Introduction

The presence of microplastic in the environment has become a global concern, as it can negatively impact agroecosystems and human health (Iqbal et al. 2023a). However, microplastic can be ingested by marine organisms, causing physical harm, ingestion of toxic substances, and ultimately the transfer of these contaminants up the food chain (Huang et al. 2021). There is also growing evidence that humans may be exposed to microplastics through the consumption of contaminated seafood or drinking water (Torre 2020). Several studies have highlighted the increasing prevalence of microplastic in different parts of the world, including freshwater systems (Blackburn and Green 2022), urban environments (Li et al. 2021), and remote wilderness areas (Abbasi and Turner 2021). Thus, microplastic contamination in the soil affects the development and diversity of soil microorganisms, which in turn harms plant health (de Souza Machado et al. 2019). In addition, microplastic obstructs the movement of soil microbes, limits their access to nutrients, and stops them from interacting with plant roots (Wang et al. 2024). Intake of nutrients is also decreased by microplastic because they disrupt the advantageous interactions between fungi and plants (Liu et al. 2022; Bai et al. 2024). To date, there is still much to learn about the ecological and health effects of microplastics and more research is needed to develop effective management strategies regarding the soil microorganisms that drastically impact the growth and productivity of the crops (Zhang et al. 2020a; Khalid et al. 2021).

The particles whose diameter is smaller than 5 mm are regarded as microplastic that are further defined by the National Oceanic and Atmospheric Administration (NOAA) as small pieces of plastic that are no more than 5 mm long that can harm our coastal and aquatic resources (Gigault et al. 2021; NOAA 2023). These particles can come from various sources, such as due to the breakdown of larger plastic items, the shedding of microfibers from textiles during washing, and the abrasion of plastic materials in the environment (Lee et al. 2022; Iqbal et al. 2023a). Primary microplastics, such as blasting with an agent, products for personal care, and industrial cleaning agents, are consciously produced at a tiny size for their particular uses and mainly include polyethylene (PE), polypropylene (PP), and polystyrene (PS) (Galafassi et al. 2019; Ali et al. 2024). However, Secondary microplastic arises due to the breakdown of more oversized plastic products through weathering, fragmentation, and degradation processes and originates from various sources such as textiles, rubber tires, fishing gear, and plastic packaging (Chen et al. 2024a; Zeb et al. 2024). Moreover, recent studies have identified other types of microplastic in the environmental samples, including polyethylene terephthalate (PET), polyamide (PA), and polyvinyl chloride (PVC) which conclusively impact the below and above-ground changes and thus decline the productivity of the crops and affect human health (Nava and Leoni 2021; Khan et al. 2023; Shi et al. 2023a, b).

Thus, the current review paper critically evaluates the implications of microplastic pollution on the belowground and above-ground ecosystems, its mitigation strategies, and its amplification on human health. This includes a comprehensive study of the distribution and persistence of microplastics in the environment, mitigation strategies, and the potential pathways through which they may impact soil microorganisms, soil properties, and plant growth and productivity, which subsequently affect the human body and health.

To lessen the damaging impacts of microplastic pollution on the natural world and human health, this review attempts to consolidate the existing level of knowledge on the subject, identify knowledge gaps, and suggest future research approaches. The objectives of the current study are (1) to evaluate the scope and sources of microplastic contamination in the soil ecosystems and its possible effects on the soil microorganisms, including modifications in the physical, chemical, and biological characteristics of the soil as well as the nutrient cycling and microbial population; (2) to assess how microplastic pollution affects soil microorganisms by impacting the plant growth and development, including how they are absorbed by plants, changes to their morphology and physiological characteristics, and their possible impact on crop productivity and food security; (3) study the routes through which people come into contact with microplastic in the soil, such as ingesting contaminated soil through breathing and in the food chain, and determine the possible health impacts; (4) to identify gaps in current knowledge and research needs in soil environments and their counter effect on crop growth, development, and productivity; (5) the assessment of the long-term environmental and health impacts and the development of effective mitigation strategies to reduce microplastic contamination in the soil and its effects on the crops.

