Are biodegradable plastics an environmental rip off?

High-altitude aquatic ecosystems offer faster aging rate of plastics

While research on the aging behavior of plastics in aquatic systems is extensive, studies focusing on high-altitude ecosystems, characterized by higher solar radiation and lower temperatures, remain limited. This study investigated the long-term aging behavior of non-biodegradable plastics (non-BPs), namely polyethylene terephthalate (PET) and polypropylene (PP) and biodegradable plastics (BPs), specifically polylactic acid plus polybutylene adipate-co-terephthalate (PLA + PBAT) and starch-based plastic (SBP), in a tributary of the Yarlung Zangbo River on the high-altitude Tibetan Plateau. Over 84 days of field aging, all four types of plastics exhibited initial rapid aging followed by deceleration. This aging process can be divided into two phases: rapid surface oxidation aging and an aging plateau phase. Notably, PP aged at a rate comparable to BPs, contrary to expectations of faster aging for BPs. Compared to low-altitude aquatic ecosystems, plastics in this study showed a faster aging rate. This was primarily due to intense ultraviolet radiation causing severe photoaging. Furthermore, the lower temperatures contributed to the formation of thinner biofilms. These thinner biofilms exhibited a reduced capacity to block light, further exacerbating the photoaging process of plastics. Statistical analysis results indicated that temperature, total nitrogen TN, and total phosphorus TP were likely the main water quality parameters influencing plastic aging. The varying effects of water properties and nutrients underscore the complex interaction of water quality parameters in high-altitude environments. Given the delicate nature of the high-altitude environment, the environmental impact of plastics, especially BPs, warrants careful consideration.

Compounding one problem with another? A look at biodegradable microplastics

Environmental concerns about microplastics (MPs) have motivated research of their sources, occurrence, and fate in aquatic and soil ecosystems. To mitigate the environmental impact of MPs, biodegradable plastics are designed to naturally decompose, thus reducing the amount of environmental plastic contamination. However, the environmental fate of biodegradable plastics and the products of their incomplete biodegradation, especially micro-biodegradable plastics (MBPs), remains largely unexplored. This comprehensive review aims to assess the risks of unintended consequences associated with the introduction of biodegradable plastics into the environment, namely, whether the incomplete mineralization of biodegradable plastics could enhance the risk of MBPs formation and thus, exacerbate the problem of their environmental dispersion, representing a potentially additional environmental hazard due to their presumed ecotoxicity. Initial evidence points towards the potential for incomplete mineralization of biodegradable plastics under both controlled and uncontrolled conditions. Rapid degradation of PLA in thermophilic industrial composting contrasts with the degradation below 50 % of other biodegradables, suggesting MBPs released into the environment through compost. Moreover, degradation rates of <60 % in anaerobic digestion for polymers other than PLA and PHAs suggest a heightened risk of MBPs in digestate, risking their spread into soil and water. This could increase MBPs and adsorbed pollutants' mobilization. The exact behavior and impacts of additive leachates from faster-degrading plastics remain largely unknown. Thus, assessing the environmental fate and impacts of MBPs-laden by-products like compost or digestate is crucial. Moreover, the ecotoxicological consequences of shifting from conventional plastics to biodegradable ones are highly uncertain, as there is insufficient evidence to claim that MBPs have a milder effect on ecosystem health. Indeed, literature shows that the impact may be worse depending on the exposed species, polymer type, and the ecosystem complexity.

Comments to "Degli-Innocenti, F. The pathology of hype, hyperbole and publication bias is creating an unwarranted concern towards biodegradable mulch films" [J. Hazard. Mater. 463 (2024) 132923]

Some narratives present biodegradable plastic use for soil mulching practices in agriculture as "environmentally friendly" and "sustainable" alternatives to conventional plastics. To verify these narratives, environmental research recently started focusing on their potential impact on soil health, highlighting some concerns. The paper by Degli-Innocenti criticizes this unfolding knowledge arguing that it is affected by communication hypes, alarmistic writing and a focus on exposure scenarios purposedly crafted to yield negative effects. The quest of scientists for increased impact - the paper concludes - is the driver of such behavior. As scholars devoted to the safeguarding of scientific integrity, we set to verify whether this serious claim is grounded in evidence. Through a bibliometric analysis (using number of paper reads, citations and mentions on social media to measure the impact of publications) we found that: i) the papers pointed out by Degli-Innocenti as examples of biased works do not score higher than the median of similar publications; ii) the methodology used to support the conclusion is non-scientific; and iii) the paper does not fulfil the requirements concerning disclosure of conflicts of interests. We conclude that this paper represents a non-scientific opinion, potentially biased by a conflict of interest. We ask the paper to be clearly tagged as such, after the necessary corrections on the ethic section have been made. That being said, the paper does offer some useful insights for the definition of exposure scenarios in risk assessment. We comment and elaborate on these proposed models, hoping that this can help to advance the field.

