Plastics and biodegradable plastics: ecotoxicity comparison between polyvinylchloride and Mater-Bi® micro-debris in a freshwater biological model

Size dependent uptake and trophic transfer of polystyrene microplastics in unicellular freshwater eukaryotes

Microplastics (MP) have become a well-known and widely investigated environmental pollutant. Despite the huge amount of new studies investigating the potential threat posed by MP, the possible uptake and trophic transfer in lower trophic levels of freshwater ecosystems remains understudied. This study aims to investigate the internalization and potential trophic transfer of fluorescent polystyrene (PS) beads (0.5 μm, 3.6 × 108 particles/mL; 6 μm, 2.1 × 105 particles/mL) and fragments (<30 μm, 5 × 103 particles/mL) in three unicellular eukaryotes. This study focuses on the size-dependent uptake of MP by two freshwater Ciliophora, Tetrahymena pyriformis, Paramecium caudatum and one Amoebozoa, Amoeba proteus, serving also as predator for experiments on potential trophic transfer. Size-dependent uptake of MP in all three unicellular eukaryotes was shown. P. caudatum is able to take up MP fragments up to 27.7 μm, while T. pyriformis ingests particles up to 10 μm. In A. proteus, small MP (PS0.5μm and PS6μm) were taken up via pinocytosis and were detected in the cytoplasm for up to 14 days after exposure. Large PS-MP (PS<30μm) were detected in A. proteus only after predation on MP-fed Ciliophora. These results indicate that A. proteus ingests larger MP via predation on Ciliophora (PS<30μm), which would not be taken up otherwise. This study shows trophic transfer of MP at the base of the aquatic food web and serves as basis to study the impact of MP in freshwater ecosystems.

Nano-scale and micron-scale plastics amplify the bioaccumulation of benzophenone-3 and ciprofloxacin, as well as their co-exposure effect on disturbing the antioxidant defense system in mussels, Perna viridis

Plastics ranging from nano-scale to micron-scale are frequently ingested by many marine animals. These particles exhibit biotoxicity and additionally perform as vectors that convey and amass adsorbed chemicals within organisms. Meanwhile, the frequency of detection of the benzophenone-3 and ciprofloxacin can be adsorbed on plastic particles, then accumulated in bivalves, causing biotoxicity. To understand their unknown accumulative kinetics in vivo affected by different plastic sizes and toxic effect from co-exposure, several scenarios were set up in which the mode organism were exposed to 0.6 mg/L of polystyrene carrying benzophenone-3 and ciprofloxacin in three sizes (300 nm, 38 μm, and 0.6 mm). The live Asian green mussels were chosen as mode organism for exposure experiments, in which they were exposed to environments with plastics of different sizes laden with benzophenone-3 and ciprofloxacin, then depurated for 7 days. The bioaccumulation and depuration kinetics of benzophenone-3 and ciprofloxacin were measured using HPLC-MS/MS after one week of exposure and depuration. Meanwhile, their toxic effect were investigated by measuring the changes in six biomarkers (condition index, reactive oxygen species, catalase, glutathione, lipid peroxidation, cytochrome P450 and DNA damage). The bioconcentration factors in mussels under different exposure conditions were 41.48-111.75 for benzophenone-3 and 6.45 to 12.35 for ciprofloxacin. The results suggested that microplastics and nanoplastics can act as carriers to increase bioaccumulation and toxicity of adsorbates in mussels in a size-dependent manner. Overproduction of reactive oxygen species caused by microplastics and nanoplastics led to increased DNA damage, lipid peroxidation, and changes in antioxidant enzymes and non-enzymatic antioxidants during exposure. Marked disruption of antioxidant defenses and genotoxic effects in mussels during depuration indicated impaired recovery. Compared to micron-scale plastic with sizes over a hundred micrometers that had little effect on bivalve bioaccumulation and toxicity, nano-scale plastic greatly enhanced the biotoxicity effect.

Research advances on the toxicity of biodegradable plastics derived micro/nanoplastics in the environment: A review

The detrimental effects of plastic and microplastic accumulation on ecosystems are widely recognized and indisputable. The emergence of biodegradable plastics (BPs) offers a practical solution to plastic pollution. Problematically, however, not all BPs can be fully degraded in the environment. On the contrary, the scientific community has demonstrated that BPs are more likely than conventional plastics (CPs) to degrade into micro/nanoplastics and release additives, which can have similar or even worse effects than microplastics. However, there is very limited information available on the environmental toxicity assessment of BMPs. The absence of a toxicity evaluation system and the uncertainty regarding combined toxicity with other pollutants also impede the environmental toxicity assessment of BMPs. Currently, research is focused on thoroughly exploring the toxic effects of biodegradable microplastics (BMPs). This paper reviews the pollution status of BMPs in the environment, the degradation behavior of BPs and the influencing factors. This paper comprehensively summarizes the ecotoxicological effects of BPs on ecosystems, considering animals, plants, and microorganisms in various environments such as water bodies, soil, and sediment. The focus is on distinguishing between BMPs and conventional microplastics (CMPs). In addition, the combined toxic effects of BMPs and other pollutants are also being investigated. The findings suggest that BMPs may have different or more severe impacts on ecosystems. The rougher and more intricate surface of BMPs increases the likelihood of causing mechanical damage to organisms and breaking down into smaller plastic particles, releasing additives that lead to a series of cascading negative effects on related organisms and ecosystems. In the case of knowledge gaps, future research is also proposed and anticipated to investigate the toxic effects of BMPs and their evaluation.

