Sage Journals: Discover world-class research

Abstract

The prevalence of microplastics (MPs) in the environment is an escalating global concern, driven by their increasing abundance and potential adverse effects. Their detrimental environmental consequences and risks to public health necessitate urgent action to mitigate their impacts. To better understand MP accumulation within the environment, estimate their impacts, and develop effective mitigation strategies, it is imperative to advance our knowledge of MPs’ environmental fate and how this fate is linked with plastics’ intrinsic properties. We highlight the current research on MPs’ accumulation within different environmental sinks and identify the critical knowledge gaps in understanding the flux of MPs between these sinks. We also discuss how the intrinsic properties of MPs, including polymeric backbone, structure, chemical additives, crystallinity, molecular weight, and hydrophilicity, influence their environmental behavior and degradation pathways. Among these properties, the polymeric backbone and functional groups serve as primary drivers of MP stability when exposed to external physical and chemical factors, thereby influencing the pathway and rate of MP degradation. Other intrinsic properties and environmental conditions mostly impact the rate of MP degradation. As MPs undergo environmental degradation, changes in their intrinsic characteristics can lead to further fragmentation. This process potentially enhances environmental harm due to the resulting particles’ increased surface area, greater environmental mobility, and higher potential for contaminant transport. These factors collectively contribute to the complex dynamics of MPs’ fate and impact on the environment.

Introduction

Since the 1950s, plastics have been widely used globally owing to their wide range of utility and easy availability. By 2015, the total accumulated global plastic production was estimated to be 8.3 billion metric tons (Geyer et al., 2017). If current trends in plastic production and waste management persist, it is projected that approximately 12.0 billion metric tons of plastic waste will accumulate in the natural environment or landfills by 2050 (Geyer et al., 2017). The durability of plastics that attracts consumers also leads to long-term persistence in aquatic and terrestrial environments, contributing to subsequent human exposure and presenting substantial health risks (Parveen et al., 2022; Vethaak and Legler, 2021). Although the term “plastic” refers to general synthetic polymeric materials of any size, plastic particles smaller than 5 mm, whether originally produced at this size or formed by the fragmentation of larger objects, are typically referred to as microplastics (MPs). They can enter the human body through ingestion (food and drinking water), inhalation (indoor and outdoor), and skin contact (personal care), with potential accumulation in various organs (Sun and Wang, 2023). These particles may cause physical damage to tissues and can leach harmful chemicals such as bisphenols and phthalates or act as carriers for other environmental pollutants (Yang et al., 2022). Some studies suggest MPs could trigger inflammatory responses, disrupt the endocrine system, or alter the gut microbiome (Sofield et al., 2024). However, while these potential impacts are concerning, the long-term effects of MP exposure on human health are still being researched, and more comprehensive studies are needed to fully understand the risks.

Currently, the majority of end-of-life plastics are discarded in landfills or litter the land, water, and air. For example, in the United States, 35.7 million tons of plastic waste were generated in 2018, accounting for 12.2% of municipal solid waste (EPA, 2018). Only a small fraction, approximately 8.7%, or 3 million tons, of waste plastic is recycled. It is difficult to determine how much plastic enters aquatic systems, but Borrelle et al. (2020) estimated that approximately 11% of global plastic waste in 2016 entered aquatic environments. The impacts of MPs on aquatic and terrestrial ecosystems are extensive and potentially severe. In aquatic environments, marine life can ingest MPs, leading to physical harm and reduced feeding. This ingestion can result in the bioaccumulation and biomagnification of MPs and their associated chemical additives throughout marine food webs (Miller et al., 2020). Additionally, MPs pose a significant threat to biodiversity and overall ecosystem functioning in aquatic systems (Corinaldesi et al., 2021). In terrestrial ecosystems, MPs can alter soil structure, affect water retention, and impact soil-dwelling organisms, potentially disrupting nutrient cycles and plant growth (Jazaei et al., 2022; Yu et al., 2022). Both aquatic and terrestrial MPs can serve as habitats for microbial communities, potentially facilitating the spread of pathogens or altering local microbial ecosystems (Galafassi et al., 2021).

As plastics are released into the environment, they may degrade depending on environmental conditions and their intrinsic properties. The degradation of plastics presents a paradoxical phenomenon. Although it ultimately leads to the breakdown of plastic materials, potentially reducing their long-term environmental presence, it also generates smaller plastic fragments that can pose increased risks. These smaller fragments may have greater potential for environmental damage due to their enhanced toxicity and altered mobility (Beheshtimaal et al., 2024; Jeong et al., 2016). The reduced size facilitates their transport across different environmental systems, spreading contamination more widely. Consequently, plastic degradation simultaneously contributes to the eventual elimination of plastics from the environment and creates intermediate products that may pose significant ecological challenges, underscoring the complexity of addressing plastic pollution.

The intrinsic properties of plastic are defined as the fundamental molecular and structural characteristics of a polymer which determine its physicochemical behavior independent of its size or shape. This paper focuses on major intrinsic properties of MPs including polymeric backbone, structure, chemical additives, crystallinity, molecular weight, and hydrophilicity. Understanding this interrelation could assist plastic manufacturers in designing more environmentally friendly materials and help policymakers develop more effective waste management regulations.

Recent review articles on MPs have primarily covered their sources and distribution across various media (e.g., food, air, marine environments, freshwater, drinking water, wastewater, soil) (Koutnik et al., 2021; Padha et al., 2022; Perumal and Muthuramalingam, 2022), human health (Prata et al., 2020; Rahman et al., 2021) and environmental impacts (Du et al., 2022; Wright et al., 2013), toxicity (Rakib et al., 2023; Verla et al., 2019), removal practices for drinking water, wastewater, and stormwater (Iyare et al., 2020; Padervand et al., 2020; Shen et al., 2020; Stang et al., 2022), and challenges in their quantification and characterization (Jung et al., 2021; Samanta et al., 2022). However, limited attention has been given to understanding the link between the intrinsic characteristics of plastics, and their degradation and fate within the environment received less attention. Therefore, this paper reviews the current literature on MP degradation and identifies the critical knowledge gaps in understanding the links between the intrinsic properties of MPs and their fate. In this paper, we maintain that the paradigm developed in the past decades to characterize element biogeochemical cycles could be adapted to evaluate the fate and transport of MPs. Additionally, studying the influence of intrinsic MPs’ properties and environmental factors on their fate and contaminant uptake highlights the urgent need for comprehensive solutions to mitigate the environmental and health impacts of MPs. We particularly call attention to the connection of plastics’ intrinsic properties with the generation rates of MPs, and their degradation from physical, chemical, and biological processes.

