Persistent Plastics Research Articles

Biodegradable plastics fragments induce positive effects on the decomposition of soil organic matter

The escalating accumulation of plastic waste in ecosystems poses a significant health concern to soil environment, yet the environmental effects of plastics remains largely unexplored. Biodegradable plastics could offer a viable alternative to conventional persistent plastics, but our understanding of their potential benefits or detrimental effects on the decomposition of plant debris by soil biomass is limited. In this study, we conducted a year-long field experiment to examine the environmental response and impact on plant debris decomposition in the presence of varying quantities of persistent versus biodegradable plastics. Our findings indicate that the decomposition rate decreased by 2.8–4.9% for persistent plastics, while it increased by 1.3–4.2% for biodegradable plastics. Persistent plastics primarily induced adverse effects, including a reduction in soil nutrients, microbial diversity, bioturbation, enzyme activity, easily decomposable carbon, and microbial biomass carbon in plant debris. In contrast, biodegradable plastics resulted in beneficial effects such as an increase in enzyme activity, microbial biomass carbon, and easily decomposable carbon. We also observed that the decomposition rate of plant residues and nutrient release are closely associated with changes in the organic carbon chemical structure induced by different plastic film fragments. A significant shift in alkoxy carbon content facilitated the release of nutrients and soluble carbon, while modifications in carboxyl and aromatic carbon content hindered their release. Overall, our study reveals over one year that biodegradable plastics primarily induce positive effects on the decomposition of soil organic matter.

Gastric carboxylesterases of the edible crab Cancer pagurus (Crustacea, Decapoda) can hydrolyze biodegradable plastics

A promising strategy to counteract the progressing plastic pollution of the environment can involve the replacement of persistent plastics with biodegradable materials. Biodegradable polymers are enzymatically degradable by various hydrolytic enzymes. However, these materials can reach the environment in the same way as conventional plastics. Therefore, they are accessible to terrestrial, freshwater, and marine biota. Once ingested by marine organisms, highly active enzymes in their digestive tracts may break down biodegradable compounds. We incubated microparticles of five different biodegradable plastics, based on polylactictic acid (PLA), polybutylene succinate (PBS), polybutylene adipate terephthalate (PBAT) and polyhydroxybutyrate-co-valerate (PHBV), in-vitro with the gastric fluid of the edible crab Cancer pagurus and evaluated the hydrolysis rates by pH Stat titration. A plastic blend of PLA with PBAT showed the highest hydrolysis rate. The enzymes in the gastric fluid of crabs were separated by anion exchange chromatography. Fractions with carboxylesterase activity were identified using fluorescent methylumbelliferyl (MUF)-derivatives. Pooled fractions with high carboxylesterase activity also hydrolyzed a PLA/PBAT plastic blend. Carboxylesterases showed molecular masses of 40–45 kDa as determined by native gel electrophoresis (SDS-PAGE). Our study demonstrated that digestive carboxylesterases in the gastric fluid of C. pagurus exhibit a high potential for hydrolyzing certain biodegradable plastics. Since esterases are common in the digestive tract of organisms, it seems likely that other invertebrates possess the ability to hydrolyze biodegradable plastics.

Euphorbia tirucalli: potential plastic digester and in bioeconomics

In view of the global concern with persistent plastic waste in the environment, the present study seeks reuse and reuse alternatives to reduce pollution through extracts of the Euphorbia tirucalli specimens. The method involved collecting latex from different geographic regions and evaluating the corrosive and shrinkage effects of aqueous plant extracts on polypropylene. Results indicate variations in the ability of extracts to interact with plastic, with some showing corrosive and digesting effects over time. This approach, exploring the enzymatic and corrosive action of Euphorbia tirucalli extracts, suggests potential for the degradation of non-degradable plastics over time. The study also underscores the importance of bioengineering as an innovative approach to solving environmental problems. The research highlights the relevance of the search for sustainable solutions for the management of plastic waste, aiming at promoting environmental sustainability and mitigating environmental impacts. Although more in-depth research is needed to understand the mechanisms of action of Euphorbia tirucalli extracts and their viability on a large scale, this approach offers promising bioeconomics perspectives for the degradation of persistent plastics in nature and the appreciation of ethnic communities that already practice these precepts. In summary, the study highlights the importance of exploring natural alternatives to deal with plastic pollution and contribute to the conservation of the environment.

Integrating the latest biological advances in the key steps of a food packaging life cycle.

