Personal protective equipment (PPE) pollution driven by the COVID-19 pandemic along the shoreline of Lake Tana, Bahir Dar, Ethiopia.

Personal protective equipment (PPE) pollution has become one of the most pending environmental challenges resulting from the pandemic. While various studies investigated PPE pollution in the marine environment, freshwater bodies have been largely overlooked. In the present study, PPE monitoring was carried out in the vicinity of Lake Tana, the largest lake in Ethiopia. PPE density, types, and chemical composition (FTIR spectroscopy) were reported. A total of 221 PPEs were identified with a density ranging from 1.22 × 10-5 PPE m-2 (control site S1) to 2.88× 10-4 PPE m-2 with a mean density of 1.54 × 10-4 ± 2.58 × 10-5 PPE m-2. Mismanaged PPE waste was found in all the sampling sites, mostly consisting of surgical face masks (93.7%). Statistical analyzes revealed significantly higher PPE densities in sites where several recreational, touristic, and commercial activities take place, thus, revealing the main sources of PPE pollution. Furthermore, polypropylene and polyester fabrics were identified as the main components of surgical and reusable cloth masks, respectively. Given the hazard that PPEs represent to aquatic biota (e.g., entanglement, ingestion) and their ability to release microplastics (MPs), it is necessary to implement sufficient solid waste management plans and infrastructure where lake activities take place. Additionally, local authorities must promote and ensure sustainable tourism in order to maintain the ecosystems in Lake Tana. Prospective research priorities regarding the colonization and degradation of PPE, as well as the release of toxic chemicals, were identified and discussed.

Introduction

Plastic wastes in aquatic environments are a global environmental challenge. Global plastic production reached 368 million metric tons in 2019 and is expected to increase continuously (PlasticEurope, 2020). More recently, starting from the outbreak of the novel coronavirus disease (COVID-19) (Xu et al., 2020), another type of plastics started entering the environment in large amounts (Alfonso et al., 2021). This type of plastic pollution is driven by the use of personal protective equipment (PPE), such as face masks, gloves, hazmat suits, among others (Ammendolia et al., 2021). PPEs are largely used to prevent the transmission of the virus and their use is enforced in most countries (Siam et al., 2020). Due to the unprecedented nature of the ongoing COVID-19 pandemic, solid waste management practices and infrastructure around the world lacked sufficient capacity and strategies to treat and promote the correct disposal of PPEs (Haque et al., 2021; Patrício Silva et al., 2021), thus resulting in PPEs littering the streets (Akarsu et al., 2021; Ammendolia et al., 2021; Fadare and Okoffo, 2020), canals (Aragaw, 2020), coastal sites (Ben-Haddad et al., 2021; De-la-Torre et al., 2021a; De-la-Torre et al., 2022; Mghili et al., 2021; Rakib et al., 2021), and terrestrial environments (Kwak and An, 2021) in multiple countries. Most PPEs are made of various synthetic non-degradable polymers (Aragaw, 2020; Fadare and Okoffo, 2020). For instance, PPEs found contaminating beaches from Argentina were analyzed and determined to consist mainly from polypropylene (PP) layers and polyethylene terephthalate (PET) elastic cords (single-use surgical mask), polyester-cotton layer, and polyamide (PA) elastic cords (reusable mask), and latex (glove) (De-la-Torre et al., 2022). These types of materials do not degrade rapidly regardless of the environmental conditions (Min et al., 2020), and are likely to break into smaller pieces (Mateos-Cárdenas et al., 2020; Tziourrou et al., 2021).

