Adverse effects of oxo-degradable plastic leachates in freshwater environment

Influences of bisphenol A on hydrogen production from food waste by thermophilic dark fermentation

The extensive use of plastic products in food packaging and daily life makes them inevitably enter the treatment process of food waste (FW). Plasticizer as a new pollutant is threatening the dark fermentation of FW. Our study showed that bisphenol A (BPA) at > 250 mg/L had a significant inhibition on hydrogen production from FW by thermophilic dark fermentation. The endogenous ATP content and lactate dehydrogenase (LDH) release showed that high level of BPA not only inhibited the growth of hydrogen-producing consortium, but also led to cell death. In addition, BPA mainly affects the hydrogen-producing consortium by reducing cell membrane fluidity, damaging cell membrane integrity and reducing cell membrane potential, resulting in cell death. This study provides some new insights into the mechanism of the effect of BPA on hydrogen production from FW by thermophilic dark fermentation, and lays the foundation on the utilization of FW.

Environmental occurrence and ecotoxicological risks of plastic leachates in aquatic and terrestrial environments

Plastic pollution poses a significant threat to environmental and human health, with microplastics widely distributed across various ecosystems. Although current ecotoxicological studies have primarily focused on the inherent toxicity of plastics in natural environments, the role of chemical additives leaching from plastics into the environment remains underexplored despite their significant contribution to the overall toxic potential of plastics. Existing systematic studies on plastic leachates have often examined isolated additive compounds, neglecting the ecotoxicological effects of multiple compounds present in plastic leachates. Additionally, most previous research has focused on aquatic environments, overlooking the leaching mechanisms and ecological risks to diverse species with various ecological roles in aquatic and terrestrial ecosystems. This oversight hinders comprehensive ecological risk assessments. This study addresses these research gaps by reviewing the environmental occurrence of plastic leachates and their ecotoxicological impacts on aquatic and terrestrial ecosystems. Key findings reveal the pervasive presence of plastic leachates in various environments, identifying common additives such as phthalates, polybrominated diphenyl ethers (PBDEs), bisphenol A (BPA), and nonylphenols (NPs). Ecotoxicologically, chemical additives leaching from plastics under specific environmental conditions can influence their bioavailability and subsequent uptake by organisms. This review proposes a novel ecotoxicity risk assessment framework that integrates chemical analysis, ecotoxicological testing, and exposure assessment, offering a comprehensive approach to evaluating the risks of plastic leachates. This underscores the importance of interdisciplinary research that combines advanced analytical techniques with ecotoxicological studies across diverse species and environmental conditions to enhance the understanding of the complex impacts of plastic leachates and inform future research and regulatory policies.

Microbial strategies for effective microplastics biodegradation: Insights and innovations in environmental remediation

Microplastics (MPs), diminutive yet ubiquitous fragments arising from the degradation of plastic waste, pervade environmental matrices, posing substantial risks to ecological systems and trophic dynamics. This review meticulously examines the origins, distribution, and biological impacts of MPs, with an incisive focus on elucidating the molecular and cellular mechanisms underpinning their toxicity. We highlight the indispensable role of microbial consortia and enzymatic pathways in the oxidative degradation of MPs, offering insights into enhanced biodegradation processes facilitated by innovative pretreatment methodologies. Central to our discourse is the interplay between MPs and biota, emphasizing the detoxification capabilities of microbial metabolisms and enzymatic functions in ameliorating MPs' deleterious effects. Additionally, we address the practical implementations of MP biodegradation in environmental remediation, advocating for intensified research to unravel the complex biodegradation pathways and to forge effective strategies for the expeditious elimination of MPs from diverse ecosystems. This review not only articulates the pervasive challenges posed by MPs but also positions microbial strategies at the forefront of remedial interventions, thereby paving the way for groundbreaking advancements in environmental conservation.

Research progress on degradation of biodegradable micro-nano plastics and its toxic effect mechanism on soil ecosystem

Biodegradable plastics (BPs) are known to decompose into micro-nano plastics (BMNPs) more readily than conventional plastics (CPs). Given the environmental risks posed by BMNPs in soil ecosystems, their impact has garnered increasing attention. However, research focusing on the toxic effects of BMNPs on soils remains relatively limited. The degradation process and duration of BMNPs in soil are influenced by numerous factors, which directly impact the toxic effects of BMNPs. This highlights the urgent need for further research. In this context, this review delineates the classification of BPs, investigates the degradation processes of BPs along with their influencing factors, summarizes the toxic effects on soil ecosystems, and explores the potential mechanisms that underlie these toxic effects. Finally, it provides an outlook on related research concerning BMNPs in soil. The results indicate that specific BMNPs release additives at a faster rate during decomposition, degradation, and aging, with certain compounds exhibiting increased bioavailability. Importantly, a substantial body of research has shown that BMNPs generally manifest more pronounced toxic effects in comparison to conventional micro-nano plastics (CMNPs). The toxic effects associated with BMNPs encompass a decline in soil quality and microbial biomass, disruption of nutrient cycling, inhibition of plant root growth, and negative impacts on invertebrate reproduction, survival, and fertilization rates. The rough and complex surfaces of BMNPs contribute to increased mechanical damage to tested organisms, enhance absorption by microorganisms, and disrupt normal physiological functions. Notably, the toxic effects of BMNPs on soil ecosystems are influenced by factors including concentration, type of BMNPs, exposure conditions, degradation products, and the nature of additives used. Therefore, it is crucial to standardize detection technologies and toxicity testing conditions for BMNPs. In conclusion, this review provides scientific evidence that supports effective prevention and management of BMNP pollution, assessment of its ecological risks, and governance of BMNPs-related products.

Assessing genotoxic effects of plastic leachates in Drosophila melanogaster

Plastic polymers were largely added with chemical substances to be utilized in the items and product manufacturing. The leachability of these substances is a matter of concern given the wide amount of plastic waste, particularly in terrestrial environments, where soil represents a sink for these novel contaminants and a possible pathway of human health risk. In this study, we integrated genetic, molecular, and behavioral approaches to comparatively evaluate toxicological effects of plastic leachates, virgin and oxodegradable polypropylene (PP) and polyethylene (PE), in Drosophila melanogaster, a novel in vivo model organism for environmental monitoring studies and (eco)toxicological research. The results of this study revealed that while conventional toxicological endpoints such as developmental times and longevity remain largely unaffected, exposure to plastic leachates induces chromosomal abnormalities and transposable element (TE) activation in neural tissues. The combined effects of DNA damage and TE mobilization contribute to genome instability and increase the likelihood of LOH events, thus potentiating tumor growth and metastatic behavior ofRasV12 clones. Collectively, these findings indicate that plastic leachates exert genotoxic effects in Drosophila thus highlighting potential risks associated with leachate-related plastic pollution and their implications for ecosystems and human health.