Contamination of the agricultural ecosystem

Microplastics can enter agricultural ecosystems through various routes, including irrigation, fertilization, and land application of biosolids and composts (Lwanga et al. 2022). Irrigation with contaminated water sources, such as rivers and lakes, can introduce these particles into agronomic soils by contaminating the cropland (Liu et al. 2023; Iqbal et al. 2023b). Thus, microplastic can enter agricultural fields through the use of recycled water and wastewater, which are often used for irrigation in areas with water scarcity. Fertilization with sewage sludge, biosolids, and other organic amendments containing these particles can lead to their accumulation in agricultural soils (Iqbal et al. 2023b). Additionally, the use of plastic mulch film in agriculture fields may potentially contribute to microplastic contamination (Huang et al. 2020). These films are applied to soil to raise soil temperature, keep moisture in the soil, and prevent weed development (Prem et al. 2020; Tang et al. 2023a, b), but they can also break down over time, releasing microplastic into the soil where they might linger for a long period and damage the fertility and health of the soil (Yang et al. 2022). In addition, microplastic can also enter agricultural ecosystems by using composts and manure derived from animal production (Zhang et al. 2020a). These organic amendments are the carriers of microplastic that negatively impact the productivity of the crops (Porterfield et al. 2022; Iqbal et al. 2023a). Once microplastics enter agricultural ecosystems and can accumulate in soil and water, potentially leading to their ingestion by plants and soil-dwelling organisms (Tang et al. 2023a, b). It can also affect soil structure, physicochemical properties, nutrient availability, and water-holding capacity, negatively impacting crop growth and yield (Boots et al. 2019; De Souza Machado et al. 2019; Khalid et al. 2020; Liu et al. 2022).

Soil micro-organisms and feedback mechanism in the crops

Biotic components present in the soil play a critical role in the cycling of nutrient contents and keep them balanced inside the soil particles (Iqbal et al. 2023c). Thus, the soil pollutants especially microplastics and other heavy metals contamination which interact with each other in the soil can also have significant impacts on the soil microorganisms, which are crucial for maintaining soil health and ecosystem functioning (Iqbal et al. 2023b; Schmid and Schöb 2023). A thorough review of the effects of microplastic on the soil microorganisms and their roles has an impact on the abundance and activity of soil microorganisms as well as their function in soil nutrient cycling and organic matter decomposition (Sun et al. 2022; Li et al. 2023a, b, c). Relying on the microbial species and soil characteristics, different microplastics have different effects on soil microbial communities. Microorganisms may quickly adhere to and inhibit microplastic with a large surface area and significant roughness, which may hinder their evolution by forming dynamic biofilms and developing special microbial communities (Qiu et al. 2022; Zeb et al. 2024).

By changing their environment, microplastics can indirectly affect the composition and function of microbial communities (Khalid et al. 2020). They can interact with the soil matrix to create water transportation pathways that speed up soil water evaporation (Iqbal et al. 2023c). This process results in the soil surface drying up and cracking, which alters the soil’s oxygen flow and alters its distribution of aerobic microbes. As a result, microplastic could also be ingested by large soil organisms like nematodes and earthworms by changing the microbial ecology (Wan et al. 2019; Rong et al. 2021). Furthermore, the diversity, evenness, and richness of soil microbial populations were all dramatically changed by polypropylene fibers (Huang et al. 2021). On the other hand, adding PE initially had little impact on the variety of soil microorganisms, but after a culture period, bacterial aggregates with distinctive community structures (Huang et al. 2022).

Thus, the potential effects of microplastic exposure revealed a greater change in the soil microbial communities and ecosystem functioning (Rong et al. 2021). Soil microbial diversity, abundance, and activity, as well as their role in soil nutrient cycling and organic matter decomposition at different levels of CO2 affected due to microplastic contamination (Zhu et al. 2022; Buzhdygan and Petermann 2023; Li et al. 2023a). Similarly, microplastics can alter the structure and function of soil microbial communities, potentially leading to cascading effects on soil health and ecosystem functioning (Huang et al. 2022). Microplastics negatively affect the soil microbial communities in the rhizosphere of lettuce plants and significantly alter the soil microbial community, reducing the abundance and diversity of bacteria and fungi (Rong et al. 2021). Similarly, microplastics significantly reduced the diversity and abundance of microbial communities, which could impact soil nutrient cycling and plant growth of lettuce crops (Zhuang et al. 2023). Conclusively, we found that microplastics significantly altered the microbial community composition and reduced soil enzyme activities, which could impact plant growth and nutrient cycling (Fig. 1).

Fig. 1
figure 1

Schematic diagram of microplastic contamination in the soil by penetrating the root and negatively affecting the biotic and abiotic components in the soil, especially soil microorganisms by interacting with the plant community

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Overall, these reviews suggest that microplastic can have significant impacts on soil microorganisms, potentially leading to disruptions in soil nutrient cycling, organic matter decomposition, and ecosystem functioning.

