key: cord-1001454-vvntpz9r
authors: Kutralam-Muniasamy, Gurusamy; Pérez-Guevara, Fermín; Shruti, V.C.
title: 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
date: 2021-08-18
journal: J Hazard Mater
DOI: 10.1016/j.jhazmat.2021.126945
sha: 16e633f38a11c9c8c998162a294c4d853bac7162
doc_id: 1001454
cord_uid: vvntpz9r

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.

Worryingly, at the time of writing, the global COVID-19 case count had surpassed 191 million, with nearly 4 million casualties and numerous hospitalizations. Many countries continue to rely on billions of personal protective equipment more than a year after the World Health Organization declared COVID-19 a global pandemic. Personal protective equipment (PPE) such as face masks, gloves, and face shields, as well as wet wipes, have been shown to prevent contracting COVID-19 (WHO, 2020) . The majority of PPE contains plastics or plastic derivatives, with higher percentages of polypropylene (PP) and polyethylene (PE), as well as other polymeric materials such as polyester, polyurethane, nylon, and polystyrene (Fadare and for a variety of contaminants and being toxic to organisms. Meanwhile, evidence of intentionally or unintentionally added chemicals in the production of polymer-based face masks is only now emerging (Fernández-Arribas et al., 2021; Sullivan et al., 2021; Liu and Mabury, 2021) , indicating that they could be a source of chemicals to the environment. The discovery of these new findings improved our understanding and insight into the fate of PPE under environmental conditions. Despite its potentially important role in shaping public health, PPE, particularly face masks, has emerged as a major environmental and health concern in terms of plastic pollution, including micro-and nano-plastics.

In the midst of COVID-19, we can remark that the scientific community has been working tirelessly on designing strategies and building increasingly active research efforts in multiple directions to bring novel insights into the effects of PPE. The availability of analytical methods has aided researchers in conducting newer research studies on previously unknown harmful aspects of environmental issues associated with PPE items. The breadth of the area of PPE research, as well as the seemingly exponential increase in the number of publications on the subject, can be intimidating to scientists who are new to the field. Furthermore, accurate data requires proper sample processing, identification, quantification, and characterization, and existing methodology differs significantly between studies. It is critical to be well-versed in the currently established new approaches, the application of methods and control measures, and the impact of PPE on the environment and human health in order to identify important, unanswered research questions. In contrast to the reviews that are currently available in the literature, there are no systematic reviews of comparable scope for PPE researchers. Herein, this has prompted us to conduct a systematic scientific-based review of recent advances in PPE environmental research, organized by related topics, in order to establish an integrative perspective of recent J o u r n a l P r e -p r o o f advances and provide guidance for future research in this space. Specifically, we analyzed recent global peer-reviewed articles on PPE to synthesize a comprehensive overview of available methods, control measures, and documented evidence on (1) investigation of the discarded PPE in a variety of environments (Section 3); (2) determination of the microplastics discharge in the aquatic environment (Section 4); and (3) examination of the intentionally or unintentionally added chemicals in the production of PPE (Section 5). In each section, we also highlight future directions. Finally, we evaluate potential human health hazards and exposure pathways using evidence from the current literature. We anticipate that this review will assist those interested in PPE research in identifying methods and contributions that will be useful in the development of their own investigations. Furthermore, we hope that this review will attract researchers from various disciplines to gain a comprehensive understanding of recent advancements and challenges in the field, as well as inspire new ideas and research directions.