The retention of plastic particles by macrophytes in the Amazon River, Brazil

This study evaluated the presence of plastics and microplastics in macrophytes in an urbanized sector of the Amazon River. A total of 77 quadrats in 23 macrophyte banks were sampled during the dry (September 2020) and rainy (June 2021) season. Five species were identified: Paspalum repens, Pontederia rotundifolia, Pistia stratiotes, Salvinia auriculata and Limnobium laevigatum, with P. repens being dominant during the dry season (47.54%) and P. rotundifolia during the rainy season (78.96%). Most of the plastic particles accumulated in Paspalum repens (49.3%) and P. rotundifolia (32.4%), likely due to their morphological structure and volume. The dry season showed a higher accumulation of plastic particles than the rainy season. Microplastics were found in most samples, during both the dry (75.98%) and rainy seasons (74.03%). The upstream macrophyte banks retained more plastic particles compared to the downstream banks. A moderate positive correlation was observed between the presence of plastic particles and macrophyte biomass, and a weak positive correlation between the occurrence of microplastics and mesoplastics. White and blue fragments, ranging from 1 to 5 mm were the most common microplastics found in the macrophyte banks. Green fragments and green and blue fibers were identified as polypropylene, blue and red fragments as polyethylene, and white fragments as polystyrene. Therefore, the results of this study highlight the first evidence of the retention of plastic particles in macrophytes of the Amazon and highlight a significant risk due to the harmful effects that this type of plastic can cause to the fauna and flora of aquatic ecosystems.

Revealing chemical release from plastic debris in animals' digestive systems using nontarget and suspect screening and simulating digestive fluids

Plastic debris in the environment are not only pollutants but may also be important sources of a variety of contaminants. This work simulated kinetics and potential of chemical leaching from plastic debris in animals' digestive systems by incubating polyvinyl chloride (PVC) cord particles in artificial digestive fluids combined with nontarget and suspect screening based on UHPLC-Orbitrap HRMS. Impacts of particle size, aging, and digestive fluid were investigated to elucidate mechanisms of chemical leaching. Thousands of chemical features were screened in the leachates of PVC cord particles in the artificial digestive fluids, among which >60% were unknown. Bisphenol A (BPA) and bis(2-ethylhexyl) phthalate (DEHP) were the dominant identified CL1 compounds. Finer size and aging of the PVC particles and prolonged incubation time enhanced chemical release, resulting in greater numbers, higher levels, and more complexity in components of the released chemicals. The gastrointestinal fluid was more favorable for chemical leaching than the gastric fluid, with greater numbers and higher levels. Hundreds to thousands of chemical features were screened and filtered in the leachates of consumer plastic products, including food contact products (FCPs) in the artificial bird gastrointestinal fluid. In addition to BPA and DEHP, several novel bisphenol analogues were identified in the leachate of at least one FCP. The results revealed that once plastic debris are ingested by animals, hundreds to thousands of chemicals may be released into animals' digestive tracts in hours, posing potential synergistic risks of plastic debris and chemicals to plastic-ingesting animals. Future research should pay more attentions to identification, ecotoxicities, and environmental fate of vast amounts of unknown chemicals potentially released from plastics in order to gain full pictures of plastic pollution in the environment.

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

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

An insight decipher on photocatalytic degradation of microplastics: Mechanism, limitations, and future outlook

Plastic material manufacturing and buildup over the past 50 years has significantly increased pollution levels. Microplastics (MPs) and non-biodegradable residual plastic films have become the two most pressing environmental issues among the numerous types of plastic pollution. These tiny plastic flakes enter water systems from a variety of sources, contaminating the water. Since MPs can be consumed by people and aquatic species and eventually make their way into the food chain, their presence in the environment poses a serious concern. Traditional technologies can remove MPs to some extent, but their functional groups, stable covalent bonds, and hydrophobic nature make them difficult to eliminate completely. The urgent need to develop a sustainable solution to the worldwide contamination caused by MPs has led to the exploration of various techniques. Advanced oxidation processes (AOPs) such as photo-catalytic oxidation, photo-degradation, and electrochemical oxidation have been investigated. Among these, photocatalysis stands out as the most promising method for degrading MPs. Photocatalysis is an environmentally friendly process that utilizes light energy to facilitate a chemical reaction, breaking down MPs into carbon dioxide and water-soluble hydrocarbons under aqueous conditions. In photocatalysis, semiconductors act as photocatalysts by absorbing energy from a light source, becoming excited, and generating reactive oxygen species (ROS). These ROS, including hydroxyl radicals (•OH) and superoxide ions ( [Formula: see text] ), play a crucial role in the degradation of MPs. This extensive review provides a detailed exploration of the mechanisms and processes underlying the photocatalytic removal of MPs, emphasizing its potential as an efficient and environmentally friendly approach to address the issue of plastic pollution.

Effects of primary leachates of conventional and alternative plastics in Cyprinodon variegatus fish larvae: Endocrine disruption and toxicological responses

The inclusion of hazardous substances in the formulation of plastics raises significant concerns, particularly, if those substances are released as primary leachates during plastic degradation and/or fragmentation. In this sense, the production of degradable plastics holding deleterious additives can increase the release of harmful substances into the environment. Additionally, the effects of primary leachates of "eco-friendly" materials remain unexplored. To address this, we performed exposures to primary leachates of alternative polymers, and commercial bags to verify possible responses associated with endocrine disruption and/or activation of the detoxification pathway in larvae of the marine fish model Cyprinodon variegatus. The chemical characterization evidenced a great number of additives in the formulation of the materials analyzed in this study. Those include, except for the PLA sample, relevant levels of the hazardous phthalates DEHP and DiBP. Regarding the effects on marine fish larvae, exposure to leachates from alternative polymers (10 g/L) PHB and PHBV produced remarkable mortality (100%). While the exposure to bag leachates of all tested materials (1 and 10 g/L) produced alterations in biomarkers for steroidogenic and detoxification pathways. To a lesser extent (10 g/L), three materials produced significant alterations in estrogenic biomarkers (Home-compostable bag 1, LDPE and Recycled PE bags). Although the alterations in gene expression were not directly correlated to the amount of DEHP or DiBP, we can conclude that primary leachates of "eco-friendly" bags are harmful to marine vertebrates.