This literature review provides a focus on the potential of integrating the latest scientific and technological advances in the biological field to improve the status of the key steps of a food packaging life cycle: production, usage, post-usage, and long-term fate. A case study of such multi-biological food packaging is demonstrated based on the use of PHAs (polyhydroxyalkanoates) polymer, a microbiologically produced polymer from non-food renewable resources, activated by the use of bioactive components to enhance its usage benefits by reducing food loss and waste, displaying potential for reusability, compostability as post-usage, and finally, being ultimately biodegradable in most common natural conditions to considerably reduce the negative impact that persistent plastics have on the environment. We discuss how designing safe and efficient multi "bio" food packaging implies finding a compromise between sometimes contradictory functional properties. For example, active antimicrobials help preserve food but can hamper the ultimate biodegradation rate of the polymer. This review presents such antagonisms as well as techniques (e.g., coatings, nanoencapsulation) and tools (e.g., release kinetic) that can help design optimized, safe, and efficient active food packaging.

Redesigning Carbon-Carbon Backbone Polymers for Biodegradability-Compostability at the End-of-Life Stage.

Carbon-carbon backbone polymers are non-biodegradable, persistent plastics that have accumulated on land and oceans due to human activities. They degrade and fragment into microplastics and smaller particle sizes but do not biodegrade at an acceptable and practical rate. Their continual buildup in the natural environment precipitates serious detrimental impacts on human health and the environment, as extensively documented in the literature and media. Nearly 77% of global plastics produced are carbon-carbon backbone polymers. More importantly, 90% of packaging plastics (153.8 million metric tons) are non-biodegradable, persistent carbon-carbon backbone polymers. The recycling rate of these non-durable packaging plastics ranges from 0 to 4%. Re-designing carbon-carbon backbone polymers to labile ester backbone biodegradable-compostable polymers and treating them along with biodegradable organic waste (such as food, paper, and organic wastes) in managed industrial composting is environmentally responsible. Diverting 1 million metric tons of biodegradable organic wastes in MSW bound for landfills and open dumps to industrial composting results in 0.95 million metric tons CO2 equivalents of GHG emissions reduction. This perspective paper discusses strategies and rationales regarding the redesign of carbon-carbon backbone polymer molecules. It describes the carbon footprint reductions achievable by replacing petro-fossil carbon with plant biomass carbon. Biodegradability and compostability are frequently used but misunderstood and misused terms, leading to misleading claims in the marketplace. This paper presents the fundamentals of biodegradability and compostability of plastics and the requirements to be met according to ASTM/ISO international standards.

Amorphous Sugar Materials as Sustainable and Scalable Alternatives for Rigid, Short-Term-Use Products

Plastics are the prevailing materials for short-term-use applications, despite being designed to last far longer than often is needed or desired. This article describes a class of materials that are formed from small-molecule sugars, rather than polymers, as a scalable and environmentally friendly replacement for rigid thermoplastics for short-term-use applications. The materials use amorphous isomalt as a matrix and natural additives to tune the mechanical properties. Like plastics, this class of materials is lightweight and can be produced efficiently at low temperatures via injection molding, yet the materials emulate the rigidity and strength of ceramics and stones. Repeated recycling is achieved via a closed-loop process without degradation of the isomalt binder and without loss of mechanical properties. Finally, these materials are resistant to water for hours when coated, yet ultimately dissolve within minutes when broken, with the resulting products being nontoxic small-molecule and degradable bio-based materials. This combination of traits makes amorphous isomalt materials suitable as an alternative to persistent plastics in short-term-use applications.

Biodegradation of polystyrene and low-density polyethylene by Zophobas atratus larvae: Fragmentation into microplastics, gut microbiota shift, and microbial functional enzymes

In this study, biodegradation of polystyrene (PS) and low-density polyethylene (LDPE) by Zophobas atratus larvae was characterized to investigate fragmentation of ingested polymers, larval physiology, gut microbiota, and microbial functional enzymes over a 28-day test. The larvae maintained high survival rates and low cannibal rates, but their body fat content decreased when fed with PS or LDPE with respective consumption rates of 43.3 ± 1.5 and 52.9 ± 3.1 mg plastics/100 larvae per day. The larvae biodegraded PS via broad depolymerization and LDPE via limited-extent depolymerization. The ingested PS and LDPE were fragmented into microplastics with a mean size of 174 and 185 μm on a volume basis, and the particles with a size of 6.3 and 5.9 μm reached a maximum number, respectively, with no nanoplastics generated. Chemical modifications of the polymers were confirmed. Significant shifts and clustering in the gut microbiota were detected with the relative abundance of Citrobacter sp. increasing when PS and LDPE were fed, as reported for other species of Tenebrionidae. Microbial functional enzymes, possibly associated with plastic degradation, including arylesterase and serine-hydrolase, were upregulated in both PS-fed and PE-fed larvae. This work provides new insights into insect-mediated biodegradation of persistent plastics for future investigations.

Sustainable edible packaging systems based on active compounds from food processing byproducts: A review.