We developed a set of keywords to enable a comprehensive search of all peer-reviewed articles on PPE pollution and its associated contaminants. These keywords included COVID-19 pandemic, PPE, face masks, wipes, gloves, chemicals, microplastics, degradation, nanoplastics, metals, additives, plasticizers, and organic compounds. We searched peer-reviewed published papers in scientific databases such as Web of Science, Google Scholar, and Pubmed in July 2021 using Boolean operators and the keywords indicated above. The articles published between December 2019 and July 2021 were first narrowed down from the search results. After reviewing the title, abstract, and content of the papers, review articles, discussion, editorials, focus, commentary, viewpoints and papers that have not been published in English were omitted. In addition, estimates of PPE waste for individual parts of the world that lack environmental J o u r n a l P r e -p r o o f monitoring fall outside the scope of this review and were excluded. Furthermore, preprint articles that were available on the internet were eliminated. The remaining publications were then carefully evaluated, and studies that did not undertake experiments on PPE in relation to microand nano-plastics and chemicals were excluded. By this way, we were able to select a total of 22 peer-reviewed journal articles that described the prevalence and abundance of PPE in environment (n = 9), the attribution of PPE to micro-and nano-plastics (n = 9), and the presence of organic and inorganic contaminants in PPE (n = 4). Supplementary Material Table S1 provides a compiled list of publications organized by the type of PPE research. All data, including current analytical methods, sampling procedures, sample processing, quality assurance and quality control (QA/QC) measures, and documented results were extracted from these articles and organized in Tables 1-3 and Figure 1 .

Since the detection of COVID-19-related PPE wastes on the world's shorelines, there has been an increased interest in determining and comprehending the extent to which these wastes accumulate in the environment. Depending on the resources available and accessibility to a region of interest, a PPE litter monitoring survey can be either nationwide or regional with the goal of collecting daily/weekly data from both aquatic and terrestrial environments. There is currently no internationally accepted standard procedure for surveying PPE debris. As a result, the sampling methods of the PPE survey have varied depending on the habitat (marine or urban) and the specific objective of the study (floating PPE debris) ( Table 1) . Six of the nine studies examined the amount of PPE along the shorelines by monitoring marine beaches, whereas other studies focused on floating PPE debris in water (river or marine) and improperly discarded PPE J o u r n a l P r e -p r o o f in streets of metropolitan cities near schools, hospitals, and residential areas (Fig. 1a) (Ryan et al., 2021; Ammendolia et al., 2021) . While transects and quadrats were commonly used for PPE monitoring along coastal shorelines (Haddad et al., 2021; De-la-Torre et al., 2021) , tools such as manta trawls and deep nets were used to investigate floating PPE debris (Okuku et al., 2021; Cordova et al., 2021) . It is strongly recommended to conduct the beach survey early in the morning before personnel clean them, and it also applies to surveying PPE litter in streets of metropolitan cities and urban areas. The PPE survey was mostly conducted along the entire beach, with some variations in the areas covered for item collection. Thiel et al. (2021) collected PPE washed up by the last high tide along the last strand line, while other researchers traversed the entire width of the beaches from the edge of the water up to 2 m into the vegetation De-la-Torre et al., 2021; Okuku et al., 2021) . In the case of a street survey, PPE litter was collected as close to the street margins as possible. In addition to manual collection by researchers, a citizen science program involving volunteers for PPE litter sampling on beaches or city streets is regarded as a valuable approach for a national and local survey. Two of eight studies for daily PPE surveys used such citizen science programs (Ammendolia et al., 2021; Thiel et al., 2021) . It should be noted that the time frame observed here for the global PPE survey may represent a majority of the period between April 2020 and May 2021. Nonetheless, the sampling period varied between studies, ranging from 4.7 (approximately 33 days) to 16 weeks (112 days). After data collection, the PPE density was calculated by using the formula: C = n/a, where C is PPE density (PPE m -2 ), n is the number of PPE, and a is the covered area (m 2 ).

There are significant health risks associated with the COVID-19 survey of discarded PPE in the environment, such as the possibility of SARS CoV-2 transmission via handling or contact J o u r n a l P r e -p r o o f with PPE litter, and strict safety procedures must be implemented. Only two of the eight studies mentioned the safety measures adopted during sampling (Theil et al., 2021; Ammendolia et al., 2021) . The researchers followed the social distancing by working in small groups or when there were few people outside. The PPE litter should be handled with extreme caution in the sampling areas. Ammendolia et al. (2021) , for example, avoided direct contact by collecting discarded PPE with a specialized metal stick equipped with a hand-held claw. Furthermore, the researchers wore PPE and frequently used hand sanitizer during the surveys to ensure their own safety.