An investigation into the stability and degradation of plastics in aquatic environments using a large-scale field-deployment study

The fragmentation of plastic debris is a key pathway to the formation of microplastic pollution. These disintegration processes depend on the materials' physical and chemical characteristics, but insight into these interrelationships is still limited, especially under natural conditions. Five plastics of known polymer/additive compositions and processing histories were deployed in aquatic environments and recovered after six and twelve months. The polymer types used were linear low density polyethylene (LLDPE), oxo-degradable LLDPE (oxoLLDPE), poly(ethylene terephthalate) (PET), polyamide-6 (PA6), and poly(lactic acid) (PLA). Four geographically distinct locations across Aotearoa/New Zealand were chosen: three marine sites and a wastewater treatment plant (WWTP). Accelerated UV-weathering under controlled laboratory conditions was also carried out to evaluate artificial ageing as a model for plastic degradation in the natural environment. The samples' physical characteristics and surface microstructures were studied for each deployment location and exposure time. The strongest effects were found for oxoLLDPE upon artificial ageing, with increased crystallinity, intense surface cracking, and substantial deterioration of its mechanical properties. However, no changes to the same extent were found after recovery of the deployed material. In the deployment environments, the chemical nature of the plastics was the most relevant factor determining their behaviours. Few significant differences between the four aquatic locations were identified, except for PA6, where indications for biological surface degradation were found only in seawater, not the WWTP. In some cases, artificial ageing reasonably mimicked the changes which some plastic properties underwent in aquatic environments, but generally, it was no reliable model for natural degradation processes. The findings from this study have implications for the understanding of the initial phases of plastic degradation in aquatic environments, eventually leading to microplastics formation. They can also guide the interpretation of accelerated laboratory ageing for the fate of aquatic plastic pollution, and for the testing of aged plastic samples.

Synthetic and natural rubber associated chemicals drive functional and structural changes as well as adaptations to antibiotics in in vitro marine microbiomes

The leaching of additives from plastics and elastomers (rubbers) has raised concerns due to their potential negative impacts on the environment and the development of antibiotic resistance. In this study, we investigated the effects of chemicals extracted from two types of rubber on microbiomes derived from a benthic sea urchin and two pelagic fish species. Additionally, we examined whether bacterial communities preconditioned with rubber-associated chemicals displayed adaptations to antibiotics. At the highest tested concentrations of chemicals, we observed reduced maximum growth rates and yields, prolonged lag phases, and increased alpha diversity. While the effects on alpha and beta diversity were not always conclusive, several bacterial genera were significantly influenced by chemicals from the two rubber sources. Subsequent exposure of sea urchin microbiomes preconditioned with rubber chemicals to the antibiotic ciprofloxacin resulted in decreased maximum growth rates. This indicates a more sensitive microbiome to ciprofloxacin when preconditioned with rubber chemicals. Although no significant interaction effects between rubber chemicals and ciprofloxacin exposure were observed in bacterial alpha and beta diversity, we observed log-fold changes in two bacterial genera in response to ciprofloxacin exposure. These findings highlight the structural and functional alterations in microbiomes originating from various marine species when exposed to rubber-associated chemicals and underscore the potential risks posed to marine life.

Oxidative stress and energy metabolic response of Isochrysis galbana induced by different types of pristine and aging microplastics and their leachates

The aging process and leachate composition of different types of MPs (PS, PS-NH2, PS-COOH and PMMA) with a particle size of 1.0 μm were characterized, and marine microalgae Isochrysis galbana OA3011(I. galbana) was used as test organism to investigate the 96 h toxic effects of MPs before and after aging as well as leachate exposure. Except for polymethyl methacrylate (PMMA), all other tested microplastics showed significant aggregation in seawater, which increased with the presence of surface amino and carboxyl groups, in addition, the increase in polymer dispersibility index (PDI) values after aging reflected more severe aggregation. Fourier transform infrared spectrometer (FTIR) showed that the surface amino groups were shed during the aging of PS-NH2, which can likewise be demonstrated by the change in surface electric potential from positive to negative before and after aging. PMMA, due to the addition of plasticizers (HEHP and DIBP detected in high concentration) and its own structure, has stronger resistance to aging than the other three microplastics, and no significant aging phenomenon occurs. As for I. galbana, growth inhibition, oxidative stress and energy metabolism were tested after exposure to different microplastics and their leachate. It was found that high concentrations of A-PS had a greater negative impact on I. galbana, while the toxic effects of PS-NH2 and PS-COOH on I. galbana behaved in a diametrically opposite way before and after aging compared to PS with the inhibitory effect decreasing after aging, which was caused by the shedding of surface groups. As for PMMA, the differences in the toxic effects on microalgae before and after aging were not significant. The inhibitory effect of low concentrations of PAEs (Phthalate acid esters) in the leachate of PS-COOH on I. galbana was not significant, and the stronger inhibitory effect of 4 d L-PS-NH2 was presumed to be the shedding of positively charged groups.

Leaching and transformation of chemical additives from weathered plastic deployed in the marine environment

Plastic pollution causes detrimental environmental impacts, which are increasingly attributed to chemical additives. However, the behaviour of plastic additives in the marine environment is poorly understood. We used a marine deployment experiment to examine the impact of weathering on the extractables profile, analysed by liquid chromatography-mass spectrometry, of four plastics at two locations over nine months in Aotearoa/New Zealand. The concentration of additives in polyethylene and oxo-degradable polyethylene were strongly influenced by artificial weathering, with deployment location and time less influential. By comparison, polyamide 6 and polyethylene terephthalate were comparatively inert with minimal change in response to artificial weathering or deployment time. Non-target analysis revealed extensive differentiation between non-aged and aged polyethylene after deployment, concordant with the targeted analysis. These observations highlight the need to consider the impact of leaching and weathering on plastic composition when quantifying the potential impact and risk of plastic pollution within receiving environments.

Intraspecific genetic lineages of a marine mussel show behavioural divergence when exposed to microplastic leachates

Worldwide, microplastic pollution has numerous negative implications for marine biota, exacerbating the effects of other forms of global anthropogenic disturbance. Mounting evidence shows that microplastics (MPs) not only cause physical damage through their ingestion, but also act as vectors for hazardous compounds by leaching absorbed and adsorbed chemicals. Research on the effects of plastic pollution has, however, largely assumed that species respond uniformly, while ignoring intraspecific diversity (i.e., variation within a single species). We investigated the effects of plastic leachates derived from factory-fresh (virgin) and beached microplastics on the behavioural responses of two genetic lineages of the Mediterranean mussel Mytilus galloprovincialis. Through laboratory behavioural experiments, we found that during exposure to leachates from beached microplastics (beached MPLs), Atlantic specimens moved significantly less than Mediterranean individuals in terms of both (i) proportion of individuals responding through movement and (ii) net and gross distances crawled. In contrast, no significant intraspecific differences were observed in the behaviour of either adults or recruits when exposed to MPLs from virgin microplastics (virgin MPLs). Additionally, the reception of cues from three amino acids (L-cysteine, proline and L-leucine) at increasing concentrations (10-5 M to 10-3 M in charcoal-filtered seawater) was tested by electrophysiological analysis using mussels exposed to beached MPLs or control seawater. We found significant intraspecific differences in response to 10-3 M L-cysteine (regardless of treatment) and 10-4 M L-cysteine (in mussels exposed to beached MPLs) and to 10-3 M proline (in mussels exposed to beached MPLs) and 10-5 M L-leucine. Our study suggests that intraspecific variation in a marine mussel may prompt different responses to plastic pollution, potentially triggered by local adaptation and physiological variability between lineages. Our work highlights the importance of assessing the effects of intraspecific variation, especially in environmental sentinel species as this level of diversity could modulate responses to plastic pollution.