Defining Plastics and Microplastics

Although the word “plastics” is a part of our daily conversation, its meaning is not well-defined. Chemical composition, solid state, and solubility characteristics have been suggested as three primary criteria for classifying plastic (UNECE, 2013; ECHA, 2011). According to the International Organization for Standardization (ISO), a high molecular weight polymer, shaped by flow, is considered a plastic material (ISO 472, 1999). Natural polymers with high molecular weight (e.g., cellulose, silk) are excluded from the definition of plastics, whereas modified natural polymers (e.g., rayon) can be considered synthetic and categorized as plastics. In addition to petroleum-based commodity plastics (e.g., polyethylene [PE], polystyrene), bio-based (e.g., bio-polyethylene), and biodegradable plastics (e.g., polylactic acid), as well as inorganic or hybrid polymers (e.g., silicone) are considered plastics due to their synthetic nature. We will simply define plastic pollutants as insoluble solid debris whose major component is a synthetic high molecular-weight polymer that is not readily decomposed to bioavailable carbon sources.

In defining MPs, size criteria are incorporated alongside the aforementioned features of plastics. MPs are typically characterized as plastic fragments with diameters smaller than 5 mm. Plastic fragments with a size smaller than 1 or 0.1 µm have further been defined as nanoplastics because of their distinct physicochemical and transport characteristics (Gigault et al., 2021); however, nanosized plastics are sometimes lumped to be part of MPs (Lin et al., 2024; Vethaak and Legler, 2021). Primary MPs are intentionally manufactured to be small in size, such as microbeads used in personal care products or pellets used in industrial processes. In contrast, secondary MPs result from the fragmentation of larger plastic materials as they undergo physicochemical and biological processes throughout their life cycle or after disposal.

Although recent plastic pollution studies have mostly focused on particles composed solely of plastic materials, it remains unclear whether particles consisting of a mixture of plastics with other materials such as paper or metals should also be classified as MPs. This ambiguity underscores the need for further investigation into their quantification methods and environmental implications of particles composed of plastic-containing mixtures.

Environmental Fate of Microplastics

One proposed model for describing how MPs move through the environment is a biogeochemical cycle for plastics that tracks the sources, sinks, and fluxes of plastics (Allen et al 2022; Bank and Hansson, 2019; Brahney et al., 2021; Hoellein and Rochman, 2021) (Fig. 1). One important caveat to applying this model of biogeochemical cycling to plastics is that, unlike inorganic contaminants, plastics will ultimately be mineralized to CO₂. The timescale of the mineralization of MPs varies significantly depending on plastic type and environmental conditions, and remains an understudied area. Critically though, this “cycle” is not a closed system.

FIG. 1.

Biogeochemical cycle of microplastics (MPs) in the environment including sources of MP generation and mechanisms for transport, chemical processes, and mineralization of MPs.

MP sources are relatively well understood with numerous published works identifying mechanisms of MP generation (Alimi et al., 2018; Ateia et al., 2022; Bank and Hansson, 2019) and quantifying the number of MPs produced from these sources (Alimi et al., 2018; Allen et al., 2022). Several of these sources of MP generation are shown in Figure 1 (purple arrows). Another very popular topic in the literature is the quantification of the amount of MP in a given environment (sink) ranging from studies of local environments (e.g., number of MPs at a given field site) to efforts to estimate the total amount of MPs in freshwater, marine, terrestrial, and atmospheric systems (Akbari et al., 2024; Bowman et al., 2024; Johnson et al., 2024; Kryl et al., 2024; Setiawati et al., 2024). Although some MP sinks are well-defined (e.g., marine and coastal systems), other environmental sinks are understudied such as terrestrial and atmospheric systems (Allen et al., 2022; Brahney et al., 2021; Horton et al., 2017; Hurley and Nizzetto, 2018). One understudied area related to MP occurrence in different environments is understanding the impacts of high concentrations of MPs on the characteristics of soil systems. For example, high levels of MP in soil can affect soil drainage properties and nutrient retention (de Souza Machado et al., 2019). Additionally, far less is known about fluxes of MP between sinks; there is a need to both identify the nature of MP transport processes and quantify these fluxes (Alimi et al., 2018; Allen et al., 2022; Boyer et al., 2024; Haque et al., 2024; Hasenmueller and Ritter, 2024; Hernandez and Hasenmueller, 2024). Essential factors may include the intrinsic properties of MPs (e.g., density, crystallinity, hydrophobicity) as well as their size and shapes (Horton and Dixon, 2018). Several types of MP transport processes are shown in Figure 1 (blue arrows). Co-occurring with MP transport processes are physicochemical and biological weathering processes (red arrows in Fig. 1) including chemical and biological degradation reactions that change the surface chemistry of plastics and in some instances result in their eventual mineralization within the environment (Alimi et al., 2018; Luo et al., 2022). In addition to the natural processes that result in fluxes of MPs among various environmental compartments, the critical role of anthropogenic processes, such as water and wastewater treatment, in influencing these fluxes and further degradation of MPs should not be overlooked (Crossman et al., 2020; Jeong et al., 2023; Panigrahi et al., 2024; Yu et al., 2024). These engineered systems significantly impact the distribution and fate of MPs in the environment. Furthermore, advancing analytical techniques for the quantification and characterization of MPs could enhance our understanding of their transport across different environmental compartments (Kosuth et al., 2023; Zhu et al., 2024). Improved methodologies would enable more accurate tracking of MP movement and transformation in various ecosystems.

Numerous studies have examined individual mechanisms of plastic degradation, particularly in laboratory settings. Relatively few have focused on the effects that environmental conditions can have on MP degradation pathways. Environmental conditions such as terrestrial versus aqueous environments, salinity, temperature, redox potential, and exposure to sunlight can all affect the mechanisms by which plastics degrade and the rates of their degradation (Andrady et al., 2022; Ren et al., 2021). In an aqueous environment, plastics floating on the surface of the water are exposed to far more UV light and so are more oxidized than denser plastics that fall through the water column (Andrady et al., 2022). Growth of biofilms on MPs (which is more common in aqueous environments) can also slow the rate of oxidative degradation of plastics both by blocking the surface of MPs from UV exposure and by increasing the density of MPs causing them to fall deeper in the water column (Andrady et al., 2022). Biofilm formation may also promote the colonization of microorganisms which can facilitate further degradation, depending on the environmental conditions and the specific microbial communities involved (Debroy et al., 2022). In terrestrial environments, MPs on a soil surface are exposed to far more UV radiation and higher temperatures than those incorporated into the soil through tilling, burrowing by organisms, or vertical transport (Ren et al., 2021). MPs within the soil are exposed to potentially anoxic conditions and high levels of biodegradation compared to MPs on the soil surface or in aqueous environments (Ren et al., 2021). The influence of environmental conditions on MP degradation pathways is complex and while researchers have begun to examine these phenomena, there is much more research to be done.