Plastics can severely impact the wellbeing of marine and terrestrial biota (Miranda-Urbina et al., 2015). Among the observed causes, the entanglement of marine fauna, such as turtles and seabirds have been reported (Thiel et al., 2018), as well as ingestion of plastic debris (Kühn and van Franeker, 2020). Moreover, plastics may serve as a substrate for marine invertebrates to proliferate and inhabit (De-la-Torre et al., 2021a), which has been discussed as a potential source of alien invasive species (Rech et al., 2018). Furthermore, fragmented plastics, known as meso-, micro-, and nanoplastics depending on their size (25–5 mm, 4.99 mm – 1 μm, and < 1 μm, respectively) (Shim et al., 2018), are ubiquitous in the environment. These contaminants have been found at every environmental compartment, including freshwater and marine waters (Forero-López et al., 2021; Forero López et al., 2021; Su et al., 2016; Wang et al., 2019), sediments (Erni-Cassola et al., 2019; Torres and De-la-Torre, 2021a; Wessel et al., 2016), soils (Dioses-Salinas et al., 2020; Kumar et al., 2020), atmosphere (Akhbarizadeh et al., 2021a; Llorca et al., 2021), and the highest points on Earth, such as Mt. Everest (Napper et al., 2020). Due to their small size and distribution, microplastics (MPs) and nanoplastics (NPs) are prone to be ingested by a wide range of organisms, potentially causing chronic ecotoxicological effects (Aragaw and Mekonnen, 2021). While most plastic and MP studies focused on the various compartments of the marine environment, investigations carried out in freshwater bodies have expanded significantly in recent years (Talbot and Chang, 2022). Freshwater bodies, such as rivers, lakes, and lagoons, display different types of hydrodynamics compared to the marine environment and may act as transport pathways for litter to reach the oceans (Cai et al., 2021). For this reason, freshwater bodies play an important role in the litter dynamics across aquatic systems.

The studies surveying litter in aquatic environments mostly categorized a wide range of materials and types of litter (e.g., plastics, metals, ceramics, etc.) (Ribeiro et al., 2021a, Ribeiro et al., 2021b). Other studies focused on a single type of litter. For instance, the abundance of cigarette butts in touristic beaches has been investigated due to the potential release of highly toxic chemicals, such as heavy metals, aliphatic and unsaturated hydrocarbons, polycyclic aromatic hydrocarbons, among others (Asensio-Montesinos et al., 2021; Soleimani et al., 2022). In the case of PPE, the most recent studies focused solely on this type of litter due to its unique characteristics (e.g., structure, components, and release of contaminants) (Kutralam-Muniasamy et al., 2022; Sullivan et al., 2021) and unprecedented occurrence (Cordova et al., 2021). To this end, it is important to focus on this new type of plastic contaminant while providing in-depth details concerning its characteristics and risks.

Surgical face masks have been regarded as a significant source of MPs in experiments under controlled conditions (Morgana et al., 2021; Saliu et al., 2021). In this sense, monitoring the occurrence of PPEs in coastal sites is essential (De-la-Torre and Aragaw, 2021). PPE monitoring has been extensively carried out in the marine environment and coastal sites. For instance, mean PPE density along the coast of Chile, Peru, and Argentina have been reported as 6.00 × 10−3, 7.21 × 10−4, and 6.60 × 10−4 PPE m−2, respectively (De-la-Torre et al., 2022; Thiel et al., 2021). In Morocco, mean PPE density reached 1.13 × 10−5 PPE m−2 in Agadir (Ben-Haddad et al., 2021) and 1.20 × 10−3 in Teouan (Mghili et al., 2021). In most cases, single-use surgical face masks are the most common type of PPE waste. The general methodology applied in the studies aforementioned indicates that the PPE densities reported are representative of the total number of PPE per total beach area, which has been applied to compare beaches characterized by specific activities, such as fisheries, recreational, or touristic activities. While recent studies focused on beaches and coastal areas, inland waters, such as lakes and lagoons, have been largely understudied. Ethiopia is a landlocked country, where the main fishing activities are carried out in inland water. Lake Tana, the largest lake in Ethiopia, has been subject to rapid urbanization leading to the affectation of its natural habitats (McCann and Blanc, 2016). Solid waste management in Bahir Dar, the main city located south of Lake Tana, executes basic strategies consisting of collection, gathering, and disposal in landfills. In the coastal areas of Lake Tana, a few dumpsters are found various meters away from the beach area but these may not be sufficient to properly gather the waste generated. A recent macro-debris survey along the shores of Lake Tana revealed litter accumulation rates ranging from 4.9 and 30.5 items m−1 day−1, mainly composed of plastics (Aragaw, 2021). Given the face mask use mandates imposed by the government as a key measure to control the spread of the pandemic, as well as the lack of sufficient solid waste infrastructure, it is likely that PPE contributes to the accumulation of litter after public places and fishing activities reopened. The objective of the present study was to report the abundance, characteristics, and chemical characterization of PPEs found along the coast of Lake Tana, Bahir Dar, Ethiopia. Standardized litter monitoring protocols were carried out from April to June 2021 in 9 sampling locations along the coast of Bahir Dar. To the best of our knowledge, the is the first PPE monitoring study carried out in a lake, thus providing valuable information concerning the extent of PPE pollution in freshwater bodies and the threat it represents to aquatic biota.

