The impact of plastic during the COVID-19 pandemic: The point of view of the environmental science literature

Abstract

COVID-19 is the official name of the disease provoked by a coronavirus called SARS-CoV-2. Since the advent of the first cases of the new coronavirus, our society has been completely changed. Due to the changes, new environmental challenges were imposed, principally due to the considerable growth in using plastic materials in packages and personal protective equipment such as face masks. The impact of plastic during the COVID-19 pandemic was discussed in the present work from the point of view of the environmental science area. Bibliometric analysis and mapping were performed based on Scopus database search results. Emphasis was placed on analyzing the authors' keywords of the publications. The main concern of the research area concerning the use of plastic during the COVID-19 pandemic is the pollution of water bodies by plastic.

1. Introduction

Plastic plays a vital role in our modern society. However, its frequent trivialized use and inadequate final disposal make it a villain. Its share of the blame for much of the environmental pollution and aggravated socio-environmental problems cannot be overlooked.

Restrictions on the use of single-use plastics came into effect worldwide until the COVID-19 pandemic began to change the scenario. Plastic in coping with COVID-19 plays an essential role since lots of equipment and devices used to reduce the transmission rate and even to maintain vital functions of patients in hospitals have at least parts made of some type of plastic material, such as respirators, heart and blood pressure monitors, oximeters, among many others, and no less important personal protective equipment (PPE) [1], [2]. However, the same material responsible for saving millions of lives become a villain when by being incorrectly disposed of in the environment, whether due to the poor waste management in cities and/or the lack of knowledge/responsibility of consumers [1], [2].

Bibliometric analysis and mapping have become essential tools to analyze literary data, whether from a given research area or a group of publications. While bibliometric analysis quantitatively analyzes the data of publications (such as sources, affiliations, keywords, etc.), mapping investigates the connections from the data organized in networks [3]. These results can demonstrate trends and gaps, thus helping improve the research and development of a given scientific area.

In the present work, the impact of plastic during the COVID-19 pandemic will be analyzed regarding the literature on the environmental science area through bibliographic analysis and mapping, based on the results of a search in the Scopus database. Emphasis will be placed on analyzing the authors' keywords of the publications.

2. Methods

2.1. Review methodology

A Scopus search was carried out on 26 May 2021 to acquire the bibliographic data inputs using the keywords (COVID-19 OR SARS-CoV-2) AND (plastic* OR polymer*). Reviews and articles in English were considered from the environmental science area.

From Scopus, two files containing the results were obtained, a scopus.csv and a scopus.bib. By using the software programs VOSviewer version 1.6.18 and Bibliometrix (an R-package), bibliometric mapping and analysis were performed, respectively.

3. Results

3.1. Bibliometric mapping and analysis

The Scopus search for (COVID-19 OR SARS-CoV-2) AND (plastic* OR polymer*) of the environmental area resulted in 334 documents, 275 articles and 59 reviews, 118 publications in 2020, and 216 publications in 2021 up to the search date. Table 1 contains the primary information about the data.

Table 1.

General information about the data obtained from Scopus search.

Description	Results
Main information about data
Timespan	2020:2021
Sources	93
Documents	334
Average years from publication	0.35
Average citations per document	11.89
Average citations per year per doc	6.936
References	17,596
Document types
Article	275
Review	59
Document contents
Keywords plus	3709
Authors' keywords	920
Authors
Authors	2460
Author appearances	2686
Authors of single-authored documents	15
Authors of multi-authored documents	2445
Authors' collaboration
Single-authored documents	15
Documents per author	0.136
Authors per document	7.37
Co-authors per documents	8.04
Collaboration index	7.66

The pandemic has changed habits, changed the world economy, and generated suffering in the world population by the loss of their loved ones, in addition to worsening hunger, and unemployment. There is no doubt that the subject is very relevant and current, and many researchers worldwide are not sparing efforts to help in any way. The high number of publications in just over a year, the high number of authors involved, and the high collaboration rate evidence the magnitude of the subject currently.

To facilitate the discussion of the results from Table 1, they will be divided into the following topics: sources, authors, affiliations, countries, publications, and keywords, emphasizing the analysis of the keywords.

