Association of microplastics with heavy metals and antibiotic resistance bacteria/genes in natural ecosystems - A perspective through science mapping approach

Micro and nano-plastics (MNPs) have been considered one of the major emerging contaminants that require immediate attention. Their potential impact on the natural ecosystems is yet to be understood, especially their associations with other contaminants like heavy metals and organisms essential for the sustenance of life, i.e., microbes. Microplastics (MPs) also act as sources and carriers of pollutants, similar to macro and mesoplastics, that leach harmful chemicals such as Polybrominated Diphenyl Ethers (PBDEs), Pharmaceutical and Personal Care Products (PPCPs), Endocrine Disruptive Chemicals (EDCs), etc. They also behave like super sponge materials which adsorb microbes such as antibiotic resistance bacteria (ARBs), and coronavirus, making their concentration much higher than the ambient environment. Among these microbes, heavy metal-resistance (MRGs) and antibiotic-resistance genes (ARGs) carry immense significance. The present study provides an in-depth review analysis of the works published related to the association of MPs to heavy metals and ARGs. 1526 articles were investigated after the dataset was subjected to a three-stage screening process. A scientometric analysis revealing details about the most productive and influential journals, co-authorship details, most influential publications, most cited keywords, and most active countries in the research domain was conducted. This provided significant information regarding various aspects of the published works of literature. Subsequently, a qualitative discussion was carried out wherein a detailed discussion with regard to the trends in research on sub-areas in the broad domain was conducted. This resulted in identifying the gaps in the available literature, which paved the way for providing a framework for future research. Through this study, it is expected that the readers will be exposed to a summary of the overall research that has been conducted to date, and the manuscript will act as a guide for future research.

Plastic or plastic-free life: From formation to removal.

Microplastics (MPs) and nanoplastics (NPs) have caused global environmental concerns due to their ubiquitous existence in our surrounding environment and the potential threats posed to the ecosystem and human health. This review aims to extend current knowledge on the formation and degradation of MPs and NPs. The paper presents the potential sources of MPs and NPs including plastic containers, textiles, cosmetics, personal care products, COVID-19 wastes, and other plastic products. Once in the natural environment, the fragmentation and degradation of plastic wastes are thought to be initiated by physical, chemical, and biological factors. The corresponding degradation mechanism will be presented in the present review. Given the plastic life and environment, humans are inevitably exposed to MPs and NPs through ingestion, inhalation, and dermal contact. The potential risks MPs/NPs pose to humans will be also discussed in our study. Currently, the relevance of MP/NP exposure to human health outcomes is still controversial and not yet fully understood. Deciphering the translocation and degradation of plastics in the human body will be helpful to reveal their potential organotoxicity. In this case, available approaches to alleviate MP/NP pollution and advanced strategies to reduce MP/NP toxicity in humans are recommended to build a plastic-free life.

Personal protective equipment and micro-nano plastics: A review of an unavoidable interrelation for a global well-being hazard.

The usage and the demand for personal protective equipments (PPEs) for our day-to-day survival in this pandemic period of COVID-19 have seen a steep rise which has consequently led to improper disposal and littering. Fragmentation of these PPE units has eventually given way to micro-nano plastics (MNPs) emission in the various environmental matrices and exposure of living organisms to these MNPs has proven to be severely toxic. Numerous factors contribute to the toxicity imparted by these MNPs that mainly include their shape, size, functional groups and their chemical diversity. Even though multiple studies on the impacts of MNPs toxicity are available for other organisms, human cell line studies for various plastic polymers, other than the most common ones namely polyethylene (PE), polystyrene (PS) and polypropylene (PP), are still at their nascent stage and need to be explored more. In this article, we cover a concise review of the literature on the impact of these MNPs in biotic and human systems focusing on the constituents of the PPE units and the additives that are essentially used for their manufacturing. This review will subsequently identify the need to gather scientific evidence at the smaller level to help combat this microplastic pollution and induce a more in-depth understanding of its adverse effect on our existence.

Physical and biomimetic treatment methods to reduce microplastic waste accumulation.