Plastics’ intrinsic properties and the linkage to their degradation

The intrinsic properties of plastics play a critical role in determining MP performance throughout the use phase and influencing their primary environmental degradation pathways, as outlined in Table 1. Moreover, knowledge of these chemical attributes enables a comprehensive evaluation of MPs’ susceptibility to degradation, aiding the design of environmentally conscious materials. The literature has underscored the polymeric backbone and functional groups as primary drivers of plastics’ environmental degradation characteristics. For instance, extensive research has focused on elucidating mechanisms of photodegradation in plastics with a saturated polymeric backbone such as PE, emphasizing the role of structural defects and impurities introduced during manufacturing or subsequent weathering (Ainali et al., 2021; Fairbrother et al., 2019). Yet, further investigations are needed to identify the type and magnitude of these impurities and the extent of defects generated during weathering processes, which accelerate further degradation of MPs. Understanding their interplay is essential for elucidating the kinetics of MPs’ photooxidation. On the other hand, the presence of unsaturated bonds in polymeric backbones enhances MPs’ susceptibility to oxidation and photodegradation. Plastics with a heteroatom in their polymeric backbone, such as polyethylene terephthalate (PET) and polyurethane (PU), undergo hydrolytic cleavage of ester or amide bonds. This abiotic degradation process not only breaks down the polymeric chains but also creates conditions that can enhance subsequent biodegradation. Plastics containing hydrolyzable covalent bonds (e.g., ester, amide, anhydride, ether, carbamide, or ester amide) may undergo hydrolytic and photodegradation, but the process is slow (Chamas et al., 2020). To expedite these processes, research efforts have been directed toward both modifying the polymer structure (Chen et al., 2022) and promoting biodegradation. Biodegradable plastics are intentionally designed with specific functional groups, such as enzyme-sensitive ester groups, which can be targeted and processed by microorganisms. Enhanced biodegradation can be achieved through the metabolic engineering of microorganisms to enhance the rates of plastic biodegradation (Urbanek et al., 2021). Further investigation is required to examine how undergoing physicochemical degradation in the environment impacts the diversity, composition, and abundance of microbial communities, and thus the biodegradation rates of MPs.

Table 1.

A Summary of the Influence of Microplastics’ Intrinsic Properties on Their Degradation and Their Variations During Degradation

Plastic properties	Classification	Examples	Impacts on degradation	Effects of degradation	Ref
Polymeric backbone	Saturated (>C-C<)	LDPE, HDPE, PP, PVC	Impurities with chromophoric groups [e.g., catalysis residue, traces of solvents, additives, traces of metals, or metal oxides] are necessary to initiate the photodegradation process. They exhibit high stability for biodegradation.	Degradation of plastics could result in chain scission, the formation of free radicals and oxygen-containing functional groups, and the generation of low- or medium-molecular weight byproducts. It results in degradation byproducts and short molecular fragments leaching out of plastics.	(Ainali et al., 2021; Chamas et al., 2020; Fairbrother et al., 2019)
	Unsaturated (>C = C<)	PS, PB	Unsaturated polymeric backbones in plastics can accelerate environmental degradation through increased susceptibility to oxidation, photochemical degradation, and thermal breakdown.
	Heterogenous chain	PET, PU	Their degradation pathways vary by their chemical compositions. For instance, hydrolytic cleavage of ester or amide bonds could result in abiotic degradation of these plastics.
Polymeric structure	Linear	HDPE, PVC	Linear plastics are generally more environmentally stable than branched plastics because of their tightly packed structure. Crosslinked plastics form a three-dimensional network that is highly resistant to environmental degradation.	Radicals formed during the photodegradation of plastic could result in crosslinking and subsequently embrittlement of the polymer. However, prolonged exposure to UV radiation can also lead to the breakage of crosslinks, affecting the polymer’s overall structure. An increased degree of branching for biodegradable plastics promotes their biodegradation.	(Formela et al., 2016; Herath and Salehi, 2022)
	Branched	LDPE
	Crosslinked	PEX
Molecular weight	Low Mw	<10 kDa	Plastics with high molecular weights, characterized by longer polymer chains, tend to exhibit greater resistance to degradation.	Photodegradation may result in the reduction of the average molecular weight due to the polymeric chain scission. On the other hand, it could result in increasing the average molar mass by crosslinking the polymer. Other degradation mechanisms may also result in the reduction of molecular weight.	(Bonyadinejad et al., 2022; Yousif and Haddad, 2013)
	Medium Mw	10–100 kDa
	High Mw	>100 kDa
Crystallinity	Semicrystalline	LDPE, HDPE, PVDF	Amorphous plastics, due to their limited number of crystalline regions allow UV radiation to penetrate more easily, leading to increased chain scission and chemical changes, compared to the more crystalline plastics.	The generated low molecular weight segments can reorganize or act as nucleating agents resulting in an increase in crystallinity. However, extended degradation could result in the reduction of the crystallinity. Degradation of amorphous regions due to biodegradation could enhance the crystallinity.	(Aguiar et al., 2024; Bonyadinejad et al., 2022)
Crystallinity	Amorphous	PS			(Aguiar et al., 2024; Bonyadinejad et al., 2022)
Hydrophilicity	Hydrophilic	PEO, PVA	Hydrophilic plastics are more prone to hydrolysis and hydrolytic degradation compared to hydrophobic plastics.	The formation of oxidized carbon functional groups on polymer surfaces due to photodegradation makes it more hydrophilic.	(Gewert et al., 2015; Hadiuzzaman et al., 2022)
Hydrophilicity	Hydrophobic	LDPE, HDPE			(Gewert et al., 2015; Hadiuzzaman et al., 2022)

LDPE, Low Density Polyethylene; MP, microplastics; HDPE, High Density Polyethylene; PP, Polypropylene; PVC, Polyvinyl Chloride; PS, Polystyrene; PB, Polybutadiene; PET, Polyethylene Terephthalate; PU, Polyurethane; PEX, Crosslinked Polyethylene; PVDF, Polyvinylidene Fluoride; PEO, Polyethylene Oxide.