3.2. Sources

The five most significant journals, according to the number of publications, are as follow (number of publications in parenthesis): Science of the Total Environment (85), International Journal of Environmental Research and Public Health (54), Indian Journal of Forensic Medicine and Toxicology (11), Environmental Science and Pollution Research (10), and Water Research (8). All journals are recognized internationally for the excellence of published works, providing greater security to authors. However, Science of the Total Environment is the primary choice of environmental science authors to discuss the plastic impacts during the COVID-19 pandemic.

3.3. Authors

The most relevant authors concerning the number of publications are as follows (the number of publications in parenthesis): Li J (8), Kitajima M (6), Ahmed W (5), Bibby K (5), Hu X (5), La Rosa G (5), and Sanchez G (5).

3.4. Affiliations

The five most relevant affiliations, according to the number of publications, are (number of publications in parenthesis) Tehran University of Medical Sciences (15), Ardabil University of Medical Sciences (14), Iran University of Medical Sciences (14), Charituniversittsmedizin Berlin (9), University of Washington (9), Zhejiang University (9), Sapienza University of Rome (8), University of Aveiro (8), Aristotle University of Thessaloniki (7), and University of Catania (7).

3.5. Countries

The country's scientific production is shown in Fig. 1 .

Fig. 1.

Country's scientific production.

Fig. 1 shows the world map showing each country's scientific production on a blue scale. The countries in darker shades of blue are the most productive, and those in gray do not present publications. The ten most productive countries are (number of publications in parenthesis) the USA (226), Italy (153), China (150), India (105), Iran (95), Spain (79), Brazil (57), Australia (54), Canada (42), and Germany (42). The most cited countries are (number of citations in parenthesis): Italy (579), Australia (447), India (435), Spain (298), China (276), the USA (274), Japan (271), Portugal (222), Netherlands (188), and Iran (176). So, Italy seems to be a critical country in the literature about the plastic impact during the COVID-19 pandemic.

These results corroborate the main affiliations since several institutions are from the most productive countries.

3.6. Publications

Table 2 indicates the top 10 GCS publications (global citation score) and the top 10 LCS publications (local citation score). LCS is about the total citations of publications from the Scopus search. Contrariwise, GCS is about the total citations of publications in the Scopus database. The higher the LCS, the more influential the publication is on the plastic impact during the COVID-19 pandemic. The higher the GCS, the more meaningful the publication is in the general literature (it may be from different areas than the plastic impact during the COVID-19 pandemic).

Table 2.

Top 10 LCS and top 10 GCS publications.

Group	Publication	GCS	LCS
Top 10 GCS	Ahmed et al. [4]	316	66
	Randazzo et al. [5]	213	47
	Medema et al. [6]	188	40
	Vellingiri et al. [7]	184	0
	La Rosa et al. [8]	154	45
	Kitajima et al. [9]	140	30
	Di Gennaro et al. [10]	137	3
	Faridi et al. [11]	98	14
	Haramoto et al. [12]	87	29
	Fadare and Okoffo [13]	82	22
Top 10 LCS	Ahmed et al. [4]	316	66
	Randazzo et al. [5]	213	47
	La Rosa et al. [8]	154	45
	Medema et al. [6]	188	40
	Ahmed et al. [14]	80	32
	Kitajima et al. [9]	140	30
	Haramoto et al. [12]	87	29
	Prata et al. [15]	80	26
	Fadare and Okoffo [13]	82	22
	Patrício Silva et al. [16]	67	20

LCS: local citation score, GCS: global citation score.

Most of the top 10 GCS and LCS present concerns about the presence of SARS-CoV-2 in wastewaters and sewages [4], [5], [6], [8], [9], [12], [14], being that the presence of the virus has been confirmed in different countries. Detecting the virus in wastewater is vital since the quantification of SARS-CoV-2 in wastewater allows the ability to monitor the prevalence of infections among the population via wastewater-based epidemiology [4].

Patrício Silva et al. and Prata et al. [15], [16] discuss the repercussions of the use and management of plastics during the COVID-19 pandemic. Fadare and Okoffo [13] depict face masks' potential source of microplastics in the environment.

3.7. Keywords

The in-deep analysis of the authors' keywords is indispensable to determining the research trend (or hotspots). Provides an overview of the research area of plastic impact during the COVID-19 pandemic from the point of view of the environmental science area.