Impacts on the soil properties and characteristics

The soil properties mainly include the soil structure, porosity, pH, microbial community, bulk density, and enzymatic activities, which are strongly affected by the pollutants present in the soil (Wan et al. 2019; Yu et al. 2020; Zhang et al. 2020a; Nazir et al. 2024). Thus, microplastic is considered the major pollutant nowadays, which is mainly composed of carbon contents, and negatively affects the soil properties and functioning (Yu et al. 2020). Moreover, previous researchers reported that microplastics could negatively affect soil structure, soil organic matter, soil nutrient availability, as well as microbial activities (De Souza Machado et al. 2019; Iqbal et al. 2023b; Shi et al. 2023a, b). Additionally, microplastic present in the soil adhere to the root surface through mucilage present and can penetrate through the root structure, move through the xylem inside the plant, and interfere with plant growth, including stunted root growth, changes in nutrient uptake, and alterations in the physiological properties of the plants (Li et al. 2020a; Kumar et al. 2022).

Microplastics have been discovered to have an impact on soil porosity, which can therefore affect the soil’s ability to hold water and nutrients for plants, as well as the structure of the soil, however, it creates soil cracks, which can increase soil porosity (Wan et al. 2019; Zhang et al. 2019; Iqbal et al. 2023a). In addition, bulk density is regarded as a significant indicator of soil health that influences the aeration of the soil, soil structure, soil compaction, and water and solute transport (Ingraffia et al. 2022; Brooker et al. 2023; Zeb et al. 2024). The hydrodynamic and agricultural ecosystem processes of soil are also connected to the bulk density of the soil, which affects crop productivity (Lu et al. 2019). Soil contamination with polyester microplastic did not significantly affect soil bulk density; however, it mainly affects the soil biogeochemical cycle and nutrient availability to the crops (Bosker et al. 2019; Zhang et al. 2019). In addition, a prior study showed that changes in soil bulk density were mainly affected due to the shape, size, and relative density of the microplastic contamination in the soil (Lozano et al. 2021; Sajjad et al. 2022; Zeb et al. 2024). As a result, the concentration of microplastic smaller than 100 µm is determined by the amount of sand, silt, and clay in the soil, all of which have a detrimental impact on the physicochemical characteristics of the soil (Liu et al. 2023). Similarly, higher silt and clay content leads to lower porosity, inhibiting the migration of microplastic into deeper soil layers, and resulting in the accumulation of microplastic in the smaller soil pores (Liu et al. 2023). Conversely, soils with higher sand content and greater porosity have lower water and fertilizer retention capacity, allowing microplastic to migrate vertically in the sandier soil layer, leading to a negative correlation between sand content and microplastic abundance (Liu et al. 2023; Ran et al. 2023). Microplastic contamination impacts the physical, chemical, and biological properties of the soil thus impacting plant growth and productivity (Lozano et al. 2021; Ali et al. 2024). Similarly, microplastic contamination in the soil negatively affects plant growth, including changes in the antioxidant enzyme activity, reactive oxygen species, and proteomics profiling by affecting the final yield of the crop (Boots et al. 2019; Li et al. 2022; Iqbal et al. 2023a, b; Iqbal et al. 2024).

Impacts on the soil nutrients availability

The nutrients are the significant growth limiting factor which mainly includes nitrogen (N), phosphorus (P), potassium (K), and other micronutrients. These nutrients are beneficial for the development and growth of crops. Thus, microplastic interacts with the soil organic matter which releases nutrients in the soil, and sometimes toxic materials are also released from the surface of microplastic which negatively affects the crops (Li et al. 2023b; Zhou et al. 2023). Moreover, microplastic influences the nutrient contents present in the soil by releasing more carbon thus strongly impacting the organic matter cycling and contents in the belowground ecosystem (Shen et al. 2023). The microplastics’ interactions with nutrients, however, rely on the shape, polymer structure, degradation, additives, and concentration of the microplastic as well as their location (Lozano et al. 2021). Previous researchers found that dissolved organic P and dissolved organic N increase with PP at 7% w/w but total N, total N, and K decrease with PE at 28% w/w in soil (Yu et al. 2020). In addition to this, the concentration of NO3-N and NO2-N increased with the addition of microplastic by changing the N cycling irrespective of their shape and type (Chen et al. 2022). Despite this, the addition of microplastic decreased the concentration of NH4 contents in the soil which is mainly dependent on the soil water availability (Ma et al. 2022a, b). The leachate of NO3−N under drought conditions is higher than under non-drought conditions, but the addition of microplastic to the soil decreases the leachate of nutrients (Lozano et al. 2021). In addition, the degradation of microplastic by microbes and enzymes is determined by their internal bonds, which release greater carbon contents (Rillig 2018). Similarly, phosphates are more strongly bound to soil particles than nitrate and sulfates and therefore not affected by drought conditions in the soil (Lozano et al. 2021).