The global food processing industries represent a challenge and a risk to the environment due to the poor handling of residues, which are often discarded as waste without being used in further sidestreams. Although some part of this biomass is utilized, large quantities are, however, still under- or unutilized despite these byproducts being a rich resource of valuable compounds. These biowastes contain biopolymers and other compounds such as proteins, polysaccharides, lipids, pigments, micronutrients, and minerals with good nutritional values and active biological properties with applications in various fields including the development of sustainable food packaging. This review offers an update on the recent advancement of food byproducts recycling and upgrading toward the production of food packaging materials, which could be edible, (bio)degradable, and act as carriers of biobased active agents such as antimicrobials, antioxidants, flavoring additives, and health-promoting compounds. This should be a global initiative to promote the well-being of humans and achieve sustainability while respecting the ecological boundaries of our planet. Edible films and coatings formulations based on biopolymers and active compounds extracted from biowastes offer great opportunities to decrease the devastating overuse of plastic-based packaging. It has become evident that a transition from a fuel-based to a circular bio-based economy is potentially beneficial. Therefore, the exploitation of food discards within the context of a zero-waste biorefinery approach would improve waste management by minimizing its generation, reduce pollution, and provide value-added compounds. Most importantly, the development of edible packaging materials from food byproducts does not compete with food resources, and it also helps decrease our dependency on petroleum-based products. Practical Application Almost 99% of current plastics are petroleum-based, and their continuous use has been devastating to the planet as plastic-derived components have been detected in all trophic levels. Besides, the increasing amounts of food by-products are a socioeconomic and environmental challenge, and halving food loss and waste and turning it into valuable products has become necessary to achieve sustainability and economic circularity. The development of new packaging systems such as edible materials could be one of the solutions to limit the use of persistent plastics. Edible films and coatings by-products-based could also enhance food packaging performance due to their compounds' bioactivities.

Knowledge gaps on micro and nanoplastics and human health: A critical review

Recent research has made it clear that humans are ubiquitously exposed to microplastics and nanoplastics (MPs/NPs) via inhalation, dermal exposure and ingestion. Global plastic production has increased considerably with 400 million tonnes of plastic produced annually while plastic waste predominantly ends up in landfill. The accumulation of plastic in our water-bodies has detrimental long-term impacts, with persistent plastics degrading into smaller microplastics and nanoplastics (MPs/NPs). The presence of MPs/NPs in many food and beverages is a stark reminder of their pervasion into every aspect of the food chain. We have yet to determine if this long-term, chronic exposure to MPs/NPs has adverse effects on human health. This review examines the evidence in the literature highlighting the challenges of performing human studies including the lack of quantitative evidence, which is needed to make realistic estimates on the level of exposure and therefore risk. While occupational exposure to synthetic fibers in textile workers has been associated with respiratory disease, lung cancer, and bowel cancer, there are no other human studies. However, there are some rodent studies highlighting adverse effects on gut homeostasis, male reproduction, F1 offspring, and inflammation. Given these findings, further studies in human populations and model systems is a priority.

Microplastics - from Anthropogenic to Natural.

In the context of the ongoing discussion of accumulating plastic debris in the environment, this article summarizes recent reports on the topic of microplastic pollution. Moreover, it gives an overview of the results from the activities of the research group for Biotechnology and Sustainable Chemistry of the Institute of Life Technologies at the HES-SO ValaisWallis concerning the fabrication of biodegradable microstructured plastics and microplastics from renewable resources. Polyhydroxyalkanoate biopolyesters are proposed as one suitable alternative in specific applications to reduce the use of persistent plastics. Standard techniques are described that have been successfully applied to produce porous materials, fibers and particles in the micro- and nanometer range.

Marine litter plastics and microplastics and their toxic chemicals components: the need for urgent preventive measures

Persistent plastics, with an estimated lifetime for degradation of hundreds of years in marine conditions, can break up into micro- and nanoplastics over shorter timescales, thus facilitating their uptake by marine biota throughout the food chain. These polymers may contain chemical additives and contaminants, including some known endocrine disruptors that may be harmful at extremely low concentrations for marine biota, thus posing potential risks to marine ecosystems, biodiversity and food availability. Although there is still need to carry out focused scientific research to fill the knowledge gaps about the impacts of plastic litter in the marine environment (Wagner et al. in Environ Sci Eur 26:9, 2014), the food chain and human health, existing scientific evidence and concerns are already sufficient to support actions by the scientific, industry, policy and civil society communities to curb the ongoing flow of plastics and the toxic chemicals they contain into the marine environment. Without immediate strong preventive measures, the environmental impacts and the economic costs are set only to become worse, even in the short term. Continued increases in plastic production and consumption, combined with wasteful uses, inefficient waste collection infrastructures and insufficient waste management facilities, especially in developing countries, mean that even achieving already established objectives for reductions in marine litter remains a huge challenge, and one unlikely to be met without a fundamental rethink of the ways in which we consume plastics. This document was prepared by a working group of Regional Centres of the Stockholm and Basel Conventions and related colleagues intended to be a background document for discussion in the 2017 Conference of the Parties (COP) of the Basel Convention on hazardous wastes and the Stockholm Convention on persistent organic pollutants (POPs). The COP finally approved that the issue of plastic waste could be dealt by its Regional Centres and consistently report their activities on the matter to next COP’s meetings.

