Nanoplastics (NPs): Environmental Presence, Ecological Implications, and Mitigation Approaches

Abstract

Nanoplastics (NPs), the tiniest and one of the most problematic fractions of plastic pollution, present dangers because of their size, reactivity, and ecosystem interactions. This review highlights the distinct characteristics, sources, routes, and ecological effects of NPs, a substantial subgroup of plastic pollution. With a focus on their ecological and toxicological implications, this review highlights the unique qualities of NPs and their functions in wastewater and urban runoff systems. The analysis of NPs’ entry points into terrestrial, aquatic, and atmospheric ecosystems reveals difficulties with detection and quantification that make monitoring more difficult. Filtration technologies, adsorption-based techniques, and membrane bioreactors are examples of advanced technical solutions emphasized as efficient NP mitigation measures that can integrated into current infrastructure. Environmental effects are examined, including toxicological hazards to organisms in freshwater, terrestrial, and marine environments, bioaccumulation, and biomagnification. This analysis emphasizes the serious ecological problems that NPs present and the necessity of using civil and environmental engineering techniques to improve detection techniques, enact stronger laws, and encourage public participation.

1. Introduction

Nanoplastics (NPs), defined as plastic particles smaller than 1 µm, are generating numerous concerns about both environmental and human health [1]. These minute particles can easily penetrate biological barriers within organisms [2]. Recent evidence confirms the ubiquitous presence of NPs across ecosystems and, importantly, within human biological systems including the bloodstream, placenta, and even breast milk [3,4]. This raising concern highlights the urgency of further research on these pollutants and necessitates a greater understanding of (1) the complex impacts of NPs on ecosystems and human health; (2) their mechanism of action; and (3) the development of effective strategies to prevent NP pollution. This review studies the current knowledge on their occurrence in the environment, ecological impacts, and toxicological mechanisms, and mitigation strategies for NPs. Also, it highlights the gaps in current research and proposes some directions for future studies.

The term “polymer” refers to a structure composed of long chains of repeating molecules called “monomers”, meaning “many parts”. Plastic manufacturers usually utilize two types of polymers: natural and synthetic. In contrast to natural polymers like silk, cellulose, muscle fiber, rubber, hair, and DNA, synthetic polymers are artificial. These are produced using natural raw materials, including oil, coal, and natural gas [5]. Besides natural and synthetic polymers, there are two additional types of plastics: bioplastics and biodegradable plastics. Bioplastics are created solely from biomass-based materials, while biodegradable plastics can originate from either petroleum-based or biomass-based resources [6,7]. Leo Baekeland invented the first synthetic plastic in 1907 by combining phenol and formaldehyde. This resulting material was inexpensive, durable, heat-resistant, and perfect for large-scale mechanical production [8,9,10]. The first modern plastic invented was polyvinyl chloride (PVC), which continues to be produced and utilized for numerous products globally.

The most produced synthetic plastics are thermoplastics and thermoset plastics. Thermoplastics, including high-density polyethylene (HDPE), polyvinyl chloride (PVC), polyethylene (PE), polyethylene terephthalate (PET), low-density polyethylene (LDPE), polypropylene (PP), polyamide (PA), and polystyrene (PS), are favored for their ability to be quickly melted and reshaped. In contrast, thermoset plastics lack these reshaping properties, such as polyurethanes, phenolic, unsaturated polyester, silicone, melamine, epoxy, and acrylic resins. Consequently, thermoplastics are the most widely used plastic material [11].

By 2015, plastics had become the third most-produced material globally, with an estimated 8.3 billion metric tons [12], roughly double the mass of all animals on Earth [13,14]. Plastics are integral to modern industry and society, providing various advantages and creating significant environmental problems. Microplastics (MPs) and nanoplastics (NPs) have spread to nearly every corner of the globe, including rivers [15], lakes [16], soils [17], sediments [18], and marine environments, ranging from coastal waters near human activity to the most remote oceans [19]. They have even been detected in the deepest ocean sediments [20], the Earth’s poles [21], the biosphere [22], and throughout the atmosphere [23]. Thus, NPs are found in soil, freshwater, snow, sea ice, and seawater [24]. These findings underscore the urgent need for engineering solutions to tackle NP contamination, particularly in urban environments and wastewater systems. Experts predict the worldwide population will grow from 7 billion to 10 billion by 2050 [25]. This surge will require a 50% increase in annual food production. To meet this demand, the yearly growth rate of crop production must exceed the rates observed in recent periods. Conversely, the growing population imposes an increased burden on the limited resources available for global food production [26]. The COVID-19 pandemic has further complicated progress by creating unexpected negative global situations [27]. During the pandemic, the global economy, human health, the agricultural sector, and food security were significantly impacted [28,29]. Social distancing restrictions led to an unforeseen shift in food supply dynamics, transferring much of the food supply to households.

Additionally, plastics are increasingly significant in achieving sustainability goals and are considered crucial in modern agriculture worldwide. They are widely used in various agricultural activities such as mulching, seedling trays, pesticide containers, and drip irrigation [30,31]. These plastics have undeniably contributed to increased crop production. However, they have also become a primary environmental concern, adversely affecting water, soil, and plants [32].

While existing studies have investigated MPs and their effects on the environment, a significant gap exists in comprehensive reviews discussing NPs regarding their nanoscopic size and their greater toxicological effects. Many existing studies tend to generalize results from MPs or focus on isolated aspects, such as detection methods, toxicological impacts, etc. However, NPs exhibit unique behaviors due to their size, reactivity, and capacity to traverse biological membranes leading towards more severe ecological and health impacts. Additionally, numerous studies discuss individual detection methods or toxicological mechanisms, but integrative analysis is inadequate. There is a need for research that combines information on NP sources, environmental pathways, and risks for all ecosystems; explores NPs’ bioaccumulation and biomagnification patterns; evaluates current and emerging mitigation methods; assesses policy, public awareness, and waste management strategies; and, importantly, outlines the limitations of existing removal methods. This review intends to bridge this gap by providing a holistic overview of NPs and their detection, fate, impacts, and mitigations, and highlight the knowledge gap in regulation and innovations.

The background and historical context of plastics and NPs are discussed in Section 1. Section 2 provides information on existing studies available and reviews methodology. Section 3 details the sources, distribution, and detection of NPs. It also provides details on the ecological impacts and human health risks. A detailed discussion on the exposure pathways of NPs in the aquatic, terrestrial, and atmospheric systems is included in Section 4. Details on ecological impacts such as toxicological processes, biomagnification, and bioaccumulation are discussed in Section 5. Several mitigation strategies, including regulatory measures, behavioral changes, and technological advancements, are discussed in response to the escalating problem of NP pollution in Section 6. The objectives are to understand NP dynamics and comprehensively identify effective mitigation strategies. This study is driven by a noticeable gap in current research regarding the effects of NPs on the environment and ecosystems. While the impacts of larger plastic debris and MPs are well-documented, the unique challenges posed by NPs remain poorly understood. By recognizing these knowledge gaps, the review advocates for future research to improve understanding and underscores the urgent need for action to address NP contamination and protect the global environment ecosystems.