A review on fate and ecotoxicity of biodegradable microplastics in aquatic system: Are biodegradable plastics truly safe for the environment?

Plastic products are extensively used worldwide, but inadequate management of plastic waste results in significant plastic pollution. Biodegradable plastic (BPs) offers an alternative to traditional plastics, however, not all BPs can fully degrade under natural conditions. Instead, they may deteriorate into biodegradable microplastic (BMPs) at a faster rate than conventional plastic, thereby posing an additional hazard to aquatic environments. This study provides a comprehensive overview of the fate of BPs in aquatic systems and their eco-toxicological effects on aquatic organisms such as algae, invertebrates, and fish. The findings highlight that BMPs have comparable or heightened effects compared to conventional microplastics (MPs) which physiochemical characteristic of the polymer itself or by the chemical leached from the polymeric matrix can affect aquatic organisms. While BPs is not a flawless solution to address plastic pollution, future research should prioritize investigating their production, environmental behavior, ecological impact, and whether BMPs inflict greater harm than conventional MPs.

Microplastics from agricultural mulch films: Biodegradation and ecotoxicity in freshwater systems

The application of bio-based biodegradable mulch films in agriculture has raised environmental concerns regarding their potential impacts on adjacent freshwater ecosystems. This study investigated the biodegradation of microplastics derived from a bio-based biodegradable mulch (bio-MPs) and its acute and chronic ecotoxicity considering relevant scenarios (up to 200 and 250 mg/kg of sediment, using pristine and/or UV-aged particles), using the fungus Penicillium brevicompactum and the dipteran Chironomus riparius as model organisms, respectively, due to their ecological relevance in freshwater environments. Fourier-transform infrared spectroscopy analysis suggested changes in the fungus's carbohydrate reserves and bio-MP degradation through the appearance of low molecular weight esters throughout a 28 day biodegradation test. In a short-term exposure (48 h), C. riparius larvae exposed to pristine or UV-aged bio-MPs had up to 2 particles in their gut. Exposure to pristine bio-MPs decreased larval aerobic metabolism (<20 %) and increased neurotransmission (>15 %), whereas exposure to UV-aged bio-MPs activated larval aerobic metabolism (>20 %) and increased antioxidant defences (catalase activity by >30 % and glutathione-s-transferase by >20 %) and neurotransmission (>30 %). Longer-term (28-d) exposure to UV-aged bio-MPs did not affect larval survival and growth nor the dipteran's emergence but increased male numbers (>30 %) at higher concentrations. This study suggests that the selected agricultural bio-based mulch film is prone to biodegradation by a naturally occurring fungus. However, there is a potential for endocrine disruption in the case of prolonged exposures to UV-aged microplastics. This study emphasises the importance of further research to elucidate the potential ecological effects of these plastic products, to ensure effective management practices, and to establish new regulations governing their use.

Characterization of Moringa oleifera Seed Oil for the Development of a Biopackage Applied to Maintain the Quality of Turkey Ham

Moringa oleifera has a high level of active chemicals that are useful in the food industry, and they have antibacterial and food preservation properties. The characterization of M. oleifera seed oil (MOS) may vary due to agronomic and environmental factors. Therefore, it was necessary to know the composition of lipids present in our oil extracted under pressing at 180 °C and thus determine if it is suitable to produce a biopackaging. Within the characterization of the oil, it was obtained that MOS presented high-quality fatty acids (71% oleic acid) with low values of acidity (0.71 mg KOH/g) and peroxide (1.74 meq O2/kg). Furthermore, MOS was not very sensitive to lipoperoxidation by tert-butyl hydroperoxide (tBuOOH) and its phenolic components, oleic acid and tocopherols, allowed MOS to present a recovery of 70% after 30 min of treatment. Subsequently, a biopackaging was developed using a multiple emulsion containing corn starch/carboxymethylcellulose/glycerol/MOS, which presented good mechanical properties (strength and flexibility), transparency, and a barrier that prevents the transfer of UV light by 30% and UV-C by 98%, as well as a flux with the atmosphere of 5.12 × 10-8 g/ m.s. Pa that prevents moisture loss and protects the turkey ham from O2. Hence, the turkey ham suffered less weight loss and less hardness due to its preservation in the biopackaging.

