The plastic pandemic: COVID-19 has accelerated plastic pollution, but there is a cure

Establishment of tumor microenvironment following bisphenol A exposure in the testis

Although detrimental roles of bisphenol A (BPA) in xenoestrogen target organs, testis and epididymis, and male fertility are well-documented, disruption of the immune privilege system in the male reproductive tract following BPA exposure remains poorly understood. Therefore, this study aimed to explore the precise mechanisms of BPA in interfering immune privilege in the testis on RNA sequencing results. CD-1 male mice were daily treated no-observed-adverse-effect (NOAEL, 5 mg BPA/kg BW) and lowest-observed-adverse-effects (LOAEL, 50 mg BPA/kg BW) of BPA by oral gavage for 6 weeks. Following the LOAEL exposure, the expression of immune response-associated transcripts was upregulated in the testis. Moreover, BPA switch the testicular microenvironment to tumor friendly through the recruitment of tumor associated macrophages (TAMs), which can produce both anti- and pro-inflammatory cytokines, such as TNF-α, TLR2, IL-10, and CXCL9. Number of testicular blood vessels were approximately 2-times increased by upregulation of matrix metallopeptidase 2 in TAMs and upregulation of AR expression in the nucleus of Leydig cells. Moreover, we found that the tumor-supportive environment can also be generated even though NOAEL BPA concentration due to the individual's variability in cancer susceptibility.

Journalists in a circular economy: Stakeholders' engagement in the media discourse on single-use plastics during the COVID-19 pandemic

The world faces an alarming plastic waste problem. The volume of plastic waste is rapidly and continuously increasing, mainly due to the single-use plastics overconsumption, whereas its recycling and utilization leave much to be desired. Despite the negative effects of plastic on the environment and public health, the COVID-19 outbreak shifted the public attention away from the environmental issues, potentially giving space for extended lobbyism by interest groups and industry to delay or even prevent legislation to combat plastic pollution. Our study aims to understand how the media discourse on single-use plastic (SUP) in particular, evolves in the course of the pandemic. How it vary across EU Member States? For this purpose, we specifically analyse plastic-related articles in major prestigious daily newspapers published between June 2019 and June 2021 in four EU Member States: Germany, France, Italy, and Poland, as countries with different levels of sustainable transition to form a representative model of an European context. Additionally, between November 2022 and January 2023, we conducted a series of interviews via Google Meet, with journalists who agreed to be asked on the plastic issues they upraised. Our analysis initially covered 1076 articles, out of which 198 articles were rejected due to non-compliance with the subject or repetition, leaving 878 articles forming the database for eventual analysis. Specifically, we outline a key impact of the COVID-19 pandemic followed by a clear evolution on the number of plastic-related articles, on related stakeholder engagement, and the focus on specific SUP items. Moreover, we address a research gap - presenting a media portrait of different types of SUP in more details and highlighting the significance based on several culturally and linguistically very different countries within a single supranational state (EU). A clear trend reversal towards an informed knowledge circulation across the circular economy model of single-use plastics is ultimately essential to develop sustainable solutions to reject the disposable culture, stop the waste of natural resources, and reduce the consumption of oil or gas for plastic production and thus protect the climate.

Driving selective upcycling of mixed polyethylene waste with table salt

Advanced recycling offers a unique opportunity for the circular economy, especially for mixed and contaminated plastics that are difficult to recycle mechanically. However, advanced recycling has barriers such as poor selectivity, contaminant sensitivity, and the need for expensive catalysts. Reported herein is a simple yet scalable methodology for converting mixed polyethylene (high-density and low-density polyethylene recycled polyethylene) into upcycled waxes with up to 94% yield. This high yield was possible by performing the reaction at a mild temperature and was enabled by using inexpensive and reusable table salt. Without table salt, in otherwise identical conditions, the plastic remained essentially undegraded. These upcycled waxes were used as prototypes for applications such as water- and oil-resistant paper, as well as rheology modifiers for plastics. Their performance is similar to that of commercial wax as well as rheology modifiers. A preliminary economic analysis shows that the upcycled waxes obtained by this table salt-catalyzed approach offer three times more revenue than those reported in the literature. This pioneering discovery opens the door for a circular economy of plastics in general and polyolefins in particular.

Low-Temperature Methanolysis of Polycarbonate over Solid Base Sodium Aluminate

Herein, a low-cost and readily available sodium aluminate (NaAlO2) was used as a solid base catalyst for the depolymerization of polycarbonate (PC) via methanolysis in the presence of tetrahydrofuran (THF) as a solvent. NaAlO2 was highly active for the reaction, and the performance was comparable to that of soluble strong base SrO and much higher than those of MgO and CaO. By the reaction over the catalyst, a highly pure and crystalline bisphenol A (BPA) was obtained. Among tested organic solvents, THF was the best in aiding PC methanolysis over NaAlO2 due to the polarity similar to PC according to Hansen solubility parameters (HSPs). At 60 °C, 98.1% PC conversion and 96.8% BPA yield were achieved within just 2 h. NaAlO2 was reusable without any severe catalyst deactivation in at least four runs. The mechanistic study revealed that the reaction proceeded via the methoxide pathway, with THF aiding the dissolution of PC. The reaction over NaAlO2 possessed a low apparent activation energy (Ea) of 75.1 kJ mol-1, which is the lowest ever reported so far for the reaction over solid catalysts.

