Aquatic Microplastic Research—A Critique and Suggestions for the Future

The silent threat of plastics along the coastal frontiers of Bangladesh: Are we concerned enough?

Globally plastic pollution is posing a significant threat to the health and integrity of coastal ecosystems. This study aimed to provide a comprehensive overview of plastic pollution in the coastal areas of Bangladesh by examining land-based macroplastic distribution, exploring microplastic (MP) contamination in the coastal aquatic ecosystem and enhancing our understanding of the potential risks associated with MP contamination. Citizen science based monitoring approach using the android application was applied to understand the land-based plastic pollution in the coastal area of Bangladesh. From December 2022 to December 2023, a total of about 3600 photographs of plastic items from 215 citizen scientists were received from the coastal area of Bangladesh covering 580 km long coast line. Polymer Hazard Index (PHI) and Pollution Load Index (PLI) were also calculated to understand the risk of plastic pollution in sediment, water, aquatic organism, dried fish and sea salt. A total of 43 land-based plastic items reported from the coastal area of Bangladesh. Among these plastic items single use items contributed 58.2 % while disposable plastic items contributed 41.8 %. A strong spatial variability in the distribution of these plastic items was observed. PHI and PLI values suggested hazard category-I for MP contamination in sediment, sea salt, water, commercial fishery resources and dry fish. This study highlighted that coastal land area, sea salt, dried fish, water, sediment and organisms are contaminated with plastics which might have the potential threats to human health. Findings from this study will serve as reference data and also baseline for future research to combat the plastic pollution.

Microplastic accumulation and ecological impacts on benthic invertebrates: Insights from a microcosm experiment

Microplastic (MP) pollution poses a global concern, especially for benthic invertebrates. This one-month study investigated the accumulation of small MP polymers (polypropylene and polyester resin, 3-500 μm, 250 μg L-1) in benthic invertebrates and on one alga species. Results revealed species-specific preferences for MP size and type, driven by ingestion, adhesion, or avoidance behaviours. Polyester resin accumulated in Mytilus galloprovincialis, Chamelea gallina, Hexaplex trunculus, and Paranemonia cinerea, while polypropylene accumulated on Ulva rigida. Over time, MP accumulation decreased in count but not size, averaging 6.2 ± 5.0 particles per individual after a month. MP were mainly found inside of the organisms, especially in the gut, gills, and gonads and externally adherent MP ranged from 11 to 35 % of the total. Biochemical energy assessments after two weeks of MP exposure indicated energy gains for water column species but energy loss for sediment-associated species, highlighting the susceptibility of infaunal benthic communities to MP contamination.

Effect of microplastics deposition on human lung airways: A review with computational benefits and challenges

Microplastics have become omnipresent in the environment, including the air we inhale, the water we consume, and the food we eat. Despite limited research, the accumulation of microplastics within the human respiratory system has garnered considerable interest because of its potential implications for health. This review offers a comprehensive examination of the impacts stemming from the accumulation of microplastics on human lung airways and explores the computational benefits and challenges associated with studying this phenomenon. The existence of microplastics in the respiratory system can lead to a range of adverse effects. Research has indicated that microplastics can induce inflammation, oxidative stress, and impaired lung function. Furthermore, the small size of microplastics allows them to penetrate deep into the lungs, reaching the alveoli, where gas exchange takes place. This raises concerns about long-term health consequences, such as the development of respiratory diseases and the potential for translocation to other organs. Computational approaches have been instrumental in understanding the impact of microplastic deposition on human lung airways. Computational models and simulations enable the investigation of particle dynamics, deposition patterns, and interaction mechanisms at various levels of complexity. However, studying microplastics in the lung airways using computational methods presents several challenges. The complex anatomy and physiological processes of the respiratory system require accurate representation in computational models. Obtaining relevant data for model validation and parameterization remains a significant hurdle. Additionally, the diverse nature of microplastics, including variations in size, shape, and chemical composition, poses challenges in capturing their full range of behaviours and potential toxicological effects.