Facemasks: An insight into their abundance in wetlands, degradation, and potential ecotoxicity

Disposable facemasks represent a new form of environmental contamination worldwide. This study aimed at addressing the abundance of facemasks in an overlooked natural environment with high ecological and economic value - the wetlands (Ria de Aveiro, Portugal, as study case), evaluating their potential biodegradation using naturally occurring fungi and assessing the potential ecotoxicity of released microfibres on local bivalves. All masks collected within 6500 m2 area of Aveiro wetland were 100 % disposable ones (PP-based, confirmed by Fourier transform infrared spectroscopy - FTIR) with an initial abundance of 0.0023 items/m2 in Sept. 2021, which was reduced by ∼40 % in Apr. 2022 and ∼87 % in Sept. 2022, as a reflection of the government policies. Analysis of the carbonyl index (0.03 to 1.79) underlined their state of degradation, primarily due to sun exposure during low tides. In laboratory conditions, 1 mm2 microplastics obtained from new disposable facemasks were prone to biodegradation by Penicillium brevicompactum and Zalerion maritimum inferred from microplastics mass loss (∼22 to -26 % and ∼40 to 50 %, respectively) and FTIR spectra (particularly in the hydroxyl and carbonyl groups). In addition, microfibres released from facemasks induced sublethal effects on the clam, Venerupis corrugata, mostly in their UV-aged form when compared to pristine ones, characterised by a decrease in cellular energy allocation (CEA) and an increase in aerobic energy metabolism (ETS). Concomitantly, clams exposed to 1250 items/L of UV-aged microplastics (similar to field-reported concentrations) expressed greater clearance capacity, indicating a need to compensate for the potential energy unbalance. This study provides the first baseline monitoring of facemasks in wetlands while bringing new evidence on their biodegradation and ecotoxicity, considering environmentally relevant conditions and keystone organisms in such environments. Such studies require scientific attention for rapid regulatory action against this emerging and persistent pollutant, also targeting remediation and mitigation strategies considering these items under pandemic scenarios.

Current advances in the structural biology and molecular engineering of PETase

Poly(ethylene terephthalate) (PET) is a highly useful synthetic polyester plastic that is widely used in daily life. However, the increase in postconsumer PET as plastic waste that is recalcitrant to biodegradation in landfills and the natural environment has raised worldwide concern. Currently, traditional PET recycling processes with thermomechanical or chemical methods also result in the deterioration of the mechanical properties of PET. Therefore, it is urgent to develop more efficient and green strategies to address this problem. Recently, a novel mesophilic PET-degrading enzyme (IsPETase) from Ideonella sakaiensis was found to streamline PET biodegradation at 30°C, albeit with a lower PET-degrading activity than chitinase or chitinase-like PET-degrading enzymes. Consequently, the molecular engineering of more efficient PETases is still required for further industrial applications. This review details current knowledge on IsPETase, MHETase, and IsPETase-like hydrolases, including the structures, ligand‒protein interactions, and rational protein engineering for improved PET-degrading performance. In particular, applications of the engineered catalysts are highlighted, including metabolic engineering of the cell factories, enzyme immobilization or cell surface display. The information is expected to provide novel insights for the biodegradation of complex polymers.

First comparative assessment of contamination by plastics and non-synthetic particles in three bivalve species from an Italian sub-alpine lake

This study aimed to compare the contamination from plastics and non-synthetic particles in the three freshwater bivalve mollusks Unio elongatulus, (native) and Corbicula fluminea and Dreissena polymorpha (invasive), collected in Lake Maggiore, the second greatest Italian lake. Organisms were collected from eight sites located throughout the lake, during three years (2019-2021). The quali-quantitative characterization of particles has been carried out using a Fourier Transform Infrared Microscope System (μFT-IR). Results showed that both plastics and non-synthetic particles released in the water are taken up by bivalves, even though low intake-up to 6 particles/individuals-were measured for all the three species. Microfibers of both synthetic (polyester, polyamide) and natural (cellulose) origin represented the particles mostly ingested by bivalves. A significant decrease of particle loads was observed in 2020 with respect to 2019 and 2021, significantly different for D. polymorpha and U. elongatulus, suggesting a transient reduction of the particle release in the lake in this year. Our findings highlight the need to improve the understanding of the mechanisms of uptake and clearance of these contaminants by filter feeding organisms, and their adverse consequences in realistic environmental conditions.

Sustainable and Bio-Based Food Packaging: A Review on Past and Current Design Innovations

Food loss and waste occur for many reasons, from crop processing to household leftovers. Even though some waste generation is unavoidable, a considerable amount is due to supply chain inefficiencies and damage during transport and handling. Packaging design and materials innovations represent real opportunities to reduce food waste within the supply chain. Besides, changes in people's lifestyles have increased the demand for high-quality, fresh, minimally processed, and ready-to-eat food products with extended shelf-life, that need to meet strict and constantly renewed food safety regulations. In this regard, accurate monitoring of food quality and spoilage is necessary to diminish both health hazards and food waste. Thus, this work provides an overview of the most recent advances in the investigation and development of food packaging materials and design with the aim to improve food chain sustainability. Enhanced barrier and surface properties as well as active materials for food conservation are reviewed. Likewise, the function, importance, current availability, and future trends of intelligent and smart packaging systems are presented, especially considering biobased sensor development by 3D printing technology. In addition, driving factors affecting fully biobased packaging design and materials development and production are discussed, considering byproducts and waste minimization and revalorization, recyclability, biodegradability, and other possible ends-of-life and their impact on product/package system sustainability.