Background: Since the Covid-19 pandemic in 2019, the use of plastics has increased exponentially, so it is imperative to manage and dispose of these plastic wastes safely. Objectives: This review focuses on the management strategies governed by the policies of each country to reduce plastic waste through physical collection methods and methods that use eco-imitation technologies. Results: Thus far, physical treatment methods have been applied to sewage and drinking water treatment. The abilities of bio-inspired treatment methods are being assessed in terms of capturing microplastics (MPs) and nanoplastics (NPs), extracting substances from marine organisms, reducing toxicity, and developing alternatives to petroleum-based plastics. Conclusions: Various post-treatment methods have been proposed to collect and remove MPs and NPs that have reached into aquatic ecosystems and subsequently reduce their toxicity. However, there are limitations that the effectiveness of these methods is hindered by the lack of policies governing the entire process of plastic use before the post-treatment. Purpose of Review: We purpose to reduce plastic waste through methods that use eco-imitation technologies. Recent Findings: These eco-imitation methods are attracting attention as viable future plastic waste treatment options in line with the goals of sustainable development.

Generation and consequence of nano/microplastics from medical waste and household plastic during the COVID-19 pandemic.

Since the end of 2019, the world has faced a major crisis because of the outbreak of COVID-19 disease which has created a severe threat to humanity. To control this pandemic, the World Health Organization gave some guidelines like wearing PPE (personal protective equipment) (e.g., face masks, overshoes, gloves), social distancing, hand hygiene and shutting down all modes of public transport services. During this pandemic, plastic products (e.g., household plastics, PPE and sanitizer bottles) have substantially prevented the spread of this virus. Since the outbreak, approximately 1.6 million tons of plastic waste have been generated daily. However, single-use PPE like face masks (N95), surgical masks and hand gloves contain many non-biodegradable plastics materials. These abandoned products have created a huge number of plastic debris which ended up as microplastics (MPs) followed by nanoplastics (NPs) in nature that are hazardous to the eco-system. These MPs and NPs also act as vectors for the various pathogenic contaminants. The goal of this review is to offer an extensive discussion on the formation of NPs and MPs from all of these abandoned plastics and their long-term impact on the environment as well as human health. This review paper also attempts to assess the present global scenario and the main challenge of waste management to reduce the potential NP/MPs pollution to improve the eco-systems.

Probing nanoplastics derived from polypropylene face masks with hyperspectral dark-field microscopy.

The high worldwide consumption of cheap plastic goods has already resulted in a serious environmental plastic pollution, exacerbated by piling of disposed personal protective equipment because of the recent outbreak of COVID-19. The aim of this study was to assess the feasibility of dark-field hyperspectral microscopy in the 400-1000 wavelength range for detection of nanoplastics derived from weathered polypropylene masks. A surgical mask was separated to layers and exposed to UV radiation (254 nm) for 192 h. Oxidative degradation of the polypropylene was evidenced by ATR FT-IR analysis. UV treatment for 192 h resulted in generation of differently shaped micro- and nano-sized particles, visualized by dark-field microscopy. The presence of nanoparticles was confirmed by AFM studies. The hyperspectral profiles (400-1000 nm) were collected after every 48 h of the UV treatment. The distinct hyperspectral features faded after prolonged UV exposure, but the assignment of some particles to either blue or white layers of mask could still be made based on spectral characteristics.

Call for biotechnological approach to degrade plastic in the era of COVID-19 pandemic.

Plastic pollution is a global issue and has become a major concern since Coronavirus disease (COVID)-19. In developing nations, landfilling and illegal waste disposal are typical ways to dispose of COVID-19-infected material. These technologies worsen plastic pollution and other human and animal health problems. Plastic degrades in light and heat, generating hazardous primary and secondary micro-plastic. Certain bacteria can degrade artificial polymers using genes, enzymes, and metabolic pathways. Microorganisms including bacteria degrade petrochemical plastics slowly. High molecular weight, strong chemical bonds, and excessive hydrophobicity reduce plastic biodegradation. There is not enough study on genes, enzymes, and bacteria-plastic interactions. Synthetic biology, metabolic engineering, and bioinformatics methods have been created to biodegrade synthetic polymers. This review will focus on how microorganisms' degrading capacity can be increased using recent biotechnological techniques.

Unraveling the potential human health risks from used disposable face mask-derived micro/nanoplastics during the COVID-19 pandemic scenario: A critical review.