Effect of microplastic particles on the population growth rate and clearance rate of selected ciliates (Protista, Ciliophora)

Microplastics (MPs), due to their micro size, which overlaps with the typical food size of various aquatic organisms, can be ingested and move up the food chain, accumulating in the bodies of organisms at higher trophic levels. Few studies have focused on the uptake of MPs by ciliates, which are an important element of the microbial cycle. Three different ciliate species were used in this study: Blepharisma japonicum, Euplotes sp., and Spirostomum teres, as well as polystyrene beads with diameters of 1 and 2 µm at two concentrations (106 and 107 beads × mL-1). The results of the experiments showed that MPs have a variable, species-specific effect on the population growth rate of ciliates, which is directly dependent on their concentration in the environment (P < 0.01). It was also observed that the number of MPs ingested changed over time depending on their concentration and size. On average, the highest number of ingested MPs (883.11 ± 521.47) was recorded at 60 min of exposure to a low concentration of small beads in B. japonicum. The lowest number of beads was ingested after 5 min of exposure to a low concentration of large beads in the same species. The rate of MP uptake by the ciliate species was significantly dependent on their concentration, exposure time, and size (P < 0.001). The highest clearance rate was observed in the fifth minute of the experiment in the environment with the lowest MP concentration.

Review: Mitigation measures to reduce tire and road wear particles

The generation of tire wear is an inevitable outcome of the friction between the road and the tire which is necessary for the safe operation of vehicles on roadways. Tire wear particles form agglomerates with road surface material. These agglomerates are called tire and road wear particles (TRWP). Due to their persistence in the environmental compartments and their potentially harmful effects, research on preventative and end-of-pipe mitigation strategies for TRWP is essential. The major goal of this study is to summarize and assess the state of the art in science and technology of mitigation measures for TRWP as the basis for further research activities. Approximately 500 literature sources were found and analyzed in terms of the efficiency, maturity, implementation, and impact of the mitigation measures. Generally, technological and management mitigation measures to reduce the generation of TRWP are beneficial since they prevent TRWP from entering the environment. Once released into environmental compartments, their mobility and dispersion would increase, making removing the particles more challenging. Technological and management mitigation measures after the release of TRWP into the environment are mainly well established in industrialized countries. Street cleaning and wastewater technologies show good removal efficiencies for TRWP and microplastics. In any case, no individual measure can solely solve the TRWP issue, but a set of combined measures could potentially be more effective. The absence of fully-developed and standardized methods for tire abrasion testing and measuring TRWP in the environment makes it impossible to reliably compare the tire abrasion behavior of different tire types, determine thresholds, and control mitigation actions. Field tests and pilot studies are highly needed to demonstrate the effectiveness of the abatement measures under real conditions.

A novel simplified method for extraction of microplastic particles from face scrub and laundry wastewater

Microplastic pollution in different environmental matrices is a serious concern in the recent times. Personal care products and washing of synthetic fabrics are some of the main sources of microplastic pollution. In this work, a novel simplified, effective and sustainable method for extraction of microplastic particles from face scrub and laundry wastewater was developed. Different parameters affecting the extraction were analysed and the extraction process was optimised. The extraction efficiency of the proposed method was found to be ~ 94.1 ± 1.65%, which was slightly better than the previously available method with an advantage of ease in extraction and lesser time and resource consuming. The developed method was used to demonstrate the extraction of microplastic particles from 12 face scrub samples with different brands. It was found that the samples contained microplastic particles of varying size. The physical and chemical structure intactness of microplastic particles during the extraction was also analysed and found to be acceptable. The developed extraction method was also applied for the extraction of microfibers from the laundry wastewater. It was found that this proposed method is suitable to make the cleaner extracted samples for an easy and more effective qualitative and quantitative analysis of MPs.