A Biodegradable, Bio-Based Polymer for the Production of Tools for Aquaculture: Processing, Properties and Biodegradation in Sea Water

Bio-based, biodegradable polymers can dramatically reduce the carbon dioxide released into the environment by substituting fossil-derived polymers in some applications. In this work, prototypes of trays for aquaculture applications were produced via injection molding by using a biodegradable polymer, Mater-Bi^®. A characterization carried out via calorimetric, rheological and mechanical tests revealed that the polymer employed shows properties suitable for the production of tools to be used in aquaculture applications. Moreover, the samples were subjected to a biodegradation test in conditions that simulate the marine environment. The as-treated samples were characterized from gravimetrical, morphological and calorimetric point of views. The obtained data showed a relatively low biodegradation rate of the thick molded samples. This behavior is of crucial importance since it implies a long life in marine water for these manufacts before their disappearing.

Distinguish the toxic differentiations between acute exposure of micro- and nano-plastics on bivalves: An integrated study based on transcriptomic sequencing

Plastic pollution represents one of the most severe marine environmental issues today. In the present study, mussel Mytilus coruscus, was selected as the model organism to probe the toxic effects of acute exposure to different sizes of plastic particles using integrated transcriptomic techniques and histological and biochemical analysis. Nanoplastics (NPs) were efficiently ingested by mussels, thereby inducing a severe inflammatory response. Although no distinct aggregation of microplastics (MPs) was observed, a slight inflammatory response has still occurred. Biochemical analysis revealed a significant up-regulation of biomarkers after exposure to plastic particles. Further, NPs caused more ROS production and higher T-AOC level than MPs. Transcriptomic sequencing was performed, and these differentially expressed genes after MNPs exposure were mostly enriched in pathways involved in stress and immune response. Notably, a contrast expression, substantial upregulation in MPs treatment and downregulation in NPs treatment of specific genes include in these pathways were revealed. Collectively, these results indicated that acute exposure to NPs is more toxic than MPs. Additionally, MPs exposure perhaps caused the impairment of olfactory function and neurotoxicity to mussels. These data provided some new clues for the elucidating of ecotoxicological mechanisms underlying plastic particles exposure.

Effects of microplastics on physiological performance of marine bivalves, potential impacts, and enlightening the future based on a comparative study

This review aims to explore the effects of microplastics and their corresponding additives on the physiological performances of marine bivalves together with their related genes. We identified gaps based on studies that were conducted on other organisms, and we conducted a comparative study on similar and relevant aspects for exploring future potential areas of study and interest. Microplastics are widely dispersed in all forms of media (solid, liquid, and gas). Exposure to an organism (including humans) is inevitable. However, impacts depend on the concentration of exposure, location of a biomarker being observed, and treatment involved. Different shapes, colors, and polymer types are reported and the transfer of microplastics along the food chain are recorded. The impacts of microplastics intensify when coupled with other chemicals or additives (referred to as xenobiotics) in a treated group. Thus, the degree of inhibition or enhancement of a physiological response magnifies when a coexposure of microplastic and a xenobiotic occurs. Microplastics have been observed to reduce immune system functionality by reducing hemocytes count, distorting oxidative system, respiration, and increasing energy consumption in bivalves due to physiological modulations that result from ingestion of microplastics or their additives. We found knowledge gaps and suggested future research directions to fully understand the impact of microplastics and their additives on marine bivalves.

Effect of landfill age on the physical and chemical characteristics of waste plastics/microplastics in a waste landfill sites

The landfills store a lot of waste plastics, thus it has been confirmed a main source for the occurrence of plastics/microplastic. Although there are some reports that microplastics (MPs) can generate in leachate and refuse samples from the landfill, it exist many blanks for the evolution of physical and chemical characteristics of waste plastics and microplastics with different landfill age. To explore the process that large pieces of plastic are fractured into microplastics, the waste plastics with landfill age from 7 to 30 years are surveyed from a typical landfill in Shanghai. The results show that PE and PP are the most common types of landfilling plastics, and their chemical composition also have changed due to the creation of CO and -OH. Moreover, the crystallinity is affected by plastic type and landfill age. The crystallinity of PP increased from 24.9% to 56.8%, but for PE, the crystallinity decreased from 55.6% to 20.8%. The mechanical properties of waste plastics were reduced significantly, which may be caused by changes in carbon-chain molecules. Al, Ti, Co, and other metal elements were detected on the plastic surface. The hydrophobic behavior of waste plastic is constantly decreasing (102.2°-80.1°) under long-term landfilling. By investigating the changes in the physical and chemical characteristics of waste plastics with different landfill age can shed light upon the process of environmental weathering of waste plastics. This provide theoretical guidance for reducing the transport of microplastics to the environment.