Another challenge is the safe preservation of collected PPE litter. This was accomplished by securely tying the samples and storing them in woven garbage bags, aluminum foil, or plastic bags for further analysis. In the case of citizen science programs, the volunteers taking part in the survey must be thoroughly instructed on all of the above-mentioned safety precautions to be followed throughout the survey and collection of PPE litter.

The most recent PPE surveys focused on a variety of environments, including streets nearby beaches and metropolitan areas (Canada and South Africa), river outlets (Indonesia), and coastal shorelines (Peru, Chile, Bangladesh, Persian Gulf, and Morocco) ( Table 1 ). The lower number of studies could be attributed to the impact of the COVID-19 pandemic on local or global surveys. Nonetheless, thanks to the researchers who made the PPE pollution survey possible after the COVID-19 restrictions were relaxed, or even while the COVID-19 restrictions were in effect. The findings revealed that PPE litter was prevalent in all of the environments studied (Table 1) . Face masks (disposable medical, N95 masks, cotton, sponge, and reusable), face shields, gloves, hazard suit material, and disinfectant wipes were among the numerous PPE items identified in the studies reviewed. According to all studies, face masks have never been J o u r n a l P r e -p r o o f seen in previous surveys. Face masks and disinfectant wipes were commonly encountered in all surveys (shoreline, street, and floating debris), accounting for more than half of total PPE debris (Table 1) . Moreover, face masks accounted for 80 -98 % of all PPE types in a few studies conducted in Peru and Bangladesh De-la-Torre et al., 2021; Haddad et al., 2021) . The reported PPE density varied by region of the world, which can be influenced by sampling methods, area sampled, region type (tourist or non-tourist), and COVID-19 restrictions, resulting in incomparable results. The PPE density found along Moroccan, Bangladesh, Peruvian, and Chilean coastal shorelines was 1.13 x 10 -5 PPE m -2 , 7.44 x 10 -4 PPE m -2 , 6.29 x 10 -made of low-density polymers, such as polypropylene, polyethylene, and polyester, on the other hand, can float in water, travel long distances in the environment, and reach the shorelines.

Despite methodological differences, the current literature strongly suggests that PPE litter has a greater impact on aquatic environments. These data also indicated an unprecedented prevalence and growth of PPE in plastic litter across a wide range of environments worldwide, contributing significantly more than originally understood to the ongoing plastic waste problem.

Protocol standardization is required to ensure reliable, reproducible, and comparable results, along with a list of safety risk measures. More PPE surveys are urgently needed around the world in order to have a comprehensive data structure for understanding the magnitude and density of PPE pollution. More research on the occurrence of PPE in bottom marine sediments is needed because PPE made of high-density polymers like polyurethane and polyacrylonitrile can sink and light-density PPE may undergo biofouling processes that increase their density, allowing them to reach bottom marine sediments. Recent evidence demonstrates that PPE has a negative impact on wildlife through entanglement and ingestion (Gallo Neto et al., 2021; Silva et al., 2021) , and more research into the effects of PPE pollution on organisms is required. Given that tourism activities are resuming in many parts of the world, PPE disposal should be strictly regulated, with specific waste bins installed for proper disposal of used face masks. Beach management programs must conduct educational campaigns to motivate locals and visitors to practice responsible behavior in terms of environmental governance and proper PPE disposal.

Beach managers and sanitary workers must be cautious in separating collected PPE litter and transporting it to a designated location, such as a landfill or incineration plant. More importantly, we are concerned with the volume of waste that improper PPE disposal would generate during J o u r n a l P r e -p r o o f the post-covid19 pandemic, as there is a risk that people might take disposal for granted if PPE is of no longer useful. As a result, the government must develop new protocols based on environmentally sustainable practices for effective PPE collection and disposal.