Microplastics pollution in freshwater fishes in the South of Italy: Characterization, distribution, and correlation with environmental pollutants

In this study, we investigated the presence, abundance, and chemical nature of microplastics (MPs) in the freshwater fish gastrointestinal tract in the South of Italy, and evaluated the possible correlation between MPs and environmental pollutants. Fifty specimens belonging to five species (Scardinius erythrophthalmus, Barbus barbus, Rutilus rubilio, Leuciscus cephalus, Salmo trutta), from twenty sites were collected. MPs chemical feature was identified by means of Attenuated Total Reflection-Fourier Transform Infrared (ATR-FTIR) and Raman microscopy. MPs were represented by 34.86 % fragments, film, and foam (all together MPs) and 65.14 % by fibers (MFs). The mean number of MPs/MFs per fish ranged from 6.25 ± 4.35 in R. rubilio and 2.26 ± 1.94 in B. barbus. The highest number of MPs/MFs per g of GIT was found in R. rubilio (9.07 ± 9.66), and the lowest in S. erythrophthalmus (0.75 ± 0.53). The highest number of MPs/MFs per fish species was found in L. cephalus (16), and the lowest in S. erythrophthalmus (4). Black predominated in every type of plastic debris identified, followed by blue and white, respectively for MFs and MPs. Polyethylene (PE), polyethylene terephthalate (PET), polystyrene (PS), and polypropylene (PP), were the main plastic polymers found. At fish sampling sites, comparing concentrations in soils of potentially toxic elements and persistent organic pollutants with the number of MPs/MFs in fish, a significant correlation was noted with polychlorinated biphenyls (PCBs) and, in particular, with PCB 105, PCB 118, PCB 156, PCB 157, and PCB 167. A strong correlation was also observed with all types of polycyclic aromatic hydrocarbon (PAHs) particularly with benzo(ghi)perylene, dibenz(a,h)anthracene, benzo(b)fluoranthene, benz(a)anthracene, benzo(a)pyrene, and pyrene. The results of this study would be useful to draft management and action plans, promote intervention plans aiming at removing threats to species and habitats, and address ways of renaturalization.

Microplastic transfer from the American horseshoe crab to shorebirds through consumption of horseshoe crab eggs in Jamaica Bay, NY

Microplastic transfer between horseshoe crabs (Limulus polyphemus) and migratory shorebirds through consumption of crab eggs was examined in Jamaica Bay, New York. Fertilized and unfertilized crab eggs, shorebird fecal pellets, beach sand, and bay water were processed with a hydrogen peroxide solution to remove organic material, then stained with a Nile Red to identify microplastics using fluorescence microscopy. Microplastics were present in all samples and ranged from approximately26-1300 μm. Unfertilized and fertilized eggs contained significantly higher numbers of microplastic particles per gram than shorebird fecal pellets, beach sand, and bay water. The presence of microplastics in unfertilized egg samples indicates that microplastics undergo maternal transfer during oogenesis. We estimated that 1 g of horseshoe crab eggs could contain approximately 426 to 840 microplastic particles, suggesting that shorebirds feeding on this resource could be ingesting a substantial burden of microplastics during their migratory stopover, much of which appears to be retained by shorebirds, rather than being eliminated in their fecal pellets.