2. Review Methodology

To further explore the existing body of research on this topic, a bibliometric analysis was conducted using VOSviewer 1.6.20, a popular tool for visualizing and generating bibliometric networks to further explore the existing body of research on this topic. The analysis was focused on the keywords “nano plastics”, “impacts”, “environmental”, and “pathways”. These keywords were used in various ways to find related publications from “Scopus”, “Google Scholar”, and “ScienceDirect”. Additional search settings included (1) Years from 2017 to 2025. (2) Article types: Review, Article, Book Chapter, Short Survey, Conference Paper, and Notes. (3) Language: English. A total of 172 peer-reviewed publications from different countries were considered for this review. These 172 publications represent contributions from multiple countries, underlining growing concern around NP pollution. However, despite this increased attention, the literature on NPs remains significantly lower compared to MPs, indicating a research gap.

Figure 1 presents a visualization of the co-occurrence of these keywords; by inputting these keywords, VOSviewer generated a comprehensive visualization of how these terms converge in the scientific literature. This analysis revealed key research clusters and connections between studies on NPs and their effects, highlighting major themes and emerging trends. Each node represents a keyword found in the analyzed literature, with the node’s size indicating the keyword’s frequency. Larger nodes signify the more frequent appearance of the keyword. Edges between nodes illustrate the co-occurrence of keywords within the same document, while the thickness of the edges reflects the strength of the co-occurrence relationship. Different colors depict clusters of related keywords. For instance, the red cluster emphasizes environmental impacts and human health, featuring keywords such as “microplastics”, “nano plastics”, and “toxicity”, underscoring significant research interest in the adverse effects of NPs and MPs on health and ecosystems. This study also includes reviews addressing civil and environmental engineering approaches to detecting and mitigating NPs, including wastewater treatment, urban infrastructure, and material engineering. The bibliometric analysis provides valuable insights into this field’s current state of research, identifying gaps in knowledge and potential areas for future exploration. These findings enhance our understanding of the pervasive issue of plastic pollution and its profound environmental consequences.

This review focuses on the emergence of NPs, their sizes and sources, environmental presence, pathways in various ecosystems, mechanisms of toxicity, and mitigation strategies. It employs a systematic approach to gathering all relevant studies. Additionally, the review emphasizes the role of engineering innovations, including membrane bioreactors, advanced filtration systems, and urban stormwater management strategies, in addressing NP pollution. Figure 2 shows the scope of the review.

3. Nanoplastics: Definition, Distribution, Detection, and Risk Analysis

3.1. Definition and Sources

NPs are tiny plastic particles from 1 to 100 nm in diameter [33]. However, other studies have defined NPs with upper size limits up to 1000 nm depending on the context and behavior [34]. They can be formed through the fragmentation of larger plastic debris, such as MPs, via various processes, including physical, chemical, and biological mechanisms. NPs also encompass particles intentionally manufactured in this size range for specialized applications such as drug delivery systems, cosmetics, and other advanced industrial uses. Their small size imparts unique chemical and physical properties, enabling them to penetrate biological membranes, enter cellular structures, and even cross the blood–brain barrier in organisms [35]. NPs exhibit colloidal characteristics like Brownian motion and high surface reactivity, making them susceptible to aggregation [36]. Furthermore, they can leach additives and traverse physiological barriers more rapidly than larger plastic particles. This increased mobility can lead to greater organism exposure to toxins than micro- and macroplastics [37,38].

The widespread occurrence of NPs poses significant challenges for engineered systems, such as wastewater treatment plants (WWTP) and stormwater management infrastructures, where their nanoscale properties complicate detection, quantification, and removal. This persistence and mobility have heightened the need for scientists, policymakers, government officials, and the public to understand their environmental impacts and develop mitigation strategies [39,40]. The production and subsequent breakdown of everyday plastics have unintentionally increased the presence of these tiny particles in various ecosystems [41]. NPs are now found in aquatic, terrestrial, and atmospheric environments, underscoring the urgent need for advanced strategies to manage their impacts. Practical solutions include integrating advanced filtration technologies, adsorption systems, and sediment management into infrastructure designs to mitigate NP contamination.

While some studies adhere to a stricter 100 nm size limit, others classify NPs by their origin and include particles up to 1000 nm. Generally, NPs are categorized into two types: primary and secondary. Primary NPs are intentionally produced and smaller than 1000 nm [34]. They are discharged into the environment through various sources, such as personal care products (e.g., cosmetics, facial scrubs), engineered materials (coatings and membranes used in construction and water management systems), and industrial activities (e.g., 3D printing, polystyrene foam cutting) [34]. Additional sources of primary NPs include daily-use plastic items, such as medical diagnostics, plastic chopping boards in food processing, nanocapsules from drug delivery systems, and biomedical products. Secondary NPs are created from the fragmentation of larger plastic particles into smaller sizes of less than 100 nm. They primarily arise from the degradation of larger plastic items in aquatic and soil environments, including land-based plastic litter, which undergoes physical, chemical, and biological weathering processes [42]. The unique properties of NPs, such as their high surface-area-to-volume ratio and reactivity, distinguish them from MPs. Consequently, the classification of NPs extends beyond that of MPs. These characteristics influence their environmental behavior, biological interactions, and ability to penetrate biological barriers. Therefore, it is crucial to understand the pathways of NPs and design effective mitigation strategies and technologies. In this review, NPs are considered as plastic particles smaller than 1000 nm, acknowledging that particles <100 nm often exhibit distinct nanoscale behavior.

3.2. Environmental Presence

3.2.1. Distribution

The distribution of NPs in the environment depends on various factors, including their shape, size, density, surface properties, environmental conditions like wind patterns, water currents, and other contaminants. NPs have been found in diverse environments ranging from surface waters and sediments to atmospheric samples and isolated areas, indicating their widespread distribution on the Earth [40].

In aquatic systems, NPs are transported over long distances by water currents and can accumulate in sediments, where they may stay for extended periods [43]. This causes significant challenges for WWTPs, often serving as both sources and sinks for NPs. Enhancing filtration and sedimentation technologies in WWTPs is critical for mitigating their distribution into natural water systems.

In the atmospheric systems, NPs are transferred by winds and deposited in aquatic and terrestrial environments through dry and wet deposition processes [23]. Urban areas are particularly susceptible, as stormwater runoff and combined sewer overflows can further facilitate NP movement into water bodies. Addressing this issue requires advanced stormwater management systems with pollutant separators and sediment traps. NPs interact with abiotic and biotic components, affecting their distribution and probably leading to bioaccumulation and biomagnification in food chains. Understanding these distribution patterns is important for evaluating environmental risks and impacts associated with NPs.

3.2.2. Environmental Sampling

Environmental sampling is essential for understanding the distribution and abundance of NPs in various ecosystems. Filtration is one of the most used techniques for separating NPs from environmental water samples. Typically, filters with pore sizes of 0.1 µm to 0.45 µm are used to capture nanoparticles effectively, as the upper size limit for NPs is 1 µm. This range ensures the collection of most NPs while reducing the loss of smaller particles. However, using such fine pore sizes can result in frequent clogging, especially when dealing with samples high in organic matter or suspended solids. To address this issue, pre-filtration steps or the use of multiple filters in series may be necessary to maintain the flow and efficiency of the filtration [44].

Different filter materials, like cellulose acetate, polycarbonate, nylon, etc., are selected based on the specific application and required characteristics, including chemical compatibility and flow rate. Filtration efficiency can also be affected by NP aggregation and electrostatic interactions with the filter membrane, which may change the retention of smaller particles. After filtration, density separation techniques, like centrifugation or gradient separation, are commonly used to isolate NPs from other components in environmental samples. For example, centrifugation can help to separate NPs based on their density differences, enabling further analysis [45].