The adsorption capacity of zinc is increased by the number of microplastic particles and the rise in organic matter contents, which also improves the availability of zinc to the plants in the soils (Holden et al. 2017). Alternately, worn microplastic particles also boost soil’s adsorption capabilities for its total organic carbon, calcium, copper, and chloride contents. However, they impair the desorption of heavy metals and cause them to release more of them into the soil (Holden et al. 2017; Yu et al. 2020; Iqbal et al. 2023c). As a result, the heavy metals in the soil have a stronger affinity for the worn microplastic particles, which unintentionally depletes minerals and affects the above-ground population (Yu et al. 2020).

The size of microplastic has a great influence on the adsorption of moisture contents from the soil and alternately affects the accumulation and uptake of nutrients in the plant’s body which diminishes crop growth and yield (Wu et al. 2021; Iqbal et al. 2023a). The size of the microplastic plays a significant role in how the physical, chemical, and biological aspects of the soil interact with the crops, either favorably or unfavorably impacting crop yield and productivity (De Souza Machado et al. 2019; Chen et al. 2024b). Larger surface areas of smaller microplastics make them better carriers of other pollutants including heavy metals and persistent organic pollutants (Xiang et al. 2022). In addition, the cells absorbed polystyrene beads of tiny sizes, but not the larger ones, which sealed the pores in the cell wall (Jiang et al. 2019; Li et al. 2019). Furthermore, PS beads up to 0.2 mm in size penetrate cell walls and persist in cortical tissues and the vascular system, while large-sized microplastics attached to the surface of the root but were unable to penetrate the body of the plant due to the permeability of the cell wall (Jiang et al. 2019; Wu et al. 2021). Since it is widely believed that microplastic fibers and films may have more significant impacts on soil particles than microplastic beads and spheres (Wang et al. 2022). However, microplastic fibers increase the soil’s capacity to retain the nutrients present in the soil and make them available to the plants for better growth and productivity (Liu et al. 2023). The accumulation and translocation of microplastic also depend on the charge on its body (Wu et al. 2021). Thus, microplastic with a positive charge can pass easily through cell membranes due to the oppositely charged characteristic of plants, and therefore it can accumulate more in plants than negatively charged particles (Sun et al. 2020).

Mechanisms inside the plants

There are several mechanisms through which microplastic can penetrate plant roots and move inside the plant body. The most common way through which it enters the roots is through root root hair; there are two main pathways through which it penetrates the root hairs, (1) the apoplastic pathway, and (2) the symplastic pathway (Ruiz et al. 2020). The apoplastic pathway is the pathway that refers to the movement of water and dissolved substances outside the cells (Liu et al. 2020). The symplastic pathway involves the transport of water and dissolved substances through the cytoplasm of cells via plasmodesmata. Thus, we briefly discussed the movement of microplastic inside the soil and penetrating the root hairs which further move it through the plant body through xylem sap (Fig. 1).

Negative effect on the belowground plant parts

The plant belowground part i.e., roots play an important role in nutrient absorption, water movement inside the crop body, and interaction with various organelles to fix nitrogen and other nutrients to fulfill the needs of the crop for better productivity (Lynch et al. 2021). However, the sticking of various pollutants present in the soil to the root system negatively affected crop growth and productivity (Fig. 2). Therefore, the microplastic clings on the surface of the root due to the secretion of root mucilage, adhesive capacity, large specific surface area, and finally uptake by the roots (Wu et al. 2021). Thus, microplastic of submicron size penetrates the roots of plants and then transfers to the above-ground parts with the flow of water and nutrients (Li et al. 2020b). Endocytosis, apoplastic processes, and crack entry mode are the primary mechanisms for the absorption and accumulation of microplastics (Li et al. 2020b). Small-size microplastic-like nanobeads are internalized by cells through endocytosis which are further concentrated by the mucus layer of roots and then transported through other tissues by apoplastic mechanisms (Sun et al. 2020). However, the root cap mucilage allows the large-sized microplastic to pass through the cell wall, and the apical meristem tissues allow the microplastic to diffuse during active cell division (Li et al. 2020b). Due to its accumulation in the root system’s aggregation sites, microplastic prevents nutrients and water from being absorbed by plants (Rillig et al. 2019). This is mainly due to the blocking of root surface pores reducing the ability of plants to absorb nutrients (Jiang et al. 2019). Some microplastics contain abundant C, and thus their exposure changes the carbon allocation of belowground parts of the plants (Zang et al. 2020). This change in carbon allocation may have an impact on enzyme activity, the connection between soil microbial populations and plant mycorrhiza, and ultimately the development of the plant (Wu et al. 2021).