Processing recommendations for using low-solids digestate as nutrient solution for poly-ß-hydroxybutyrate production with Synechocystis salina

Within the last decades, environmental pollution with persistent plastics steadily increased; therefore the production of biodegradable materials like poly-ß-hydroxybutyrate (PHB) is essential. Currently, PHB is produced with heterotrophic bacteria from crops. This leads to competition with food and feed production, which can be avoided by using photoautotrophic cyanobacteria, as Synechocystis salina, synthesizing PHB from CO2 at nutrient limitation. This study aims to increase the economic efficiency of PHB production with cyanobacteria by using nutrients from anaerobic digestate. First, growth and PHB production of S. salina in digestate fractions (supernatant and permeate, with/without precipitating agents) and dilutions thereof and then the scale-up (photobioreactor, 200 L working volume) were evaluated. With precipitated and centrifuged digestate diluted 1/3 the highest biomass (1.55gL-1) and PHB concentrations (95.4mgL-1), being 78% of those in mineral media, were achieved. In the photobioreactor-experiments biomass (1.63gL-1) and PHB concentrations (88.7mgL-1), being 79% and 72% of those in mineral medium, were reached, but in a cultivation time 10days longer than in mineral medium. The possibility to use digestate as sustainable and low cost nutrient solution for microalgae cultivation and photoautotrophic PHB production, instead of applying it on fields or processing it to achieve discharge limits, makes this application a highly valid option.

Extinguishment of plastics fires with plain water and wet water

The extinction properties for 10 commonly used solid plastics and three foam plastics were tested with ‘plain water’ and ‘wet water’. There were large differences between persistent polypropylene and easily extinguished phenol formaldehyde resin. Some thermoplastics generated large fire balls when water was sprayed. Unretarded foam plastics were generally difficult to extinguish. Wet water was remarkably effective for persistent plastics and was made by diluting readily available foam agents with tap water. Even the wet water made by diluting 6% foam agent 10 000-fold reduced the extinction time by 30–50%.

Legal strategies for reducing persistent plastics in the marine environment

A variety of legal strategies could be employed to address aspects of the problem of persistent plastics in the marine environment. These include strategies based on international agreements, federal legislation, and state law. At the international level, plastic pollution from vessels is addressed by the International Convention Relating to Pollution from Ships (MARPOL), though its operative provisions are not yet in force. Vesselsource pollution can also be addressed, with varying degrees of effectiveness, through pollution laws, fishery and wildlife conservation laws, and fishing gear compensation programmes. These authorities provide a diverse set of opportunities for addressing the entanglement problem, though realizing such opportunities is likely to require an expanded perception on the part of their administrators of the types of hazards addressed by the pollution laws. Various state measures focus primarily on reducing or preventing the problem of generation of plastic pollution from land-based sources. These include several laws that impose degradability standards for certain plastic products or attempt to encourage recycling of plastic waste. The experiences of various states that have enacted such laws are described and recommendations are made with respect to needed measures for more effective implementation of such laws.

Persistent plastics and debris in the Ocean: an international problem of Ocean disposal

Persistent plastics and debris in the Ocean: an international problem of Ocean disposal

Sources, quantities and distribution of persistent plastics in the marine environment

Persistent plastics are widely distributed at the surface and coastal margins of the global oceans, but many uncertainties remain about their specific sources, quantities and distribution. Awareness of the problem of plastic pollution has grown only recently. Thus, systematic observations have not been either extensive enough or long enough to document the situation adequately. Major sources of these materials are from land, vessels and beachgoers. This paper reviews recent literature on the sources, amounts and distribution of various types of plastics in the marine environment.

Impact of nondegradable marine debris on the ecology and survival outlook of sea turtles

Sea turtles of all kinds are peculiarly prone to eat plastic scraps and other buoyant debris and to tangle themselves in lines and netting discarded by fishermen, and records of such mishaps have increased markedly in recent years. Advances in our understanding of the developmental ecology of sea turtles shed new light on the impact of buoyant wastes on the juvenile stages. The initial developmental stages of all species are passed in the open sea. In the case of the loggerhead Caretta this period of pelagic life is likely to include 3–5 years of planktonic open-ocean travel, which may involve multiple transatlantic crossings. During this time both the young turtles and their buoyant food are drawn by advection into fronts (convergences, rips, driftlines) and the same process also brings in and aligns persistent plastics and lost fishing gear. This effect exacerbates survival problems for sea turtles that are dependent on driftlines for their food supply or shelter.