Passive samplers are another effective tool for environmental sampling. They provide a time-integrated measurement of NP presence and average concentration over a specific period [46]. These samplers are cost-effective, relatively easy to deploy, and offer the long-term monitoring of NPs in aquatic environments. The material properties of the sampler affect the types of NPs captured, and factors such as water flow and biofouling can affect sampling efficiency.

3.2.3. Detection, Characterization, and Quantification

Understanding the presence of NPs and possible effects requires their identification and measurement in environmental samples. Advanced microscopic techniques like scanning electron microscopy (SEM) and transmission electron microscopy (TEM) visualize NPs at the nanoscale, making it possible to identify their structural characteristics [47]. Because mass spectrometry techniques like pyrolysis, gas chromatography, and mass spectroscopy break down NPs into recognizable bits, they help evaluate complicated environmental samples [48].

According to Balakrishnan et al. (2023), the Dynamic Light Scattering (DLS) approach determines the size distribution of nanoparticles (NPs) in a suspension by measuring their Brownian motion [49]. Flow Cytometry is a technique that uses lasers to examine individual particles as they move through a stream of fluid. Fluorescent tags may be utilized to determine the type of polymer in nanoparticles and count and size them [50]. X-ray photoelectron spectroscopy (XPS) is a surface-sensitive method that details the atoms’ oxidation state and elemental makeup at the surface of nanoparticles. Understanding how NPs might interact with environmental elements can be aided by XPS [51].

Spectroscopic methods, including Raman spectroscopy and FTIR, are used in analytical NP characterization approaches. These methods can differentiate plastic particles according to their chemical composition [52]. Although Raman spectroscopy can precisely assess particles as small as 1 micrometer, signal constraints make it challenging to use this technique for particles smaller than 1 micron [53]. The vibrational modes of molecules inside a sample are examined using Raman spectroscopy. Additionally, it can offer supplementary data regarding the chemical makeup and possible impurities on the NPs’ surface [53]. Conversely, FTIR measures how a sample interacts with infrared light to determine its chemical makeup. Based on their distinct spectral fingerprint, FTIR can determine the sort of NPs that are plastic [52]. For MP analysis, FTIR is frequently utilized. It works well for particles larger than 20 microns but has sensitivity problems when detecting particles more minor than that.

Despite these developments, NPs are still difficult to detect and measure because of their small size, low concentrations, and complex nature in environmental samples. Limitations of current approaches include sensitive thresholds and challenges in differentiating NPs in mixed matrices. Researchers frequently combine different approaches for more thorough characterization, such as spectroscopic techniques with thermal analysis or microscopy, to circumvent the limitations of individual detection methods. It is crucial to remember that there is no one-size-fits-all approach, and efforts are being made to increase the sensitivity and precision of these methods to detect NPs better.

Table 1. NP detection methods.

Technique	Detection Principle	Advantages	Limitations	Reference
Microscopy	Light Microscopy: Direct visualization and differentiation by size and morphology (limited to ~1 µm). Confocal Laser Scanning Microscopy: High-resolution 3D imaging.	Non-destructive Visualizes particle size and morphology	Limited size resolution (especially for particles smaller than 1 µm) Difficulty differentiating NPs from natural materials	[54]
Spectroscopy	Raman Spectroscopy: Identifies materials based on their vibrational fingerprint. Fourier-Transform Infrared Spectroscopy (FTIR): Analyzes chemical bonds to identify the polymer types. Fluorescence Spectroscopy: Detects fluorescent nanoparticles.	Highly specific for polymer identification It can be used with small sample volumes	Requires pre-concentration of samples Potential interference from background materials May not detect all types of NPs Limited sensitivity for detecting NPs below 1 µm, especially without enrichment techniques	[55]
Thermal Analysis	Pyrolysis-Gas Chromatography/Mass Spectrometry (Py-GC/MS): Analyzes the breakdown products of a sample to identify and quantify polymers.	Quantifies total plastic mass Identifies specific polymer types	Destructive technique Requires complex instrumentation Limited information on particle size and morphology	[56]
Flow Cytometry	Analyzes individual particles as they flow through a laser beam, measuring properties like size, fluorescence, and light scattering.	Fast analysis, automatable, and suitable for large numbers of particles Can differentiate some natural from synthetic particles based on fluorescence	Limited ability to differentiate between natural and synthetic particles requires pre-staining for some functionalities Reduced accuracy for detecting particles below ~300 nm	[50]
Dynamic Light Scattering (DLS)	Measures the Brownian motion of nanoparticles in a liquid suspension to determine their hydrodynamic size.	Rapid analysis is non-destructive and provides size distribution information	Limited information on particle composition may not be suitable for irregularly shaped particles Struggles with differentiating individual particles in complex environmental samples	[49]
Inductively Coupled Plasma Mass Spectrometry (ICP-MS)	Detects and quantifies specific elements present in NPs after dissolving the sample.	Highly sensitive, can identify specific types of plastic based on elemental composition	Destructive technique requires complex instrumentation and may not differentiate between pristine and degraded plastics	[57]
Atomic Force Microscopy with Infrared Spectroscopy (AfFIRM)	Combines high-resolution imaging of AFM with chemical identification capabilities of infrared spectroscopy for individual nanoparticle analysis.	Provides detailed information on size, morphology, and chemical composition at the nanoscale	Expensive, time-consuming analysis, limited sample throughput	[58]
Biosensors	Utilize biological elements like antibodies or enzymes that specifically bind to NPs, generating a measurable signal.	Highly specific for certain types of plastics, potential for developing portable and field-deployable devices	Under development, a limited range of detectable plastic types may require complex pre-treatment steps	[59]

Note: While techniques like FTIR and Raman spectroscopy are powerful for polymer identification, their sensitivity drops significantly for particles <1 µm without specialized equipment or enrichment steps.

below provides an overview of the standard techniques currently employed for NP detection.

3.3. Potential Risks

The widespread presence of NPs in the environment has raised significant concerns about their probable impact on living organisms. These NPs can enter food webs, accumulate in tissues, and possibly cause harmful effects. The inhalation and/or ingestion of NPs poses additional health risks to humans, potentially leading to respiratory, gastrointestinal, or systemic issues [60]. In urban and industrial areas, NPs released from construction materials, tire wear, and wastewater can accumulate in stormwater systems and urban soils. This accumulation threatens ecosystem health and infrastructure stability [23,45,60]. Table 2 provides a more detailed overview of the potential risks of NPs on ecological systems and human health.

3.4. Ecological and Health Risk

The presence of NPs in the environment poses substantial risks to ecological systems and human health. Due to their minute size and high surface-to-volume ratio, they can easily interact with biological membranes, leading to physical and chemical toxicology. Their small size allows them to infiltrate various environments and interact with organisms concerningly [61].

3.4.1. Ecological Risks

In terms of ecology, NPs can be consumed by a wide range of creatures at different trophic levels, which causes bioaccumulation and biomagnification in food webs. In aquatic environments, NPs have been shown to disrupt feeding behavior, impair reproduction, and reduce survival rates in various marine species such as fish, mollusks, and zooplankton [62,63]. In terrestrial systems, NPs alter soil microbial communities and reduce nutrient cycling, ultimately affecting plant growth and agricultural productivity [63]. The ingestion of NPs disrupts the dynamics of the food chain at lower trophic levels by reducing the nutritional value of organisms for predators and impairing their ability to hunt [64] (Wright et al., 2020). Food webs may become less stable and resilient because of this disturbance. Long-term exposure to NPs causes functional changes in ecosystems, mortality, and reproductive impairments, all of which contribute to the loss of biodiversity [65,66].