Among the 920 authors' keywords (Table 1), the ten most popular ones are as follows (number of occurrences in parenthesis): COVID-19 (190), SARS-CoV-2 (129), coronavirus (44), wastewater (26), pandemic (18), wastewater-based epidemiology (17), sewage (13), waste management (13), plastic pollution (11), and plastic waste (9). These most frequent authors' keywords represent the trends in the literature about plastic effects during the COVID-19 pandemic (up to the research date).

Fig. 2a presents the word cloud containing the most frequent 50 authors' keywords in the analyzed publications. Fig. 2b shows the co-occurrence of the 31 principal authors' keywords, with a minimum number of occurrences of 5.

Fig. 2.

(a) Word cloud containing the 50 most popular authors' keywords. (b) Co-occurrence of the 31 principal authors' keywords, with the minimum number of occurrences of 5.

In the word cloud, the keywords' frequency or popularity is shown by the letters' size. In the sequence, the current scenario of the research area will be briefly described.

Some single-use plastic items, such as cutlery and cups, were banned in many regions. However, due to the importance of these items, during the pandemic their use was allowed again in many places, trying to reduce the virus transmission. Many of these items have water bodies as their final destination, and due to degrading processes, they become microplastic over the years, polluting the environment.

It is known that microplastics are ubiquitous, and humans are exposed to them. Literature has depicted several risks to human health due to exposure to microplastics, mainly inflammation [17], [18], [19], [20], [21], [22], [23], [24], [25], [26], [27], [28], [29], [30]. Recently, some authors revealed a correlation between fecal microplastics and inflammatory bowel disease [31].

Microplastics can absorb contaminants and release contaminants present in the plastic formulation itself. They are also pollutant carriers [32] and can thus contaminate animals and humans (even COVID-19) as a source of transferring epidemic diseases [33]. Current research associated aerosol transmission of COVID-19 with the levels of microplastics in the air [34].

To reduce the transmission of the virus, the use of face masks has become mandatory worldwide. The improper disposal of these PPEs used to save lives contaminates water bodies. Face mask is a powerful source of microplastics released into the environment [13], [35]. In addition to releasing microplastics, they can release other contaminants such as iron, copper, aluminum, zinc, barry, and manganese [36].

Several devices used to save lives in hospitals are made of plastic. As an important example, disposable breathing apparatus is made of poly(ethylene terephthalate) (PET) [37]. Huge amounts of medical plastic waste have been produced every day, turning into a major challenge imposed by the COVID-19 pandemic. Pyrolysis is an effective technique to degrade contaminated medical waste [38].

During the COVID-19 pandemic, plastic pollution worsened mainly due to the increase in the packages and use of PPEs made of plastic. Because of the restrictions imposed, online purchases and by app significantly increased, resulting in more packages. Additionally, the recycling sector in several cities was closed, which evidenced the fragility of waste management systems [1]. Waste management in cities was tested [39], evidencing critical problems.

The stability of SARS-CoV-2 on surfaces and in aerosols was verified by Van Doremalen et al. [40]. In plastic (polypropylene), the virus was stable for up to 72 h. Thus, this result warns that it is necessary to disinfect surfaces to avoid contamination via fomite [1]. For example, some authors observed that during an exchange of banknotes, SARS-CoV-2 virus transmission could happen [41]. So, using the correct agents, the constant disinfection is essential for health care [42].

Another significant point, the detection of viruses, such as SARS-CoV-2, through surveillance of wastewaters [43] and sewages [44] has extreme relevance. Polo et al. [43] noticed SARS-CoV-2 RNA in the marine environment. Some authors used RT-qPCR (reverse transcription-quantitative polymerase chain reaction) to quantify SARS-CoV-2 [45], [46].

So, in a few words, the word cloud evidences the problems that plastic may cause, such as plastic pollution and microplastics. Also, some devices made of plastic may worsen socio-environmental problems, such as personal protective equipment, PPE, single-use plastic, RT-PCR and RT-QPCR (COVID-19 tests), and face masks. Plastic pollution is a severe task that results in several consequences to fauna, flora, and human health, being the central concern of the environmental science area.

In Fig. 2b, the number of occurrences is equivalent to the size of the letters and the frames. There seems to be a balanced frequency between all keywords, except for 'SARS-CoV-2′ and 'COVID-19′.