Prepared microplastics interaction with Artemia salina under low pH conditions representing ocean acidification; a simulated environmental exposure

Ocean acidification and microplastic pollution are two of the major ecological concerns. The distribution of large quantities of plastic debris and microplastics all across the oceans emphasises the need to determine the influence of microplastics in ocean acidification and to evaluate its concomitant toxicological effects on aquatic life forms. Studies on the combined impact of both the stressors are very limited, but much needed in the current scenario. Where most of the present-day research use purchased microplastics of defined size and morphology (microspheres, fibres, rods, etc.), the present study employs prepared "true to life microplastics" that resemble the environmental microplastic pollutants in morphology and size heterogeneity. The present study focusses on evaluating the fate and impact of oceanic microplastics on the physiology and development of Artemia salina (Brine shrimp), one among the most ecologically significant zooplankton species. Natural sea water was acidified by controlled perturbation of carbon dioxide using a valve system. The hatching rate of A. salina cysts receded significantly (p < 0.05) upon singular exposures to microplastics and low pH (7.80), whereas combined effect was insignificant. The reactive oxygen species (ROS) elevated as a result of individual exposures to microplastics and low pH. However, only in 0.5 mg mL-1 PE treatments at pH 7.80, an additive impact was reported for ROS activity (p < 0.05). The SOD activities increased significantly but it can be attributed as the individual responses towards exposure to both the stressors. A significant additive impact was not observed for SOD activity (p > 0.05). But during the development, significant morphological anomalies were observed. Changes in the appendages of nauplii and juveniles as a result of combined exposure to microplastics and low pH treatments are significant findings. Our observations suggest that coupled exposure to microplastics and low pH could induce significant oxidative stress in the marine zooplanktons and also adversely affect their normal development. Findings from the current study emphasise the need for further research to understand the coupled toxicological impacts of ocean acidification and predominant pollutants such as microplastics to other marine animals as well.

Adverse effects of plastic leachate and its component 2,4-DTBP on the early development of zebrafish embryos

Plastic waste has become a global environmental problem threatening the health of aquatic organisms especially via leachate. In this study, the test of zebrafish embryo showed adverse effects of leachate from some agricultural mulching films after UV light aging for 60 h. A typical phenolic antioxidant 2,4-di-tert-butylphenol (2,4-DTBP) was detected in the leachate and tested further for the zebrafish embryo biotoxicity. The microplastic leachate (6, 8 g/L, mass concentration measured by weight of plastic) increased the death and malformation rates, and reduced the hatching rate, heart rate, and body length of zebrafish larvae in the 96-hour early development period. Similar adverse effects were also caused by the 2,4-DTBP (0.01, 0.1, 1.0 mg/L, corresponding to 0.049, 0.49, and 4.85 μM) to some degree but could not completely explain the significant influences caused by the plastic leachate. Transcriptome analysis of zebrafish embryos exposed to the 2,4-DTBP for 96 h showed that the protein, fat, and carbohydrate digestion and absorption pathways, pancreatic secretion, PPAR signaling pathway, tryptophan metabolism, and adipocytokine signaling pathway were considerably down-regulated, but the cholesterol metabolism pathway was up-regulated in larval zebrafish. The altered transcriptional expression of mRNA at early development stage (96 h post fertilization) of zebrafish suggested that the 2,4-DTBP caused reduction of digestive capacity and pancreatic secretory function, and adversely affected processes associated with energy metabolism and glycolipid metabolism of larval zebrafish. This study helps us further understanding the effects of plastic leachate on the early development of fishes.

The toxicity of microplastics and their leachates to embryonic development of the sea cucumber Apostichopus japonicus

Microplastic pollution has been widely detected across the global ocean, posing a major threat to a wide variety of marine biota. To date, the deleterious impacts of microplastics have predominantly been linked to their direct exposure, while the potential risks posed by the leachates emanating from microplastics have received comparatively less attention. Here, the toxicity of virgin plasticized polyvinyl chloride (PVC) microspheres and their leachates were evaluated on the embryo-larval development of sea cucumber Apostichopus japonicus using an in-vitro assay. Results showed that a significant toxic effect of both PVC microspheres and their leachates on the embryo development and larval growth of sea cucumbers follows a dose-dependent and time-dependent pattern. Nonetheless, the toxicity of PVC leachates surpasses that of the microspheres themselves. Abnormal developmental phenotypes, such as aberrant gastrulation, misaligned mesenchymal cells, and delayed arm development, were also observed in embryos and larvae treated with PVC. Further chemical analyses of PVC microspheres and leachates revealed the existence of five distinct phthalate esters (PAEs), with DIBP (diisobutyl phthalate) and DBP (dibutyl phthalate) exhibiting higher concentrations in the PVC leachates. This finding suggests that the elevated toxicity of plastic leachate may be attributed to the leaching of phthalate additives from the plastic particles.

A Review of Biodegradable Plastics: Chemistry, Applications, Properties, and Future Research Needs

Environmental concerns over waste plastics' effect on the environment are leading to the creation of biodegradable plastics. Biodegradable plastics may serve as a promising approach to manage the issue of environmental accumulation of plastic waste in the ocean and soil. Biodegradable plastics are the type of polymers that can be degraded by microorganisms into small molecules (e.g., H2O, CO2, and CH4). However, there are misconceptions surrounding biodegradable plastics. For example, the term "biodegradable" on product labeling can be misconstrued by the public to imply that the product will degrade under any environmental conditions. Such misleading information leads to consumer encouragement of excessive consumption of certain goods and increased littering of products labeled as "biodegradable". This review not only provides a comprehensive overview of the state-of-the-art biodegradable plastics but also clarifies the definitions and various terms associated with biodegradable plastics, including oxo-degradable plastics, enzyme-mediated plastics, and biodegradation agents. Analytical techniques and standard test methods to evaluate the biodegradability of polymeric materials in alignment with international standards are summarized. The review summarizes the properties and industrial applications of previously developed biodegradable plastics and then discusses how biomass-derived monomers can create new types of biodegradable polymers by utilizing their unique chemical properties from oxygen-containing functional groups. The terminology and methodologies covered in the paper provide a perspective on directions for the design of new biodegradable polymers that possess not only advanced performance for practical applications but also environmental benefits.