Rebuttal of the arguments put forward in the Letter to the Editor by Nizzetto et al

In their Letter to the Editor, Nizzetto et al. challange a recent article in which I show that there has been unwarranted alarmism about biodegradable mulch films due to the publication of numerous articles based on preliminary data that are irrelevant for drawing conclusions on environmental risk. The tendency to over-emphasise results in order to attract attention is a growing problem in the scientific world and has been studied by many scholars. Nizzetto et al. accuse me of not using scientific methodology and of not disclosing that I am a scientist working for a company that produces biodegradable plastics. In this rebuttal I show that Nizzetto et al.'s accusations suffer from a number of logical fallacies, in particular the "straw man" fallacy and the "ad hominem" fallacy.

Polyester biodegradability: importance and potential for optimisation

To reduce global CO2 emissions in line with EU targets, it is essential that we replace fossil-derived plastics with renewable alternatives. This provides an opportunity to develop novel plastics with improved design features, such as better reusability, recyclability, and environmental biodegradability. Although recycling and reuse of plastics is favoured, this relies heavily on the infrastructure of waste management, which is not consistently advanced on a worldwide scale. Furthermore, today's bulk polyolefin plastics are inherently unsuitable for closed-loop recycling, but the introduction of plastics with enhanced biodegradability could help to combat issues with plastic accumulation, especially for packaging applications. It is also important to recognise that plastics enter the environment through littering, even where the best waste-collection infrastructure is in place. This causes endless environmental accumulation when the plastics are non-(bio)degradable. Biodegradability depends heavily on circumstances; some biodegradable polymers degrade rapidly under tropical conditions in soil, but they may not also degrade at the bottom of the sea. Biodegradable polyesters are theoretically recyclable, and even if mechanical recycling is difficult, they can be broken down to their monomers by hydrolysis for subsequent purification and re-polymerisation. Additionally, both the physical properties and the biodegradability of polyesters are tuneable by varying their building blocks. The relationship between the (chemical) structures/compositions (aromatic, branched, linear, polar/apolar monomers; monomer chain length) and biodegradation/hydrolysis of polyesters is discussed here in the context of the design of biodegradable polyesters.

Marine biodegradation of plastic films by Alcanivorax under various ambient temperatures: Bacterial enrichment, morphology alteration, and release of degradation products

The global ocean has been receiving massive amounts of plastic wastes. Marine biodegradation, influenced by global climate, naturally breaks down these wastes. In this study, we systematically compared the biodegradation performance of petroleum- and bio-based plastic films, i.e., low-density polyethylene (LDPE), polylactic acid (PLA), and polyhydroxyalkanoates (PHAs) under three ambient temperatures (4, 15, and 22 °C). We deployed the our previously isolated cold-tolerant plastic-degrading Alcanivorax to simulate the accelerated marine biodegradation process and evaluated the alteration of bacterial growth, plastic films, and released degradation products. Notably, we found that marine biodegradation of PHA films enriched more bacterial amounts, induced more conspicuous morphological damage, and released more microplastics (MPs) and dissolved organic carbon (DOC) under all temperatures compared to LDPE and PLA. Particularly, MPs were released from film edges and cracks with a mean size of 2.8 μm under all temperatures. In addition, the degradation products released by biodegradation of PHA under 22 °C induced the highest acute toxicity to Vibrio fischeri. Our results highlighted that: (1) marine biodegradation of plastics would release millions of MPs per cm2 exposed surface area even in cold environments within 60 days; (2) different marine biodegradation scenarios of these plastics may raise disparate impacts and mitigation-related studies.

Deterioration of single-use biodegradable plastics in high-humidity air and freshwaters over one year: Significant disparities in surface physicochemical characteristics and degradation rates

More single-use plastics are accumulating in the environment, and likewise biodegradable plastics (BPs), which are being vigorously promoted, cannot escape the fate. Currently, studies on the actual degradation of BPs in open-air and freshwaters are underrepresented despite they are potentially headmost leakage and contamination sites for disposable BPs. Herein, we compared the degradation behavior of six BP materials and non-degradable polypropylene (PP) plastics over a 1-year in situ suspension in the high-humidity air, a eutrophic river, and an oligotrophic lake. Moreover, a 3-months laboratory incubation was performed to detect the release of dissolved organic carbon (DOC) from BPs. In both air and freshwaters, poly(p-dioxanone) (PPDO) degraded significantly while PP and polylactic acid (PLA) showed no signs of degradation. The average degradation rates of three poly(butylene adipate-co-terephthalate) (PBAT)-based films varied: 100% in river, 55% in lake, and 10% in air. In addition to PLA, surface chemical groups, hydrophilicity, and thermal stability of BPs changed, and microplastics were found on their surfaces. Correspondingly, BPs with faster degradation rates released relatively higher amounts of DOC. Environmental microbial and chemical characteristics may contribute to differences in BP degradation besides polymer specificity. Altogether, our results indicate the need for appropriate monitoring of BPs.