Materials and methods

Area of study

Bahir Dar metropolis (the capital city of Amhara national regional state, Ethiopia) is located in the Northwest of Addis Ababa (Fig. 1 ), with a growing population of about 308,877 as of 2017 (Belachew, 2019). It is home to the biggest Lake in Ethiopia and is located at the exit of the Abbay river from Lake Tana. Lake Tana is home to more than 60 species of fish, out of which around 70% are endemic (UNESCO, 2014). It is one of the most touristic cities in the country and was awarded the UNESCO Cities for Peace Prize for addressing the challenges of rapid urbanization (UNESCO, 2002). Being an important touristic destination and rapidly urbanized site, the Bahir Dar shore of Lake Tana is under significant anthropogenic pressure leading to environmental deterioration (Aragaw, 2021). In particular, activities such as tourism, industrialization, fishing, among others are major sources of plastic pollution. Moreover, poor solid waste management practices may exacerbate the leakage of plastics into Lake Tana during the pandemic.

Fig. 1

Map displaying the sampling sites. Yellow dots indicate the sampling points.

PPE monitoring

PPE monitoring was carried out in nine sites along the shoreline of Lake Tana, Bahir Dar city (Fig. 1). These sites were selected because various fishing and recreational activities take place (Table 1 ), which gather a significant number of workers and beachgoers wearing different types of PPE. Moreover, this is the first litter survey focusing on PPE in Lake Tana. The selected sites were assumed to be representative and were assigned based on their popularity and preliminary trip observations. To confirm the influence of the activities carried out as the main drivers of PPE into coastal areas, a control site (S1) where no activity is carried out, was monitored. On the other hand, in sites S4, S5, S7, and S9 occasional beach cleanings (not scheduled) are carried out by the public or municipality; potentially influencing PPE accumulation. In order to sample PPEs in each site, the methodology developed by De-la-Torre et al. (2021a) was adapted. In brief, several transects were established covering the entirety of the sidewalk in the vicinity of the lake. Each transect was separated by 8–10 m parallel to each other and extended about 150 m in length. The sidewalks consisted of a muddy or rocky substrate. PPEs were visually identified by walking along each transect. The number and length of transects varied according to the size and topography of the shoreline. The area covered along with the coordinates of each site is listed in Table S1. Each PPE was reported, photographed, and classified as a surgical mask, reusable cloth mask, or gloves based on the observations made on preliminary surveys. No respirators (e.g., KN95) and only nitrile gloves were found. A total of 9 sampling sites were surveyed for 12 consecutive weeks starting from the first of April 2021 to the end of June 2021. The PPEs density was calculated using Eq. (1) (Okuku et al., 2021).where C is the density of PPE per m2, n is the number of PPEs enumerated, and a is the surveyed area.

Table 1

Summary of the main activities and area covered in each site. Recreational activities encompass mainly sunbathing, swimming, and other activities carried out in the beach area. Exercising mainly refers to jogging or walking.

Site code	Site name	Activities	Area covered
S1	Control	No activity	13,650 m2
S2	Tana Hotel	Tourism (hotels) and exercising	10,560m2
S3	Moon light recreational	Recreational and exercising	14,940 m2
S4	Lakeshore resort	Recreational	11,070 m2
S5	Marine authority boat & ferry launch	Recreational and boating	15,360 m2
S6	Hidar 11 recreation	Recreational	14,300 m2
S7	Dessert lodge	Recreational	14,175 m2
S8	Keste demean fish house	Fishing	12,075 m2
S9	Shimela lodge	Recreational	13,720 m2

FTIR analysis

In order to provide preliminary information concerning the polymer composition and chemical degradation of the two main types of face masks used, one surgical (3-ply surgical mask) and one reusable (single-layer cloth/fabric mask) face mask were collected from the field for further analysis. The brand or manufacturer of the recovered masks was not shown on the fabric/material, thus was undetermined. The three layers that comprised the surgical face mask were separated and analyzed independently by Fourier transformed infrared (FTIR) spectroscopy (JASCO-6600 spectrometer) to understand if degradation occurs differently in the face mask layers. Similarly, one layer of the reusable cloth mask was analyzed. Additionally, unused face masks were analyzed for comparison. The scanning range was 400–4000 cm−1 at the default number of spectral scans and resolution. Each sample was washed with distilled water and over-dried at ~45 °C.