Effect of enrichment conditions of secondary feeding on the synthesis of polyhydroxyalkanoates (PHAs) by activated sludge

Polyhydroxyalkanoates (PHAs) are biodegradable plastics with great performance and development prospects. However, their traditional anaerobic/aerobic enrichment process requires a high concentration of dissolved oxygen (DO), resulting in high energy consumption. In this study, an anaerobic/oxygen-limited with secondary feeding enrichment mode was used to enhance the synthesis of PHAs while reducing energy consumption. The enrichment process of PHAs-synthesizing bacteria lasted up to 100 days, and the experiment was conducted to investigate the change of the PHAs synthesizing ability of the system in this mode by detecting the PHAs content and community distribution of the activated sludge under different stages. Under these conditions, the system enriched two major genera of PHAs-synthesizing bacteria, Thauera (30.21%) and Thiothrix (21.30%). The content of PHAs in the sludge increased from 4.51% to 30.87% and was able to achieve a concomitant increase in poly(3-hydroxyvalerate) (PHV) monomer content. After nitrogen limitation (C/N = 150) treatment, the content of PHAs reached 63.05%. The results showed that the enrichment mode of anaerobic/oxygen-limited with secondary feeding could enrich more PHAs-synthesizing bacteria and significantly increase the synthesis amount of PHAs, which revealed the great potential of this mode in solid waste value-added and reduce the production cost of PHAs and could provide a theoretical basis for the production of PHAs from activated sludge.

Identifying laboratory sources of microplastic and nanoplastic contamination from the air, water, and consumables

Microplastic and nanoplastic research has proliferated in recent years in response to the escalating plastic pollution crisis. However, a lack of optimised methods for sampling and sample processing has potential implications for contaminating samples resulting in an overestimation of the quantity of microplastics and nanoplastics present in environmental samples. In response, a series of recommendations have been made, but most have not been quantified or validated sources of contamination. In the present study, we investigated sources of plastic contamination in common laboratory procedures including water sources (e.g., Milli-Q), consumables (e.g., unburnt glassware), airflow (e.g., fume hood) and dust. Using flow cytometry, we identified water, air flow and dust as sources of significant contamination. Milli-Q and reverse osmosis were the least contaminated sources when compared with tap water. Interestingly, current recommendations are to use glass consumables in replacement of plastic consumables, however, we have identified glassware and glass consumables as a significant source of contamination. Current best practice is to cover the glass tube with aluminium foil to reduce airborne contamination, but we found fresh aluminium foil to be a significant source of contamination, bringing light to the limitations foil has as a contamination control measure. Lastly, we identified significant quantities of microplastics and nanoplastics present in dust collected within the laboratory, suggesting this is a widespread and underestimated source of contamination. We have provided validated sources of contamination for both consumables and common laboratory procedures and provided mitigation strategies based on these. Additional recommendations include the appropriate design of experimental controls to quantify levels of introduced contamination based on methods and the detection techniques utilised. The application of these mitigation strategies and appropriate experimental design will allow for more accurate estimations on the level of microplastic and nanoplastic contamination within environmental samples.

Growth, physiological parameters and DNA methylation in Spirodela polyrhiza (L.) Schleid exposed to PET micro-nanoplastic contaminated waters

The effects of polyethylene terephthalate micro-nanoplastics (PET-MNPs) were tested on the model freshwater species Spirodela polyrhiza (L.) Schleid., with focus on possible particle-induced epigenetic effects (i.e. alteration of DNA methylation status). MNPs (size ∼ 200-300 nm) were produced as water dispersions from PET bottles through repeated cycles of homogenization and used to prepare N-medium at two environmentally relevant concentrations (∼0.05 g L-1 and ∼0.1 g L-1 of MNPs). After 10 days of exposure, a reduction in fresh and dry weight was observed in treated plants, even if the average specific growth rate for both frond number and area was not altered. Impaired growth was coupled with a MNP-induced decrease of chlorophyll fluorescence parameters (i.e. ΨETo and Piabs, indicators of photochemical efficiency) and starch concentration, as well as with alterations in plant ionomic profile and oxidative status. The methylation-sensitive amplification polymorphism (MSAP) technique was used to assess possible changes in DNA methylation levels induced by plastic particles. The analysis showed unusual hypermethylation in 5'-CCGG sites that could be implicated in DNA protection from dangerous agents (i.e. reactive oxygen species) or in the formation of new epialleles. This work represents the first evidence of MNP-induced epigenetic modifications in the plant world.