Additionally, NPs multiply and accumulate in tissues when they enter the food chain, offering serious dangers to apex predators, including weakened survival and health [67]. Furthermore, NPs change how ecosystems work by interfering with the behavior of organisms and biochemical processes, which impacts soil health, water quality, and nutrient cycling [68]. These imbalances can hinder environmental damage and lessen the ecosystem’s capacity to deliver necessary services. Protecting ecological integrity and putting sustainable management techniques into place requires addressing these complex effects of NPs. Further details on ecological impacts are discussed in Section 5.

3.4.2. Human Health Risks

NPs can cause several health risks, including inflammation, respiratory issues, reproduction problems, and even disruption of cellular processes [35]. As previously mentioned, recent studies have detected NPs in the human placenta, breast milk, and blood, raising serious concerns about their potential impact on fetal development and long-term health [3,69]. For humans, the primary exposure routes of NPs are through ingestion, inhalation, and dermal contact. The ingestion of NPs can occur through contaminated food and water, which might result in gastrointestinal distress and systemic exposure as NPs translocate across the gut barrier. The inhalation of airborne NPs can trigger pulmonary inflammation and worsen respiratory illnesses. Once inhaled, these particles may cross the alveolar–capillary barrier and enter the bloodstream, raising concerns about systemic distribution [63,70]. Reports have shown that NPs can accumulate in various human tissues, potentially disrupting cellular processes and triggering oxidative stress and inflammation [35,60]. This oxidative imbalance can damage cellular components and trigger inflammation, further exacerbating tissue injury [62]. Cutaneous exposure, though less studied, is also relevant, especially when using personal care products like exfoliants and cosmetics. While human skin acts as a barrier, NPs smaller than 100 nm may still penetrate the dermal layers [71]. Once internalized, they have the potential to be distributed throughout the human body, reaching organs like the lungs, kidneys, liver, intestines, and even the brain [71]. There is also growing evidence suggesting immunotoxicity, with NPs potentially impairing immune cell function—particularly T lymphocytes—thereby increasing susceptibility to infections and autoimmune diseases. These risks highlight the need for proactive strategies to minimize NP release into the environment.

Table 2. Potential risks of NPs on ecological systems and human health.

Area of Concern	Potential Risks	Mechanism Description	Potential Sources	References
Ecological Systems	Trophic distribution and biodiversity loss	NPs (<100 nm) damage feeding in Daphnia manga and reduce reproduction in Mytilus galloprovincialis (mussels). Reduced prey quality affects predators like fish and seabirds.	Plastic degradation in the environment WWTP effluent Synthetic textiles runoff	[72,73]
	Bioaccumulation and biomagnification	Risk of trophic transfer in marine food chains Artemia (brine shrimp) exposed to NPs are consumed by fish (Danio rerio), resulting in NP buildup in gills and liver.	Treated wastewater Urban runoff	[73,74]
	Soil and water function disruption	NPs reduced soil microbial diversity and nutrient cycling in agricultural soils near plastic mulch zones in China.	Plastic mulch breakdown WWTP sludge reuse	[67,68]
Human Health	Respiratory problems	Inhalation of airborne NPs from tire wear and incinerators linked to chronic bronchiris in urban workers (e.g., Italy, Milan).	Urban air pollution Industrial emission	[75]
	Systemic inflammation and organ damage	Ingested NPs found in bottled water and seafood (e.g., mussels from French coast) can cross gut barrier and affect liver/kidney function in humans.	Plastic packaging Seafood Tap/bottled water	[35,76]
	DNA damage and developmental problems	NPs from microbead-containing cosmetics caused DNA strand breaks in human epithelial cells in lab studies. Potential fetal toxicity via placenta.	Personal care products Drinking water	[77,78]

Table 2. Potential risks of NPs on ecological systems and human health.

Area of Concern	Potential Risks	Mechanism Description	Potential Sources	References
Ecological Systems	Trophic distribution and biodiversity loss	NPs (<100 nm) damage feeding in Daphnia manga and reduce reproduction in Mytilus galloprovincialis (mussels). Reduced prey quality affects predators like fish and seabirds.	Plastic degradation in the environment WWTP effluent Synthetic textiles runoff	[72,73]
	Bioaccumulation and biomagnification	Risk of trophic transfer in marine food chains Artemia (brine shrimp) exposed to NPs are consumed by fish (Danio rerio), resulting in NP buildup in gills and liver.	Treated wastewater Urban runoff	[73,74]
	Soil and water function disruption	NPs reduced soil microbial diversity and nutrient cycling in agricultural soils near plastic mulch zones in China.	Plastic mulch breakdown WWTP sludge reuse	[67,68]
Human Health	Respiratory problems	Inhalation of airborne NPs from tire wear and incinerators linked to chronic bronchiris in urban workers (e.g., Italy, Milan).	Urban air pollution Industrial emission	[75]
	Systemic inflammation and organ damage	Ingested NPs found in bottled water and seafood (e.g., mussels from French coast) can cross gut barrier and affect liver/kidney function in humans.	Plastic packaging Seafood Tap/bottled water	[35,76]
	DNA damage and developmental problems	NPs from microbead-containing cosmetics caused DNA strand breaks in human epithelial cells in lab studies. Potential fetal toxicity via placenta.	Personal care products Drinking water	[77,78]

3.4.3. Mitigation Strategies

Effective urban design strategies can lessen the hazards posed by NPs. These strategies include enhanced stormwater management systems, green infrastructure, and efficient wastewater treatment procedures. Preventing NPs from entering drinking water requires cutting-edge technology like nanofiltration and adsorption-based techniques in wastewater systems. It is critical to comprehend the environmental fate and influence of NPs to establish solutions that safeguard human health and ecological systems.

4. Fate and Impacts of NPs

4.1. Pathways and Impacts on the Ecosystem

There are various ways that NPs might enter ecosystems. Due to their size and chemical makeup, these tiny plastic particles quickly move throughout the environment and human bodies, connecting with different ambient elements and organs. Aquatic, terrestrial, and atmospheric routes are the main ways that NPs enter and spread throughout ecosystems. Understanding these pathways is crucial for determining the amount of NP pollution, measuring its concentrations, and creating plans to lessen its effects. Figure 3 shows the different ways that NPs might enter different ecosystems.

4.1.1. Aquatic Pathways

NPs can reach aquatic habitats via various pathways, such as air deposition, land runoff, and wastewater discharge. Depending on how close to pollution sources an aquatic ecosystem is, the concentration of NPs has been found to range from 0.01 to 10 particles per liter [2,79]. NPs seriously threaten aquatic ecosystems because they are carried by water currents and build up in sediments after being introduced into water bodies. NPs can absorb dangerous pollutants such as heavy metals and persistent organic pollutants, which increases their toxicity [2]. These contaminants can disturb aquatic ecosystems because zooplankton, essential to the marine food web, may consume them [80].

Plankton and larger marine creatures are among the trophic levels in marine ecosystems that NPs impact. Physical obstructions decreased feeding effectiveness, and toxicological effects from the leaching of hazardous substances can all result from NP ingestion. Additionally, NPs can carry contaminants and diseases, worsening mortality and detrimental effects on marine life. The potential for NPs to disturb marine ecosystems is further highlighted by studies showing that they may change marine animal’s gene expression and metabolic processes. The necessity for localized concentration-based risk evaluations is further supported by studies that have revealed that NP concentrations in coastal waters are noticeably more significant than in open oceans [81,82,83].