Statistical analysis

The results were expressed in terms of PPE density (PPE m−2 ± standard error of the mean) and accumulation rate (items day−1). The accumulation rate was estimated by dividing the total number of PPE counts per beach per sampling week by 7 (Ammendolia et al., 2021). To compare PPE density among sampling sites, each sampling campaign was treated as a repetition (n = 12). The Kolmogorov–Smirnov test invalidated the assumption of normality of the datasets. Hence, the nonparametric Kruskal-Wallis test was conducted, followed by Dunn's multiple comparisons test. The level of significance was set to 0.05. All the statistical analyses and graphs were performed in GraphPad Prism (version 8.4.3 for Windows).

Results and discussion

A total of 221 PPEs were identified in the 12 consecutive weeks of sampling surveys. As expected, surgical face masks were the most abundant type of PPE (93.7%), followed by reusable masks (4.5%), and gloves (1.8%) (Fig. 2b) (some examples are displayed in Fig. 2a). These results are similar to those from coastal sites from Peru (87.7% face masks) (De-la-Torre et al., 2021a), Morocco (96.8–100% face masks) (Ben-Haddad et al., 2021; Mghili et al., 2021), and Bangladesh (97.8% face masks) (Rakib et al., 2021). However, in Argentina, the number of face masks was equal to the number of gloves (48.8% each) (De-la-Torre et al., 2022). The previous studies were conducted in different timeframes. For instance, the first study in Peru, conducted by the end of 2020, reported diverse PPEs, such as face shields (6.5%), gloves (4.3%), and others (1.5%) (De-la-Torre et al., 2021a). However, a later study carried out between March and July of 2021 indicated a lower proportion of face shields (2.9%) and gloves (2.0%) (De-la-Torre et al., 2022). In Morocco, the studies from Agadir and Tetouan were carried out in similar timeframes but reported different PPE diversity, namely 100% face masks in Teouan and 96.8% face masks, and 2.8% face shields in Agadir (Ben-Haddad et al., 2021; Mghili et al., 2021). These studies suggest that the preference of certain types of PPEs is dependent on the population's behavior and perception of safety, which could change as the measures taken against the pandemic (e.g., vaccination rates) progresses. In Ethiopia, the government mandated and enforced the use of face masks in shore areas shortly after the pandemic was declared as such. However, by the time the surveys were conducted, the face mask mandates were already halted. Thus, the population may be wearing face masks strictly based on perception or safety, although the Ministry of Health publicly recommends face mask-wearing.

Fig. 2

a) Photographs of surgical and reusable masks and gloves. b) Proportion of each type of PPE. c) Graph indicating the mean accumulation rates in all sampling sites per sampling week. Error bars indicate the standard error of the mean.

The mean accumulation rates ranged from 0.023 PPE day−1 (S1) to 0.630 PPE day−1 (S5) and an overall mean of 0.292 PPE day−1. These values are several orders of magnitude lower than those reported by Ammendolia et al. (2021) from the metropolitan city of Toronto, Canada (ranging from 1.8 to 16 items day−1). However, the latter study was conducted earlier during the pandemic (May – Jun. 2020) and, unlike coastal areas, different sources of PPE were identified (e.g., hospitals, residential areas, stores, etc.). However, none of the studies summarized in Table 2 calculated accumulation rates. Concerning time variability, the first sampling campaign (week 1) showed the highest number of PPEs identified in total and then almost sustainably declined. This is probably because many PPEs that were already accumulating in the sampled sites were removed and recorded in week 1. Regardless, the later weeks showed an obvious decline in the number of PPEs found, which is shown in terms of accumulation rate in Fig. 2c. Despite various sites (e.g., S4, S5, S7, and S9) being regarded as popular touristic destinations, no particular event, gathering, or show/presentation that could have led to an unusual influx of PPE was conducted while the sampling lasted. Conversely, it is possible that unscheduled beach cleaning initiatives occurred between sampling days. The lowest total number of PPEs was recorded in the last three sampling campaigns. Contrary to our results, De-la-Torre et al. (2021c) reported a continuous increase of PPEs on the beach of Peru. Time variability may be subject to seasonal changes, including opening/closure of public places, reactivation of local tourism, and waste management measures. Although Lake Tana is an inland freshwater body, unlike previous studies, the activities carried out are similar to those in marine coastal sites worldwide.

Table 2

Results summary of PPE monitoring studies in coastal sites around the world.