Microplastic stress in plants: effects on plant growth and their remediations

Microplastic (MP) pollution is becoming a global problem due to the resilience, long-term persistence, and robustness of MPs in different ecosystems. In terrestrial ecosystems, plants are exposed to MP stress, thereby affecting overall plant growth and development. This review article has critically analyzed the effects of MP stress in plants. We found that MP stress-induced reduction in plant physical growth is accompanied by two complementary effects: (i) blockage of pores in seed coat or roots to alter water and nutrient uptake, and (ii) induction of drought due to increased soil cracking effects of MPs. Nonetheless, the reduction in physiological growth under MP stress is accompanied by four complementary effects: (i) excessive production of ROS, (ii) alteration in leaf and root ionome, (iii) impaired hormonal regulation, and (iv) decline in chlorophyll and photosynthesis. Considering that, we suggested that targeting the redox regulatory mechanisms could be beneficial in improving tolerance to MPs in plants; however, antioxidant activities are highly dependent on plant species, plant tissue, MP type, and MP dose. MP stress also indirectly reduces plant growth by altering soil productivity. However, MP-induced negative effects vary due to the presence of different surface functional groups and particle sizes. In the end, we suggested the utilization of agronomic approaches, including the application of growth regulators, biochar, and replacing plastic mulch with crop residues, crop diversification, and biological degradation, to ameliorate the effects of MP stress in plants. The efficiency of these methods is also MP-type-specific and dose-dependent.

Environmental occurrence and ecotoxicity of aquaculture-derived plastic leachates

Plastic products such as fishing nets and foam buoys have been widely used in aquaculture. To enhance the desirable characteristics of the final equipment, plastic gear for aquaculture is mixed with a wide range of additives. Recent studies have shown that additives could be leached out to the environment with a long-term use of aquaculture plastics, forming aquaculture-derived plastic leachates. It should be emphasized that some leachates such as phthalic acid esters (PAEs) and organophosphate esters (OPEs) are endocrine disruptors, which could increase the exposure risk of aquatic products and subsequently display potential threats to human health via food chain. However, systematic studies on the release, occurrence, bioaccumulation, and toxic effects of aquaculture-derived plastic leachates are missing, overlooking their potential sources and ecotoxicological risks in aquatic environments. We have reviewed and compared the concentrations of major plastic leachates in the water environment and organisms of global aquaculture and non-farmed areas, confirming that aquaculture leachate is an important source of contaminants in the environment. Moreover, the toxic effects of aquaculture-derived plastic additives and the related mechanisms are summarized with fish as a representative, revealing their potential health risk. In addition, we proposed current challenges and future research needs, which provides scientific guidance for the use and management of plastic products in aquaculture industries.

Microplastics and leachate materials from pharmaceutical bottle: An in vivo study in Donax faba (Marine Clam)

Most pharmaceuticals are stored in synthetic polymer bottles, manufactured using polyethylene as the base material. The toxicological impact of pharmaceutical container leachate was studied on Donax faba. Several organics and inorganics were identified from the leachate. The concentrations of heavy metals in the leachate was higher than standard reference value for drinking water. In the leachate treatment the protein concentration increased to 8.5% more than the control. The reactive oxygen species (ROS) level elevated by 3 folds and malondialdehyde (MDA) increased by 4.3% in comparison to the control. Superoxide dismutase (SOD) and catalase (CAT) showed a decrease by 14 and 70.5% respectively. The leachate affected the antioxidant machinery of D. faba. Similarly, these PET (polyethylene terephthalate) pharmaceutical containers could potentially leach additives into the drugs and may cause oxidative and metabolic damages to higher organisms including human beings.

Do new cement-based mortars pose a significant threat to the aquatic environment?

Nowadays, the use of multi-functional mortars has increased significantly, with interesting applications in the sustainable construction. In the environment, the cement-based materials are subjected to leaching, so the assessment of potential adverse effects upon aquatic ecosystem is necessary. This study focuses on the evaluation of the ecotoxicological threat and of a new type of cement-based mortar (CPM-D) and its raw materials leachates. A screening risk assessment were performed by Hazard Quotient methods. The ecotoxicological effects were investigated by a test battery with bacteria, crustacean, and algae. Two different procedures, Toxicity test Battery Index (TBI) and Toxicity Classification System (TCS), to obtain a single value for toxicity rank were used. Raw materials showed the highest metal mobility and in particular, for Cu, Cd and V potential hazard was evidenced. Leachate toxicity assessment evidenced the highest effects linked to cement and glass while the mortar showed the lowest ecotoxicological risk. TBI procedure allows a finer classification of effect linked to materials with respect to TCS which is based on worst case approach. A safe by design approach taking into account the potential and the effective hazard of the raw materials and of their combinations could allow to achieve sustainable formulations for building materials.

The monetary facilities payment for ecosystem services as an approach to restore the Degraded Urmia Lake in Iran

This study analyzed the potential use of Payment for Ecosystem Services (PES) as a strategy for improving water supply management. This study focused on the Siminehroud Sub-basin due to its high importance to the Basin of Urmia Lake (UL). Siminehroud is the second provider of water (by volume) to Urmia Lake. To evaluate the technical and economic feasibility of a PES scheme, the current land use map was extracted using satellite imagery. In addition, the two algorithms of Support Vector Machines (SVMs) and Maximum Likelihood (ML) are used for Landsat images classification, rather than analyzing the relationship between land use and ecosystem services. Then, the most relevant ecosystem services provided in the region were evaluated using the Benefit Transfer Method. In the last step, by designing and implementing a survey, on the one hand, the local farmers' Willingness to Accept (WTA) cash payments for reducing the area they cultivate, and on the other hand, the farmers' Willingness to Pay (WTP) for managing the water consumption were determined. The results illustrated that the WTA program is more acceptable among the beneficiaries. It is also notable that this program needs very high governmental funding. Furthermore, the results of the program indicate that the land area out of the cultivation cycle will gradually increase while the price of agricultural water will also increase.