In freshwater ecosystems, regions with high levels of human activity tend to have NP concentrations ranging from 0.1 to 5 particles per liter. Due to NP exposure, freshwater creatures may experience physiological stress, behavioral abnormalities, and physical injury. Furthermore, NPs might upset the ecological balance by changing the water quality and nutrient cycling. According to recent research, the decomposition of organic matter and the dynamics of nutrients may be impacted by NPs’ effects on microbial communities in freshwater environments [84,85].

4.1.2. Terrestrial Pathways

In terrestrial ecosystems, NPs are carried by soil infiltration, surface water runoff, atmospheric deposition, and bioturbation. The breadth of terrestrial NP pollution is demonstrated by studies that found NP concentrations in urban areas as high as 3000 particles per kilogram of dry soil [86]. Additionally, NPs travel from terrestrial to aquatic systems by soil infiltration and surface water runoff, although many questions remain unanswered about their environmental routes. Heinze (2019) highlights the function of earthworm bioturbation in soil NP redistribution [87]. Although there is negligible advection through percolating water, bioturbation significantly increases NP mobility in soil systems.

According to Babele et al. (2023), NPs have been demonstrated to modify soil geochemistry, damage soil biota, and carry other contaminants in agricultural ecosystems, influencing plant development and performance [88]. NPs can reach soils through biosolids, plastic trash, and agricultural practices by influencing microbial communities and enzyme activities. They may disrupt the nutrient cycle and lower soil fertility [89]. Depending on exposure levels, studies of root uptake have shown that NP accumulates in plants at concentrations ranging from 1 to 50 particles per gram of plant tissue. The possibility that NPs would enter the food chain, move to herbivores, and affect higher trophic levels, ultimately endangering the health of the ecosystem, is raised by this buildup [90,91].

Additionally, the soil characteristics can be changed by NPs, which can impact water retention, nutrient availability, and microbial activity. According to research, NPs can also alter the shape of roots and decrease photosynthetic efficiency, which can have long-term effects on plant productivity and health [92,93]. Green infrastructure technologies, such as bio-retention systems and permeable pavements, can solve these issues by capturing and filtering NPs before they enter water bodies. In agricultural settings, NP pollution can be reduced by engineering soil amendments and filtration systems, enhancing soil health and lowering ecological hazards.

4.1.3. Atmospheric Pathways

The atmospheric ecosystem pathways for NPs include several processes, including deposition, transport, and emission. Research has shown that the concentrations of NP in urban air range from 0.1 to 5 particles per cubic meter, while the concentrations in remote places are much lower [86]. Additionally, this study summarizes the movement, destiny, and occurrence of plastics and NPs. In moving these particles from terrestrial to aquatic environments, they have observed that air deposition plays a critical role. The transport of nanoparticles (NPs) in soils by advection and bioturbation is covered by [87]. Percolating water and earthworm activity disperse NPs in soil layers, which may release them into the atmosphere [87]. Their work further emphasizes that NP behavior in unsaturated soils, which is more realistic in field settings, exhibits significant redistribution due to bioturbation but minimal mobility through percolating water. The phytotoxicity of NPs, on the other hand, is discussed in the study on agroecosystems by [88], which highlights how they can carry other pollutants and induce oxidative stress in plants, thereby indirectly influencing atmospheric ecosystems through interactions between soil and plants.

It has been reported that NPs can travel long distances via atmospheric transport. According to Dris et al. (2016) and Bergmann et al. (2019), ice cores from the Arctic Ocean have shown NP concentrations of up to 10 particles per liter, indicating global dispersion [55,79,94]. Since atmospheric transmission can pollute soils and aquatic bodies far from the source, NP pollution is pervasive. These findings highlight how quantitative assessments of NP concentration levels in diverse environments are essential to understanding their environmental impact. By installing vegetation barriers and rooftop gardens, urban sustainability can be enhanced and atmospheric NP burdens reduced. Furthermore, advanced air filtration technologies for industrial buildings and urban green spaces can significantly decrease NP deposition into ecosystems.

5. Ecological Impacts of NPs

5.1. Accumulation and Trophic Transfer of NPs

5.1.1. Bioaccumulation

The ecological impacts of NPs on biodiversity and ecosystems are multidimensional and intense. Bioaccumulation refers to the accumulation of NPs in organisms over time. Since NPs can interact with environmental toxins, act as transporters, and affect toxicity toward freshwater biota, their bioaccumulation in ecosystems is a worrying problem [95]. According to research, NPs can move across the environment, be absorbed by living things, and accelerate the bioaccumulation of pollutants in freshwater species. The physicochemical properties of NPs, such as charge, and size also affect the bioaccumulation. For example, positively charged NPs tend to accumulate more in organisms compared to negatively charged NPs [72]. Also, smaller-sized NPs are more easily taken up by cells due to their larger surface-area-to-volume ratio, leading to enhanced bioaccumulation [96].

Polystyrene nanoparticles have caused concern in several ecosystems, including terrestrial and marine ones, because they can enter animals through various pathways and then build up along food webs [97]. Additionally, knowing how NPs bioaccumulate is essential for determining how they affect ecosystem health and creating efficient remediation plans.

NPs can enter organisms through food chain transfer or direct exposure. The bioaccumulation of NPs can lead to several physiological and ecological effects. In terrestrial ecosystems, NPs can be taken up by plant roots, causing physiological issues and altering gene expression, which potentially impacts plant growth and ecosystem productivity [98]. Also, in plants, metal-based NPs can interfere with nutrient uptake and translocation, which affects development and plant growth [99]. In aquatic water organisms, bioaccumulated NPs can cause oxidative stress, impaired reproduction, and inflammation [72,100]. Additionally, NPs can accumulate in the tissues of fishes and other organisms, leading to oxidative stress and behavioral changes. Bioaccumulation can disrupt food webs by affecting key species such as phytoplankton and planktonic grazers, which are foundational species of aquatic food chains [101]. In aquatic environments, phytoplankton and zooplankton are the main organisms that uptake NPs, which then move up the food webs. Wang and Wang, 2023 reported that NPs can aggregate in planktonic algae, promoting their entry into the food chain [72]. Additionally, metallic NPs particles can accumulate in aquatic insects, which are further consumed by riparian spiders, transferring NPs from aquatic to terrestrial ecosystems [102]. Furthermore, it has been discovered that NPs affect greenhouse gas emissions in terrestrial ecosystems by changing the organization of the soil microbial community and impeding nitrogen removal processes [96]. Specifically, NPs can significantly alter soil microbial community structures and can affect key processes such as denitrification and anammox, which play important roles in nitrogen cycling [96]. This disruption can lead to increased emissions of greenhouse gases such as CO₂ and CH₄ and increasing global warming effects [96]. In aquatic ecosystems, NPs can affect the microbial decomposition process, causing harm to nutrient availability and ecosystem productivity [103]. NPs can carry toxic substances and pathogens that can be ingested by primary organisms, posing significant risks to food security and safety, as they can move up the food chain, ultimately affecting human health [98,104]. These effects can cascade through ecosystems, impacting community structure and population dynamics. Environmental variables significantly influence the bioaccumulation of NPs. The transit and accumulation of NPs in aquatic settings are greatly influenced by gravity, density-dependent buoyancy, biofouling processes, topography, and flow conditions [105]. Furthermore, NPs can change how environmental pollutants bioaccumulate in freshwater and terrestrial environments, which has varying effects on different taxonomic groupings. Due to dermal damage and alterations in contaminant-degrading bacteria, NPs frequently cause an increase in contaminant bioaccumulation in terrestrial organisms such as earthworms [105]; in freshwater species, NPs can serve as vectors for other contaminants, making them more toxic to biota [95]. Engineering systems must thoroughly understand these channels to reduce NP mobility. NPs can be efficiently captured before they reach delicate ecosystems, for instance, via improved sediment traps in stormwater and wastewater systems or built wetlands. The complex interaction between environmental conditions and NP bioaccumulation is further highlighted by the fact that NPs can enter organisms by a variety of pathways, including the skin, digestive tract, and respiratory systems, which all contribute to their accumulation along the food chain [97]. While the detrimental impacts of NPs on ecosystems and biodiversity are evident, there is still a need for more in-depth research to understand their long-term impacts. The complex interactions of NPs within ecosystems require in-depth research and global collaboration to address their impacts on humans and the environment [106].