Country	Sampling dates	Mean PPE density (PPE m−2)	Total number of PPE	Most abundant type of PPE	Reference
Morocco	Feb. – May 2021	1.13 × 10−5	689	Face masks	Ben-Haddad et al. (2021)
Morocco	Feb. – Jun. 2021	1.20 × 10−3	321	Face masks	Mghili et al. (2021)
Iran	Nov. – Dec. 2020	1.72 × 10−2	2382	Face masks	Akhbarizadeh et al. (2021b)
Bangladesh	Nov. 2020 – Jan. 2021	3.16 × 10−4	29,254	Face masks	Rakib et al. (2021)
Argentina	Mar. – Jul. 2021	7.21 × 10−4	43	Face masks & gloves	De-la-Torre et al. (2022)
Peru		6.60 × 10−4	489	Face masks
Peru	Sep. – Dec. 2020	6.42 × 10−5	138	Face masks	De-la-Torre et al. (2021c)
Chile	Dec. 2020	6.00 × 10−3	17	Face masks	Thiel et al. (2021)
Ethiopia	Apr. – Jun. 2021	1.54 × 10−4	221	Face masks	This study

PPE density ranged from 1.22 × 10−5 PPE m−2 (control site S1) to 2.88× 10−4 PPE m−2 (S5) with a mean density of 1.54 × 10−4 ± 2.58 × 10−5 PPE m−2. Individual results in each sampling week and site are shown in Table S2. As displayed in Table 2, the density results in the present study are of similar orders of magnitudes to those carried out in marine coastal sites. This is probably due to the similarities in terms of activities carried out in Lake Tana, including touristic, recreational, sports, and fishing activities (specified in Table S1). Previous reports indicated a notorious influence of the type of activity on the mean PPE density. For instance, recreational activities (sunbathing, swimming, etc.) in Cox's Bazar beach (Bangladesh) and Lima (Peru) were significantly more contaminated than in fishing sites (De-la-Torre et al., 2021a; Rakib et al., 2021). In the sites selected for the present study, activities such as sports (e.g., jogging, walking), tourism, recreation, sailing, and fishing are notorious. However, because various sites share multiple activities that are possible sources of PPE pollution, these were not compared statistically.

The results from the Kruskal-Wallis test indicated significant differences (Chi-square = 33.9, p < 0.0001) in the PPE density across sampling sites. The Dunn's multiple comparison test indicated that S1 (control site) differed significantly (p < 0.05) from S2, S4, S5, S7, and S9 (Fig. 3 ). No other site differed significantly from each other, which supports the hypothesis that the multiple activities carried out (e.g., sports, commercial, touristic, recreational, etc.) in the vicinity of the lake are the main drivers of PPE pollution. Likewise, PPE density was significantly higher in beaches where recreational and sports activities take place than in control sites from Peru and Morocco (Ben-Haddad et al., 2021; De-la-Torre et al., 2021a). These results suggest the necessity to implement improved solid waste collection and disposal plans and infrastructure in touristic and popular sites.

Fig. 3

Boxplot and individual values of PPE density in each sampling site. Letters indicate significant differences (Dunn's multiple comparisons test; p < 0.05).

Two types of face masks, surgical and reusable, were analyzed by FTIR spectroscopy. The three layers of the surgical masks showed typical PP bands (Fig. 4a, b) at around 2950, 2915, 2838 cm−1 assigned to C—H stretch, 1455 cm−1 assigned to CH2 bend, 1377 cm−1 assigned to CH3 bend, 1166 cm−1 assigned to CH bend, CH3 rock, and C—C stretch, and other smaller peaks (Jung et al., 2018). In the case of the reusable cloth mask, the occurrence of a strong peak at around 1715 cm−1 (Fig. 4c) is likely due to the stretching of carbonyl groups (Neves et al., 2015), as well as bands at around 2970 and 3430 cm−1 probably associated with C—H stretch and O—H bonded to CO group (Parvinzadeh and Ebrahimi, 2011), suggesting that the mask is made of polyester fabric. Typically, surgical face masks recovered from the environment are composed of PP-based fiber layers (Aragaw, 2020; Fadare and Okoffo, 2020). A reusable cloth mask recovered from a beach in Peru also showed a distinctive polyester fabric FTIR spectra, although a similar mask from Argentina was composed of 60% cotton and 40% polyester blend (De-la-Torre et al., 2022). Hence, the specific composition of reusable face masks is dependent on the manufacturer. Regardless, is it safe to assume that most reusable cloth masks may be entirely or partially composed of polyester fabric as it is the most commonly used fiber worldwide.