Distribution, biological effects and biofilms of microplastics in freshwater systems - A review

The rapidly rising output and mass use of plastics have made plastics pollution a major environmental problem. Since plastics are persistent in the environment, understanding the migration transformation characteristics of plastics is critical. Given the ever-increasing concern about the environmental risks posed by microplastics, their prevalence, fate, abundance and impact have been intensively studied. Most of these investigations focused on the marine environment, but research on freshwater microplastics is less extensive. This article aims to briefly summarize the research progress of freshwater microplastics, identify existing gaps and draw novel conclusions, so as to provide useful information for the research of freshwater microplastics. Using the statistics and analysis of freshwater microplastics studies in 2016-2021, this review systematically discusses microplastics in globally freshwater systems. The biological effects of microplastics on freshwater organisms were discussed as well. Some potential ecological effects of microplastic biofilms were shown, such as climate change and material circulation. More importantly, we present some unique conclusions. For example, the detection of freshwater microplastics is mainly concentrated in natural freshwater systems, while few are concentrated in artificial freshwater systems. In addition, polystyrene is the main mode for testing the biological effects of freshwater microplastics, and polyethene and polypropylene which are the most common in freshwater environments, have not been taken seriously. We also pointed out that studies on advanced freshwater plants in the topic of biological effects of microplastics still need strengthen.

Impacts of conventional and biodegradable microplastics on juvenile Lates calcarifer: Bioaccumulation, antioxidant response, microbiome, and proteome alteration

Discarded plastic bag is a main component of marine debris, posing potential threats to marine biota. This study was conducted to assess the potential effects of microplastics on juvenile Lates calcarifer. Fish were exposed via diet to two microplastic types from conventional polyethylene (PE) and biodegradable (Bio) plastic bags for 21 days. Antioxidative enzymes activity, intestinal microbiome and proteome were determined. PE and Bio microplastics were found to accumulate in gastrointestinal tracts, and no mortality was observed. Microplastics exposure did not induce significant antioxidant response except for the glutathione reductase (GR) modulation. Intestinal microbiome diversity decreased significantly in PE group based on Simpson index. Both types of microplastics induced proteome modulation by down-regulating proteins associated with immune homeostasis. Bio microplastics maintained higher intestinal microbial diversity and induced more proteins alteration than PE microplastics. This study provides toxicological insights into the impacts of conventional and biodegradable microplastics on juvenile L. calcarifer.

Ecological Impact of End-of-Life-Tire (ELT)-Derived Rubbers: Acute and Chronic Effects at Organism and Population Levels

Considering the large amount of tires that reach the end of life every year, the aim of this study was the evaluation of both acute and chronic effects of end-of-life-tire (ELT)-derived rubber granules (ELT-dg) and powder (ELT-dp) on a freshwater trophic chain represented by the green alga Pseudokirchneriella subcapitata, the crustacean Daphnia magna and the teleost Danio rerio (zebrafish). Adverse effects were evaluated at the organism and population levels through the classical ecotoxicological tests. Acute tests on D. magna and D. rerio revealed a 50% effect concentration (EC50) > 100.0 mg/L for both ELT-dg and ELT-dp. Chronic exposures had a lowest observed effect concentration (LOEC) of 100.0 mg/L for both ELT-dg and ELT-dp on P. subcapitata grow rate and yield. LOEC decreased in the other model organisms, with a value of 9.8 mg/L for D. magna, referring to the number of living offspring, exposed to ELT-dg suspension. Similarly, in D. rerio, the main results highlighted a LOEC of 10.0 mg/L regarding the survival and juvenile weight parameters for ELT-dg and a LOEC of 10.0 mg/L concerning the survival and abnormal behavior in specimens exposed to ELT-dp. Tested materials exhibited a threshold of toxicity of 9.8 mg/L, probably a non-environmental concentration, although further investigations are needed to clarify the potential ecological impact of these emerging contaminants.