5.1.2. Biomagnification

The process by which NPs build up and become more concentrated as they ascend the food chain, potentially endangering higher trophic levels, is known as biomagnification. The fragmentation of bulk plastic trash has resulted in NPs being present in the environment, which emphasizes the necessity of improved treatment procedures to stop their percolation and buildup in different ecosystems [107]. The environmental impact of plastic contamination on marine ecosystems is further highlighted by the fact that NPs can be produced through microbial activity during the biodeterioration and bio-fragmentation of weathered plastic particles [108]. Ecological variables significantly influence NP biomagnification. The bioavailability and potential to concentrate organic pollutants of nanoparticles can be affected by many factors, including organic matter content, particle interactions, and salinity. These factors can cause NPs to aggregate or stay dispersed [109]. Biomagnification occurs in the food chain because of nanoparticles’ easier absorption, ingestion, and translocation through ecosystems and organisms [110]. According to Venel et al. (2021), the presence of NPs in aquatic settings, including mangrove swamps, might affect their flow dynamics and aggregation pathways, affecting their dispersion and bioaccumulation potential [111]. Measuring the ecological danger of NPs and the degree of biomagnification in aquatic environments requires understanding how environmental parameters such as salinity, organic matter, and particle interactions impact their fate and behavior.

By building up in various environmental niches, such as soils, water bodies, and the atmosphere, NPs eventually enter the food chain and aid in ecosystem biomagnification [112]. According to studies, NPs can drastically change the structure and functions of the soil microbial community, affecting greenhouse gas emissions and nitrogen removal processes, which can result in modifications to the multifunctionality of ecosystems [96]. Additionally, NPs can enter natural soils by various routes, and earthworms are essential for redistributing and moving NPs into deeper soil layers, where they may impact crops and terrestrial life [87]. Additional research is necessary to understand the combined effects of NPs and other pollutants on aquatic ecosystems. NPs interact with other contaminants, such as arsenic, in aquatic systems, affecting organisms’ responses and making them more vulnerable to environmental stressors [113].

5.2. Mechanisms of Toxicity

5.2.1. Physical and Chemical Properties Affecting Toxicity

NPs’ toxicity is influenced by their physical and chemical properties, such as size, polymer type, and surface charge. These properties determine how NPs interact with the environmental biological systems.

The size of NPs plays an essential role in their toxicity. Smaller NPs, due to a larger surface-to-volume ratio, tend to present higher reactivity and bioavailability. For example, 70 nm polystyrene NPs have been showing more accumulation in marine medaka (Oryzias melastigma) compared to larger particles (500 nm to 2 μm), and, therefore, had greater toxic effects [70]. Similarly, 75 nm polystyrene NPs induced greater apoptosis in freshwater shrimp (Neocaridina palmata) than 200 nm polystyrene particles [114]. The surface charge of NPs plays an essential role in their interaction with biological systems. As previously discussed, positively charged NPs are reported to be more toxic due to their strong interaction with negatively charged cell membranes. For example, positively charged PS-NPs were reported to cause mitochondrial dysfunction and ferroptosis in marine clams (Ruditapes philippinarum), while negatively charged PS-NPs affected immunity only [96]. The chemical composition of NPs as well as their types and additives can also affect their toxic effects. Non-polystyrene NPs, which are less studied, have been shown to display unique fate and transport behavior in terrestrial and aquatic systems [115]. NPs are also capable of leaching plastic additives and monomers, which are toxic to organisms [116].

5.2.2. Molecular Mechanisms of NP Toxicity

NP toxicity has an impact on cells through a mix of responses such as oxidative stress, inflammation, and DNA damage. NPs create reactive oxygen species (ROS), which harm cell parts like lipids, proteins, and DNA. This leads to oxidative stress. Young red swamp crayfish (Procambarus clarkii) exposed to NPs showed signs of an active antioxidant defense system, lipid peroxidation, and oxidative damage [72]. Zebrafish also experienced oxidative stress and inflammation in their brain and gonad tissues when exposed to NPs [117]. Many organisms suffer DNA damage, apoptosis, and cell death due to NPs. Marine nitrogen-fixing cyanobacteria exposed to NPs had less active DNA repair genes, which slowed their growth and reduced nitrogen fixation [118]. NPs can also disturb the balance in cells by affecting normal physiological processes. In marine medaka, long-term exposure to NPs altered liver and muscle tissue metabolism and caused changes in triglyceride, lactate, protein, and glycogen content [70]. Moreover, NPs have been shown to affect energy metabolism and ion transport in crustaceans [72].

6. Mitigation Pathways

Mitigating NP pollution in ecosystems requires a comprehensive interdisciplinary approach that addresses their complex behavior and multifaceted impacts on environmental and biological systems. Recent studies suggest that both conventional and emerging techniques—spanning biological-, chemical-, physical-, and material-based strategies—must be integrated for effective NP control [119,120]. Biological remediation has emerged as a promising eco-friendly solution. Phytoremediation, the use of plants to absorb and sequester NPs, is being explored for its sustainability and low cost [121]. Microbial degradation, involving bacteria and fungi, also plays a crucial role; for example, Pseudomonas aeruginosa and bacteria from mealworm guts have shown strong degradation capabilities for polystyrene NPs [122]. Microalgae offer a dual benefit: they not only remove NPs through adsorption and degradation, but also contribute to bioenergy production in wastewater systems [123]. Chemical and physical techniques are also advancing. Catalytic ozonation, particularly with Fe³⁺ and Co²⁺ ions, has achieved up to 70% mineralization of polystyrene NPs, offering an efficient oxidative treatment [124]. Electrolysis-assisted flotation has reached nearly 95% removal efficiency, providing a scalable and environmentally friendly method for water treatment [125]. Similarly, magnetic nanoparticles (MNPs) allow for the easy separation of adsorbed NP, with removal efficiencies exceeding 90% [126]. Material-based innovations further enhance removal efficiency. Micro/nanorobots (MNRs) have demonstrated over 90% NP removal in just 120 min, marking a breakthrough in real-time active remediation strategies [76,127]. Metal–organic frameworks (MOFs) show high NP adsorption capacity due to their large surface area and tunable porosity [128]. Biodegradable seaweed cellulose nanofibers, meanwhile, offer up to 98.71% removal in both single and co-pollutant systems while remaining safe and sustainable [129]. Despite these advances, the ecological implications of NPs must also be addressed. NPs disrupt soil microbial structures, affecting ecosystem multifunctionality, including greenhouse gas emissions and nitrogen cycling [96,130]. Aquatic systems face additional threats from the “Trojan Horse” effect, wherein NPs adsorb hydrophobic organic contaminants and facilitate their uptake by aquatic organisms, exacerbating toxicity [131]. This calls for a better understanding of NP interactions with natural organic matter and contaminants. To enhance mitigation, the standardization of NP analytical methods is essential, as current techniques struggle to differentiate NPs from natural particulates [132]. Implementing advanced wastewater treatment technologies such as membrane bioreactors (MBRs), adsorption-based filtration, and advanced oxidation processes (AOPs) will help reduce NP loads in effluent streams [133]. In parallel, source control measures—like minimizing plastic use, enhancing stormwater management, and enforcing pollution control policies—are vital to limit NP entry into the environment [119,134]. In conclusion, a multifaceted systems-based approach that combines innovative remediation technologies with source prevention, monitoring standardization, and public engagement is essential to effectively tackle the growing environmental challenge of NPs. To further mitigate NP pollution and protect the ecosystem’s health and services, it is crucial to increase public awareness, decrease plastic use, improve stormwater management strategies, and enforce laws on sources of NPs.