Fig. 4

Photograph and FTIR spectra of the inner, middle, and outer layers of new (a) and discarded (b) surgical face masks, and reusable cloth masks (c).

The FTIR spectra of the recovered masks were compared to that of identical unused face masks. No significant changes can be observed in the FTIR spectra from the three PP layers in discarded and unused surgical masks. Under natural weathering conditions (e.g., exposure to UV radiation from the sun), polyolefin polymers exhibit chain scission, leading to the formation of O-containing functional groups. These changes generally result in the occurrence of additional FTIR bands around 3400 and 1650–1850 cm−1 (Ainali et al., 2021). However, these additional peaks are not observed in the FTIR spectra from the surgical masks recovered from the environment. This is probably because the analyzed face masks were not exposed sufficiently to environmental weathering, although the exact time is unknown. In the case of the reusable cloth, several broader and stronger peaks can be observed, including the band around 1715 cm−1 associated with carbonyl groups, which are likely due to natural weathering. While various laboratory studies have evaluated the degradation of surgical face masks under simulated environmental conditions, more realistic studies are largely lacking. Hence, it is imperative that future research assess the physical and chemical changes that different types of face masks (and PPE in general) undergo after entering the environment through in situ studies.

According to Vijverberg et al. (2009), cyprinids are the main fish communities in Lake Tana, such as Labeobarbus spp., Barbus spp., Garra spp., which are endemic to the Lake. Other species are commercially important for local fisheries, such as the Nile tilapia (Oreochromis niloticus), which accounted for 65% of the total annual catch (Degsera et al., 2021). Lake Tana is also home to over 200 species of birds (Worku, 2014), and mammals, like the African clawless otter (Ergete et al., 2018). The species in Lake Tana are part of a complex food web, consisting of species that feed on aquatic vegetation (e.g., Labeobarbus surkis), carnivorous species (e.g., L. crassibarbis), while top predators (e.g., marine birds and mammals) feed on various fish species (Mengistu et al., 2017). Despite its ecological importance, Lake Tana has exhibited biodiversity loss and degradation due to anthropogenic activities (Eneyew and Assefa, 2021). A recent study indicated that plastics were the most abundant type of macro-debris in shorelines of Lake Tana, with estimated accumulation rates ranging from 4.9 to 30.5 items m−1 day−1 (Aragaw, 2021). The raise of PPE pollution in Lake Tana will significantly contribute to litter pollution with relevant environmental impacts. Hiemstra et al. (2021) compiled photographic evidence of the multiple types of PPE-biota interactions, including entrapment, entanglement, and ingestion of face masks or gloves. Likewise, Mghili et al. (2021) reported a marine bird picking up a face mask, which poses a serious entanglement hazard. Furthermore, the presence of a face mask in the stomach of a dead Magellanic penguin (Spheniscus magellanicus) has been found and attributed to its cause of death (Gallo Neto et al., 2021). Given the evident impact that PPEs pose to aquatic biota, investigating the exposure of the most vulnerable species is crucial.