The protective layer formed by soil particles on plastics decreases the toxicity of polystyrene microplastics to earthworms (Eisenia fetida)

The recent discovery of microplastics contaminants in most ecosystems has raised major health issues, yet knowledge on their impact on soil organisms is limited, especially their toxicity evolution with aging. Herein, the toxicity of polystyrene microplastic (PS-MP) to earthworm (Eisenia fetida) along with aging was investigated. Results showed that the 28 d-LC₅₀ (50% lethal concentration) of PS-MP was 25.67 g kg^-1, whereas that increased to 96.47 g kg^-1 after PS-MP initially aged in soil for 28 days, indicating the toxicity of PS-MP decreased with aging. Laser scanning confocal microscope and scanning electron microscope (SEM) found that the toxicity of PS-MP to earthworm may be due to the ingestion of PS-MP by earthworms and the physical damage (e.g., epidermis abrasion and setae loss) of PS-MP to earthworms. Similarly, the levels of reactive oxygen species, antioxidant enzyme activities and malondialdehyde content increased with PS-MP concentrations from 0.1 to 1.5 g kg^-1, but decreased with aging from 7 to 28 days. The integrated biomarker response index also confirmed that the toxicity of PS-MP decreased with aging. SEM found that PS-MP were progressively covered by soil particles during soil aging, inducing the formation of protective layer and increasing the particle size of PS-MP, which prevented direct contact with earthworms and decreased the ingestion of PS-MP, in turn decreased PS-MP toxicity. Overall, our study provides valuable insights for elucidating the effect of aging on the toxicity of microplastics.

A shelf-life study for the evaluation of a new biopackaging to preserve the quality of organic chicken meat

Widespread use of traditional packaging constitutes a serious ecological problem leading to a shift to biodegradable and compostable materials. The aim of this work is to study the ability of a new biopackaging (BP), based on biodegradable and compostable material, to preserve the quality of organic chicken meat for 14 days in comparison with a polyethylene terephthalate (PET) material. Results showed that the indices of Biogenic Amines (BAs) and the 18 monitored Volatile Organic Compounds (VOCs) have a similar trend in both packaged meats. For example, the total BAs concentration in meat increased from 390 to 961 mg Kg^-1 in BP and from 393 to 800 mg Kg^-1 in PET, as well as the microbiological counts. The new biopackaging (BP) showed similar properties of non-biodegradable material (PET) to preserve the shelf life of organic chicken meat and it could be used instead of plastic materials to promote a circular economy.

Is microplastic an oxidative stressor? Evidence from a meta-analysis on bivalves

Microplastic pollution is a major threat to the marine environment attracting attention from scientific and public communities. Although we have sufficient evidence that microplastic is ubiquitous in all ecosystems, the question of the harmfulness of microplastic exposure is still under debate. Filter feeders like bivalves are commonly exposed to microplastics in water and sediments and thus can serve as excellent biological indicators for microplastic pollution. A relatively rich toxicological literature has been focusing on microplastic effects on bivalves but we have yet to reach an agreement on the toxic effects and mechanisms of microplastics. Here, we conducted a meta-analysis and bibliometrics analysis of the microplastic studies in bivalves. The bibliometric analysis (used to evaluate the general research trends) showed that the investigation of microplastic distribution in the marine environment and the molecular mechanisms of microplastic toxicity are the two major hot spots of research. Based on analyses of ecologically and environmentally relevant microplastics concentrations, particle sizes and polymer types, we discuss the physiological effects of microplastics on bivalves, and the severity and direction of the effects at the cellular, tissue, organ and organismal levels. The meta-analysis results show that microplastics can induce time-dependent oxidative stress in bivalves. Generally, the activities of antioxidant enzymes, such as glutathione peroxidase (GPx), glutathione-S-transferase (GST) and superoxide dismutase (SOD) increased during short-term exposure but declined after long-term exposure to microplastics. Non-linear response of GPx, GST and SOD enzymes to MP exposure over time indicate that these enzymes are not good biomarkers of MPs effects in marine bivalves. The tissue glutathione levels and catalase (CAT activity) showed an increase during both short- and long term MP exposures and thus can be used as oxidative stress biomarkers of sublethal MPs effects in marine bivalves.

Biodegradable microplastics (BMPs): a new cause for concern?

With the increasingly serious pollution of plastics, biodegradable plastics (BDPs) have attracted attention as a new material that can replace conventional plastics in certain applications. The global production of BDPs also gradually increases in recent years. However, unfortunately, with the application of BDPs, some potential problems are gradually exposed. The biodegradability of BDPs needs suitable conditions, which is difficult for the natural environment to reach the necessary conditions. If the degradation conditions are not met, BDPs and conventional plastics are basically the same in terms of the longevity. The biodegradable microplastics (BMPs) can also be formed by BDPs entering the environment. Up to now, the research on the degradation and application of BDPs is relatively common. The environmental and ecological effects of the BMPs, the adsorption and release of toxic substances, and the role of BMPs as vectors of microorganisms, epiphytes, and plants still need to be studied. This paper focuses on the formation mechanism and the environmental behavior of BMPs. The role of BMPs as multiple stronger vectors of microorganisms and pollutants compared to conventional microplastics is also discussed. Systematic research on environmental pollution and ecotoxicology of BMPs should be carried out as soon as possible.