The polymer structures, which can be categorized as linear, branched, and crosslinked configurations, can influence the rate of MPs’ degradation. Although research indicates a greater photostability for linear polymers compared to branched polymers, which is attributed to their ability to allow more UV and oxygen penetration as well as greater radical mobility (Herath and Salehi, 2022). However, less information is available regarding how the degree of branching could impact degradation rates. Moreover, the molecular weight of plastics significantly influences their susceptibility to photodegradation. Plastics with lower molecular weights are more vulnerable to degradation. The decrease in molecular chain length also makes MPs more accessible for enzymatic degradation by microorganisms and accelerates their abiotic hydrolysis (Min et al., 2020). Despite the importance of polymeric molecular weight, limited investigations have been conducted to elucidate its critical role in MPs’ environmental degradation and subsequent byproduct release.

The density of MPs significantly affects their environmental fate. Factors such as crystallinity, molecular weight and structure determine the density of MPs, whether they float or sink, and subsequently influence their exposure to environmental factors. Lighter, buoyant MPs remain on the water’s surface, exposing them to aerobic conditions and facilitating longer-distance transport in the atmosphere. Conversely, denser MPs sink into the sediment, potentially undergoing anaerobic biodegradation, and settle more quickly, leading to localized deposition (Beheshtimaal et al., 2024). Future research is needed to examine the variations in MPs’ density as they undergo different degradation processes. This investigation is crucial for enhancing our understanding of their fate and distribution within the environment. Moreover, the hydrophilicity of plastics influences their susceptibility to environmental degradation. Hydrophilic plastics are more prone to hydrolysis and subject to microbial colonization, leading to subsequent biodegradation and additive leaching. However, there has been limited focus on modifying plastics to reduce their hydrophobicity and consequently enhance their biodegradation (Ray et al., 2023).

Most MP environmental degradation studies have been conducted using pure plastic materials; however, the presence of additives within the plastics can significantly influence their degradation kinetics. These additives include a diverse group of compounds, such as plasticizers, slip agents, fillers, light stabilizers, antioxidants, heat stabilizers, biostabilizers, and pigments, that are incorporated into plastics to improve their processability, performance, and durability. The potential role of common plastic additives in degradation is summarized in Figure 2. The intricate role of these additives allows for tailoring plastic formulations to resist the degrading effects of sunlight, ultimately extending the material’s lifespan and functionality during the use phase. Despite their widespread use, there is limited information available regarding the chemical composition and concentration of additives present in commercially available plastics used in everyday life. This lack of data limits our understanding of how additives may influence the environmental degradation of MPs. Additionally, it remains unclear as to what percentage of the additives added during the manufacturing process remains within the plastic structure when they are disposed in the environment. This ambiguity poses a significant challenge in predicting the degradation kinetics of MPs once they are released into the environment. Moreover, in recent years, there has been increasing interest in utilizing additives to enhance the degradation of commodity plastics (Abdelmoez et al., 2021; Selke et al., 2015). However, it is essential to consider the potential environmental impacts of synthetic additives incorporated into the plastics, such as prooxidant/prodegradants designed to accelerate degradation. It remains unclear whether these additives themselves can undergo complete biodegradation. Nevertheless, the development of bioplastics could offer a more sustainable solution for enhancing the degradation of plastics.

FIG. 2.

Summary of the potential roles of common plastic additives on degradation.

The effects of environmental degradation on the intrinsic properties of microplastics

The literature has extensively documented changes in MPs’ surface chemistry and morphology due to environmental degradation, including increasing surface roughness, formation of surface cracks, color change, and creation of oxidized carbon functional groups, along with changing hydrophobicity (Aghilinasrollahabadi et al., 2021; McColley and Nason, 2024; Miranda et al., 2021). However, there has been relatively less focus on investigating the variations in the bulk properties and microstructure of MPs. Crystalline zones typically remain intact upon degradation, because cleavage primarily occurs within the amorphous region of the polymer. However, the generation of low molecular weight fragments, their reorientation into crystalline regions, and the crosslinking caused by radicals formed during degradation could alter the molecular weight and crystallinity of MPs (Bonyadinejad et al., 2022; Yousif and Haddad, 2013). Despite their critical importance, the interrelationship of these microstructural changes and the degree of additives and byproducts leaching remains less understood.

As reported in the literature, the degradation of MPs can induce chain scission, thereby weakening the polymer’s overall structure, decreasing its mechanical strength, and facilitating the rapid leaching of additives and degradation/oxidation byproducts. Additionally, mechanical degradation, which enhances surface roughness and fragmentation, contributes to an overall increase in surface area, further accelerating the leaching of additives, unreacted monomers, and oligomers into the environment. The extent of chemical leaching varies depending on environmental conditions, MP properties (e.g., crystallinity, molecular weight), and the structure of the additives. Although more research investigated the leaching of additives from degrading plastics (Luo et al., 2020; Suhrhoff and Scholz-Böttcher, 2016), there has been less investigation into the release of low molecular weight fragments from plastics as oxidation or degradation byproducts (Biale et al., 2022).

Most research on the mechanical degradation of MPs has primarily focused on quantifying the extent of their fragmentation when subjected to various mechanical forces in the aquatic and terrestrial environment or by organisms (Battacharjee et al., 2023; Julienne et al., 2019; Mateos-Cárdenas et al., 2020). However, less attention has been devoted to investigating the linkage between MPs’ intrinsic properties and their mechanical fragmentation. However, the influence of mechanical degradation on the intrinsic properties of plastics could be size-dependent. The strains induced by mechanical forces, including tension, shear, bending, and compression, exerted on polymeric backbones may lead to their breakage at points of physical entanglement. This fragmentation could consequently reduce the average molecular weight of the material (Ravishankar et al., 2018). Moreover, depending on the type of biodegradation including bacterial degradation, fungal degradation, enzymatic degradation, and combined biological degradation, the extent of changes in the intrinsic properties of plastics could be different. Enzymatic degradation results in depolymerization and the formation of shorter molecular chains, oligomers, dimers, and monomers. The small oligomers and monomers could eventually get integrated into the cells by bacteria and be mineralized. Through the biodegradation of plastics, the amorphous regions of the plastics are preferentially attacked by enzymes thus the relative crystallinity of plastic increases following the biodegradation (Aguiar et al., 2024). Although enhanced fragmentation is expected due to increased crystallinity and depolymerization of MPs following biodegradation, further studies are needed to elucidate the links between biodegradation and fragmentation. Such research could offer insights into the long-term transport and ecological impacts of MPs in terrestrial or aquatic systems, particularly considering the reduction in size distribution of MPs resulting from these degradation processes.