With the increase in marine PPE pollution during the pandemic, it is expected that any improperly discarded PPE will remain in the environment for years, contributing significantly to the plastics pollution, particularly micro-and nano-plastics. As a result, quantifying the microand nano-plastics release into the environment by PPE via fragmentation/degradation is considered critical. Laboratory studies, which mimic environmental conditions, are the most reliable way to assess and understand the mechanisms influencing the release ability of microand nano-plastics by PPE. As shown in Table 2 and Fig. 1b , researchers have adopted various strategies and characterization methods to address the PPE degradation features as well as the discharge of micro-and nano-plastics in the aquatic environment. Of a total of 9 studies, face masks have received the most attention (n = 8) in comparison to other PPE materials (n = 1; disinfectant wipes) due to their widespread production, use, and disposal. Face masks of various types, including medical surgical face masks, disposal medical face masks, normal disposal face masks, and N95 face masks with respirators, have been tested for micro-and nano-plastics release ability. The majority of studies (n = 5) focused on disposable face masks, which are the most common PPE found in the environment.

The three main steps in recent studies on microplastics release by PPE were: (1) sample preparation, (2) microplastics separation, and (3) quantification and characterization (Fig. 1b) .

Recognizing that PPE is subjected to various forms of fragmentation and weathering once it J o u r n a l P r e -p r o o f reaches the environment, researchers set out to recreate similar conditions in the lab. Thus, the first step in sample preparation was to subject the selected PPE either whole or in pieces, to a simulated experiment, which can include natural weathering, artificial aging under UV radiation/stirring, submerging in artificial seawater/distilled water/ultrapure water, washing with detergents and disinfectants, mechanical sand abrasion, and hand rubbing (in case of wipes).

While many researchers used new masks/wipes purchased online, at a drug store, or from a manufacturer, only a few utilized used masks by asking volunteers to wear them for a period of time (Chen et al., 2021a) . Prior to the analysis, the ear strip and nose bridge were removed in order to estimate the micro-and nano-plastics released by the face masks alone. Some researchers have even separated and weathered each layer of mask (outer, middle, and inner) to account for the amount of microplastics released (Ma et al., 2021; Wang et al., 2021) . The weathering conditions, such as incubation time (1 -48 h), temperature (25 -65ºC), and stirring speed (e.g., 120 rpm), varied between studies. In addition, a few studies repeated the experiment ten to eighteen times to better understand the pattern of micro-and nano-plastics release from PPE. At the end of the experiment, the PPE was dried and weighed to determine how much mass had been lost due to fragmentation/degradation. Apart from the aging experiments, only one study collected nasal mucus from adult after wearing masks for 12 h to investigate the presence of micro-and nano-plastics using saline solution (Ma et al., 2021) . In many studies, the microplastics released during the above-mentioned simulated experiments were separated directly through filtration. However, in some cases, the samples were digested with wet oxidant (e.g., H 2 O 2 ) to remove organic impurities that were present (Ma et al., 2021; Lee et al., 2021) .

Following digestion, microplastics were separated by density using a ZnCl 2 salt solution and then separated from supernatant fluids via filtration (Lee et al., 2021) . For microplastics separation, a J o u r n a l P r e -p r o o f variety of filter membranes with pore sizes ranging from 0.1 to 0.8 μm were used, including anodisc filters, aluminum oxide filters, mixed cellulose filters, and nitrocellulose filters.

Several methods are used to quantify (i.e., count) and characterize (i.e., morphology, size, and polymer type) the micro (nano) plastics released by PPE, which can have a significant impact on their reported size ranges and abundances between studies. Microplastics, for example, are frequently detected using a microscope with a size limit detection of 0.5 mm, while other methods for identifying micro-and nano-plastics included FTIR, Raman, LDIR, SEM-EDX, AFM, and laser in-situ scattering and transmissometry, all of which have various detection limits (from 20 micron to 0.1 nm).

Several precautionary measures have been established in the laboratory to avoid secondary contamination (e.g., airborne, dress) and limit overestimation of microplastics counts.