Microplastics-Induced Eryptosis and Poikilocytosis in Early-Juvenile Nile Tilapia (Oreochromis niloticus)

This study aims to assess the impact of microplastics (MPs) on erythrocytes using eryptosis (apoptosis) and an erythron profile (poikilocytosis and nuclear abnormalities), considered to be novel biomarkers in Nile tilapia (Oreochromis niloticus). In this study, four groups of fish were used: The first was the control group. In the second group, 1 mg/L of MPs was introduced to the samples. The third group was exposed to 10 mg/L of MPs. Finally, the fourth group was exposed to 100 mg/L of MPs for 15 days, following 15 days of recovery. The fish treated with MPs experienced an immense rise in the eryptosis percentage, poikilocytosis, and nuclear abnormalities of red blood cells (RBCs) compared with the control group in a concentration-dependent manner. Poikilocytosis of MP-exposed groups included sickle cell shape, schistocyte, elliptocyte, acanthocyte, and other shapes. Nuclear abnormalities of the MPs-exposed groups included micronuclei, binucleated erythrocytes, notched, lobed, blebbed, and hemolyzed nuclei. After the recovery period, a greater percentage of eryptosis, poikilocytotic cells, and nuclear abnormalities in RBCs were still evident in the groups exposed to MPs when crosschecked with the control group. The results show concerning facts regarding the toxicity of MPs in tilapia.

Quality of nanoplastics and microplastics ecotoxicity studies: Refining quality criteria for nanomaterial studies

It is becoming increasingly important to develop assessment criteria for the quality of nanoplastics studies. This study is an attempt to establish such criteria based on those developed for engineered nanomaterials, the GUIDEnano and DaNa criteria being two representatives. These criteria were applied to studies on polystyrene nanoparticles (PS NPs), which currently represent the majority of studies on nanoplastics. We compiled a list of existing nanomaterial-related criteria that are not fully relevant to PS NPs and propose additional nanoplastic-specific criteria targeting polymer chemical composition, source, production and field collection, impurities/chemical additives, density, hydrophobicity, colour, and chemical leaching. For each criterion, scientific justification is provided. We conclude that the existing study quality assessments originally developed for nano(eco)toxicity studies can, through refinements, be applied to those dealing with nanoplastics studies, with a further outlook on microplastics. The final quality criteria catalogue presented here is intended as a starting point for further elaborations considering different purposes of an assessment.

Ingestion and Toxicity of Polystyrene Microplastics in Freshwater Bivalves

The ubiquity of microplastics in aquatic ecosystems has raised concerns over their interaction with biota. However, microplastics research on freshwater species, especially mollusks, is still scarce. We, therefore, investigated the factors affecting microplastics ingestion in the freshwater mussel Dreissena polymorpha. Using polystyrene spheres (5, 10, 45, 90 µm), we determined the body burden of microplastics in the mussels in relation to 1) exposure and depuration time, 2) body size, 3) food abundance, and 4) microplastic concentrations. D. polymorpha rapidly ingested microplastics and excreted most particles within 12 h. A few microplastics were retained for up to 1 wk. Smaller individuals had a higher relative body burden of microplastics than larger individuals. The uptake of microplastics was concentration-dependent, whereas an additional food supply (algae) reduced it. We also compared the ingestion of microplastics by D. polymorpha with 2 other freshwater species (Anodonta anatina, Sinanodonta woodiana), highlighting that absolute and relative uptake depends on the species and the size of the mussels. In addition, we determined toxicity of polystyrene fragments (≤63 µm, 6.4-100 000 p mL^-1 ) and diatomite (natural particle, 100 000 p mL^-1 ) in D. polymorpha after 1, 3, 7, and 42 d of exposure, investigating clearance rate, energy reserves, and oxidative stress. Despite ingesting large quantities, exposure to polystyrene fragments only affected the clearance rate of D. polymorpha. Further, results of the microplastic and diatomite exposure did not differ significantly. Therefore, D. polymorpha is unaffected by or can compensate for polystyrene fragment toxicity even at concentrations above current environmental levels. Environ Toxicol Chem 2021;40:2247-2260. © 2021 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Characterization of plastics and their ecotoxicological effects in the Lambro River (N. Italy)

This study had the dual objective of both the qualitative and quantitative assessment of plastic mixtures sampled in 5 different sites located along the Lambro River (northern Italy), and the contemporarily determination of the ecotoxicological effects of the same mixtures sampled, through 21-day laboratory exposures of the freshwater bivalve Dreissena polymorpha. The monitoring survey was carried out by a Fourier Transform Infrared Microscope System, while the ecotoxicological assessment was performed by the mussel mortality, a biomarker suite and the proteomics. The main results of the monitoring have highlighted some critical points, related to the concentration of plastics detected at Milan and, especially at the southernmost sampling station, where a daily flow of more than 6 million plastic debris has been estimated, ending directly into the Po River, the main Italian river. The ecotoxicological analysis highlighted how the toxicity is not exclusively due to the plastic concentration, but that the different characteristics of the polymers probably become more important. Furthermore, we observed an extensive mortality of bivalves exposed to the sampled mixtures in the two southernmost sampling stations, while the battery of biomarkers and the results of proteomics have highlighted how the sampled plastic mixtures caused an imbalance in the redox state, already indicated as a classic effect due to plastic exposure, but also an impact on energy stock and on some fundamental cellular pathways always linked to energy metabolism.