6.1. Policy and Regulation

Regulations and policies about NP mitigation in ecosystems are essential because of the widespread danger that these newly discovered pollutants represent. To combat NPs, the European Union has passed laws that define nanoparticles according to particle size and aims to restrict their release into the environment. One such measure is a future prohibition on purposefully adding micro(nano)plastics in products [135]. This underscores the need for more extensive regulatory frameworks, as micro(nano)plastics require more precise legal definitions in various instances [135]. These microscopic particles in ecosystems have the potential to impact human health and living things negatively, highlighting the significance of cooperation between academic researchers and politicians in order to create efficient management plans [135]. Identifying NPs’ sources, distribution, effects, detection methods, and mitigation measures in aquatic, terrestrial, atmospheric, and food chain settings should be the main goals of these initiatives [136]. To protect ecosystems and human health from the detrimental effects of NPs, these gaps in policy formulation and implementation must be filled.

6.1.1. Current Policies

Due to the need to comprehend the effects of NPs and the difficulties in regulating these new contaminants, policies currently in place to manage them in ecosystems are still developing. Plastic pollution in terrestrial and marine ecosystems is becoming more widely recognized [137]. However, more research is needed to understand NPs better, leaving gaps in management techniques and policy frameworks [135]. According to research, NPs can drastically change nitrogen removal mechanisms, soil microbial populations, greenhouse gas emissions, and ecosystem multifunctionality. This suggests that specific strategies are required to lessen these consequences [96].

Additionally, a meta-analysis highlights the crucial importance of considering toxicity measures, NP features, exposure duration, and environmental factors when developing policies to adequately address the various effects of NPs on terrestrial plants and ecosystems [138]. Effective NP management in ecosystems depends on iterative approaches, as researchers and policymakers work together to improve knowledge and create evidence-based solutions [135].

Table 3. Policies and regulations on NP mitigation.

Country/Location	Year Implemented	Policy/Regulation Details	Reference
European Union	2006 (REACH), Future ban on MPs/NPs by 2021	Regulation on Registration, Evaluation, Authorization, and Restriction of Chemicals (REACH) defines nanomaterials based on particle size and seeks to limit their environmental release. Future legislation should ban the intentional addition of MPs and NPs to various products.	[135]
USA	Proposed in 2023	Proposal to utilize the Toxic Substances Control Act (TSCA) to test the safety of plastics and redefine NPs as contaminants to set tolerances in food and beverages.	[139]
Canada	2020	Introduction of policies to limit the release of MPs and NPs from industrial and consumer products. Specific details on the policies may be forthcoming.	[6]
Australia	2020	Ban on certain single-use plastic products (e.g., straws, cutlery) and measures to manage MP and NP pollution in marine environments.	[140]
Japan	2019	Regulation requiring the assessment and management of risks associated with nanomaterials, including NPs.	[141]
South Korea	2019	Restriction on the use of MPs in microbeads contained in cosmetics and personal care products.	[142]
China	2020	Action Plan for Prevention and Control of MP Pollution: This plan outlines a multi-pronged approach to addressing MP pollution, including legislation. Specific details of the regulations may vary by province.	[117]

shows the various NP mitigation policies implemented in different nations.

6.1.2. Recommended Policies

The focus of suggested NP strategies should be on characterizing and controlling these new contaminants to reduce their harmful impacts on the environment and human health. Through laws based on definitions of particle sizes and specific requirements for safe usage, the European Union has progressed in managing nanomaterials [143]. In the USA, there is a movement to redefine NPs as pollutants to establish limits in food and beverages and to assess the safety of plastics using legislation such as the Toxic Substances Control Act [144]. Given their ability to carry pollutants and affect ecosystems and human health, policymakers and researchers must collaborate to develop comprehensive management plans for NPs [143]. Globally, implementing laws, regulations, bans, and restrictions that limit the release and disposal of NPs while promoting reuse, recycling, and the exploration of alternatives to plastic products calls for a coordinated strategy involving various stakeholders at different levels [143,145].

6.2. Technological Innovations

Recent studies have focused on technological advancements for NP mitigation. According to Gupta et al. (2021), one such invention is the creation of a 3D-printed moving bed water filter (M-3DPWF), which effectively scavenges NPs by selectively capturing surface-charged nanoparticles [146]. Furthermore, MPs have been remedied by nanotechnological methods employing bionanomaterials, underscoring the significance of cutting-edge environmentally friendly tactics in the fight against NP pollution [147]. Furthermore, conjugated polymer nanoparticles (CPN) with a high affinity for different polymers have been used to selectively detect MPs, providing a promising platform for developing innovative detection tools and mitigation techniques [148]. High efficiency in eliminating MPs and NPs from water and wastewater has been demonstrated by nanotechnology-based techniques such as adsorption, photocatalysis, and membrane filtration employing nanomaterials, highlighting the critical significance of nanotechnology in tackling these problematic pollutants [120]. Under certain circumstances, electrocoagulation successfully eliminates NP pollution from synthetic wastewater, with removal efficiencies above 95% [125].

6.2.1. Alternative Materials

Alternative materials can mitigate the potential risk associated with NPs in various applications. Studies have shown that antioxidants can serve as effective supplements to prevent and alleviate the harmful effects of NP exposure [149]. Additionally, nanomaterials, particularly biosynthetic nanoparticles, have shown promising results in reducing plant stresses and enhancing growth conditions, offering eco-friendly alternatives to traditional methods like agrochemicals [143]. Moreover, when assessing the toxicity of metal-bearing NPs like ZnO, SiO₂, TiO₂, and Ag on marine phytoplankton, it was found that the toxic mechanism varied depending on the physicochemical behavior of the NPs in seawater, emphasizing the need for further toxicological studies to understand their impact on the food chain [150]. By exploring these alternative materials and approaches, it is possible to address and mitigate the potential adverse effects of NPs in various fields.