Lines denote the most robust co-occurrences. Among the analyzed keywords, the most robust co-occurrences seem to be between 'SARS-CoV-2′, 'wastewater', and 'wastewater-based epidemiology', and 'COVID-19′, 'plastic pollution', and 'waste management'.

Concerning the clusters, six clusters, each with a different color and dealing with a different subject, can be observed. Each cluster describes a strand in the literature about plastic effects during the COVID-19 pandemic.

Cluster one is the biggest one, containing 13 keywords ('coronavirus', 'COVID-19′, 'COVID-19 pandemic', 'face masks', 'medical waste', 'microplastics', 'plastic', 'plastic pollution', 'plastic waste', 'pollution', 'public health', 'solid waste', and 'waste management). This cluster deals with the protection provided by plastic (e.g. face masks) against the virus, and the consequences when it is improperly disposed of (plastic pollution). Cluster two deals with wastewater-based epidemiology and contains six keywords ('epidemiology', 'pneumonia', 'RT-PCR', 'sewage', 'surveillance', and 'wastewater-based epidemiology'). Cluster three concerns virus concentration in wastewater, containing six keywords ('RT-QPCR', 'SARS-CoV-2′, 'virus', 'virus concentration', 'wastewater', and 'wastewater-based epidemiology'). Cluster four is about transmission, and contains four keywords ('disinfection', 'environment', 'pandemic', and 'transmission'). Cluster five concerns the healthcare workers, containing only the keyword 'healthcare workers'. And cluster six deals with environmental surveillance, containing only the keyword 'environmental surveillance'.

Distances between the keywords represent the connection in terms of co-occurrence links. So, there is a closer connection between the keywords 'environment', 'solid waste', 'plastic waste', 'medical waste', and 'waste management'. This straight connection depicts that managing waste, especially plastic waste, is essential to avoiding the environmental problems that plastic may cause.

It is interesting to be noticed the authors' keywords that co-occur with the keyword 'face masks': 'coronavirus', 'COVID-19′, and 'waste management'. There is a small distance between the keywords 'face masks' and 'waste management', which means a strong relatedness. This distance is considerably smaller than the distances between the keywords 'coronavirus'-'face masks' and 'COVID-19′-'face masks'. This means that, in the environmental science area, waste management of face masks has a higher priority than protection against the disease. Another important observation is that the keyword 'face masks' does not co-occur in publications with the keyword 'microplastics'. This demonstrates that, probably to the search date in the Scopus database, the literature has not yet addressed face masks as sources of microplastics in the environment with intensity. Nevertheless, as aforementioned, literature has proven that they are powerful sources producing microplastics, when face masks are improperly disposed of [13], [35].

The basis for cluster analysis is the frequency of two keywords occurring together. Measurable techniques are used to break down the complicated keyword association into a small number of relative groups [47]. The conceptual structure map of the keywords according to the multiple correspondence analysis (MCA) method is shown in Fig. 3 .

Fig. 3.

Conceptual structure map of the keywords based on the MCA method.

The MCA approach compresses large amounts of data with several variables into a two- or three-dimensional structure, where the plane distance shows how similar the keywords are to one another. The proximity of the keyword to the cluster's focal point indicates its significance, whereas narrow topics are close to the cluster's edge [48].

In Fig. 3, the clusters of red and blue are observed. Both are related to pollution caused by plastic, directly or indirectly. It seems that the blue cluster is more directly associated with the contamination that plastic can cause to the environment due to the presence of the keywords 'plastic waste', 'single-use plastic', 'PPE', and 'pollution'. Regardless, this cluster does not have keywords close to the center point but on the edges, which means that these keywords are transitions to different themes. This can be proven by the proximity of some keywords from the two clusters, such as 'transmission' and 'virus' (edge of the red cluster), and 'PPE' and 'personal protective equipment (PPE)' (edge of the red cluster).

In the red cluster, some keywords close to the central point are 'coronavirus', 'pandemic', 'COVID-19′, 'microplastics', and 'pyrolysis' (among others), showing to be themes that receive singular attention currently. It is important to observe the proximity among the keywords 'microplastics', 'plastic pollution', and 'personal protective equipment (PPE)', indicating a direct connection among them. It is known that face masks, PPEs largely used to avoid transmission, are a potential source of microplastics in the environment when incorrectly disposed of [13], [35]. Additionally, regarding the proximity of the keywords, some connections can be observed, according to the clusters aforementioned in Fig. 2b.