Fig. 2
figure 2

Microplastic contamination in the soil affects the soil fauna which alternatively affects the soil and plant functions

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Exposure of microplastic to plants, reduced root growth, nutrient uptake, and photosynthetic pigment content, indicating that it can have negative impacts on plant health (Yu et al. 2022). Similarly, microplastic also significantly reduces mycorrhizal colonization and has detrimental effects on the symbiotic relationship between plants and mycorrhizal fungi (Yang et al. 2021). Low concentrations of PVC, PE, and PS significantly decreased the fresh and dry weights of the belowground parts of the crops, which suggests that microplastic significantly inhibits root growth (Wang et al. 2020; Zhuang et al. 2023). Inhibition of root growth by low concentrations of PVC and PE was stronger and caused more serious mechanical damage to the root cells than that by PS, which was possibly due to the morphologies of the microplastic present in the soil (Zhuang et al. 2023). In addition, microplastic has complex indirect effects on plant growth as it alters soil microbial communities and enzyme activities, which in turn suppresses plant growth and nutrient uptake (Li et al. 2023a). Furthermore, microplastic has negative impacts on plant–microbe interactions, as the exposure changes the rhizosphere microbial communities, ultimately reducing plant growth (Ren et al. 2021). Moreover, microplastic also has a direct impact on plant growth by affecting root development and function as it reduces nutrient uptake and root exudation by altering root morphology and physiology of the plants (Liu et al. 2023; Khan et al. 2024).

Microplastic penetration, uptake, and translocation in the plants

Microplastics can enter plants through different pathways such as uptake by roots, adsorption to leaves from the outside environment, and via soil or water uptake by the plants (Liu et al. 2022). The microplastic that is absorbed in the roots of plants may go to their aerial parts, where they may subsequently assemble in the vascular system (Dong et al. 2021). Thus, microplastic first attached to the root hairs of Arabidopsis thaliana and then entered the root cells (Liu et al. 2022), however, microplastic can penetrate the roots of rice plants through plasmodesmata (Li et al. 2020a, b). In addition, microplastic can alter the root, make abrupt changes in the morphology and physiology of wheat plants, reduce the length and surface area of the roots, and increase the diameter of the root cells (Pignattelli et al. 2021). Moreover, PS- microplastic was taken up by the lettuce and radish plants and accumulated in their tissues, including the roots, leaves, and stem (Ma et al. 2022a, b), while PE-microplastic was observed in the roots of maize plants that translocated to the shoots of the crops (Urbina et al. 2020). In addition, microplastic altered the expression of genes involved in root development and stress responses; thereby, affecting the growth and expansion of the root system which alternately affects the physiology and final yield of the crops (Liu et al. 2022; Li et al. 2023a, b, c).

The mechanisms by which microplastic affects plant growth and development have yet to be fully understood. However, it has been suggested that microplastic may disrupt the microbial communities in the soil surrounding plant roots, leading to greater changes in nutrient availability and uptake (Kumar et al. 2022). Additionally, microplastic may directly affect plant physiology and metabolism of the crop by disrupting the cell membrane and causing oxidative stress (Wang et al. 2023). The detrimental effects of microplastic on plants have been explained by several different mechanisms. One possibility is that microplastic may physically obstruct the root hairs’ passage and restrict the nutrient availability and uptake by plant roots (Huang et al. 2022; Li et al. 2023a, b, c). The exposure of crops to microplastic led to reduced photosynthetic capacity and increased oxidative stress in the maize plants. These might be due to the blockage of stomata, alternately changing the photosynthetic capacity of the crops (Sun et al. 2023).

