.72 %, 47.68 %, and 15.04 % respectively. The SWT also resulted in reduced photosynthetic electron-transfer reaction and Calvin-Benson cycle in NPs-treated plants. Under NPs, SWT stimulated the tricarboxylic acid (TCA) metabolism and bio-oxidation process. The decrease in photosynthesis and the increase in respiration resulted in an 11.94 % decrease in net photosynthetic rate (Pn). These results indicated the complicated interplay between climate change and nanoplastic pollution in crop growth and underscored the potential risk of nanoplastic pollution on crop production in the future climate.

Biodegradable microplastics: Uptake by and effects on the rockpool shrimp Palaemon elegans (Crustacea: Decapoda).

Ingestion of microplastics can lead to deleterious consequences for organisms, as documented by numerous laboratory studies. The current knowledge is based on a multitude of effect studies, conducted with conventional fossil-based and non-degradable plastics. However, there is a lack of information about the acceptance and the effects of novel bio-based and biodegradable plastics. Biodegradable plastics are considered an alternative to conventional plastics and are showing rapidly growing production rates. Biodegradable plastics can disperse into the environment in the same way as conventional plastics do, becoming available to marine organisms. This study aims to provide new insights into the uptake and effects of biodegradable microplastics on marine invertebrates. Rockpool shrimp, Palaemon elegans, were fed with algal flakes coated with polylactic acid (PLA), polyhydroxybutyrate-co-valerate (PHBV) and conventional low-density polyethylene (LDPE) microparticles. Live observations showed that all of the different types of microplastics were ingested. After dissection of the shrimp, less LDPE particles were found in the stomachs than PLA and PHBV particles. This indicates a longer retention time of biodegradable microplastics compared to conventional microplastics. Presumably, less LDPE particles were ingested or evacuated from the stomach, probably by regurgitation. The ingestion of microparticles of all types of plastics induced enzymatic activity of short-chain carboxylesterases in the midgut glands of the shrimp. However, only PLA induced enzymatic activity of medium-chain carboxylesterases. Palaemon elegans showed no oxidative stress response after ingestion of microparticles, irrespective of polymer type. From our results we conclude that biodegradable plastics might have different effects than conventional plastics. The longer retention times of biodegradable plastics might enhance exposure to leaching additives and other harmful substances. Our study provides new insights into how biodegradable plastics might affect aquatic fauna and indicate that the use of biodegradable plastics needs to be reconsidered to some extent.

The promoting effects of soil microplastics on alien plant invasion depend on microplastic shape and concentration.

Both alien plant invasions and soil microplastic pollution have become a concerning threat for terrestrial ecosystems, with consequences on the human well-being. However, our current knowledge of microplastic effects on the successful invasion of plants remains limited, despite numerous studies demonstrating the direct and indirect impacts of microplastics on plant performance. To address this knowledge gap, we conducted a greenhouse experiment involving the mixtures of soil and low-density polyethylene (LDPE) microplastic pellets and fragments at the concentrations of 0, 0.5 % and 2.0 %. Additionally, we included Solidago decurrens (native plant) and S. canadensis (alien invasive plant) as the target plants. Each pot contained an individual of either species, after six-month cultivation, plant biomass and antioxidant enzymes, as well as soil properties including soil moisture, pH, available nutrient, and microbial biomass were measured. Our results indicated that microplastic effects on soil properties and plant growth indices depended on the Solidago species, microplastic shapes and concentrations. For example, microplastics exerted positive effects on soil moisture of the soil with native species but negative effects with invasive species, which were impacted by microplastic shapes and concentrations, respectively. Microplastics significantly impacted catalase (P < 0.05) and superoxide dismutase (P < 0.01), aboveground biomass (P < 0.01), and belowground/aboveground biomass (P < 0.01) of the native species depending on microplastic shapes, but no significant effects on those of the invasive species. Furthermore, microplastics effects on soil properties, nutrient, nutrient ratio, and plant antioxidant enzyme activities contributed to plant biomass differently among these two species. These results suggested that the microplastics exerted a more pronounced impact on native Solidago plants than the invasive ones. This implies that the alien invasive species displays greater resistance to microplastic pollution, potentially promoting their invasion. Overall, our study contributes to a better understanding of the promoting effects of microplastic pollution on plant invasion.