All studies determining the release or degradation of PPE masks and wet wipes adhered to the QA/QC measures. Preliminary steps included maintaining a clean laboratory environment, as well as wearing cotton lab coats and clean gloves throughout the experiments. Except for the study by Li et al. (2021) , in which the goal was to simulate a realistic situation of microplastics inhalation, the experiments were not conducted in a super-clean laboratory and no contamination control measures were used. All glassware used in experiments was pre-cleaned with Milli-Q, ultrapure, or deionized water, and in a few studies, heat treatment (400-500°C) was used to remove organic impurities. Similarly, all solutions were pre-filtered to prevent contamination in the experimental analysis. Pre-cleaned metal tweezers were preferably used to recover the PPE samples submerged in water without having any contact with other materials (Shen et al., 2021; Morgana et al., 2021) . The use of replicates, blanks, and control samples is critical for ensuring J o u r n a l P r e -p r o o f the quality of the analysis. Triplicates for each mask layer or batch/brand and wipes were conducted in the reviewed studies. Blank samples were used in these studies to identify secondary contamination from the laboratory (i.e., airborne) or from analytical procedures performed (i.e., equipment, filtering unit, solutions). Similarly, Wang et al. (2021) conducted control experiments without mask under the same analytical conditions as those with mask samples. Procedural blank samples prepared with deionized water (n = 2) were run with each batch of analysis. While, in the experimental study conducted by Li et al. (2021), a blank suction test without a mask was performed throughout the experiment, allowing only air to pass through the filter membrane. Also, covering the filter samples and instruments with aluminum foil with minimum exposure to air is highly recommendable. It is noteworthy that all of the studies used QA/QC measures, implying confidentiality in the results obtained.

Various studies to date indicate that the release of micro-and nano-plastics is caused by a variety of factors. Mechanical abrasion while wearing, adjustment, folding, and pulling of the PPE, as well as breakage and fragmentation due to sand abrasion and UV weathering, are all examples (Han and He, 2021; Saliu et al., 2021; Shen et al., 2021; Wang et al., 2021) . As seen in Table 2 , all of the tested PPE (masks and wipes) degraded/fragmented into micro-and nanoplastics under various aging/environmental conditions, with concentrations reaching upto 6.0 x 10 9 per mask. Nonetheless, the release behavior of the masks differed before and after natural aging, indicating that the natural environment had an impact on the PPE (Shen et al., 2021; Saliu et al., 2021; Wang et al., 2021) . Furthermore, we found a significant difference in the amount of microplastics released between surgical and nonwoven masks, which is most likely due to the fact that surgical masks have a middle layer made of melt-blown fabric, whereas nonwoven J o u r n a l P r e -p r o o f masks have all layers made of nonwoven fiber. For example, the discharge of micro-and nanoplastics from middle layer was greater compared to outer and inner layers (Ma et al., 2021; Wang et al., 2021) . Thus, the type of masks used in the studies must be considered when comparing the total of microplastics released. Surprisingly, Li et al. (2021) indicating yet another route of human plastic particle exposure.

Micro-and nano-plastics in a wide range of shapes are discharged from masks and wipes, including fibers, fragments, irregularly shaped clumps/aggregates, and spherical type, with fibers accounting for more than 80% of the total. Th f m 5 m > 2000 μm w h h m j b p h 100 μm The size distribution was found to vary with aging process, layer in masks, and the type of PPE used (Table 2) . Nevertheless, it is important to bear in mind that the disparity of methods used for separation, identification, and quantification of micro-and nano-plastics can also affect the comparability of the results between studies. The color of the particles differed depending on the type of mask. For example, Chen et al. (2021a) and Sullivan et al. (2021) found a variety of colored microplastics released from masks, including green, orange, blue, pink, transparent, yellow, black, grey, and purple. Polymers such as PP, PE, PET, and dye molecules such as eriochrome black and congo red were found during the polymer characterization. PP type micro-and nano-plastics were common among those reported, indicating an unprecedented increase in their ambient concentration with the ongoing COVID-19 pandemic.

These findings provided a strong foundation of what could happen to PPE in the environment and how humans are exposed to plastic particles through PPE use in daily life. If artificial weathering can cause fragmentation of face masks/wipes into millions of microplastics within a few days, it is possible that the gradual aging and decomposition of the entire masks in the environment increases the release, resulting in billions of micro-and nano-plastics having significant environmental impact and being immediately bioavailable to organisms.