Genotoxic effect of microplastics and COVID-19: The hidden threat

Microplastics (MPs) are ubiquitous anthropogenic contaminants, and their abundance in the entire ecosystem raises the question of how far is the impact of these MPs on the biota, humans, and the environment. Recent research has overemphasized the occurrence, characterization, and direct toxicity of MPs; however, determining and understanding their genotoxic effect is still limited. Thus, the present review addresses the genotoxic potential of these emerging contaminants in aquatic organisms and in human peripheral lymphocytes and identified the research gaps in this area. Several genotoxic endpoints were implicated, including the frequency of micronuclei (MN), nucleoplasmic bridge (NPB), nuclear buds (NBUD), DNA strand breaks, and the percentage of DNA in the tail (%Tail DNA). In addition, the mechanism of MPs-induced genotoxicity seems to be closely associated with reactive oxygen species (ROS) production, inflammatory responses, and DNA repair interference. However, the gathered information urges the need for more studies that present environmentally relevant conditions. Taken into consideration, the lifestyle changes within the COVID-19 pandemic, we discussed the impact of the pandemic on enhancing the genotoxic potential of MPs whether through increasing human exposure to MPs via inappropriate disposal and overconsumption of plastic-based products or by disrupting the defense system owing to unhealthy food and sleep deprivation as well as stress. Overall, this review provided a reference for the genotoxic effect of MPs, their mechanism of action, as well as the contribution of COVID-19 to increase the genotoxic risk of MPs.

Evidence for Microplastics Contamination of the Remote Tributary of the Yenisei River, Siberia—The Pilot Study Results

This study is a pioneering attempt to count microplastics (MPs) in the Yenisei River system to clarify the role of Siberian Rivers in the transport of MPs to the Arctic Ocean. The average MPs content in the surface water of the Yenisei large tributary, the Nizhnyaya Tunguska River, varied from 1.20 ± 0.70 to 4.53 ± 2.04 items/m3, tending to increase along the watercourse (p < 0.05). Concentrations of MPs in bottom sediments of the two rivers were 235 ± 83.0 to 543 ± 94.1 with no tendency of downstream increasing. Linear association (r = 0.952) between average organic matter content and average counts of MPs in bottom sediments occurred. Presumably MPs originated from the daily activities of the in-situ population. Further spatial-temporal studies are needed to estimate the riverine MPs fluxes into the Eurasian Arctic seas.

Methods of Analyzing Microsized Plastics in the Environment

Microplastics are found in various environments with the increasing use of plastics worldwide. Several methods have been developed for the sampling, extraction, purification, identification, and quantification of microplastics in complex environmental matrices. This study intends to summarize recent research trends on the subject. Large microplastic particles can be sorted manually and identified through chemical analysis; however, sample preparation for small microplastic analysis is usually more difficult. Microplastics are identified by evaluating the physical and chemical properties of plastic particles separated through extraction and washing steps from a mixture of inorganic and organic particles. This identification has a high risk of producing false-positive and false-negative results in the analysis of small microplastics. Currently, a combination of physical (e.g., microscopy), chemical (e.g., spectroscopy), and thermal analyses is widely used. We aim to summarize the best strategies for microplastic analysis by comparing the strengths and limitations of each identification method.

Assessment of Microplastics in a Municipal Wastewater Treatment Plant with Tertiary Treatment: Removal Efficiencies and Loading per Day into the Environment

This study investigates the removal of microplastics from wastewater in an urban wastewater treatment plant located in Southeast Spain, including an oxidation ditch, rapid sand filtration, and ultraviolet disinfection. A total of 146.73 L of wastewater samples from influent and effluent were processed, following a density separation methodology, visual classification under a stereomicroscope, and FTIR analysis for polymer identification. Microplastics proved to be 72.41% of total microparticles collected, with a global removal rate of 64.26% after the tertiary treatment and within the average retention for European WWTPs. Three different shapes were identified: i.e., microfiber (79.65%), film (11.26%), and fragment (9.09%), without the identification of microbeads despite the proximity to a plastic compounding factory. Fibers were less efficiently removed (56.16%) than particulate microplastics (90.03%), suggesting that tertiary treatments clearly discriminate between forms, and reporting a daily emission of 1.6 × 107 microplastics to the environment. Year variability in microplastic burden was cushioned at the effluent, reporting a stable performance of the sewage plant. Eight different polymer families were identified, LDPE film being the most abundant form, with 10 different colors and sizes mainly between 1–2 mm. Future efforts should be dedicated to source control, plastic waste management, improvement of legislation, and specific microplastic-targeted treatment units, especially for microfiber removal.