The pathology of hype, hyperbole and publication bias is creating an unwarranted concern towards biodegradable mulch films

The idea that it is a risk to promote biodegradable mulch films on a large scale is becoming established at academic level based on a series of articles similar in approach and conclusions. However, a critical analysis shows that the results do not justify the alarmist tones. The negative effects of hand-cut pieces of virgin material added in pots at concentrations up to 714 times the application doses are ascribed to the "accumulation" and "contamination" of "residues" and "debris" of biodegradable plastics. Yet, no accumulation and no contamination of biodegradable microplastics has actually been shown. No Predicted Environmental Concentration was established, thus the use of the term risk is inappropriate. The hypothesis of transient phytotoxicity of organic matter under decomposition i.e., an artificial outcome of the experimental scheme used, was not considered. A scrupulous approach to terminology is very important for the quality of communication and for the development of innovations. Scientific communication is a delicate process in which and to avoid hyperbole, there must be strict logical and lexical consistency between results and conclusions. Guidelines on the communication of the results of studies on biodegradable mulch must be developed to avoid the spread of unjustified concerns.

Insights into adsorption behavior and mechanism of Cu(II) onto biodegradable and conventional microplastics: Effect of aging process and environmental factors

The widespread promotion attempt of biodegradable plastics is considered as an effective solution to address conventional plastic pollution. However, the interaction of microplastics (MPs) easily broken down from biodegradable plastics with the coexisting pollutants in aquatic environments has gained less attention. Herein, we investigated the effects of the aging process and environmental factors on copper (Cu(II)) adsorption behavior by biodegradable polylactic acid and conventional polystyrene MPs. Results demonstrated that the aging process significantly altered physicochemical properties of both types of MPs, and PLA showed less resistance to aging. The aged polylactic acid MPs (aged-PLA) exhibited the far highest Cu(II) maximum adsorption capacity (7.13 mg/g) mainly due to its abundant oxygen-containing functional groups (OCFGs), followed by pristine polylactic acid (PLA, 6.08 mg/g), aged polystyrene (aged-PS, 0.489 mg/g) and pristine polystyrene (PS, 0.365 mg/g). The adsorption kinetics of Cu(II) on PLA MPs were controlled by film and intraparticle diffusion, while film diffusion governed the Cu(II) adsorption onto PS MPs. In addition to roles of rougher surface structure, greater surface area and pore filling, the complexation of OCFGs and electrostatic interaction were critical to the adsorption mechanism of aged-PLA and aged-PS, and cation-π interaction was associated with adsorption of aged-PS. Moreover, the adsorption capacity of Cu(II) on aged MPs gradually grew with the increasing pH from 4 to 7. Besides, humic acid significantly promoted the adsorption of Cu(II) at a low concentration (0-20 mg/L) due to the formation of binary mixtures of MPs-HA but inhibited the adsorption at a high concentration (50 mg/L) because of its competitive effect, suggesting the dual roles of humic acid in the adsorption process. Overall, our findings provide a better understanding of the adsorption behavior of metals on biodegradable MPs and emphasize their non-negligible risk as carriers of contaminant.

Assessment of biodegradation of lignocellulosic fiber-based composites - A systematic review

Lignocellulosic fiber-reinforced polymer composites are the most extensively used modern-day materials with low density and better specific strength specifically developed to render better physical, mechanical, and thermal properties. Synthetic fiber-reinforced composites face some serious issues like low biodegradability, non-environmentally friendly, and low disposability. Lignocellulosic or natural fiber-reinforced composites, which are developed from various plant-based fibers and animal-based fibers are considered potential substitutes for synthetic fiber composites because they are characterized by lightweight, better biodegradability, and are available at low cost. It is very much essential to study end-of-life (EoL) conditions like biodegradability for the biocomposites which occur commonly after their service life. During biodegradation, the physicochemical arrangement of the natural fibers, the environmental conditions, and the microbial populations, to which the natural fiber composites are exposed, play the most influential factors. The current review focuses on a comprehensive discussion of the standards and assessment methods of biodegradation in aerobic and anaerobic conditions on a laboratory scale. This review is expected to serve the materialists and technologists who work on the EoL behaviour of various materials, particularly in natural fiber-reinforced polymer composites to apply these standards and test methods to various classes of biocomposites for developing sustainable materials.