Environmental Implications of Microplastic Degradation

Given that environmental persistence is one of the major concerns of MPs as a class of pollutants, it is commonly thought that any degradation of plastics is of environmental benefit. Although the ultimate goal of complete degradation of MPs remains, incremental degradation of plastics can result in materials that have similar or more environmental harm than the initial material. As detailed above, the degradation of MPs results in many changes to their physical and chemical properties, some of which make them more prone to causing deleterious environmental effects. For example, the increased brittleness of plastics degraded through mechanisms such as mechanical abrasion and UV photo-oxidation makes plastics more prone to fragmentation (Andrady et al., 2022). Smaller MPs have a triple threat of an increased surface area to volume ratio (and thus, a higher sorption capacity for pollutants), greater environmental mobility due to their small size, and easier ingestion by organisms due to their small size (Pincus et al., 2023; Ren et al., 2021). MPs, owing to their hydrophobic nature, have a natural tendency to strongly adsorb organic pollutants through multiple mechanisms such as hydrophobic interactions, hydrogen bonding, Van der Waals forces, and π–π interactions (Ren et al., 2021). As MPs degrade, they are often oxidized through mechanisms such as UV photo-oxidation or chemical oxidation, resulting in less hydrophobic more polar surfaces with a higher carbonyl index that has much stronger sorption capacities for inorganic contaminants such as toxic metals and oxyanions (Cai et al., 2024; Herath et al., 2023; Ren et al., 2021). Inorganic contaminants are adsorbed through mechanisms such as electrostatic interactions, surface complexation, precipitation, and coprecipitation (Miller et al., 2024; Quiambao et al., 2023; Ren et al., 2021). Environmental factors such as pH, pe, salinity, and coexistence of other competing molecules in solution can all strongly affect the sorption mechanism and capacity of MPs toward inorganic and organic contaminants (Ren et al., 2021; Wang et al., 2021). Accumulation of contaminants on MPs is of concern due to the increased potential for environmental transport of pollutants, and bioaccumulation and biomagnification of contaminants as MPs are ingested by organisms (Engler, 2012). Thus, it is important to consider that not only are MPs themselves of concern as pollutants but their capacity to serve as vectors for other inorganic and organic contaminants needs to be accounted for as well.

Summary

This paper highlights the critical linkages between MPs’ intrinsic properties and their environmental fate, focusing on degradation processes. The polymeric backbone and functional groups of MPs primarily drive their stability when exposed to environmental factors, significantly influencing degradation pathways and rates. As MPs degrade, their properties undergo substantial changes, affecting further degradation and interactions with contaminants. Most important, the degradation process presents a paradox: while it reduces the duration of MPs’ existence in the environment, the incremental breakdown can result in materials potentially posing greater environmental harm than the initial plastic particles. This complexity underscores the challenges in addressing MP pollution and its long-term environmental impacts. The complex interplay between MPs’ properties, environmental conditions, and degradation processes emphasizes the need for comprehensive research to elucidate mechanisms by which intrinsic properties influence MP degradation under various conditions, investigate the long-term fate of degradation byproducts and their environmental impacts, and develop standardized methods for characterizing changes in MPs’ properties during environmental weathering. This knowledge is crucial for accurately predicting MP’s accumulation in the environment, assessing ecological and health risks, and informing effective policies and technologies to mitigate global plastic pollution.

Footnotes

Authors’ Contributions

M.S.: Conceptualization, investigation, visualization, and writing. L.N.P.: Conceptualization, investigation, visualization, and writing. B.D.: Conceptualization and writing: C.A.P.: Conceptualization and writing.

Author Disclosure Statement

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.

Funding Information

Funding for this work was provided by the United States National Science Foundation (NSF) grant CBET-2305189 to the University of Missouri.

References

Abdelmoez

, Dahab

, Ragab

, et al. Bio- and oxo-degradable plastics: Insights on facts and challenges. Polym Advan Technol, 2021; 32(5):1981–1996; doi: 10.1002/pat.5253

Aghilinasrollahabadi

, Salehi

, Fujiwara

. Investigate the influence of microplastics weathering on their heavy metals uptake in stormwater. J Hazard Mater, 2021; 408:124439; doi: 10.1016/j.jhazmat.2020.124439

Aguiar

MIS

, Sousa

, Teixeira

, et al. Enhancing plastic waste recycling: Evaluating the impact of additives on the enzymatic polymer degradation. Catal Today, 2024; 429:114492; doi: 10.1016/j.cattod.2023.114492

Ainali

, Bikiaris

, Lambropoulou

. Aging effects on low- and high-density polyethylene, polypropylene and polystyrene under UV irradiation: An insight into decomposition mechanism by Py-GC/MS for microplastic analysis. J Anal Appl Pyrolysis, 2021; 158:105207; doi: 10.1016/j.jaap.2021.105207

Akbari

, Powers

, Shah

, et al. Microplastics in the Delaware River estuary: Mapping the distribution and modeling hydrodynamic transport. Environ Eng Sci, 2024; doi: 10.1089/ees.2024.0041

Alimi

, Farner Budarz

, Hernandez

, et al. Microplastics and nanoplastics in aquatic environments: Aggregation, deposition, and enhanced contaminant transport. Environ Sci Technol, 2018; 52(4):1704–1724; doi: 10.1021/acs.est.7b05559

Allen

, Allen

, Abbasi

, et al. Microplastics and nanoplastics in the marine-atmosphere environment. Nat Rev Earth Environ, 2022; 3(6):393–405; doi: 10.1038/s43017-022-00292-x

Andrady

, Barnes

, Bornman

, et al. Oxidation and fragmentation of plastics in a changing environment; from UV-radiation to biological degradation. Sci Total Environ, 2022; 851(Pt 2)b:158022; doi: 10.1016/j.scitotenv.2022.158022

Ateia

, Ersan

, Alalm

, et al. Emerging investigator series: Microplastic sources, fate, toxicity, detection, and interactions with micropollutants in aquatic ecosystems – a review of reviews. Environ Sci Process Impacts, 2022; 24(2):172–195; doi: 10.1039/D1EM00443C

10.

Bank

, Hansson

. The plastic cycle: A novel and holistic paradigm for the anthropocene. Environ Sci Technol, 2019; 53(13):7177–7179; doi: 10.1021/acs.est.9b02942

11.

Battacharjee

, Jazaei

, Salehi

. Insights into the mechanism of plastics’ fragmentation under abrasive mechanical forces: An implication for agricultural soil health. J Clear Air Water Soil, 2023; 51(8):2200395; doi: 10.1002/clen.202200395

12.

Beheshtimaal

, Alamdari

, Wang

, et al. Understanding the dynamics of microplastics transport in urban stormwater runoff: Implications for pollution control and management. Environ Pollut, 2024; 356:124302; doi: 10.1016/j.envpol.2024.124302

13.