Alginate coating modifies the biological effects of cerium oxide nanoparticles to the freshwater bivalve Dreissena polymorpha

The adsorption of biomacromolecules is a fundamental process that can alter the behaviour and adverse effects of nanoparticles (NPs) in natural systems. While the interaction of NPs with natural molecules present in the environment has been described, their biological impacts are largely unknown. Therefore, this study aims to provide a first evidence of the influence of biomolecules sorption on the toxicity of cerium oxide nanoparticles (CeO₂NPs) towards the freshwater bivalve Dreissena polymorpha. To this aim, we compared naked CeO₂NPs and coated with alginate and chitosan, two polysaccharides abundant in aquatic environments. Mussels were exposed to the three CeO₂NPs (naked, chitosan- and alginate-coated) up to 14 days at 100 μg L^-1, which is a concentration higher than the environmental one predicted for this type of NP. A suite of biomarkers related to oxidative stress and energy metabolism was applied, and metabolomics was also carried out to identify metabolic pathways potentially targeted by CeO₂NPs. Results showed that the coating with chitosan reduced NP aggregation and increased the stability in water. Nonetheless, the Ce accumulation in mussels was similar in all treatments. As for biological effects, all three types of CeO₂NPs reduced significantly the level of reactive oxygen species and the activity of superoxide dismutase, glutathione peroxidase and glutathione-S-transferase. The effect was more pronounced in individuals exposed to CeO₂NPs coated with alginate, which also significantly induced the activity of the electron transport system. Metabolomics analysis of amino acid metabolism showed modulation only in mussels treated with CeO₂NPs coated with alginate. In this group, 25 metabolites belonging to nucleotides, lipids/sterols and organic osmolytes were also modulated, suggesting that the nanoparticles affect energetic metabolism and osmoregulation of mussels. This study highlights the key role of the interaction between nanoparticles and natural molecules as a driver of nanoparticle ecotoxicity.

China's plastic import ban increases prospects of environmental impact mitigation of plastic waste trade flow worldwide

Since the late 1990s, the trend of plastic waste shipment from developed to developing countries has been increasing. In 2017, China announced an unprecedented ban on its import of most plastic waste, resulting in a sharp decline in global plastic waste trade flow and changes in the treatment structure of countries, whose impacts on global environmental sustainability are enormous but yet unexamined. Here, through the life cycle assessment (LCA) method, we quantified the environmental impacts of changes in the flow patterns and treatment methods of 6 types of plastic waste in 18 countries subsequent to the ban. In the short term, the ban significantly improved four midpoint indicators of environmental impact, albeit contributed to global warming. An annual saving of about 2.35 billion euros of eco-cost was realized, which is equivalent to 56% of plastic waste global trade value in 2017. To achieve global environmental sustainability in the long run, countries should gradually realize the transition from export to domestic management, and from landfill to recycling, which would realize eco-costs savings of about 1.54–3.20 billion euros.

China announced a ban on its import of most plastic waste in 2017, resulting in an impact on global environmental sustainability. Here the authors quantify the environmental impacts of changes in the flow patterns and treatment methods of 6 types of plastic waste in 18 countries subsequent to the ban.

Photo-Oxidative Degradation Mitigated the Developmental Toxicity of Polyamide Microplastics to Zebrafish Larvae by Modulating Macrophage-Triggered Proinflammatory Responses and Apoptosis

Microplastics (MPs) are ubiquitous in the environment and pose substantial threats to the water ecosystem. However, the impact of natural aging of MPs on their toxicity has rarely been considered. This study found that visible light irradiation with hydrogen peroxide at environmentally relevant concentration for 90 days significantly altered the physicochemical properties and mitigated the toxicity of polyamide (PA) fragments to infantile zebrafish. The size of PA particles was reduced from ∼8.13 to ∼6.37 μm, and nanoparticles were produced with a maximum yield of 5.03%. The end amino groups were volatilized, and abundant oxygen-containing groups (e.g., hydroxyl and carboxyl) and carbon-centered free radicals were generated, improving the hydrophilicity and colloidal stability of degraded MPs. Compared with pristine PA, the depuration of degraded MPs mediated by multixenobiotics resistance was much quicker, leading to markedly lower bioaccumulation in fish and weaker inhibition on musculoskeletal development. By integrating transcriptomics and transgenic zebrafish [Tg(lyz:EGFP)] tests, differences in macrophages-triggered proinflammatory effects, apoptosis via IL-17 signaling pathway, and antioxidant damages were identified as the underlying mechanisms for the attenuated toxicity of degraded MPs. This work highlights the importance of natural degradation on the toxicity of MPs, which has great implications for risk assessment of MPs.