Environmental safety of second and third generation bioplastics in the context of the circular economy

Bioplastics derived from organic materials other than crude oil are often suggested as sustainable solutions for tackling end-of-life plastic waste, but little is known of their ecotoxicity to aquatic species. Here, we investigated the ecotoxicity of second and third generation bioplastics toward the freshwater zooplankton Daphnia magna. In acute toxicity tests (48 h), survival was impacted at high concentrations (g.L^-1 range), within the range of salinity-induced toxicity. Macroalgae-derived bioplastic induced hormetic responses under chronic exposure (21 d). Most biological traits were enhanced from 0.06 to 0.25 g.L^-1 (reproduction rate, body length, width, apical spine, protein concentration), while most of these traits returned to controls level at 0.5 g.L^-1. Phenol-oxidase activity, indicative of immune function, was enhanced only at the lowest concentration (0.06 g.L^-1). We hypothesise these suggested health benefits were due to assimilation of carbon derived from the macroalgae-based bioplastic as food. Polymer identity was confirmed by infra-red spectroscopy. Chemical analysis of each bioplastic revealed low metal abundance whilst non target exploration of organic compounds revealed trace amounts of phthalates and flame retardants. The macroalgae-bioplastic disintegrated completely in compost and biodegraded up to 86 % in aqueous medium. All bioplastics acidified the test medium. In conclusion, the tested bioplastics were classified as environmentally safe. Nonetheless, a reasonable end-of-life management of these safer-by-design materials is advised to ensure the absence of harmful effects at high concentrations, depending on the receiving environment.

Transport of microplastics in the body and interaction with biological barriers, and controlling of microplastics pollution

Microplastics (MPs) are one novel environmental pollutant sized < 5 mm that is ubiquitously present in numerous environmental media and particularly susceptible to interact with various toxic chemicals. Importantly, MPs can enter the food chain, and are bio-enriched and bio-accumulated with trophic levels, eventually endangering ecosystems and human health. However, there need to be more understanding regarding the bio-interaction of MPs with the host, particularly for biological barriers. This review aimed to summarize the latest findings regarding the main exposure routes of MPs that generated health burdens on humans. Furthermore, their interactions with biological barriers that generate adverse health effects and the underlying mechanisms were also reviewed. Additionally, we provided a comprehensive overview of recent advances regarding the removing and controlling of MPs. Finally, we discussed the future directions for MPs hazard prevention to provide helpful information for regulating decision-making and guiding safer plastics applications.

Adsorption of heavy metals on biodegradable and conventional microplastics in the Pearl River Estuary, China

In recent years, microplastics (MPs) as emerging carriers for environmental pollutants have attracted increasing worldwide attention. However, the adsorption of heavy metals on MPs, especially for biodegradable MPs, has been still poorly understood in estuarine environments. In this study, we investigated the aging of biodegradable and conventional MPs in the Pearl River Estuary after long-term exposure and their impacts on the adsorption of heavy metals from seawater. The results showed that the changes in surface characteristics were more prominent on biodegradable MPs than on conventional MPs after aging. Both biodegradable and conventional MPs could adsorb heavy metals, and their adsorption capacities fluctuated greatly on different MPs and different exposure times. The adsorption capacities of Cu, Pb, and As on biodegradable MPs were higher than those on conventional MPs, whereas Mn, Cr, and Co had lower adsorption on biodegradable MPs after 9-12 months by inductively coupled plasma-mass spectrometry (ICP-MS). The aging characteristics (CI, O/C, and X_c) of MPs accounted for a contribution of 51.0% on heavy metal adsorption, while the environmental factors (temperature, salinity, pH, and heavy metal concentration) only contributed to 13.2%. Therefore, the present study can provide important evidence on the environmental behaviors and ecological risks of biodegradable and conventional MPs in estuarine systems.