Biale

, Nasa

, Mattonai

, et al. Seeping plastics: Potentially harmful molecular fragments leaching out from microplastics during accelerated aging in seawater. Water Res, 2022; 219:118521; doi: 10.1016/j.watres.2022.118521

14.

Bonyadinejad

, Salehi

, Herath

. Investigating the sustainability of agricultural plastic products, combined influence of polymer characteristics and environmental conditions on microplastics aging. Sci Total Environ, 2022; 839:156385; doi: 10.1016/j.scitotenv.2022.156385

15.

Borrelle

, Ringma

, Law

, et al. Predicted growth in plastic waste exceeds efforts to mitigate plastic pollution. Science, 2020; 369(6510):1515–1518; doi: 10.1126/science.aba3656

16.

Bowman

, Lazar

, Carraway

, et al. Fluvial concentrations of microplastics in a suburban micro-watershed: Sampling methodology and analysis. Environ Eng Sci, 2024; Accepted; doi:10.1089/ees.2024.0109

17.

Boyer

, Brooks

, Arias

. Microplastics in a large constructed wetland: Retention, transport, and characteristics. Environ Eng Sci, 2024; doi: 10.1089/ees.2024.0083

18.

Brahney

, Mahowald

, Prank

, et al. Constraining the atmospheric limb of the plastic cycle. Proc Natl Acad Sci USA, 2021; 118(16):e2020719118; doi: 10.1073/pnas.2020719118

19.

Cai

, Scott

, Thennakoon

, et al. Adsorption of alachlor, lindane, and methomyl onto polystyrene microplastics: Effects of aging treatments. Environ Eng Sci, 2024; Accepted; doi:10.1089/ees.2024.0104

20.

Chamas

, Hyunjin

, Jiajia

, et al. Degradation rates of plastics in the environment. ACS Sustainable Chem Eng, 2020; 8(9):3494–3511; doi: 10.1021/acssuschemeng.9b06635

21.

Chen

, Guo

, Wang

, et al. Directional-path modification strategy enhances PET hydrolase catalysis of plastic degradation. J Hazard Mater, 2022; 433:128816; doi: 10.1016/j.jhazmat.2022.128816

22.

Corinaldesi

, Canensi

, Dell’Anno

, et al. Multiple impacts of microplastics can threaten marine habitat-forming species. Commun Biol, 2021; 4(1):431; doi: 10.1038/s42003-021-01961-1

23.

Crossman

, Hurley

, Futter

, et al. Transfer and transport of microplastics from biosolids to agricultural soils and the wider environment. Sci Total Environ, 2020; 724:138334; doi: 10.1016/j.scitotenv.2020.138334

24.

de Souza Machado

, Lau

, Kloas

, et al. Microplastics can change soil properties and affect plant performance. Environ Sci Technol, 2019; 53(10):6044–6052; doi: 10.1021/acs.est.9b01339

25.

Debroy

, George

, Mukherjee

. Role of biofilms in the degradation of microplastics in aquatic environments. J of Chemical Tech & Biotech, 2022; 97(12):3271–3282; doi: 10.1002/jctb.6978

26.

, Xie

, Wang

. Environmental impacts of microplastics on fishery products: An overview. Gondwana Res, 2022; 108:213–220; doi: 10.1016/j.gr.2021.08.013

27.

Engler

. The complex interaction between marine debris and toxic chemicals in the ocean. Environ Sci Technol, 2012; 46(22):12302–12315; doi: 10.1021/es3027105

28.

Fairbrother

, Hsueh

, Kim

, et al. Temperature and light intensity effects on photodegradation of high-density polyethylene. Polym Degrad Stab, 2019; 161:43–51; doi: 10.1016/j.polymdegradstab.2018.11.002

29.

Formela

, Wołosiak

, Klein

, et al. Characterization of volatile compounds, structural, thermal, and physico-mechanical properties of cross-linked polyethylene foams degraded thermo-mechanically at variable times. Polym Degrad Stab, 2016; 134:383–393; doi: 10.1016/j.polymdegradstab.2016.11.011

30.

Galafassi

, Sabatino

, Sathicq

, et al. Contribution of microplastic particles to the spread of resistances and pathogenic bacteria in treated wastewaters. Water Res, 2021; 201:117368; doi: 10.1016/j.watres.2021.117368

31.

Gewert

, Plassmann

, MacLeod

. Pathways for degradation of plastic polymers floating in the marine environment. Environ Sci Process Impacts, 2015; 17(9):1513–1521; doi: 10.1039/c5em00207a

32.

Geyer

, Jambeck

, Law

. Production, use, and fate of all plastics ever made. Sci Adv, 2017; 3(7):e1700782; doi: 10.1126/sciadv.1700782

33.

Gigault

, Hadri

, Nguyen

, et al. Nanoplastics are neither microplastics nor engineered nanoparticles. Nat Nanotechnol, 2021; 16(5):501–507.

34.

Hadiuzzaman

, Salehi

, Fujiwara

. Plastic litter fate and contaminant transport within the urban environment: Photodegradation, fragmentation, and heavy metal uptake from storm runoff. Environ Res, 2022; 212(Pt A):113183; doi: 10.1016/j.envres.2022.113183

35.

Haque

, Shenderovich

, Treichel

, et al. Microplastics pollution status in a tributary of the Hudson River: Fishkill Creek. Environ Eng Sci, 2024; doi: 10.1089/ees.2024.0105

36.

Hasenmueller

, Ritter

. Microplastic chemostasis and homogeneity during a historic flood on the Mississippi River. Environ Eng Sci, 2024; Accepted; doi:10.1089/ees.2024.0133

37.

Herath

, Datta

, Bonyadinejad

, et al. Partitioning of heavy metals in sediments and microplastics from stormwater runoff. Chemosphere, 2023; 332:138844; doi: 10.1016/j.chemosphere.2023.138844

38.

Herath

, Salehi

. Studying the intrinsic and extrinsic factors influence microplastics photodegradation behavior and heavy metals uptake in urban stormwater. Environ Pollut, 2022; 308:119629; doi: 10.1016/j.envpol.2022.119628

39.

Hernandez

, Hasenmueller

. Anthropogenic macroscale and microscale debris (including plastics) have differing spatial distributions across a small urban watershed. Environ Eng Sci, 2024; doi: 10.1089/ees.2024.0106

40.

Hoellein

, Rochman

. The “Plastic Cycle”: A Watershed-Scale Model of Plastic Pools and Fluxes. Front Ecol Environ, 2021; 19(3):176–183; doi: 10.1002/fee.2294

41.

Horton

, Dixon

. Microplastics: An introduction to environmental transport processes. WIREs Water, 2018; 5(2):e1268; doi: 10.1002/wat2.1268

42.