Similarly, the atmospheric deposition of microplastic was reported to be able to accumulate on the leaves of the maize plants and resulted in a drastic change in the physiology and metabolic profiling of the crops (Zeb et al. 2021). Similarly, the cucumber plants exposed to microplastic particles led to changes in the microbiome and relative abundance of certain bacterial taxa in the root and leaf (Li et al. 2021). In addition, microplastic penetration and movement inside the plant body resulted in reduced photosynthetic efficiency and increased lipid peroxidation in the plants (Zhuang et al. 2023). Similarly, microplastic contamination in the soil, penetration inside the plant root, and movement through vascular cells led to reduced shoot and root length, as well as decreased biomass production (Liu et al. 2021; Gu et al. 2024). They also found the accumulation of microplastic in the roots and shoots of the wheat seedlings and mustard plants which revealed a greater change in the physiology and biochemical attributes concerning the carbohydrates, amino acid, and lipids metabolisms as well as leading to reduced chlorophyll content, decreased photosynthesis, and reduced biomass production in the plants (Iqbal et al. 2023a,b, 2024).

Diverse species and their response towards microplastics

Different species of plants respond differently to environmental stresses and develop specific strategies to maintain plant growth in stressful conditions. Similarly, different plant species have different penetration abilities for the uptake of nanoparticles and have different levels of sensitivity to the toxicity of microplastic (Dilnawaz et al. 2023). For instance, PS-microplastic severely hindered the root development of lettuce and corn while just marginally affecting the root growth of radish and wheat (Gong et al. 2021). Even if small-sized microplastic cannot reach the roots, they nonetheless have an impact on plant growth because they adhere to the roots, clog pores, or break cell walls, leading to oxidative stress or blocking the uptake of nutrients and water (Jiang et al. 2019; Gong et al. 2021). Similar to this, wheat and maize plants exposed to nano- and micro-PS detached the root cells’ epidermis (Gong et al. 2021). In addition, PS nanoparticles were collected in the vessel walls of mung beans (Vigna radiate), which later moved to plant leaves (Lian et al. 2020). Therefore, microplastic is considered the source of decreasing plant photosynthesis that further affects plant growth and physiology (Chen et al. 2022; Zhao et al. 2022). Still, microplastic causes more damage to plant roots than leaves and shoots, whereas reduced oxidative stress caused by ROS is more abundant in the roots than in above-ground parts of plants (Li et al. 2023b). In addition, microplastic led to reduced photosynthetic activity, decreased chlorophyll content, reduced biomass, and growth of tomato crops (Shi et al. 2022), as well as of rice crops (Ma et al. 2022a, b). Alternatively, microplastic led to oxidative stress and DNA damage, which increased the level of reactive oxygen species and lipid peroxidation, as well as increased DNA damage in the leaves of the maize and Vigna radiata plants (Pehlivan and Gedik 2021; Lee et al. 2022).

Impacts of microplastics on plant productivity

The recent studies provide insight into the impacts of microplastic on plant productivity and suggest that it can have negative impacts on plant productivity through various mechanisms, including altering soil properties, reducing nutrient availability, and interfering with plant growth and development. The exposure of tomato plants to microplastic reduced the growth, root length, plant height, and fresh weight of tomato plants (Shi et al. 2023a, b). Reduced germination rates, interrupted root growth, and decreased nutrient absorption are reported as effects of microplastic on cereal crops, such as wheat and rice, leading to stunted growth and lower yield potential (Ma et al. 2022a, b; Iqbal et al. 2023b). The edible parts of vegetable crops can accumulate microplastic, causing environmental concerns and potential health problems (Bosker et al. 2019). They may lower the nutritional content and flavor of vegetables, which may affect consumer perception and market value (Cloete et al. 2021). Furthermore, consumers may experience health risks if they consume microplastic through contaminated foods (Gundogdu et al. 2022). Thus, microplastic may adversely affect fruit size, nutrient composition, and ripening processes, according to studies on fruit crops including strawberries and tomatoes (Amare and Desta 2021). Food safety and quality are also threatened by the accumulation of microplastic on fruit surfaces (Wang et al. 2022). Although there is little information on how microplastic affects crops, preliminary research indicates that these effects may be similar in terms of how they affect growth, biomass production, and reproductive success (Lozano and Rillig 2020). It is critical to look into the potential effects of microplastic pollution in natural settings since native plants are essential to ecosystem function and biodiversity preservation (Yu et al. 2021).