Understanding plasticiser leaching from polystyrene microplastics

Plastic pollution in our oceans is of growing concern particularly due to the presence of toxic additives, such as plasticisers. Therefore, this work aims to develop a comprehensive understanding of the leaching properties of plasticisers from microplastics. This work investigates the leaching of phthalate acid ester (dioctyl terephthalate (DEHT) and diethylhexyl phthalate (DEHP)) and diphenol (bisphenol A (BPA) and bisphenol S (BPS)) plasticisers from polystyrene (PS) microplastics (mean diameter = 136 μm to 1.4 mm) under controlled aqueous conditions (temperature, agitation, pH and salinity). The leaching behaviours of plasticised polymers were quantified using gel permeation chromatography, high performance liquid chromatography and thermal gravimetric analysis, and the particle's plasticisation characterised using differential scanning calorimetry. Leaching rates of phthalate acid ester and diphenol plasticisers were modelled using a diffusion and boundary layer model, whereby these behaviours varied depending on their plasticisation efficiency of PS, the size of the microplastic particle and the surrounding abiotic conditions. Leaching behaviours of DEHT and DEHP were strongly influenced by the microplastic-surface water boundary layer properties, thus wave action (i.e., water agitation) increased the leaching rate of these plasticiser up to 66 % over 21-days, whereas BPA and BPS plasticisers displayed temperature- and size-dependent leaching and were limited by molecular diffusion throughout the bulk polymer (i.e., the microplastic). This information will improve predictions of plasticiser concentration (both that remain in the plastic and released into the surrounding water) at specific time points during the lifetime of a plastic, ultimately ensuring greater accuracy in the assessment of toxicity responses and environmental water quality.

Ecotoxicology of microplastics in Daphnia: A review focusing on microplastic properties and multiscale attributes of Daphnia

The ubiquitous presence of microplastics in aquatic environments is considered a global threat to aquatic organisms. Species of the genus Daphnia provide an important link between aquatic primary producers and consumers of higher trophic levels; furthermore, these organisms exhibit high sensitivity to various environmental pollutants. Hence, the biological effects of microplastics on Daphnia species are well documented. This paper reviews the latest research regarding the ecotoxicological effects of microplastics on Daphnia, including the: 1) responses of individual, population, and community attributes of Daphnia to microplastics; 2) influence of the physical and chemical properties of microplastics; and 3) joint toxicity of microplastics and other pollutants on responses of Daphnia. Our literature review found that the published literature does not provide sufficient evidence to reveal the risks of microplastics at the population and community levels. Furthermore, we emphasized that high-level analysis has more general implications for understanding how individual-level research can reveal the ecological hazards of microplastics on Daphnia. Based on this review, we suggest avenues for future research, including microplastic toxicology studies based on both omics-based and community-level methods, especially the latter.

Evidence of micro and macroplastic toxicity along a stream detrital food-chain

Freshwater ecosystems are subjected to plastic extensive pollution because they are the direct link between plastic wastes and marine ecosystems. The aim of this study was to assess the impacts of different sizes of polyethylene plastics (micro: µPs and macroplastics: PBs) on freshwater decomposers of plant litter. We exposed leaf associated microbial assemblages to µPs (0.5 or 1.5 g L^-1) and discs of PBs as follows: green plastic bags (PB-G) alone or in mixtures with transparent plastic bags (PB-Mix). Then, we conducted a feeding preference experiment with the invertebrate shredder Limnephilus sp. to assess their capacity to distinguish leaf discs from PB discs of the same size (12 mm). Leaf decomposition, activities of fungal enzymes and sporulation were inhibited by µPs and PB-Mix, and shifts in fungal community composition were observed. The invertebrate shredders preferred to feed on leaves treated with µPs avoiding those exposed to PB-G/PB-Mix. Our results demonstrated that plastics can have a direct effect on stream-dwelling microbial decomposers and an indirect effect on higher trophic levels (shredders), highlighting that trophic transfer is a route of plastic exposure. The plastic properties (size, concentration, colour) appear to influence plastic toxicity to microbes and shredders, indicating the importance of considering physicochemical properties when assessing their risks to freshwater ecosystems.

Ecotoxicological effects of plastics on plants, soil fauna and microorganisms: A meta-analysis

The interactions of plastics and soil organisms are complex and inconsistent observations on the effects of plastics have been made in published studies. In this study, we assessed the effects of plastic exposure on plants, fauna and microbial communities, with a meta-analysis. Using a total of 2936 observations from 140 publications, we analysed how responses in plants, soil fauna and microorganisms depended on the plastic concentration, size, type, species and exposure media. We found that overall plastics caused substantial detrimental effects to plants and fauna, but less so to microbial diversity and richness. Plastic concentration was one of the most important factors explaining variations in plant and faunal responses. Larger plastics (>1 μm) caused unfavourable changes to plant growth, germination and oxidative stress, while nanoplastics (NPs; ≤ 1 μm) only increased oxidative stress. On the contrary, there was a clear trend showing that small plastics adversely affected fauna reproduction, survival and locomotion than large plastics. Plant responses were indifferent to plastic type, with most studies conducted using polyethylene (PE) and polystyrene (PS) plastics, but soil fauna were frequently more sensitive to PS than to PE exposure. Plant species played a vital role in some parameters, with the effects of plastics being considerably greater on vegetable plants than on cereal plants.

A battery of baseline toxicity bioassays directed evaluation of plastic leachates-Towards the establishment of bioanalytical monitoring tools for plastics

There are increasing concerns regarding the ecological risks of plastics to the natural environment, especially the potential effects of plastic leachates on organisms, which contain various toxic components. However, appropriate methods to assess the overall environmental risks of plastics are limited. In this study, five different plastic products (three conventional and two biodegradable plastics) were immersed in simulated freshwater, and their toxicity was assessed using a battery of bioassays. We evaluated the effects of plastic leachates effects on organisms from four trophic levels of species (nematodes, Caenorhabditis elegans; algae, Scenedesmus obliquus; daphnids, Daphnia magna; and fish, Danio rerio) by measuring their acute and chronic toxicity. Our results indicated that all plastic leachates exhibited poor acute and chronic toxicity to the organisms. The acute toxicity of conventional plastic leachates with EC₂₀ values <1.6 g plastic/L was higher than that of the biodegradable polydioxanone (PPDO) leachate (EC₂₀: 16.2-796.1 g plastic/L); however, the toxicity of PPDO-octane (EC₂₀: 0.04-1.9 g plastic/L) was similar to that of polyethylene or polystyrene (excluding toxicity in D. magna). Similarly, the leachates of the three conventional plastics and PPDO-octane had obvious inhibitory effects on the growth of C. elegans at exposure concentrations higher than 0.01 g plastic/L; however, the toxicity of the PPDO leachates was at least an order of magnitude lower. Therefore, the environmental related concentration of the plastic leachates did not have significant toxic effects. Considering that a single bioassay does not provide comprehensive information on biological implications, this study provided a new integrated and efficient method for the environmental risk assessment (ERA) of plastic leachates. Moreover, the toxicity sensitivity of different organisms varied following exposure to different plastics, thus demonstrating that multiple organisms from different trophic levels should be included in the ERA for plastics.