Active microbial communities during biodegradation of biodegradable plastics by mesophilic and thermophilic anaerobic digestion

Biodegradable plastics, if they are not properly managed at their end-of-life, can have the same hazardous environmental consequences as conventional plastics. This study investigates the treatment of the main biodegradable plastics under mesophilic and thermophilic anaerobic digestion using biochemical methane potential test and the microorganisms involved in the process using amplicon sequencing of the 16 S rRNA. Here we showed that, only PHB and TPS undergone important and rapid biodegradation under mesophilic condition (38 °C). By contrast, PCL and PLA exhibited very low biodegradation rate as 500 days were required to reach the ultimate methane yield. Little or no degradation occurred for PBAT and PBS at 38 °C. Under thermophilic conditions (58 °C), TPS, PHB, and PLA reached high levels of biodegradation in a relatively short period (&lt; 100 d). While PBS, PBAT, and PCL could not be converted into methane at 58 °C. PHB degraders (Enterobacter and Cupriavidus) and lactate-utilizing bacteria (Moorella and Tepidimicrobium) appeared to play an important role in the PHB and PLA degradation, respectively. This work not only provides crucial data on the anaerobic digestion of the main biodegradable plastics but also enriches the understanding of the microorganisms involved in this process, which are of great importance for future development of the treatment of biodegradable plastics in anaerobic digestion systems.

Biodegradation of macro- and micro-plastics in environment: A review on mechanism, toxicity, and future perspectives

Plastic waste has gained remarkable research attention due to its accumulation, associated environmental issues, and impact on living organisms. In order to overcome this challenge, there is an urgent need for its removal from the environment. Under this menace, finding appropriate treatment methods like biodegradation instead of typical treatment methods is of supreme importance. However, there is a limited review on bio-decomposition of plastics, existing microbial species, their degradation efficacy, and mechanism. From this point of view, this study focused on a brief overview of biodegradation such as influencing factors on biodegradation, existing species for macro- and micro-plastics, and present research gap. Degradation percentage, limitations of existing species, and future recommendations are proposed. Microbial species such as bacteria, algae, and fungi have the ability to decompose plastics but they are unable to completely mineralize the plastics. Meanwhile, there is limited knowledge about the involved enzymes in plastics degradation, especially in the case of algae. Bio-decomposition of plastics requires more stringent conditions which are usually feasible for field application. This work will be a reference for new researchers to use this effective strategy for plastic pollution removal.

Prominent toxicity of isocyanates and maleic anhydrides to Caenorhabditis elegans: Multilevel assay for typical organic additives of biodegradable plastics

Biodegradable plastics (BDP) are increasingly applied; however, there has been of concerns about their environmental safety, especially from nondegradable additive compositions. Until now, data of ecotoxicity of BDP additives is scarce. Here, nematode C. elegans was used to comparatively evaluate toxicity of an isocyanate additive, i.e., Hexamethylene diisocyanate (HDI), a maleic anhydride, i.e., Diallyl maleate (DIM), and other four BDP organic additives. These additives caused lethality of nematodes at µg L^-1 level, of lowest LC₅₀ value of HDI/DIM. Uniform exposure to these additives resulted in various degrees of inhibitions in body volumes and longevity, indicating developmental toxicity. Moreover, BDP additives induced significant elevations of gst-4 expression, especially mean 123.54 %/234.29 % increase in HDI/DIM group, but reduced ges-1 expression, which indicates oxidative damages and mitochondrial dysfunction. BDP additives further caused inhibition in locomotor and food intake/excretion behavior, and related damages of glutamatergic neurons and GABAergic neurons, indicating their neurotoxicity. We found HDI and DIM presented relatively strong effects on susceptible endpoints including lethality, gst-4, mean lifespan, food intake and excretion behavior. Overall, this study suggests prominent ecotoxic risk of isocyanates and maleic anhydrides as BDP additives, which is significant for the selection of environmentally friendly BDP additives.

Aging of poly (lactic acid)/poly (butylene adipate-co-terephthalate) blends under different conditions: Environmental concerns on biodegradable plastic

Biodegradable plastics (BPs) have been used to replace conventional plastics owing to their environmental harmless and ease of degradation. However, the aging processes of BPs in different environments remain unclear. In this study, we used poly (lactic acid)/poly (butylene adipate-co-terephthalate) (PLA/PBAT) films as model BPs and investigated the 30-d aging behavior of PLA/PBAT films under four conditions (i.e., air without ultraviolet (UV) irradiation, water without UV irradiation, air with UV irradiation, and water with UV irradiation). Our results showed that the aging of PLA/PBAT films was insignificant in all groups except the water with UV irradiation group. In the physical characterization, the PLA/PBAT films exhibited layered structures in water with UV irradiation condition, and the submicron- and nano-sized particles adhered to the bigger-sized fragments. In the chemical characterization, the carbonyl index (CI) of PLA/PBAT films in water with UV irradiation condition decreased from 3.84 to 1.36, and the oxygen-to-carbon (O/C) ratio reached a maximum of 1.78 at 20 d and declined to 0.49 at 30 d, indicating that the oxygen-containing functional groups underwent bond breaking and showed a rapid aging process. This is mainly attributed to the combined effect of hydrolysis and photolysis increases the contact area of PLA/PBAT films and accelerates the aging process. Furthermore, based on two-dimensional correlation spectroscopy (2D-COS) analysis, we suggest that free radicals generated in water with UV irradiation conditions also accelerate the aging process of PLA/PBAT films. This study explored the aging processes of PLA/PBAT films under different conditions, which could aid in clarifying the environmental behavior and provide further information to assess the potential risks of BPs.