Unveiling the detrimental effects of polylactic acid microplastics on rice seedlings and soil health.

The environmental impact of biodegradable polylactic acid microplastics (PLA-MPs) has become a global concern, with documented effects on soil health, nutrient cycling, water retention, and crop growth. This study aimed to assess the repercussions of varying concentrations of PLA-MPs on rice, encompassing aspects such as growth, physiology, and biochemistry. Additionally, the investigation delved into the influence of PLA-MPs on soil bacterial composition and soil enzyme activities. The results illustrated that the highest levels of PLA-MPs (2.5%) impaired the photosynthesis activity of rice plants and hampered plant growth. Plants exposed to the highest concentration of PLA-MPs (2.5%) displayed a significant reduction of 51.3% and 47.7% in their root and shoot dry weights, as well as a reduction of 53% and 49% in chlorophyll a and b contents, respectively. The activities of catalase (CAT), superoxide dismutase (SOD), peroxidase (POD), and ascorbate peroxidase (APX) in rice leaves increased by 3.1, 2.8, 3.5, and 5.2 folds, respectively, with the highest level of PLA-MPs (2.5%). Soil enzyme activities, such as CAT, urease, and dehydrogenase (DHA) increased by 19.2%, 10.4%, and 22.5%, respectively, in response to the highest level of PLA-MPs (2.5%) application. In addition, PLA-MPs (2.5%) resulted in a remarkable increase in the relative abundance of soil Proteobacteria, Nitrospirae, and Firmicutes by 60%, 31%, and 98.2%, respectively. These findings highlight the potential adverse effects of PLA-MPs on crops and soils. This study provides valuable insights into soil-rice interactions, environmental risks, and biodegradable plastic regulation, underscoring the need for further research.

Comparison of the potential toxicity induced by microplastics made of polyethylene terephthalate (PET) and polylactic acid (PLA) on the earthworm Eiseniafoetida.

A growing number of studies have demonstrated that microplastic (MP) contamination is widespread in terrestrial ecosystems. A wide array of MPs made of conventional, fossil-based polymers differing in size and shape has been detected in soils worldwide. Recently, also MPs made of bioplastics have been found in soils, but there is a dearth of information concerning their toxicity on soil organisms. This study aimed at exploring the potential toxicity induced by the exposure for 28 days to irregular shaped and differently sized MPs made of a fossil-based (polyethylene terephthalate - PET) and a bioplastic (polylactic acid - PLA) polymer on the earthworm Eisenia foetida. Two amounts (1 g and 10 g/kg of soil, corresponding to 0.1% and 1% of soil weight) of both MP types were administered to the earthworms. A multi-level approach was used to investigate the MP-induced effects at sub-individual and individual level. Changes in the activity of antioxidant and detoxifying enzymes, as well as in lipid peroxidation levels, were investigated at specific time-points (i.e., 7, 14, 21 and 28 days) as sub-individual responses. Histological analyses were performed to assess effects at tissue level, while the change in digging activity was considered as a proxy of behavioral effects. Earthworms ingested MPs made of both the polymers. MPs made of PET did not induce any adverse effect at none of the biological levels. In contrast, MPs made of PLA caused the modulation of earthworms' oxidative status as showed by a bell-shaped activity of superoxide dismutase coupled with an increase in glutathione peroxidase activity. However, neither oxidative and tissue damage, nor behavioral alteration occurred. These findings suggest that the exposure to bio-based MPs can cause higher toxicity compared to fossil-based MPs.