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.

The role of (bio)degradability on the management of petrochemical and bio-based plastic waste

In order to mitigate the social and ecological impacts of post-consumer plastic made of conventional petrochemical polymers, the market of (bio)degradable plastics have recently become more widespread. Although (bio)degradable plastics could be an environmentally friendly substitute of petrochemical ones, the consequences of their presence in the waste management system and in the environment (if not correctly disposed) are not always positive and plastic pollution is not automatically solved. Consequently, this work aims to review how plastic (bio)degradability affects the municipal solid waste management cycle. To this end, the state-of-the-art of the intrinsic (bio)degradability of conventional and unconventional petrochemical and bio-based polymers has been discussed, focusing on the environment related to the waste management system. Then, the focus was on strategies to improve polymer (bio)degradability: different types of eco-design and pre-treatment approach for plastics has been investigated, differently from other works that focused only on specific topics. The information gathered was used to discuss three typical disposal/treatment routes for plastic waste. Despite many of the proposed materials in eco-design have increased the plastics (bio)degradability and pre-treatments have showed interesting results, these achievements are not always positive in the current MSW management system. The effect on mechanical recycling is negative in several cases but the enhanced (bio)degradability can help the treatment with organic waste. On the other hand, the current waste treatment facility is not capable to manage this waste, leading to the incineration the most promising options. In this way, the consumption of raw materials will persist even by using (bio)degradable plastics, which strength the doubt if the solution of plastic pollution leads really on these materials. The review also highlighted the need for further research on this topic that is currently limited by the still scarce amount of (bio)degradable plastics in input to full-scale waste treatment plants.

Non-targeted analysis for organic components of microplastic leachates

Organic components of microplastic leachates were investigated in an integrated non-targeted analysis study that included statistical analysis on leachates generated under different leaching scenarios. Leaching experiments were undertaken with simulated gastric fluid (SGF), river water, and seawater with common polymer types, including polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate, and polyester fabrics comprising both raw and recycled materials. Totals of 111.0 ± 26.7, 98.5 ± 20.3, and 53.5 ± 4.7 different features were tentatively identified as compounds in SGF, freshwater, and seawater leachates, respectively, of which 5 compounds were confirmed by reference standards. The leaching capacities of the media were compared, and the clusters of structurally related features leached in the same medium were studied. For leachates generated from raw and recycled plastics, volcano plots and Pearson's Chi-squared tests were used to identify characteristic features. More characteristic features (3-20) had an average intensity across all recycled plastics that were significantly higher (p < 0.05) than that (1-3) of raw plastics under different conditions. The results indicate that gastric solution is more likely to leach components from microplastics, and there exists the difference of leachate's organic composition between raw and recycled materials, providing new insights into understanding microplastic environmental effects.

Ecotoxicological Estimation of 4-Cumylphenol, 4-t-Octylphenol, Nonylphenol, and Volatile Leachate Phenol Degradation by the Microscopic Fungus Umbelopsis isabellina Using a Battery of Biotests

The phenolic xenobiotics nonylphenol (NP), 4-tert-octylphenol (4-t-OP), and 4-cumylphenol (4-CP) have the potential to seriously disrupt the endocrine system. Volatile phenols (VPs), especially those present in landfill leachate, also adversely affect the health of numerous organisms. Microbial degradation of xenobiotics can result in the formation of intermediates with higher toxicity than the precursor substrates. Therefore, the main aim of this study was to assess the changes in environmental ecotoxicity during the biotransformation of nonylphenol, 4-tert-octylphenol, 4-cumylphenol and volatile phenols by Umbelopsis isabellina using a battery of biotests. The application of bioindicators belonging to different taxonomic groups and diverse trophic levels (producers, consumers, and reducers) indicated a significant reduction in toxicity during the cultivation of fungus cultures both for nonylphenol, 4-tert-octylphenol, 4-cumylphenol and volatile phenols. The rate of toxicity decline was correlated with the degree of xenobiotic biotransformation. Removal of 4-cumylphenol and 4-tert-octylphenol also led to a decrease in the anti-androgenic potential. Moreover, this is the first report demonstrating the anti-androgenic properties of 4-cumylphenol. The results showed that U. isabellina is an attractive tool for the bioremediation and detoxification of contaminated environments.

Towards a Circular Economy of Plastics: An Evaluation of the Systematic Transition to a New Generation of Bioplastics

Plastics have become an essential part of the modern world thanks to their appealing physical and chemical properties as well as their low production cost. The most common type of polymers used for plastic account for 90% of the total production and are made from petroleum-based nonrenewable resources. Concerns over the sustainability of the current production model and the environmental implications of traditional plastics have fueled the demand for greener formulations and alternatives. In the last decade, new plastics manufactured from renewable sources and biological processes have emerged from research and have been established as a commercially viable solution with less adverse effects. Nevertheless, economic and legislative challenges for biobased plastics hinder their widespread implementation. This review summarizes the history of plastics over the last century, including the most relevant bioplastics and production methods, the environmental impact and mitigation of the adverse effects of conventional and emerging plastics, and the regulatory landscape that renewable and recyclable bioplastics face to reach a sustainable future.

Physical and chemical threats posed by micro(nano)plastic to sea urchins

The awareness of the plastic issue is rising in recent years. Our seas and coastal seawaters are investigated with the aim to evaluate the possible fate, behavior and the impact of these novel contaminants upon marine biota. In particular, benthic organisms are exposed to micro(nano)plastics that sink and accumulated on the seabed. Sea urchins can be prone to the plastic impact for all their lifespan with effect that can be extended upon the trophic cascade since their key role as grazer organisms. Moreover, they are largely used in the assessment of contaminant impact both as adult individuals and as early larval stages. This review analyzes the recent literature about the chemical and physical hazards posed by diverse polymers to sea urchins, in relation to their peculiar characteristics and to their size. The search was based on a query of the keyword terms: microplastic _ OR nanoplastic_AND Sea urchins in Web of Science and Google Scholar. The effects provoked by exposure of different sea urchin biological form are highlighted, considering both laboratory exposure and collection in real world. Additional focus has also been given upon the exposure methods utilized in laboratory test and in the existing limitations in the testing procedures. In conclusion, the micro(nano)plastics major impact seemed to be attributable to leaching compounds, however variability and lacking of realisms in the procedures do not allow a full understanding of the hazard posed by micro(nano)plastics for sea urchins. Finally, the work provides insights into the future research strategies to better characterize the actual risk for sea urchins.