Plastic litter in coastal sand dunes: Degradation behavior and impact on native and non-native invasive plants

Pollution associated to marine plastic litter is raising increasing concerns due to its potential harmful effects on human health, biota, and coastal ecosystems. However, limited information is available on the degradation behavior of plastics, especially biodegradable ones, in dune habitats. Moreover, the effects of plastics on dune plant growth and ability to withstand environmental stresses and invasion by non-native plants have been largely neglected. This is a particularly relevant issue since biological invasions are major threats to dune ecosystems. In this 18-month study, we examined the degradation behavior of two plastic bags, non-biodegradable (NBP) or biodegradable/compostable (BP), in the dune environment by visual observations and analytical techniques. Concomitantly, we investigated the individual and combined effects of bag type and sand burial (no burial vs. partial burial) on the performance of a native dune plant (Thinopyrum junceum) and an invasive plant (Carpobrotus sp.) and on their interaction. NBP did not show relevant degradation signs over the experimental period as expected. BP exhibited gradual surface modifications and changes in chemical functionality and were almost disintegrated after 18 months. Bags and burial reduced independently T. junceum survival and growth, and most plants died within 8 months of plastic exposure. Bags and burial did not affect Carpobrotus survival. However, burial decreased Carpobrotus growth while NBP increased it. Both plastics increased Carpobrotus competitive ability, and no T. junceum plants survived to co-occurrent Carpobrotus, BP, and burial. These findings indicate that removing all littered plastics from beach-dune systems not only is critical to reduce plastic pollution but also to prevent further spread of invasive species in coastal dunes.

Degradation of polylactic acid/polybutylene adipate films in different ratios and the response of bacterial community in soil environments

Biodegradable plastic mulch film (BDM) is an environmentally friendly alternative to conventional polyethylene mulch, and has been growingly used in agriculture. However, practical degradation performance of BDM, especially the widely used type of blended polylactic acid (PLA)/polybutylene adipate (PBAT) in different ratios, and microbial alteration in soil environments, remain largely unrevealed. In this study, four types of BDM blended with 40-80% PLA and 20-60% PBAT were comparatively investigated through microcosm soil incubation experiments for 105 days, and combined with conditions of different soil moisture or pH. Microbiome within film-surrounding soil were assayed using 16 S rRNA high-throughput sequencing. Results showed a trend of increasing degradation efficiency with the increase of PLA proportion, and 70% PLA and 30% PBAT group presented the highest weight loss rate, i.e., 60.16 ± 5.86%. In addition, degradation and aging of PLA/PBAT varied among different soil moisture and pH values. A moderate moisture, i.e., 60% and a neutral pH7.0 caused significantly high degradation efficiency compared to other moisture or pH conditions. Moreover, bacterial abundance and community structure in the surrounding soil were related to soil moisture and pH. PLA/PBAT incubation treatment induced a remarkable increase in abundance of degradation-related species Pseudomonas and Sphingomonas. Bacterial richness and diversity in soil correspondingly respond to ratio-different PLA/PBAT's degradation under moisture/pH-different conditions through a redundancy analysis. Altogether, these findings indicate that practical degradation of PLA/PBAT film is closely related to soil environments and bacterial community. It is significant for the application of biodegradable plastics in agriculture on the perspective of soil sustainability.

Bioconversion of biowaste into renewable energy and resources: A sustainable strategy

Due to its high amount of organic and biodegradable components that can be recycled, biowaste is not only a major cause of environmental contamination, but also a vast store of useful materials. The transformation of biowaste into energy and resources via biorefinery is an unavoidable trend, which could aid in reducing carbon emissions and alleviating the energy crisis in light of dwindling energy supplies and mounting environmental difficulties related with solid waste. In addition, the current pandemic and the difficult worldwide situation, with their effects on the economic, social, and environmental aspects of human life, have offered an opportunity to promote the transition to greener energy and sources. In this context, the current advancements and possible trends of utilizing widely available biowaste to produce key biofuels (such as biogas and biodiesel) and resources (such as organic acid, biodegradable plastic, protein product, biopesticide, bioflocculant, and compost) are studied in this review. To achieve the goal of circular bioeconomy, it is necessary to turn biowaste into high-value energy and resources utilizing biological processes. In addition, the usage of recycling technologies and the incorporation of bioconversion to enhance process performance are analyzed critically. Lastly, this work seeks to reduce a number of enduring obstacles to the recycling of biowaste for future use in the circular economy. Although it could alleviate the global energy issue, additional study, market analysis, and finance are necessary to commercialize alternative products and promote their future use. Utilization of biowaste should incorporate a comprehensive approach and a methodical style of thinking, which can facilitate product enhancement and decision optimization through multidisciplinary integration and data-driven techniques.