Impacts on the food web and penetration of human health

Nowadays it is a hot issue to discuss the effects of microplastic effects on food chains and public health. Therefore, microplastics may be absorbed and biomagnified as they go up the food chain after entering the environment and being digested by species, having an effect on both wildlife and human health (Huang et al. 2021). In addition, microplastic has adverse impacts on human health through food consumption and potential risks of ingesting, including the potentiality concerning toxicity and the accumulation of microplastic in the human body (Prata et al. 2020). The three primary routes through which microplastic and nanoplastics reach the human body are inhalation, ingestion, and skin contact (Prata et al. 2020; Rahman et al. 2021). Among the typical types of microplastic that may be breathed through the air and arise from urban dust are synthetic textiles and rubber tires. Even though microplastic and nanoplastics enter the body through all three routes, environmental exposure through inhalation, consuming food, and seafood eating poses the greatest risk of absolute exposure (Fig. 3). This is mostly caused by environmental factors such as long-term weathering of polymers, chemical polymer additive leaching, residual monomers, exposure to pollutants, and pathogenic microbial activity (Ali et al. 2024).

Fig. 3
figure 3

The food web revealed the cycling of microplastics through bioaccumulation and biomagnification present in the aquatic, terrestrial, and agricultural land

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Ingestion is the main way that people take in microplastic particles (Lehner et al. 2019). The initial analysis revealed microplastic particles in samples of human excrement, which suggests that individuals are ingesting these particles through their food and drink. These results, along with research on digestibility absorption in environmental models, clearly show that microplastic and nanoplastics will be absorbed by people regularly (Ge et al. 2018). However, no studies have examined what happens to the micro- and nanoplastic particles once they enter the gastrointestinal tract. It would be crucial to examine the pathway of the particles through the gastrointestinal tract and determine if they pass through the gut epithelium or stay in the gut lumen. It is unlikely that microplastic may enter at the paracellular level given that the crucial holes at tight junction channels have a maximum functional size of around 1.5 nm (Alberts et al. 2002). They may enter through lymphatic tissue and phagocytose or endocytose the cells in the Peyer’s patches, which is particularly probable (Yi et al. 2023). Following intraperitoneal injections into mice, polymethacrylate and PS particles were observed to be phagocytosed by peritoneal macrophages (Carr et al. 2012). However, the results show that intestinal absorption in rodent models is just 0.04–0.3% (Carr et al. 2012).

The second most common route for humans to be exposed to microplastic and nanoplastics in the air is by inhalation. Indoor environments include airborne plastic particles, especially from synthetic materials, which can result in accidental inhalation or occupational exposure (Stapleton 2019). Inhaling polluted aerosols from the ocean’s waves or airborne fertilizer particles from dry wastewater treatment operations might result in exposure in outdoor situations (Lehner et al. 2019). The lungs’ tissue barrier is extremely thin – less than 1 µm – and their alveolar surface area is significant – about 150 m2 (Campanale et al. 2020). This barrier is sufficiently porous to allow nanoparticles to penetrate the capillary blood system, allowing them to disperse throughout the whole human body (Lehner et al. 2019). Particle toxicity, chemical toxicity, the spread of diseases, and the introduction of parasite vectors are just a few of the negative health consequences that can arise from ingesting plastic particles, especially micro- and nanoplastics (Ohlwein et al. 2019). Particles in this size range can enter the lung deeply and either stay on the alveolar surface or go to other body parts (Stapleton 2019). Particles of plastic might harm the lungs if they are inhaled. Hydrophobicity, surface charge, surface functionalization, surrounding protein coronas, and particle size all have an impact on how well micro- and nanoplastics are absorbed and expelled from the lungs (Rist et al. 2018). In addition, the research on animal absorption rates demonstrates a connection between occupational exposures and a higher risk of lung inflammation and cancer (Prata 2018).

Another significant source through which nanoplastics penetrate the body is the health and beauty industry, particularly the body and face scrubs applied directly to the skin (Hernandez et al. 2017). Despite the lack of conclusive information about the impacts of nanocarriers, small particle size and stressed skin conditions are essential for skin penetration (Schneider et al. 2009). There is currently no research that has explicitly examined how well nanoplastics can penetrate the skin’s outer layer. The skin’s outermost layer, the stratum corneum, acts as a barrier to shield the skin from injury, toxins, and microbes. The stratum corneum is made up of corneocytes, and lamellae of hydrophilic lipids including cholesterol, ceramide, and long-chain free fatty acids surrounding it (Bouwstra et al. 2001). The skin may become polluted with plastic particles by contact with contaminated water or through the use of health and beauty products. Plastic particles may still enter the body through sweat ducts, skin wounds, or hair follicles even if it is predicted that absorption through the stratum corneum through contaminated water is unlikely. This is because micro- and nanoplastics are thought to be hydrophobic (Schneider et al. 2009).