With the global spread of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), disposable face masks (DFMs) have caused negative environmental impacts. DFMs will release microplastics (MPs) and nanoplastics (NPs) during environmental degradation. However, few studies reveal the release process of MPs/NPs from masks in the natural environment. This review presents the current knowledge on the abiotic and biotic degradation of DFMs. Though MPs and NPs have raised serious concerns about their potentially detrimental effects on human health, little attention was paid to their impacts on human health from DFM-derived MPs and NPs. The potential toxicity of mask-derived MPs/NPs, such as gastrointestinal toxicity, pneumotoxicity, neurotoxicity, hepatotoxicity, reproductive and transgenerational toxicity, and the underlying mechanism will be discussed in the present study. MPs/NPs serve as carriers of toxic chemicals and pathogens, leading to their bioaccumulation and adverse effects of biomagnification by food chains. Given human experiments are facing ethical issues and animal studies cannot completely reveal human characteristics, advanced human organoids will provide promising models for MP/NP risk assessment. Moreover, in-depth investigations are required to identify the release of MPs/NPs from discarded face masks and characterize their transportation through the food chains. More importantly, innovative approaches and eco-friendly strategies are urgently demanded to reduce DFM-derived MP/NP pollution.

An ecotoxicological perspective of microplastics released by face masks.

The accelerated use, massive disposal, and contamination with face masks during the COVID-19 pandemic have raised new questions regarding their negative impact on the environment emerged. One major concern is whether microplastics (MPs) derived from face masks (FMPs) represent an important ecotoxicological hazard. Here, we discussed the shortcomings, loose ends, and considerations of the current literature investigating the ecotoxicological effects of FMPs on aquatic and terrestrial organisms. Overall, there are multiple uncertainties regarding the true impact of FMPs at a certain concentration due to the presence of uncontrolled or unknown degradation products, such as MPs of various size ranges even nano-sized (<1 µm) and chemical additives. It is apparent that FMPs may induce endocrine-disrupting and behavioral effects in different organisms. However, the results of FMPs should be carefully interpreted, as these cannot be extrapolated at a global scale, by taking into account a number of criteria such as face mask manufacturers, providers, consumer preferences, and type of face masks. Considering these uncertainties, it is still not possible to estimate the contribution of face masks to the already existing MP issue.

Release of microplastics and nanoplastics in water from disposable surgical masks after disinfection.

During the COVID-19 pandemic, disposable surgical masks were generally disinfected and reused due to mask shortages. Herein, the role of disinfected masks as a source of microplastics (MPs) and nanoplastics (NPs) was investigated. The amount of MPs and NPs released from masks disinfected by UV ranged from 1054 ± 106 to 2472 ± 70 and from 2.55 ± 0.22 × 109 to 6.72 ± 0.27 × 109 particles/piece, respectively, comparable to that of the undisinfected masks, and the MPs were changed to small-sized particles. The amount of MPs and NPs released after alcohol and steam treatment were respectively lower and higher than those from undisinfected masks, and MPs were shifted to small-sized particles. The amount of MPs and NPs released in water after autoclaving was lower than for undisinfected masks. In all, the amount of fibers released after disinfection decreased greatly, and certain disinfection processes were found to increase the amount of small-sized NPs released from masks into aqueous environments.

Ecotoxicity of Heteroaggregates of Polystyrene Nanospheres in Chironomidae and Amphibian.

Due to their various properties as polymeric materials, plastics have been produced, used and ultimately discharged into the environment. Although some studies have shown their negative impacts on the marine environment, the effects of plastics on freshwater organisms are still poorly studied, while they could be widely in contact with this pollution. The current work aimed to better elucidate the impact and the toxicity mechanisms of two kinds of commercial functionalized nanoplastics, i.e., carboxylated polystyrene microspheres of, respectively, 350 and 50 nm (PS350 and PS50), and heteroaggregated PS50 with humic acid with an apparent size of 350 nm (PSHA), all used at environmental concentrations (0.1 to 100 µg L-1). For this purpose, two relevant biological and aquatic models-amphibian larvae, Xenopus laevis, and dipters, Chironomus riparius-were used under normalized exposure conditions. The acute, chronic, and genetic toxicity parameters were examined and discussed with regard to the fundamental characterization in media exposures and, especially, the aggregation state of the nanoplastics. The size of PS350 and PSHA remained similar in the Xenopus and Chironomus exposure media. Inversely, PS50 aggregated in both exposition media and finally appeared to be micrometric during the exposition tests. Interestingly, this work highlighted that PS350 has no significant effect on the tested species, while PS50 is the most prone to alter the growth of Xenopus but not of Chironomus. Finally, PSHA induced a significant genotoxicity in Xenopus.