Horton

, Walton

, Spurgeon

, et al. Microplastics in freshwater and terrestrial environments: Evaluating the current understanding to identify the knowledge gaps and future research priorities. Sci Total Environ, 2017; 586:127–141; doi: 10.1016/j.scitotenv.2017.01.190

43.

Hurley

, Nizzetto

. Fate and occurrence of micro(nano)plastics in soils: Knowledge gaps and possible risks. Curr Opin Environ Sci Health, 2018; 1:6–11; doi: 10.1016/j.coesh.2017.10.006

44.

Iyare

, Ouki

, Bond

. Microplastics removal in wastewater treatment plants: A critical review. Environ Sci: Water Res Technol, 2020; 6(10):2664–2675; doi: 10.1039/D0EW00397B

45.

Jazaei

, Chy

, Salehi

. Can microplastic pollution change soil-water dynamics? Results from controlled laboratory experiments. Water, 2022; 14(21):3430; doi: 10.3390/w14213430

46.

Jeong

, Gong

, Lee

, et al. Transformation of microplastics by oxidative water and wastewater treatment processes: A critical review. J Hazard Mater, 2023; 443(Pt B):130313; doi: 10.1016/j.jhazmat.2022.130313

47.

Jeong

, Won

, Kang

, et al. Microplastic size-dependent toxicity, oxidative stress induction, and p-JNK and p-p38 activation in the monogonont rotifer (Brachionus koreanus). Environ Sci Technol, 2016; 50(16):8849–8857; doi: 10.1021/acs.est.6b01441

48.

Johnson

, Bailey

, Hatinoglu

, et al. Land-sea connection of microplastic fiber pollution in Frenchman Bay, Maine. Environ Eng Sci, 2024; doi: 10.1089/ees.2024.0102

49.

Julienne

, Delorme

, Lagarde

. From macroplastics to microplastics: Role of water in the fragmentation of polyethylene. Chemosphere, 2019; 236:124409; doi: 10.1016/j.chemosphere.2019.124409

50.

Jung

, Cho

S-H

, Kim

K-H

, et al. Progress in quantitative analysis of microplastics in the environment: A review. Chem Eng J, 2021; 422:130154; doi: 10.1016/j.cej.2021.130154

51.

Kosuth

, Simmerman

, Simcik

. Quality assurance and quality control in microplastics processing and enumeration. Environ Eng Sci, 2023; 40(11):605–613; doi: 10.1089/ees.2023.0063

52.

Koutnik

, Leonard

, Alkidim

, et al. Distribution of microplastics in soil and freshwater environments: Global analysis and framework for transport modeling. Environ Pollut, 2021; 274:116552; doi: 10.1016/j.envpol.2021.116552

53.

Kryl

, Lewandoski

, DiBlasio

, et al. Addressing microplastic environmental data gaps through undergraduate research. Environ Eng Sci, 2024; doi: 10.1089/ees.2024.0085

54.

Lin

, Lee

, Feng

, et al. Electrophoresis characterization of nanoplastic particle surface charge in dilute aqueous electrolytes. Environ Eng Sci, 2024; doi: 10.1089/ees.2024.0076

55.

Luo

, Liu

, He

, et al. Environmental behaviors of microplastics in aquatic systems: A systematic review on degradation, adsorption, toxicity and biofilm under aging conditions. J Hazard Mater, 2022; 423(Pt A):126915; doi: 10.1016/j.jhazmat.2021.126915

56.

Luo

, Zhao

, Li

, et al. Aging of microplastics affects their surface properties, thermal decomposition, additives leaching and interactions in simulated fluids. Sci Total Environ, 2020; 714:136862; doi: 10.1016/j.scitotenv.2020.136862

57.

Mateos-Cárdenas

, O’Halloran

, van Pelt

FNAM

, et al. Rapid fragmentation of microplastics by the freshwater amphipod Gammarus duebeni (Lillj.). Sci Rep, 2020; 10(1):12799; doi: 10.1038/s41598-020-69635-2

58.

McColley

, Nason

. Eco-Corona formation on photooxidized plastics exposed to mixed organic matter. Environ Eng Sci, 2024; doi: 10.1089/ees.2024.0103

59.

Miller

, Hamann

, Kroon

. Bioaccumulation and biomagnification of microplastics in marine organisms: A review and meta-analysis of current data. PLoS One, 2020; 15(10):e0240792; doi: 10.1371/journal.pone.0240792

60.

Miller

, Neidhart

, Hess

, et al. Uranium accumulation in environmentally relevant microplastics and agricultural soil at acidic and circumneutral pH. Sci Total Environ, 2024; 926:171834; doi: 10.1016/j.scitotenv.2024.171834

61.

Min

, Cuiffi

, Mathers

. Ranking environmental degradation trends of plastic marine debris based on physical properties and molecular structure. Nat Commun, 2020; 11(1):727; doi: 10.1038/s41467-020-14538-z

62.

Miranda

, Sampaio

, Tavares

, et al. Aging assessment of microplastics (LDPE, PET and uPVC) under urban environment stressors. Sci Total Environ, 2021; 796:148914; doi: 10.1016/j.scitotenv.2021.148914

63.

Padervand

, Lichtfouse

, Robert

, et al. Removal of microplastics from the environment: A review. Environ Chem Lett, 2020; 18(3):807–828; doi: 10.1007/s10311-020-00983-1

64.

Padha

, Kumar

, Dhar

, et al. Microplastic pollution in mountain terrains and foothills: A review on source, extraction, and distribution of microplastics in remote areas. Environ Res, 2022; 207:112232; doi: 10.1016/j.envres.2021.112232

65.

Panigrahi

, Kamal

, Qin

, et al. Removal of pristine and UV-weathered microplastics from water: Moringa oleifera seed protein as a natural coagulant. Environ Eng Sci, 2024; doi: 10.1089/ees.2024.0135

66.

Parveen

, Ranjan

, Chowdhury

, et al. Occurrence and potential health risks due to trihalomethanes and microplastics in bottled water. Environ Eng Sci, 2022; 39(6):523–534; doi: 10.1089/ees.2021.0295

67.

Perumal

, Muthuramalingam

. Global sources, abundance, size, and distribution of microplastics in marine sediments - A critical review. Estuar Coast Shelf Sci, 2022; 264:107702; doi: 10.1016/j.ecss.2021.107702

68.

Pincus

, Pattammattel

, Leshchev

, et al. Rapid accumulation of soil inorganics on plastics: Implications for plastic degradation and contaminant fate. Environ Sci Technol Lett, 2023; 10(6):538–542; doi: 10.1021/acs.estlett.3c00241

69.