Mitigation strategies to overcome microplastic contamination

Microplastic pollution is a global environmental issue with significant negative impacts on both human and environmental health. Mitigating microplastic pollution requires a multifaceted approach involving various measures ranging from source reduction to end-of-life management. Some of the points include source reduction which is one of the greatest ways to stop the contamination brought on by microplastic is to lessen the overall amount of plastic waste produced in the original environment. This might be achieved by passing laws and regulations that support the use of alternative materials, such as biodegradable plastics, or by encouraging people to utilize reusable items. To encourage their reduction, certain nations, for instance, have imposed tariffs on single-use plastics (Ali et al. 2024). Further environmentally friendly approaches that producers can embrace include decreasing packaging and creating circular designs for items (Fadeeva and Van Berkel 2021). Similarly, wastewater treatment is a major source of microplastic pollution in agricultural land. Therefore, upgrading wastewater treatment facilities with advanced treatment technologies can significantly reduce the amount of microplastic released into the environment. For example, the use of membrane filtration systems, activated carbon, and ozonation can effectively remove microplastics from wastewater (Shah et al. 2020). Additionally, consumer education about the impacts of microplastic pollution can encourage behavior change and reduce the amount of plastic waste generated. Consumer education programs can be implemented in schools, community centers, and public events. For example, the "Beat the Microbead" campaign has been successful in educating consumers about the harmful effects of microplastic in personal care products (Mitrano and Wohlleben 2020). Moreover, several innovative technologies have been developed to mitigate microplastic pollution, such as the use of magnetic nanoparticles to remove microplastic from water and the use of biodegradable plastics in packaging materials (Din et al. 2020; Goh et al. 2022). In addition, the researchers are exploring the use of enzymes and microorganisms to degrade microplastic in the environment (Zeb et al. 2024).

Government policies and regulations can play a crucial role in mitigating microplastic pollution. For example, the European Union has banned the use of microplastic in certain products, such as personal care products, and has introduced regulations to reduce plastic waste (Elliott et al. 2020). Similarly, several countries have introduced legislation to ban single-use plastics, which can significantly reduce the amount of plastic waste generated (Zeb et al. 2024). In conclusion, implementing these measures will require a collaborative effort from governments, industries, and individuals to achieve a sustainable future.

Conclusion

Microplastic pollution is a global environmental issue that poses significant risks to soil health, plant growth, and human health. Our review article highlights the current state of knowledge on the fate and effects of microplastic pollution on soil and plant systems, as well as the potential risks to human health through the food chain. The review synthesizes the latest research data and findings and identifies important research gaps and priorities for future investigation. Overall, the study shows that soil physicochemical features, microbial populations, nutrient cycling, and plant growth and development can all be profoundly impacted by microplastic contamination. Furthermore, although the entire degree of these threats is not yet known, eating food and drinking water polluted with microplastic may be harmful to human health. The review underscores the urgent need for greater awareness, policy interventions, and technological solutions to address the emerging threat of microplastic pollution in soil and plant systems and mitigate its potential impacts on human health. In summary, the review highlights the need for a comprehensive and integrated approach to address microplastic pollution, incorporating research, policy, and technological solutions, and involving interdisciplinary collaborations across multiple sectors. Only through such collective efforts can we effectively address this global environmental issue and safeguard the health of our soils, plants, and, ultimately, human populations.

Research gaps and future perspectives

  • The transfer of microplastic through trophic from plants to soil fauna is mainly unexplored. Thus, microplastic can enter the plants and transfer to other living organisms such as consumers. Therefore, the health risks associated with microplastic in edible parts of crops should be investigated.

  • Similarly, microplastic acts as a vector for various contaminants including heavy metals, antibiotics, pathogens, and organic pollutants in the plant-soil system. Therefore, it’s the need of hour to deeply investigate the co-exposure impact of microplastic with other pollutants on the physiological, biochemical, ultrastructural, and molecular levels of different crops.

  • More in-depth studies on different types of microplastics and additives according to their natural occurrence in the soil will also help to enhance our understanding of their interactive toxicities on living organisms.

  • Previous studies focused on short-term microcosm experiments. Therefore, long-term experiments at a large scale are highly recommended to fully uncover the actual effect of microplastic on edible crops. Life cycle studies are the need of hour to investigate whether microplastic can accumulate in grains of edible crops such as wheat, rice, and maize.