Is a compostable plastic biodegradable in the sea? A rapid standard protocol to test mineralization in marine conditions

Due to environmental persistence, lack of a proper land-based waste management, and global circulation, marine ecosystems are especially threatened by plastics. The search for alternatives to conventional oil-based polymers gave rise to novel materials commercialized under different "green" labels based on compostability. However, current international standards are not effective in predicting actual biodegradability of plastic objects in natural scenarios, and degradation of these novel bioplastics in marine conditions is unwarranted. We present a simple and rapid standard protocol based on their biological oxygen demand, intended to support policy-makers and plastic industry in the search for truly marine-biodegradable plastics. Improvements include: development of an environmentally relevant nutrient formulation following Redfield ratio (106C:16 N:1P); use of a natural inoculum representative of marine habitats (sediment pore water); standardization of the test material by grinding to particles below 250 μm to shorten the incubation period, and selection of a truly biodegradable biopolymer (PHB), used as positive control. This protocol was successfully applied to show that commercial compostable plastics are not biodegradable in marine environments.

Biodegradable Polymer Materials Based on Polyethylene and Natural Rubber: Acquiring, Investigation, Properties

The growing amount of synthetic polymeric materials is a great environmental problem that has to be solved as soon as possible. The main factor aggravating this problem is the abundance of products made from traditional synthetic polymer, such as packaging materials, cases, containers and other equipment with a short period of use, which quickly turns into polymer waste that pollutes the ecosystem for decades. In this paper, we consider the possibility of solving this problem by the development of biodegradable compositions based on polyolefins and elastomers. The addition of a natural component (natural rubber) to the matrix of the synthetic polymeric (polyethylene) leads to the significant changes in structure and properties of the material. Different aspects of mixing semicrystalline and amorphous polymers are discussed in the article. It was shown that addition of 10-50% wt. of the elastomers to the synthetic polymer increases wettability of the material, slightly reduces the mechanical properties, significantly affects the supramolecular structure of the crystalline phase of polyethylene and initiates microbiological degradation. In particular, in this work, the acquisition, structure and properties of biodegradable binary composites based on low-density polyethylene (LDPE) and natural rubber (NR) were studied. It has been shown that such compositions are biodegradable in soil under standard conditions.

Mesocosm trials reveal the potential toxic risk of degrading bioplastics to marine life

If biodegradable plastics tackle the marine plastic pollution problem sufficiently remains questionable. To gain more insight in degradability, performance, and the impact of degradation on the toxicity, commercial bags made from two biodegradable plastics and one conventional plastic (PE) were exposed for 120 days in a mesocosm featuring benthic, pelagic, and littoral habitat simulations. Degradability was assessed as weight loss, and specimens were tested for toxicity using Paracentrotus lividus sea-urchin larvae after different exposure times. Both biodegradable bags showed degradation within 120 days, with the littoral simulation showing the highest and the pelagic simulation the lowest decay. Disregarding habitat, the home-compostable plastic showed higher marine degradation than the industrial-compostable material. The relevant initial toxicity of both biopolymers was lost within 7 days of exposure, pointing towards easily leachable chemical additives as its cause. Interestingly, littoral exposed specimens gained toxicity after 120 days, suggesting UV- induced modifications that increase biopolymer toxicity.

Weathering pathways and protocols for environmentally relevant microplastics and nanoplastics: What are we missing?

To date, most studies of microplastics have been carried out with pristine particles. However, most plastics in the environment will be aged to some extent; hence, understanding the effects of weathering and accurately mimicking weathering processes are crucial. By using microplastics that lack environmental relevance, we are unable to fully assess the risks associated with microplastic pollution in the environment. Emerging studies advocate for harmonization of experimental methods, however, the subject of reliable weathering protocols for realistic assessment has not been addressed. In this work, we critically analysed the current knowledge regarding protocols used for generating environmentally relevant microplastics and leachates for effects studies. We present the expected and overlooked weathering pathways that plastics will undergo throughout their lifecycle. International standard weathering protocols developed for polymers were critically analysed for their appropriateness for use in microplastics research. We show that most studies using weathered microplastics involve sorption experiments followed by toxicity assays. The most frequently reported weathered plastic types in the literature are polystyrene>polyethylene>polypropylene>polyvinyl chloride, which does not reflect the global plastic production and plastic types detected globally. Only ~10% of published effect studies have used aged microplastics and of these, only 12 use aged nanoplastics. This highlights the need to embrace the use of environmentally relevant microplastics and to pay critical attention to the appropriateness of the weathering methods adopted moving forward. We advocate for quality reporting of weathering protocols and characterisation for harmonization and reproducibility across different research efforts.