Fig. 4a presents the factorial map of the most cited publications, and Fig. 4b is the factorial map of the publications with the most elevated contribution.

Fig. 4.

(a) Factorial map of the most cited publications. (b) Factorial map of the publications with the most elevated contribution.

The most cited documents concerning the red cluster are La Rosa et al. [8], Kitajima et al. [9], and Di Gennaro et al. [10]. In the same cluster, the publications with the highest contribution are Hoseinzadeh et al. [49], Torres and De-la-Torre [39], Haque et al. [50], Filimonau [51], and Ardusso et al. [52], all of them discussing the use of plastic and waste management during the COVID-19 pandemic.

It is interesting to be noticed that the most cited publications are closer to the center point than the publications with the highest contribution, depicting that plastic management is a significant concern to the environmental science during the COVID-19 pandemic.

Concerning the most relevant and cited publications of the blue cluster, Biblimetrix did not provide results. However, restricting the results obtained by Scopus with the keywords present in the blue cluster (Fig. 3), the most pertinent publications of the cluster could be observed (according to Scopus), namely: Wiktorczyk-Kapischke et al. [53], Kitajima et al. [9], Wong et al. [54], Yarahmadi et al. [55], and Kenarkoohi et al. [56], all of them discussing different transmission and spreading routes of the SARS-CoV-2. And the five most cited publications are Kitajima et al. [9], Faridi et al. [11], Fadare and Okoffo [13], Prata et al. [15], and Patrício Silva et al. [16] (three of them discussing the management of plastic during the COVID-19 pandemic).

In summarizing, through the analysis of the keywords, it is evident the concern of the literature on environmental science regarding the problem of post-used plastic that is being aggravated during the COVID-19 pandemic. It seems that face mask is the cause of more significant concern. It is known that testing and using PPEs are essential, as well as vaccination and single-use plastics. Furthermore, as aforementioned, it is known that the restrictions generated by the pandemic resulted in a significant increase in online and app purchases, which also increased the amount of packaging [1]. All the factors mentioned, among many others, produce a considerable increase in plastic residues.

Recycling was also hampered by the risk of contamination in cooperatives, demonstrating the fragility of waste management in many countries, resulting in expanded inadequate disposal of waste, aggravating environmental impacts and socio-environmental problems, and significantly increasing the pollution of water bodies.

Effective waste management and the circular economy are necessary to lessen the socio-environmental issues that plastic may cause, but perhaps most critical is the commitment of consumers, businesses, and the government to act in an integrated manner [57]. The environmental issues brought on by plastic and its management are shared by all sectors [1].

4. Conclusions

In the present work, the impact of plastic during the COVID-19 pandemic was discussed based on the point of view of the environmental science area. The results from a Scopus database search from the keywords (COVID-19 OR SARS-CoV-2) AND (plastic* OR polymer*) were imported to a .csv and a .bib files and analyzed and mapped by using the Bibliometrix R-package and VOSviewer software programs, respectively. The search resulted in 334 publications in English (275 articles and 59 reviews), 118 publications in 2020, and 216 publications in 2021 up to the search date.

In the scenario, Italy is important since it is the second most productive country and the first most referenced. Some of the primary affiliations in the area are from Italy as well. Science of the Total Environment is the journal with the highest number of publications, and Li J is the most productive author.

Ahmed et al. [4] and Randazzo et al. [5] are the publications with the highest local citation scores (LCS) and global citation score (GCS), being fundamental publications concerning the impact of plastic/polymer during the COVID-19 pandemic in the environmental science area.

Focusing on the analysis of the authors' keywords from the environmental science area, it was possible to observe the main concerns from the area concerning the impact of plastic during the COVID-19 pandemic. The use of plastic increased dramatically due to applications in the medical area, the use of personal protective equipment made of plastic, and the increase in the production of packages. All these applications result in a massive increase in the residues produced, which, when incorrectly disposed of, aggravate some known socio-environmental problems, such as the pollution of water bodies by plastic. This concern was observed, and some others regarding wastewater, sewage, the transmission of the virus, and COVID-19 itself.

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Data availability

Data will be made available on request.