6.2.2. Advanced Recycling

Modern recycling techniques are essential for reducing the adverse effects of NPs on the environment since they provide long-term solutions for resource recovery and trash management. Recycling NPs can result in a practical and eco-friendly approach by using technologies such as the RESRAD-RECYCLE code for dose assessment [151] and taking into consideration circular economy strategies that incorporate domestic recycling to reduce supply risk associated with critical raw materials [152]. The issues presented by nano waste creation also need to develop nano waste treatment methods for appropriate trash disposal or the recycling of engineered nanoparticles (ENPs) [146]. By using green technologies that recycle secondary waste resources, such as electronics waste and metallurgical slag, to create NPs, we can lessen the environmental effects of NP production and support the circular economy by using fewer primary sources [153]. By supporting the recovery and reuse of raw materials and lowering energy consumption and greenhouse gas emissions, these technologies support industrial and economic growth while upholding environmental protection regulations [154,155]. Utilizing cutting-edge recycling methods, such as membrane systems for wastewater treatment and pyrolysis for plastics, can boost recycling rates, resulting in more economical resource utilization and a reduction in the environmental effects of conventional disposal approaches.

6.3. Waste Management Strategies

Effective waste management strategies for NPs include a variety of approaches covered in the situations given. Methods for detection, recovery, disposal, treatment, and modeling to estimate waste production are all part of managing nano waste due to using NPs [156]. Similarly, to address the environmental concerns related to garbage creation, airports with trouble managing their waste are urged to use sustainable waste management techniques [157]. Furthermore, decommissioning nuclear power stations highlights the value of a clearly defined waste management process by emphasizing the necessity of efficient waste classification, treatment, and disposal to reduce project delays and expenses [43]. Furthermore, it has been demonstrated that community-based social marketing (CBSM) can increase solid waste diversion rates, highlighting the importance of behavior change tactics in trash management [158]. Finally, the necessity of circular economy solutions for managing photovoltaic (PV) waste highlights the significance of putting laws and incentives in place to encourage the recycling and reuse of valuable materials, highlighting the part that industry demand and government support play in putting sustainable waste management practices into place [159].

6.4. Public Awareness and Education

Public education and awareness campaigns are crucial in reducing nonpoint source pollution because they inform people about how their daily actions affect the environment and promote behavior adjustments to mitigate these problems [160]. Environmental education initiatives, such as those centered on air pollution and strategies to reduce it, aim to gain public knowledge of the adverse effects of NP pollution and strategies to reduce it [161,162]. To promote the adoption of best management practices and enhance water quality, studies emphasize the significance of raising land manager’s understanding of the diffusion of water pollution from agriculture [163]. Nonetheless, studies also emphasize the need for improved air quality communication tactics, stressing the significance of addressing vulnerable groups and offering comprehensive details on risk reduction practices and long-term health effects [164]. By combining technological help, education, and regulatory measures, societies can be better equipped to comprehend and address NP pollution issues [160].

7. Gaps in Knowledge and Future Research Directions

The study of NPs is undergoing significant expansion marked by a growing emphasis on their ecological impacts and health effects alongside progress in analytical and management techniques. Future academic research should focus on several critical areas to develop effective strategies for reducing NP pollution while protecting ecosystems and human health.

The complex characteristics of NPs, stemming from their tiny size and varied composition, create substantial analytical challenges. Future efforts need to prioritize the development of more sophisticated, sensitive, and accurate methods for identifying and quantifying them in various environmental and biological contexts. Recent advancements, such as Raman imaging and hyperspectral analysis, show promise for improved accuracy; however, challenges like weak signal intensity and complicated data still exist [165]. Innovative techniques, such as Field Flow Fractionation (FFF) and Hydrodynamic Chromatography (HDC), are being actively refined to enhance sampling and extraction processes. Furthermore, machine learning is being utilized to improve the accuracy of plastic-type classification within environmental samples [166]. To enhance the reliability of NP analyses, it is recommended to integrate multiple analytical techniques, including spectroscopic and thermal methods [167]. These advancements in analytical methods are crucial for enriching our understanding of NP prevalence, distribution, and concentration, thus enabling more effective evaluations of their environmental impacts [52].

Additional research is necessary to clarify the environmental fate and behavior of NPs, including their adsorption, aggregation, and movement within various ecosystems. The transport and destination of NPs in different settings represent a significant knowledge gap that requires further investigation to guide effective pollution reduction strategies [168]. A thorough understanding of these processes is essential for forecasting the long-term ecological effects of NP pollution. Extended ecological studies are also needed to clarify the cumulative effects of NPs on ecosystems, including how NPs interact with other environmental stressors, such as climate change [169], and their lasting ecological consequences in terrestrial and aquatic environments, particularly regarding their role in biodiversity loss and disruptions of biogeochemical cycles.

Given the potential health risks linked to NPs, which can lead to cardiovascular and liver issues due to their ability to penetrate human tissues and trigger oxidative stress and inflammation [170,171], future research should focus on identifying exposure pathways and developing strategies to reduce human exposure. This includes improvements in waste management practices and the implementation of more effective pollution control measures [77,172]. A comprehensive understanding of the specific pathways and mechanisms that underlie NP toxicity is vital for creating targeted mitigation strategies [81]. To assess potential risks to both environmental and human health, the creation of comprehensive risk assessment frameworks is essential. These frameworks should include exposure pathways, dose–response relationships, and cumulative effects [60].

The closure of the divide between empirical scientific insights and their practical applications necessitates the effective sharing of research findings, alongside the support of initiatives in engineering, policy formulation, and educational frameworks, all designed to promote a sustainable societal structure [168]. The establishment of regulatory measures and the promotion of global collaboration are essential for reducing nanoparticle (NP) pollution, thus protecting both environmental health and human well-being, in line with the aims of sustainable development [173,174,175]. The advancement of interdisciplinary collaborative research efforts among scientists, policymakers, and industrial partners can spark the creation of innovative solutions and the formulation of effective mitigation strategies [176,177].

8. Conclusions

This thorough review examines the extensive problem of NP pollution and shows how common it is in freshwater, marine, and terrestrial ecosystems. The fact that NPs have become a primary environmental concern highlights the urgent need for more research and practical mitigation techniques.

This review clarifies the different methods by which NPs enter and move through ecosystems. It also highlights how they may bioaccumulate and be biomagnified along food chains. Examining the physical and chemical processes of NP toxicity has revealed complex interactions with organisms at the cellular and molecular levels. These results highlight how NP pollution significantly impacts biodiversity and ecosystem health.

Current mitigation initiatives have been discussed, such as waste management plans, policy changes, and technology advancements. While the development of sophisticated recycling techniques and substitute materials has improved, significant obstacles remain to efficiently identify, measure, and eliminate NPs from the environment. This review emphasizes the importance of public education and awareness campaigns in the fight against NP pollution, underscoring the necessity of a coordinated effort by the public, industry stakeholders, academics, and policymakers.

Despite the expanding corpus of research, significant information gaps exist, especially regarding the long-term effects of NPs on ecosystems and human health. Future studies should focus on developing more sensitive detection techniques, comprehending the cumulative impacts of NP exposure, and investigating the relationships between NPs and other environmental stressors like climate change.

In conclusion, combating the problem of NP pollution necessitates a multi-pronged strategy that incorporates public involvement, policy reform, and scientific innovation. Maintaining a proactive approach in creating and implementing efficient solutions to lessen their environmental impact is essential as our understanding of NPs advances. In the face of this new worldwide contaminant, we can only hope to protect the health of our ecosystems and, consequently, our well-being via persistent cooperative efforts. Combining civil engineering solutions with environmental management techniques can reduce the dangers of NPs to ecosystem health, soil fertility, and water quality.