The Biological Effects of 3D Resins Used in Orthodontics: A Systematic Review

Three-dimensional (3D) resin medical-dental devices have been increasingly used in recent years after the emergence of digital technologies. In Orthodontics, therapies with aligners have gained popularity, mainly due to the aggressive promotion policies developed by the industry. However, their systemic effects are largely unknown, with few studies evaluating the systemic toxicity of these materials. The release of bisphenol A and other residual monomers have cytotoxic, genotoxic, and estrogenic effects. This systematic review aims to analyze the release of toxic substances from 3D resins used in Orthodontics and their toxic systemic effects systematically. The PICO question asked was, "Does the use of 3D resins in orthodontic devices induce cytotoxic effects or changes in estrogen levels?". The search was carried out in several databases and according to PRISMA guidelines. In vitro, in vivo, and clinical studies were included. The in vitro studies' risk of bias was assessed using the guidelines for the reporting of pre-clinical studies on dental materials by Faggion Jr. For the in vivo studies, the SYRCLE risk of bias tool was used, and for the clinical studies, the Cochrane tool. A total of 400 articles retrieved from the databases were initially scrutinized. Fourteen articles were included for qualitative analysis. The risk of bias was considered medium to high. Cytotoxic effects or estrogen levels cannot be confirmed based on the limited preliminary evidence given by in vitro studies. Evidence of the release of bisphenol A and other monomers from 3D resin devices, either in vitro or clinical studies, remains ambiguous. The few robust results in the current literature demonstrate the absolute need for further studies, especially given the possible implications for the young patient's fertility, which constitutes one of the largest groups of patients using these orthodontic devices.

Assessment of the Decomposition of Oxo- and Biodegradable Packaging Using FTIR Spectroscopy

The strength and resistance of plastics at the end of their service life can hinder their degradation. The solution to this problem may be materials made of biodegradable and oxo-biodegradable plastics. The aim of this research was to determine the degree and nature of changes in the composition and structure of composted biodegradable and oxo-biodegradable bags. The research involved shopping bags and waste bags available on the Polish market. The composting of the samples was conducted in an industrial composting plant. As a result of the research, only some of the composted samples decomposed. After composting, all samples were analysed using FTIR (Fourier Transformation Infrared) spectroscopy. Carbonyl index and hierarchical cluster analysis method was used to detect similarities between the spectra of the new samples. The analysis of the obtained results showed that FTIR spectroscopy is a method that can be used to confirm the degradation and detect similarities in the structure of the analysed materials. The analysis of spectra obtained with the use of FTIR spectroscopy indicated the presence of compounds that may be a potential source of compost contamination. Plastics with certificates confirming their biodegradability and compostability should be completely biodegradable, i.e., each element used in their production should be biodegradable and safe for the environment.

Recent Advances in Biotechnological Itaconic Acid Production, and Application for a Sustainable Approach

Intense research has been conducted to produce environmentally friendly biopolymers obtained from renewable feedstock to substitute fossil-based materials. This is an essential aspect for implementing the circular bioeconomy strategy, expressly declared by the European Commission in 2018 in terms of "repair, reuse, and recycling". Competent carbon-neutral alternatives are renewable biomass waste for chemical element production, with proficient recyclability properties. Itaconic acid (IA) is a valuable platform chemical integrated into the first 12 building block compounds the achievement of which is feasible from renewable biomass or bio-wastes (agricultural, food by-products, or municipal organic waste) in conformity with the US Department of Energy. IA is primarily obtained through fermentation with Aspergillus terreus, but nowadays several microorganisms are genetically engineered to produce this organic acid in high quantities and on different substrates. Given its trifunctional structure, IA allows the synthesis of various novel biopolymers, such as drug carriers, intelligent food packaging, antimicrobial biopolymers, hydrogels in water treatment and analysis, and superabsorbent polymers binding agents. In addition, IA shows antimicrobial, anti-inflammatory, and antitumor activity. Moreover, this biopolymer retains qualities like environmental effectiveness, biocompatibility, and sustainability. This manuscript aims to address the production of IA from renewable sources to create a sustainable circular economy in the future. Moreover, being an essential monomer in polymer synthesis it possesses a continuous provocation in the biopolymer chemistry domain and technologies, as defined in the present review.