A Critical Review of the Performance and Soil Biodegradability Profiles of Biobased Natural and Chemically Synthesized Polymers in Industrial Applications

This review explores biobased polymers for industrial applications, their end fate, and most importantly, origin and key aspects enabling soil biodegradation. The physicochemical properties of biobased synthetic and natural polymers and the primary factors governing degradation are explored. Current and future biobased systems and factors allowing for equivalent comparisons of degradation and possible sources for engineering improved biodegradation are reviewed. Factors impacting ultraviolet (UV) stability of biopolymers have been described including methods to enhance photoresistance and impact on biodegradation. It discusses end-fate of biopolymers in soil and impact of residues on soil health. A limited number of studies examine side effects (e.g., microbial toxicity) from soil biodegradation of composites and biopolymers. Currently available standards for biodegradation and composting have been described with limitations and scope for improvements. Finally, design considerations and implications for sustainable polymers used, under consideration, and to be considered within the context of a rational biodegradable strategy are elaborated.

Microplastics (MPs) Act as Sources and Vector of Pollutants-Impact Hazards and Preventive Measures

Currently, people are paying more and more attention to the interaction between microplastics (MPs) and chemical substances (including metals and organic substances), so it is necessary to understand the relationship between MPs and chemical substances. In this review, we explored (1) MPs may become a source of chemical substances. (2) MPs can also be used as a carrier for attaching pollutants. (3) No matter what role MPs play, MPs and the attached chemical substances will have harmful effects on biological systems. However, because the current research is not deep enough, more experimental areas are needed to explore the interaction mechanism and the principle of toxicity. In addition, laws and policies need to be developed that actively promote and strive to develop biodegradable alternative microplastics to reduce the harm of microplastics and their additives to the environment.

Weathering Plastics as a Planetary Boundary Threat: Exposure, Fate, and Hazards

We described in 2017 how weathering plastic litter in the marine environment fulfils two of three criteria to impose a planetary boundary threat related to "chemical pollution and the release of novel entities": (1) planetary-scale exposure, which (2) is not readily reversible. Whether marine plastics meet the third criterion, (3) eliciting a disruptive impact on vital earth system processes, was uncertain. Since then, several important discoveries have been made to motivate a re-evaluation. A key issue is if weathering macroplastics, microplastics, nanoplastics, and their leachates have an inherently higher potential to elicit adverse effects than natural particles of the same size. We summarize novel findings related to weathering plastic in the context of the planetary boundary threat criteria that demonstrate (1) increasing exposure, (2) fate processes leading to poorly reversible pollution, and (3) (eco)toxicological hazards and their thresholds. We provide evidence that the third criterion could be fulfilled for weathering plastics in sensitive environments and therefore conclude that weathering plastics pose a planetary boundary threat. We suggest future research priorities to better understand (eco)toxicological hazards modulated by increasing exposure and continuous weathering processes, to better parametrize the planetary boundary threshold for plastic pollution.

Plastic additives: challenges in ecotox hazard assessment

The risk of plastic debris, and specifically micro(nano)plastic particles, to ecosystems remains to be fully characterized. One particular issue that warrants further characterization is the hazards associated with chemical additives within micro(nano)plastic as they are not chemically bound within the polymers and can be persistent and biologically active. Most plastics contain additives and are therefore potential vectors for the introduction of these chemicals into the environment as they leach from plastic, a process that can be accelerated through degradation and weathering processes. There are knowledge gaps on the ecotoxicological effects of plastic additives and how they are released from parent plastic materials as they progressively fragment from the meso to micro and nano scale. This review summarizes the current state of knowledge of the ecotoxicity of plastic additives and identifies research needs to characterize the hazard they present to exposed biota. The potential ecological risk of chemical additives is of international concern so key differences in governance between the European Union and New Zealand to appropriately characterize their risk are highlighted.

Microplastic's story

The problem of microplastic pollution is now the order of the day in front of everyone's eyes affecting the environment and the health of leaving creature. This work aims to retrace the history of microplastics in a critical way through a substantial bibliographic collection, defining the points still unresolved and those that can be resolved. Presence of marine litter in different environments is reviewed on a global scale, focusing in particular on micro and macro plastics definition, classification and characterization techniques.

Microplastic acts as a vector for contaminants: the release behavior of dibutyl phthalate from polyvinyl chloride pipe fragments in water phase

The pollution of contaminants brought by plastic fragments is worth paying attention in the study of microplastic. The additives, like phthalates (PAEs), introduced during manufacture, are physically dispersed and can easily release into environment. Polyvinyl chloride pipes are widely used in China, and DBP is also a typical kind of additives in PVC materials. Here, the release behavior of DBP from PVC plastic pipe fragments was investigated in water environment under different conditions. Low-density polyethylene (LDPE) passive sampler was used to monitor the contents of DBP. The curve of DBP concentration started from the first increasing stage until a short equilibrium after 45 days' incubation followed by a second increasing part. The release kinetics and the rate-limiting step were discussed. For the whole migration period, the release process was better fitted to pseudo-second order which was participated by both intraparticle and plastic-water film diffusion processes while the two separated parts had different results. Moreover, light, smaller fragments, and higher temperature could all accelerate the release rate and increase the migration amount of DBP. The effect of temperature was the most significant of all, and higher temperature showed more significant effects. Besides, DBP tended to migrate in a long-time continuously. However, the release of additives will be promoted by various physical and chemical processes in nature compared to laboratory tests. Consequently, microplastic (plastic fragments with sizes smaller than 5 mm) with additives acts as a vector for pollutants, and will bring more threat to both environment and organisms.

The hidden threat of plastic leachates: A critical review on their impacts on aquatic organisms

Plastic products are made from the essential polymer mixed with a complex blend of substances including catalyst remnants, polymerization solvents, and a wide range of other additives deliberately added to enhance the desirable characteristics of the final product. Additives include bisphenols, phthalates, flame retardants, and further emerging and legacy contaminants. With a few exceptions, additives are not chemically bound to the polymer, and potentially migrate within the material reaching its surface, then possibly leach out to the environment. Leachates are mixtures of additives, some of which belong to the list of emerging contaminants, i.e. substances that show the potential to pose risks to the environment and human health, while are not yet regulated. The review discusses the state of the art and gaps concerning the hidden threat of plastic leachates. The focus is on reports addressing the biological impacts of plastic leachates as a whole mixture. Degradation of plastics, including the weathering-driven fragmentation, and the release of additives, are analysed together with the techniques currently employed for chemically screening leachates. Because marine plastic litter is a major concern, the review mainly focuses on the effects of plastic leachates on marine flora and fauna. Moreover, it also addresses impacts on freshwater organisms. Finally, research needs and perspectives are examined, to promote better focused investigations, that may support developing different plastic materials and new regulations.