Prata

, da Costa

, Lopes

, et al. Environmental exposure to microplastics: An overview on possible human health effects. Sci Total Environ, 2020; 702:134455; doi: 10.1016/j.scitotenv.2019.134455

70.

Quiambao

, Hess

, Johnston

, et al. Interfacial interactions of uranium and arsenic with microplastics: From field detection to controlled laboratory tests. Environ Eng Sci, 2023; 40(11):562–573; doi: 10.1089/ees.2023.0054

71.

Rahman

, Sarkar

, Yadav

, et al. Potential human health risks due to environmental exposure to nano- and microplastics and knowledge gaps: A scoping review. Sci Total Environ, 2021; 757:143872; doi: 10.1016/j.scitotenv.2020.143872

72.

Rakib

MRJ

, Sarker

, Ram

, et al. Microplastic toxicity in aquatic organisms and aquatic ecosystems: A review. Water Air Soil Pollut, 2023; 234(1):52; doi: 10.1007/s11270-023-06062-9

73.

Ravishankar

, Ramesh

, Sadhasivam

, et al. Wear-induced mechanical degradation of plastics by low-energy wet-grinding. Polym Degrad Stab, 2018; 158:212–219; doi: 10.1016/j.polymdegradstab.2018.10.026

74.

Ray

, Rajasekaran

, Uddin

, et al. Laccase driven biocatalytic oxidation to reduce polymeric surface hydrophobicity: An effective pre-treatment strategy to enhance biofilm mediated degradation of polyethylene and polycarbonate plastics. Sci Total Environ, 2023; 904:166721; doi: 10.1016/j.scitotenv.2023.166721

75.

Ren

, Gui

, Xu

, et al. Microplastics in the soil-groundwater environment: Aging, migration, and co-transport of contaminants – A critical review. J Hazard Mater, 2021; 419:126455; doi: 10.1016/j.jhazmat.2021.126455

76.

Samanta

, Dey

, Kundu

, et al. An insight on sampling, identification, quantification, and characteristics of microplastics in solid wastes. Trends Environ Anal Chem, 2022; 36:e00181; doi: 10.1016/j.teac.2022.e00181

77.

Selke

, Auras

, Nguyen

, et al. Evaluation of biodegradation-promoting additives for plastics. Environ Sci Technol, 2015; 49(6):3769–3777; doi: 10.1021/es504258u

78.

Setiawati

, Haribowo

, Kristanti

, et al. Microplastic abundance and characteristics in the Bango River, Malang, Indonesia, based on land use patterns. Environ Eng Sci, 2024; Accepted; doi:10.1089/ees.2024.0111

79.

Shen

, Song

, Zhu

, et al. Removal of microplastics via drinking water treatment: Current knowledge and future directions. Chemosphere, 2020; 251:126612; doi: 10.1016/j.chemosphere.2020.126612

80.

Sofield

, Anderton

, Gorecki

. Mind over Microplastics: Exploring Microplastic-Induced Gut Disruption and Gut-Brain-Axis Consequences. Curr Issues Mol Biol, 2024; 46(5):4186–4202; doi: 10.3390/cimb46050256

81.

Stang

, Mohamed

, Li

. Microplastic removal from urban stormwater: Current treatments and research gaps. J Environ Manage, 2022; 317:115510; doi: 10.1016/j.jenvman.2022.115510

82.

Suhrhoff

, Scholz-Böttcher

. Qualitative impact of salinity, UV radiation and turbulence on leaching of organic plastic additives from four common plastics—A lab experiment. Mar Pollut Bull, 2016; 102(1):84–94; doi: 10.1016/j.marpolbul.2015.11.054

83.

Sun

, Wang

. Human exposure to microplastics and its associated health risks. Environ Health, 2023; 1(3):139–149; doi: 10.1021/envhealth.3c00053

84.

UNECE. Globally harmonized system of classification and labelling of chemicals (GHS), Fifth revised ed. United Nations, New York and Geneva; 2013.

85.

Urbanek

, Kosiorowska

, Mirończuk

. Current knowledge on polyethylene terephthalate degradation by genetically modified microorganisms. Front Bioeng Biotechnol, 2021; 9:771133; doi: 10.3389/fbioe.2021.771133

86.

Verla

, Enyoh

, Verla

, et al. Microplastic–toxic chemical interaction: A review study on quantified levels, mechanism and implication. SN Appl Sci, 2019; 1(11):1400; doi: 10.1007/s42452-019-1352-0

87.

Vethaak

, Legler

. Microplastics and human health. Science, 2021; 371(6530):672–674; doi: 10.1126/science.abe5041

88.

Wang

, Wang

, Li

, et al. Effects of exposure of polyethylene microplastics to air, water and soil on their adsorption behaviors for copper and tetracycline. Chem Eng J, 2021; 404:126412; doi: 10.1016/j.cej.2020.126412

89.

Wright

, Thompson

, Galloway

. The physical impacts of microplastics on marine organisms: A review. Environ Pollut, 2013; 178:483–492; doi: 10.1016/j.envpol.2013.02.031

90.

Yang

, Man

, Wong

, et al. Environmental health impacts of microplastics exposure on structural organization levels in the human body. Sci Total Environ, 2022; 825:154025; doi: 10.1016/j.scitotenv.2022.154025

91.

Yousif

, Haddad

. Photodegradation and photostabilization of polymers, especially polystyrene: Review. Springerplus, 2013; 2:398; doi: 10.1186/2193-1801-2-398

92.

, Liu

, Gang

, et al. Polyethylene microplastics interfere with the nutrient cycle in water-plant-sediment systems. Water Res, 2022; 214:118191; doi: 10.1016/j.watres.2022.118191

93.

, Zhang

, Yang

, et al. Enhanced removal of polystyrene microplastics by coagulation of polyaluminum ferric chloride in the presence of three typical coagulant aids. Environ Eng Sci. Accepted, 2024; doi: 10.1089/ees.2023.0332

94.

Zhu

, Parker

, Wong

. Microplastic mass quantification using focal plane array (FPA)-based FT-IR imaging. Environ Eng Sci, 2024; doi: 10.1089/ees.2024.0017

Microplastics: From Intrinsic Properties to Environmental Fate

Abstract

Introduction

Defining Plastics and Microplastics

Environmental Fate of Microplastics

Plastics’ intrinsic properties and the linkage to their degradation

The effects of environmental degradation on the intrinsic properties of microplastics

Environmental Implications of Microplastic Degradation

Summary

Footnotes

Authors’ Contributions

Author Disclosure Statement

Funding Information

References