Plastic microfibers as a risk factor for the health of aquatic organisms: A bibliometric and systematic review of plastic pandemic

Highlights

• State-of-the-art review on the ecotoxicity of plastic microfibers (PMF) on aquatic organisms.

• PMFs as an emerging risk factor for aquatic organisms.

• Fish, Arthropoda and mussels are overrepresented in studies of PMF ecotoxicity.

• Environmental concerns about PMF produced during the pandemic period.

Abstract

Plastic microfibers (PMFs) are emerging pollutants widely distributed in the environment. In the early 2020s, the need for personal protection due to the COVID-19 pandemic led to increased consumption of plastic materials (e.g., facemasks and gloves) and ultimately to increased plastic pollution, especially by PMFs. The PMFs present in the environment may be released in this form (primary particles) or in larger materials, that will release them as a result of environmental conditions. Although a considerable number of studies have been addressing the effects of microplastics, most of them studied round particles, with fewer studies focusing on PMFs. Thus, the current study aimed to summarize and critically discuss the available data concerning the ecotoxicological impact of PMFs on aquatic organisms. Aquatic organisms exposed to PMFs showed accumulation, mainly in the digestive tract, and several toxic effects, such as DNA damage, physiological alterations, digestive damage and even mortality, suggesting that PMFs can pose a risk for the health of aquatic organisms. The PMFs induced toxicity to aquatic invertebrate and vertebrate organisms depends on size, shape, chemical association and composition of fibers. Regarding other size range (nm) of plastic fibers, the literature review highlighted a knowledge gap in terms of the effects of plastic nanofibers on aquatic organisms. There is a knowledge gap in terms of the interaction and modes of action of PMFs associated with other pollutants. In addition, studies addressing effects at different trophic levels as well as the use of other biological models should be considered. Overall, research gaps and recommendations for future research and trends considering the environmental impact of the COVID-19 pandemic are presented.

Introduction

In recent decades, population growth, urban sprawl, increasing consumption, and expansion of industrial activities have caused an increase in environmental pollution by plastics. According to the 2018 United Nations Environment Programme (UNEP) report, the global plastic production has reached more them 400 million tons, with the domestic, industrial, agricultural, and hospital waste significantly contributing to the presence of plastics and their associated chemicals in the environment (Lau et al., 2020; Liu et al., 2021). However, in the early 2020s, the emergence of COVID-19 pandemic, also known as the coronavirus pandemic, considerably increased the need for personal protection measures for the population (e.g., personal protective equipment - PPE, especially facemasks and gloves). It was estimated that >89 million medical masks were used, per month, during the pandemic (World Health Organization, 2020, World Health Organization, 2020). As observed for other single use plastic materials, PPE can become a source of plastics particles in the aquatic environment (Dissanayake et al., 2021; Sullivan et al., 2021). In this sense, it can be assumed that COVID-19 pandemic is also associated with a plastic pandemic, especially for pollution generated by plastic microfibers (PMFs), their waste and fragments (Parashar and Hait, 2021; Shammi et al., 2021; Singh et al., 2020).

Microplastics (MPs) are ubiquitous in the environment, having been found widely distributed in the atmosphere (Abbasi et al., 2019; Can-Güven, 2021), soils (Guo et al., 2020), aquatic systems (Han et al., 2020), even reaching the sediments of Arctic (González-Pleiter et al., 2020; Ross et al., 2021). Among the MPs, PMFs are frequently found in freshwater and drinking water at concentrations that vary ten orders of magnitude (1 to 10⁸ MPF m⁻³) (Koelmans et al., 2022; Wei et al., 2021). However, several challenges associated with isolation and characterization limited the information provided by monitoring studies (e.g., difficulty of isolation particles in the low μm size range, standard authorized protocols to determine MPs and nanoplastics and insufficient data to assess the potential risk). The reported levels vary. For example, 0.7 PMFs m^{− 3} (with a size range distribution between 50 and 150 μm) were reported in rivers, levels between 3 and 46 PMFs m⁻³ were detected in surface waters and drinking water samples, respectively (Koelmans et al., 2022; Mgj, 2018). Concentrations also varied from 0.3 to 8925 PMFs m⁻³ in lakes, from 0.69 to 8.7 × 10⁶ particles m⁻³ in streams and rivers, from 0.16 to 192,000 PMFs m⁻³ in estuaries, and from 0 to 4600 PMFs m⁻³ in the ocean (Arias et al., 2022).

PMFs have been reported as the most commonly detected MPs in the environment aquatic environment, resulting from release during the washing of clothing and fabrics to wastewater systems and ultimately to aquatic systems, as they are not easily retained in wastewater treatment systems (Barrows et al., 2018; Singh et al., 2020). In the aquatic ecosystem, plastics can undergo physical, chemical, and biological transformations, such as photo oxidative, thermal, catalytic, ozone and mechano-chemical and biological degradation (Kukkola et al., 2021; Manzoor et al., 2022, Manzoor et al., 2022). The incomplete degradation of plastics in the aquatic environment generates fragments that gradually turn into smaller pieces, posing a risk to the environment (UNEP, 2015).

The ecotoxicological impact of MPs to aquatic organisms has been extensively reviewed (e.g., Hirt and Body-Malapel (2020), Bucci et al. (2020) and Chang et al. (2020)). An analysis of the available data reveals that, despite the increasing number of studies addressing the effects of MPs, there is a mismatch between MPs found in the environment and those used in ecotoxicology studies (de Sá et al., 2018). Despite the wide distribution of PMFs in the aquatic ecosystem, knowledge about their effects on aquatic biota and their interaction with other environmental contaminants can be considered scarce compared to other types of MPs (Singh et al., 2020). Thus, the current study aimed to summarize and critically discuss the available data concerning the ecotoxicological impact of PMFs on aquatic organisms. Bibliometric parameters (number of papers, geographical distribution, and keyword cluster) and the data concerning the experimental design, species, PMF properties (composition, shape, length, depuration, concentration, and toxicity), and effects on aquatic organisms (e.g., metabolic alterations, tissue damage, developmental alterations) were analyzed and discussed. Furthermore, research gaps were highlighted and recommendations for future research trends, considering the environmental impact of the COVID-19 pandemic, presented.