Pollution caused by nanoplastics: adverse effects and mechanisms of interaction via molecular simulation.

The continuous increase in the production of synthetic plastics for decades and the inadequate disposal of plastic waste have resulted in a considerable increase of these materials in aquatic environments, which has developed into a major environmental concern. In addition to conventional parameters, the relevance of the environmental monitoring of microplastics (MPs) and nanoplastics (NPs) has been highlighted by the scientific community due to the potential adverse effects these materials pose to the ecosystem as well as to human health. The literature has registered an increasing interest in understanding the mechanisms, at the molecular level, of the interaction between NPs and other compounds using molecular simulation techniques. The present review aims to: (i) summarize the force fields conventionally used to describe NPs by molecular simulations; (ii) discuss the effects of NPs in the structural and dynamical properties of biological membranes; (iii) evaluate how NPs affect the folding of proteins; (iv) discuss the mechanisms by which NPs adsorb contaminants from the environment. NPs can affect the secondary structure of proteins and change the lateral organization and diffusion of lipid membranes. As a result, they may alter the lipid digestion in the gastrointestinal system representing a risk to the assimilation of the nutrients by humans. The adsorption of contaminants on MPs and NPs can potentiate their harmful effects on human health, due to a possible synergism. Therefore, understanding the mechanisms involved in these interactions is crucial to predict dangerous combinations and outline action strategies that reduce negative impacts on ecosystems and human health. Depending on the chemical properties of contaminants and NPs, electrostatic and/or van der Waals interactions can be more relevant in explaining the adsorption process. Finally, we conclude by highlighting gaps in the literature and the critical aspects for future investigations.

Microplastics and nanoplastics released from a PPE mask under a simulated bushfire condition.

Due to COVID-19, large amounts of personal protective equipment (PPE) have been used, and many PPE units are made of plastics, such as face masks. The masks can be burned naturally in a bushfire or artificially at the incineration plants, and release microplastics and nanoplastics from the mask plastic fibres. A fire can cause the plastic, such as polypropylene (PP) fibres, to be molten and stick to the solid surface, such as glass, soil, concrete or plant, as films or islands, due to the binding property of the molten plastic material. Once the films or islands are peeled off in the processes such as weathering, ageing, or treatment and clean-up, there are residuals leftover, which are identified as nanoplastics and microplastics via Raman imaging, with the significant release amount of ~1100 nanoplastics / 10 µm2 or ~11 billion / cm2, and ~50 microplastics / 420 µm2 or ~12 million / cm2. Moreover, surface group is deviated on the plastic surface, which can also be distinguished and visualised as well via Raman imaging, down to nano size. This test validates the Raman imaging approach to capture microplastics and nanoplastics, and also provides important information about the fate and transportation of PPE mask in the environment, particularly when subjected to a fire. Overall, Raman imaging can be an effective option to characterise the microplastics and nanoplastics, along with the deviated surface group.

Microplastics released from food containers can suppress lysosomal activity in mouse macrophages.

The ingestion and accumulation of microplastics is a serious threat to the health and survival of humans and other organisms given the increasing use of daily-use plastic products, especially during the COVID-19 pandemic. However, whether direct microplastic contamination from plastic packaging is a threat to human health remains unclear. We analyzed the market demand for plastic packaging in Asia-Pacific, North America, and Europe and identified the commonly used plastic food packaging products. We found that food containers exposed to high-temperature released more than 10 million microplastics per mL in water. Recycled plastic food packaging was demonstrated to continuously leach micro- and nanoplastics. In vitro cell engulfing experiments revealed that both micro- and nanoplastic leachates are readily taken up by murine macrophages without any preconditioning, and that short-term microplastic exposure may induce inflammation while exposure to nanoplastic substantially suppressed the lysosomal activities of macrophages. We demonstrated that the ingestion of micro- and nanoplastics released from food containers can exert differential negative effects on macrophage activities, proving that the explosive growth in the use of plastic packaging can poses significant health risks to consumers.

A critical synthesis of current peer-reviewed literature on the environmental and human health impacts of COVID-19 PPE litter: New findings and next steps.