The current understanding of microplastics release by PPE is based on MilliQ, distilled, and deionized water, but it is critical to conduct similar research using other bodies of water, such as rivers and seas, as well as soil environments. Other than micro-and nano-plastics, PPE breakdown is also likely to be a source of mesoplastics (> 5 -< 25 mm) (Andrady, 2011) 

Finally, plastic wraps for face masks would be a source of pollution in the environment, and they deserve special attention and consideration. All of these should be taken into account when investigating the PPE consequences of micro-and nano-plastics pollution in the environment.

A few recent studies attempted to identify a variety of organic and inorganic contaminants that were intentionally or unintentionally added to PPE during production and assess their levels in various PPE manufactured around the world. Among the PPE tested were surgical masks, self-filtering masks, cloth reusable masks, homemade masks with disposable filters, and wipes for children and adults made in China, Vietnam, Mexico, Spain, Canada, and Germany, with products from China being studied the most in the studies reviewed (Table 3) .

They were purchased from the manufacturer, local stores, or were collected from nearby households. Furthermore, packaging materials were tested alongside masks because they can be a source of chemicals once they reach the environment. Initially, the entire PPE or pieces of it were transferred into glass vials with an internal standard. The samples were then extracted with a solvent mixture to obtain leachate and filtered or centrifuged to remove the particles prior to instrumental analysis (Table 3) 

The findings of the existing peer-reviewed studies confirmed that face masks and wipes include a wide spectrum of organic and inorganic pollutants used as plasticizers, UV stabilizers, and flame retardants in plastic production that include phthalates (di and mono) and nonpthalates, antioxidants, organophosphate esters, bisphenols, and plastic additives (Supplementary   Material Table S2 ). It is worth noting that they were found in all of the samples tested, with at least one or more target chemicals identified. 

According to the current review, there is a significant research gap in understanding chemical emissions from PPE degrading mechanisms (mechanical, chemical, and biological) and

the exposure risks associated with them. Similarly, because the significant proportion of PPE is incinerated, analyzing the degradation products contained in smoke is critical. There is a lack of information on the types and concentrations of chemicals found in each layer of disposable face masks, as well as the nose strip, ear bridge, and respirators. Given that they could be a vector of organic and inorganic compounds, once they reach the environment, it is necessary to identify, characterize, and distinguish them, which is another area of research to be explored. Numerous products manufactured, used, and discarded in those unexplored country regions must be tested.

We believe that there are many other chemical additive families that are yet to be identified and characterized, indicating the need for additional research on this topic. Furthermore, the release of metal nanoparticles found in antimicrobial face masks manufactured at COVID-19 pandemic during washing and reuse of the face mask into aqueous media must be evaluated. Aside from J o u r n a l P r e -p r o o f PPE, other items of plastic packaging and wraps that witnessed the increased production during the COVID-19 pandemic must be investigated to determine the levels of additives present.

PPEs from COVID-19 present significant challenges as a contaminant category due to their complexity, diversity, and limited studies in characterization, exposure pathways and assessment of toxicological hazards limits our understanding of true fate of PPEs. It is becoming clear that PPEs contribute to the world's already significant levels of macro-, meso-, micro-, and nano-plastics pollution as well as, to a variety of other contaminants ubiquitous in the environment (Fig. 2) . The accumulation of PPE litter, like any other plastic waste, poses a number of risks to the environment, animal health, and human health ( . As a result of this situation, we are concerned that health care workers who frequently wear masks may be exposed to numerous micro-and nano-plastics.