Face masks have been recognized as an important source of MPs (De-la-Torre et al., 2021b), particularly in aquatic environments. For instance, Wang et al., 2021, Wang et al., 2021 estimated that a single surgical face mask could release up to 16 million MPs under simulated environmental conditions (stirring water in the presence of sand and UV-light irradiation). Concerning nanoplastics (NPs), Ma et al. (2021) estimated a release of about 2.43 × 109 MPs (<1 μm) per surgical mask in an aqueous solution after only 3 min of stirring. On the other hand, face masks may leach chemical additives, such as surfactants, dyes, and phthalate esters (Sullivan et al., 2021; Wang et al., 2021a), and heavy metals and metal nanoparticles (Ardusso et al., 2021). Wang et al. (2021a) demonstrated the occurrence of eight phthalate ester compounds, including di-methyl phthalate (DMP), di-ethyl phthalate (DEP), di-n-butyl phthalate (DnBP), di-isobutyl phthalate (DiBP), butylbenzyl phthalate (BBzP), di (2-ethylhexyl) phthalate (DEHP), di-cyclohexyl phthalate (DCHP), and di-n-octyl phthalate (DnOP), mostly accumulated in N95, P1, and P2 type masks. Their study focused on human exposure to these compounds due to the continuous mask usage. However, no previous study has investigated its release in aquatic environments. Ardusso et al. (2021) and De-la-Torre et al. (2022) indicated the occurrence of littered masks containing impregnated metal nanoparticles, such as Ag and Cu nanoparticles. Although these types of materials have not been investigated from an ecotoxicological point of view, recent studies raised environmental concerns regarding paint particles (<5 mm) containing Cu nanoparticle biocides (Torres and De-la-Torre, 2021b). In particular, these types of painting have been reported to cause mortality to sediment-dwelling species at environmentally relevant concentrations, such as Hediste diversicolor (LC50-5d = 19.9 g L−1) and the Common cockle (LC50-5d = 2.3 g L−1) (Muller-Karanassos et al., 2021). These secondary products derived from PPE pollution could represent considerable ecotoxicological effects. For instance, PP face mask-derived microfibers significantly declines the fecundity of the marine copepod Tigriopus japonicus (Sun et al., 2021) and inhibit the reproduction of terrestrial organisms (earthworm and springtail) (Kwak and An, 2021). Phthalate esters, commonly used as plasticizers, alter the soil microbial system and, thus, nitrogen cycling (Zhu et al., 2021) and induce a broad range of sublethal effects in aquatic organisms (Baloyi et al., 2021). While the toxicity of phthalate esters varies depending on the compound and ecotoxicological factors, mortality in model aquatic organisms generally ranges from 1 to 500 mg L−1 (Zhang et al., 2021). However, significantly lower concentrations may induce sublethal effects, particularly regarding the disruption of the reproductive cycle (Lee et al., 2019; Sohn et al., 2016). Ecotoxicological studies of MPs and chemicals derived from widespread PPEs are fairly limited, and more research is needed in this sense to understand the chronic and sublethal effects of PPE secondary contaminants.

The main limitations of the present study are regarding the methodological approach for this specific case. While the meteorological factors were beneficial to avoid the loss or transport of littered PPE through, for example, rain activity, it is plausible that beach cleaning efforts were executed between sampling dates, ultimately reducing the estimated PPE accumulation rates. Similarly, private gatherings or events (drivers of PPE pollution) may have taken place between sampling dates. To avoid this, the sampling frequency must be increased per week to allow researchers to observe social drivers of littered PPE, such as clean-up efforts or gatherings. Concerning the analytical procedures, the present study only provided preliminary data concerning the polymeric composition and state of chemical degradation of two types of face masks. It is necessary to include less investigated types of PPE, such as gloves, as well as increase the number of analyzed PPEs. Spectroscopic analyzes can be accompanied by X-ray crystallography, and scanning electron microscopy coupled to energy dispersive spectroscopy. Combining multiple analytical techniques will offer a better understanding of the chemical and physical degradation of PPEs upon entering the environment and set the groundwork for environmental impact assessments.

Conclusion

PPE pollution driven by the COVID-19 pandemic has raised concerns due to their widespread distribution, effects on biota, and release of contaminants. In the present study, PPE pollution was surveyed for 12 consecutive weeks in 9 sampling locations, considering they are high in commercial activates. The results are comparable to those from marine coastal sites and beaches. The overall PPE density ranged from 1.22 × 10−5 PPE m−2 to 2.88 × 10−4 PPE m−2 and surgical face masks were the most common type of PPE (93.7%). The FTIR analyzes indicated that surgical face masks were mainly composed of PP and reusable face masks of polyester fabric. The abundance of these materials poses entanglement and ingestion hazards to the local lake biota, as well as the release of MPs and chemical additives. It is imperative that local authorities act towards this new type of pollution, which is exacerbating environmental degradation in the already affected freshwater environment, keeping the region state as well as the country economy via touristic. The authorities should establish alternative mitigation options in a long-term plan with waste-to-energy recycling strategies. Further research is needed concerning the release of chemical additives of concern and ecotoxicological implications in order to see the bigger picture regarding the environmental implications of PPE pollution.

CRediT authorship contribution statement

Tadele Assefa Aragaw: Conceptualization, Methodology, Investigation, Writing – original draft, Writing – review & editing, Resources, Data curation, Project administration. Gabriel E. De-la-Torre: Investigation, Writing – original draft, Writing – review & editing, Methodology, Formal analysis. Alebel A. Teshager: Conceptualization, Investigation, Resources, Writing – review & editing.

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.