Prevalence of pharmaceuticals and personal care products, microplastics and co-infecting microbes in the post-COVID-19 era and its implications on antimicrobial resistance and potential endocrine disruptive effects

The COVID-19 (coronavirus disease 2019) pandemic's steady condition coupled with predominance of emerging contaminants in the environment and its synergistic implications in recent times has stoked interest in combating medical emergencies in this dynamic environment. In this context, high concentrations of pharmaceutical and personal care products (PPCPs), microplastics (MPs), antimicrobial resistance (AMR), and soaring coinfecting microbes, tied with potential endocrine disruptive (ED) are critical environmental concerns that requires a detailed documentation and analysis. During the pandemic, the identification, enumeration, and assessment of potential hazards of PPCPs and MPs and (used as anti-COVID-19 agents/applications) in aquatic habitats have been attempted globally. Albeit receding threats in the magnitude of COVID-19 infections, both these pollutants have still posed serious consequences to aquatic ecosystems and the very health and hygiene of the population in the vicinity. The surge in the contaminants post-COVID also renders them to be potent vectors to harbor and amplify AMR. Pertinently, the present work attempts to critically review such instances to understand the underlying mechanism, interactions swaying the current health of our environment during this post-COVID-19 era. During this juncture, although prevention of diseases, patient care, and self-hygiene have taken precedence, nevertheless antimicrobial stewardship (AMS) efforts have been overlooked. Unnecessary usage of PPCPs and plastics during the pandemic has resulted in increased emerging contaminants (i.e., active pharmaceutical ingredients and MPs) in various environmental matrices. It was also noticed that among COVID-19 patients, while the bacterial co-infection prevalence was 0.2-51%, the fungi, viral, protozoan and helminth were 0.3-49, 1-22, 2-15, 0.4-15% respectively, rendering them resistant to residual PPCPs. There are inevitable chances of ED effects from PPCPs and MPs applied previously, that could pose far-reaching health concerns. Furthermore, clinical and other experimental evidence for many newer compounds is very scarce and demands further research. Pro-active measures targeting effective waste management, evolved environmental policies aiding strict regulatory measures, and scientific research would be crucial in minimizing the impact and creating better preparedness towards such events among the masses fostering sustainability.

Effects of polystyrene nanoplastic gestational exposure on mice

Airborne plastic particles have received increasing attention due to their ubiquity in the atmosphere and potential human health risks. Previous studies have demonstrated that early-life exposure to environmental toxicants is associated with abnormal metabolic function. However, the impact of exposure to polystyrene nanoplastics (PSNPs) through inhalation on the development of non-alcoholic fatty liver disease (NAFLD) in mothers and offspring remains unknown. In the present study, mice were gestationally exposed to PSNPs at different doses (0, 1, 5, and 25 μg μl^-1) through inhalation to investigate health hazards to the dam at weaning and to adult offspring. Gestational exposure to PSNPs at high doses significantly induced hepatic steatosis in the dam and upregulated genes involved in de novo lipogenesis, fatty acids (FAs) uptake, and triacylglycerol (TG) synthesis in the monoacylglycerol acyltransferase pathway. Gestational exposure to high doses of PSNPs led to hepatic steatosis in adult female offspring but not male offspring, and expression levels of genes related to FAs uptake and TG synthesis in the glycerol 3-phosphate pathway were significantly elevated. Collectively, our data demonstrate that gestational exposure to airborne PSNPs induced different development processes of NAFLD in the dam and offspring, providing vital data about plastic particulate toxicology.

Plasma degradation of contaminated PPE: an energy-efficient method to treat contaminated plastic waste

The use of PPE has drastically increased because of the SARS-CoV-2 (COVID-19) pandemic as disposable surgical face masks made from non-biodegradable polypropylene (PP) polymers have generated a significant amount of waste. In this work, a low-power plasma method has been used to degrade surgical masks. Several analytical techniques (gravimetric analysis, scanning electron microscopy (SEM), attenuated total reflection-infra-red spectroscopy (ATR-IR), x-ray photoelectron spectroscopy (XPS), thermogravimetric analysis/differential scanning calorimetry (TGA/DSC) and wide-angle x-ray scattering (WAXS)) were used to evaluate the effects of plasma irradiation on mask samples. After 4 h of irradiation, an overall mass loss of 63 ± 8%, through oxidation followed by fragmentation, was observed on the non-woven 3-ply surgical mask, which is 20 times faster than degrading a bulk PP sample. Individual components of the mask also showed different degradation rates. Air plasma clearly represents an energy-efficient tool for treating contaminated PPE in an environmentally friendly approach.

Plastic Waste: Challenges and Opportunities to Mitigate Pollution and Effective Management

The present world is now facing the challenge of proper management and resource recovery of the enormous amount of plastic waste. Lack of technical skills for managing hazardous waste, insufficient infrastructure development for recycling and recovery, and above all, lack of awareness of the rules and regulations are the key factors behind this massive pile of plastic waste. The severity of plastic pollution exerts an adverse effect on the environment and total ecosystem. In this study, a comprehensive analysis of plastic waste generation, as well as its effect on the human being and ecological system, is discussed in terms of source identification with respect to developed and developing countries. A detailed review of the existing waste to energy and product conversion strategies is presented in this study. Moreover, this study sheds light on sustainable waste management procedures and identifies the key challenges to adopting effective measures to minimise the negative impact of plastic waste.