Since the emergence of Coronavirus disease (COVID-19), the threat of plastic waste pollution has grown exponentially, with a strong attention on the environmental and human health consequences of millions of personal protective equipment (PPE) (e.g., face masks, shields, gloves, and wipes) being used and discarded. In response, a massive research effort has been launched to understand, characterize, and estimate the exposure risks of PPE associated contaminants. While the number of studies examining the impacts of PPE is increasing, this review aimed to provide a quick update on the research conducted to date of this topic, as well as to identify priorities for future research. Specifically, we analyzed recent global peer-reviewed articles on PPE to synthesize methods, control measures, and documented evidence to (1) investigate the discarded PPE in a variety of environments; (2) determine the microplastics discharge in the aquatic environment; (3) examine the intentionally or unintentionally added chemicals in the production of PPE; and (4) assess potential human health hazards and exposure pathways. Despite progress, more research is needed in the future to fully understand the chemical emissions from PPE degradation mechanisms (mechanical, chemical, and biological), as well as the magnitude and density of PPE pollution in the environment.

Face masks as a source of nanoplastics and microplastics in the environment: Quantification, characterization, and potential for bioaccumulation.

Billions of disposable face masks are consumed daily due to the COVID-19 pandemic. The role of these masks as a source of nanoplastics (NPs) and microplastics (MPs) in the environment has not been studied in previous studies. We quantified and characterized face mask released particles and evaluated their potential for accumulation in humans and marine organisms. More than one billion of NPs and MPs were released from each surgical or N95 face mask. These irregularly-shaped particles sized from c. 5 nm to c. 600 µm. But most of them were nano scale sized <1 µm. The middle layers of the masks had released more particles than the outer and inner layers. That MPs were detected in the nasal mucus of mask wearers suggests they can be inhaled while wearing a mask. Mask released particles also adsorbed onto diatom surfaces and were ingested by marine organisms of different trophic levels. This data is useful for assessing the health and environmental risks of face masks.

Uncovering the release of micro/nanoplastics from disposable face masks at times of COVID-19.

Wearing face masks is a fundamental prevention and control measure to limit the spread of COVID-19. The universal use and improper disposal of single-use face masks are raising serious concerns for their environmental impact, owing to the foregone contribution to plastic water pollution during and beyond the pandemic. This study aims to uncover the release of micro/nanoplastics generated from face mask nonwoven textiles once discarded in the aquatic environment. As assessed by microscopy and flow cytometry, the exposure to different levels of mechanical stress forces (from low to high shear stress intensities) was proved effective in breaking and fragmenting face mask fabrics into smaller debris, including macro-, micro-, and nano-plastics. Even at the low level of fabric deterioration following the first second of treatment, a single mask could release in water thousands of microplastic fibers and up to 108 submicrometric particles, mostly comprised in the nano-sized domain. By contributing to the current lack of knowledge regarding the potential environmental hazards posed by universal face masking, we provided novel quantitative data, through a suitable technological approach, on the release of micro/nanoplastics from single-use face masks that can threaten the aquatic ecosystems to which they finally end-up.

Marine Waste-Sources, Fate, Risks, Challenges and Research Needs.

The article presents a comprehensive and cross-cutting review of key marine waste issues, taking into account: sources, fate, risks, transport pathways, threats, legislation, current challenges, and knowledge gaps. The growing amount of both human-created waste in seas and oceans and waste reaching marine ecosystems from land is one of today's challenges for the global economy and the European Union. It is predicted that if no decisive steps are taken to limit the amount of this type of waste, there may be more plastic waste than fish in the oceans after 2050. The influence of microplastics and nanoplastics on living organisms remains undiagnosed. Within the international and EU law, solutions are being developed to properly manage waste on board ships and to reduce the impact of processes related to the recycling of the vessels on the environment. Currently, over 80% of ships are dismantled in the countries of South Asia, in conditions that threaten the environment and the safety of workers. After World War 2, large quantities of chemical weapons were deposited in the seas. Steel containers with dangerous substances residing in the sea for over 70 years have begun leaking, thus polluting water. For many years, radioactive waste had also been dumped into marine ecosystems, although since 1993 there has been a total ban on such disposal of radionuclides. The impact of the COVID-19 pandemic on marine waste generation has also been presented as a significant factor influencing marine waste generation and management.