Effect of microplastics in water and aquatic systems

Surging dismissal of plastics into water resources results in the splintered debris generating microscopic particles called microplastics. The reduced size of microplastic makes it easier for intake by aquatic organisms resulting in amassing of noxious wastes, thereby disturbing their physiological functions. Microplastics are abundantly available and exhibit high propensity for interrelating with the ecosystem thereby disrupting the biogenic flora and fauna. About 71% of the earth surface is occupied by oceans, which holds 97% of the earth's water. The remaining 3% is present as water in ponds, streams, glaciers, ice caps, and as water vapor in the atmosphere. Microplastics can accumulate harmful pollutants from the surroundings thereby acting as transport vectors; and simultaneously can leach out chemicals (additives). Plastics in marine undergo splintering and shriveling to form micro/nanoparticles owing to the mechanical and photochemical processes accelerated by waves and sunlight, respectively. Microplastics differ in color and density, considering the type of polymers, and are generally classified according to their origins, i.e., primary and secondary. About 54.5% of microplastics floating in the ocean are polyethylene, and 16.5% are polypropylene, and the rest includes polyvinyl chloride, polystyrene, polyester, and polyamides. Polyethylene and polypropylene due to its lower density in comparison with marine water floats and affect the oceanic surfaces while materials having higher density sink affecting seafloor. The effects of plastic debris in the water and aquatic systems from various literature and on how COVID-19 has become a reason for microplastic pollution are reviewed in this paper.

The ghost nets phenomena from the chemical perspective

The XXIst century might be called the Plastic Era. With the continually growing consumption and production, low recycling level, one observes the continuous transformation of the Blue Planet into the Ocean of Plastics. Among various problems related to the presence of synthetic materials in the environment, the ghost nets draw particular attention. They are present in the global ocean due to lost or abandoned fishing gear. Their impact on the environment is represented by the tones of animals caught. Moreover, they are an abundant source of secondary marine microplastic and release a considerable amount of toxic chemical compounds. To resolve this issue, an interdisciplinary approach is needed. Chemical research enables a better understanding of polymer behaviour and their weathering, whereas spectroscopy helps in qualitative analyses and proposes solutions. This paper aims to present the interdisciplinary study of this phenomenon and its broad context, including social awareness but underlines the crucial role of chemical research. One focuses on the basic studies of chemical and physical properties as this knowledge provides the first and essential step to tackle the problem.

Immunotoxicity and intestinal effects of nano- and microplastics: a review of the literature

BACKGROUND

Together with poor biodegradability and insufficient recycling, the massive production and use of plastics have led to widespread environmental contamination by nano- and microplastics. These particles accumulate across ecosystems - even in the most remote habitats - and are transferred through food chains, leading to inevitable human ingestion, that adds to the highest one due to food processes and packaging.

OBJECTIVE

The present review aimed at providing a comprehensive overview of current knowledge regarding the effects of nano- and microplastics on intestinal homeostasis.

METHODS

We conducted a literature search focused on the in vivo effects of nano- and microplastics on gut epithelium and microbiota, as well as on immune response.

RESULTS

Numerous animal studies have shown that exposure to nano- and microplastics leads to impairments in oxidative and inflammatory intestinal balance, and disruption of the gut's epithelial permeability. Other notable effects of nano- and microplastic exposure include dysbiosis (changes in the gut microbiota) and immune cell toxicity. Moreover, microplastics contain additives, adsorb contaminants, and may promote the growth of bacterial pathogens on their surfaces: they are potential carriers of intestinal toxicants and pathogens that can potentially lead to further adverse effects.

CONCLUSION

Despite the scarcity of reports directly relevant to human, this review brings together a growing body of evidence showing that nano- and microplastic exposure disturbs the gut microbiota and critical intestinal functions. Such effects may promote the development of chronic immune disorders. Further investigation of this threat to human health is warranted.