Micro-and nano-plastics are well-known to sorb and concentrate contaminants from surrounding environment, imposing risks of transfer of contaminants in organisms across different trophic levels including humans. Not only the contaminants from environment but the release of chemical compounds (e.g., plasticizers, flame retardants and metals) found in PPE themselves (Fig. 2) are a cause of concern for environment and human health. It is important to note that most of them are ubiquitous in the environment and characterized as toxic ( In contrary, chemicals applied during production or absorbed in the environment can remain and bioaccumulate in wildlife, with trace quantities released into the environment accumulating over time and contaminating the food chain. Because the majority of used PPE in developing countries is landfilled due to a lack of infrastructure, we are concerned about the amounts of additives and monomers released from PPEs as they breakdown in landfill conditions. They leach into our soil and groundwater over time, posing environmental hazards for years. For example, about 90% of plastic waste in South Africa ends up in landfills (Olatayo et al., 2021) . Here, we attempted to estimate the amount of chemicals that would most likely be released in landfills using the assumption that 10% of all daily used face masks are landfilled (Table 4 ). In this regard, the median concentrations measured in the studies of Liu and Mabury (2021), Chen et al. (2021b) , and Fernández-Arribas et al. (2021), were adopted. According to our estimates, global environmental exposure levels correspond to tons of chemicals per year, implying that discarded PPE materials, as well as their degradation products meso-, micro-, and nano-plastics, are a source of numerous chemicals to the environment. We believe this will have a significant environmental impact, and as a result, landfill leachate should be closely monitored for the presence of plastic particles and chemicals. Though the estimates in Table 4 

We must recognize now that COVID-19-related plastics waste is an unavoidable 

Accumulation of plastic waste during COVID-19

Surgical mask dermatitis caused by formaldehyde (releasers) during the COVID-19 pandemic

Abandoned Covid-19 personal protective equipment along the Bushehr shores, the Persian Gulf: an emerging source of secondary microplastics in coastlines

Presence of airborne microplastics in human lung tissue

An emerging source of plastic pollution: environmental presence of plastic personal protective equipment (PPE) debris related to COVID-19 in a metropolitan city

Single-use surgical face masks, as a potential source of microplastics: Do they act as pollutant carriers

Microplastics in the marine environment

Surgical face masks as a potential source for microplastic pollution in the COVID-19 scenario

COVID-19 pandemic repercussions on plastic and antiviral polymeric textile causing pollution on beaches and coasts of South America

Used disposable face masks are significant sources of microplastics to environment

The High Complexity of Plastic Additives in Hand Wipes

Estimating marine plastic pollution from COVID-19 face masks in coastal regions

Unprecedented plastic-made personal protective equipment (PPE) debris in river outlets into Jakarta Bay during COVID-19 pandemic

Occurrence of personal protective equipment (PPE) associated with the COVID-19 pandemic along the coast of Lima

Covid-19 face masks: a potential source of microplastic fibers in the environment

COVID-19 face masks: A new source of human and environmental exposure to organophosphate esters

Mortality of a juvenile Magellanic penguin (Spheniscus magellanicus, Spheniscidae) associated with the ingestion of a PFF-2 protective mask during the Covid-19 pandemic

Personal protective equipment (PPE) pollution associated with the COVID-19 pandemic along the coastline of Agadir

An overview of chemical additives present in plastics: Migration, release, fate and environmental impact during their use, disposal and recycling

Need for assessing the inhalation of micro (nano) plastic debris shed from masks, respirators, and home-made face coverings during the COVID-19 pandemic

SARS-CoV-2 pandemic-induced PPE and single-use plastic waste generation scenario. Waste Manage. Res. marine litter pollution along the Kenyan Coast: a synthesis after 100 days following the first reported case in Kenya

COVID-19 PPE plastic material flows and waste management: Quantification and implications for South Africa

2020. Occurrence, analysis and risk assessment of organophosphate esters (OPEs) in biota: A review

COVID-19 pandemic repercussions on the use and management of plastics

Personal protective equipment (PPE) pollution driven by the COVID-19 pandemic in Cox's Bazar, the longest natural beach in the world

The impact of the COVID-19 lockdown on urban street litter in South Africa

The release process of microfibers: from surgical face masks into the marine environment

Neglected microplastics pollution in global COVID-19: disposable surgical masks

SPA: Synthetic phenolic antioxidants; OPA: Organophosphite antioxidants; AO: Synthetic antioxidants; OPE: Organophosphate esters; a: Study results of Liu and Mabury, 2021; b: Study results of Fernández-Arribas et al., 2021; Face mask acceptance rate adopted from Chowdhury