Microplastics in the aquatic environment: Evidence for or against adverse impacts and major knowledge gaps

Occurrence, potential sources, and ecological risk assessment of microplastics in the inland river basins in Northern China

Microplastics (MPs) are the pollutants, found widely across various environmental media. However, studies on the MP pollution in urban rivers and the necessary risk assessments remain limited. In this study, the abundance and characteristics of microplastics in a typical urban river were examined to evaluate their distribution, sources, and ecological risks. It was observed that the abundance of MPs in sediments (220-2840 items·kg-1 dry weight (DW)) was much higher than that in surface water (2.9-10.3 items·L-1), indicating that the sediment is the "sink" of river MPs. Surface water and sediment were dominated by small particle size MPs (< 0.5 mm). Fiber and debris were common shapes of MPs in rivers and sediments. The microplastics in river water and sediments were primarily white and transparent, respectively. Polypropylene (PP) and polyethylene (PE) were the major polymers found.

Suspension of micro- and nanoplastic test materials: Liquid compatibility, (bio)surfactants, toxicity and environmental relevance

Micro- and nanoplastics have been detected in environmental compartments from the highest mountains to the deepest seas. They have been shown to be present at almost all trophic levels, and within humans they have been detected in numerous organs and human stool. Whilst their ubiquitous nature is indisputable, little is known about the health risks they may present. Much current research is focussed on the production of test materials with which to perform the necessary health studies. An important aspect of this is the correct storage and suspension of the materials to ensure they remain stable both chemically and with regards to size and shape. In this review, we look at the chemical stability of nine common polymers in a range of liquids; first with the use of commercial compatibility charts and then with a more quantitative approach using Hansen solubility parameters. We then look at stability with regards to particle agglomeration, whether and how stable compositions can be predicted, and which dispersants can be added to increase stability. Finally, we discuss the role of bio-surfactants and the eco-corona and how these may offer a route to both better stability and environmental relevance.

Contamination by microplastics in oysters shows a widespread but patchy occurrence in a subtropical estuarine system

Microplastics (MPs) have been widely documented in marine biota, with a notable presence in bivalve species. This study examines microplastic (MP) contamination in oysters across a subtropical estuarine system, revealing widespread and highly variable levels of contamination. Our results indicate a general trend of higher contamination in areas with greater anthropogenic impact, and unexpectedly high values in remote Marine Protected Areas, suggesting alternative sources of MPs. We observed a 94.31 % frequency of occurrence and an average contamination level of 8.16 ± 6.39 MP.ind-1, 1.06 ± 1.28 MP.g-1ww, and 7.54 ± 6.55 MP.g-1dw. Transparent fibers, predominantly composed of polyester and polyethylene from likely textile origins, were the most common. The findings underscore the significance of MP pollution in marine environments, even in protected zones. For enhanced spatial assessment and consistent data comparison, we recommend that future studies include MP quantities in terms of dry weight (MP.g-1dw) and biometric data such as size and weight.

Neurotoxicity of Some Environmental Pollutants to Zebrafish

The aquatic environment encompasses a wide variety of pollutants, from plastics to drug residues, pesticides, food compounds, and other food by-products, and improper disposal of waste is the main cause of the accumulation of toxic substances in water. Monitoring, assessing, and attempting to control the effects of contaminants in the aquatic environment are necessary and essential to protect the environment and thus human and animal health, and the study of aquatic ecotoxicology has become topical. In this respect, zebrafish are used as model organisms to study the bioaccumulation, toxicity, and influence of environmental pollutants due to their structural, functional, and material advantages. There are many similarities between the metabolism and physiological structures of zebrafish and humans, and the nervous system structure, blood-brain barrier function, and social behavior of zebrafish are characteristics that make them an ideal animal model for studying neurotoxicity. The aim of the study was to highlight the neurotoxicity of nanoplastics, microplastics, fipronil, deltamethrin, and rotenone and to highlight the main behavioral, histological, and oxidative status changes produced in zebrafish exposed to them.

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.

Nanoplastic contamination: Impact on zebrafish liver metabolism and implications for aquatic environmental health

Nanoplastics (NPs) are increasingly pervasive in the environment, raising concerns about their potential health implications, particularly within aquatic ecosystems. This study investigated the impact of polystyrene nanoparticles (PSN) on zebrafish liver metabolism using liquid chromatography hybrid quadrupole time of flight mass spectrometry (LC-QTOF-MS) based non-targeted metabolomics. Zebrafish were exposed to 50 nm PSN for 28 days at low (L-PSN) and high (H-PSN) concentrations (0.1 and 10 mg/L, respectively) via water. The results revealed significant alterations in key metabolic pathways in low and high exposure groups. The liver metabolites showed different metabolic responses with L-PSN and H-PSN. A total of 2078 metabolite features were identified from the raw data obtained in both positive and negative ion modes, with 190 metabolites deemed statistically significant in both L-PSN and H-PSN groups. Disruptions in lipid metabolism, inflammation, oxidative stress, DNA damage, and amino acid synthesis were identified. Notably, L-PSN exposure induced changes in DNA building blocks, membrane-associated biomarkers, and immune-related metabolites, while H-PSN exposure was associated with oxidative stress, altered antioxidant metabolites, and liver injury. For the first time, L-PSN was found depolymerized in the liver by cytochrome P450 enzymes. Utilizing an analytical approach to the adverse outcome pathway (AOP), impaired lipid metabolism and oxidative stress have been identified as potentially conserved key events (KEs) associated with PSN exposure. These KEs further induced liver inflammation, steatosis, and fibrosis at the tissue and organ level. Ultimately, this could significantly impact biological health. The study highlights the PSN-induced effects on zebrafish liver metabolism, emphasizing the need for a better understanding of the risks associated with NPs contamination in aquatic ecosystems.

Hidden threats in the plastisphere: Carbapenemase-producing Enterobacterales colonizing microplastics in river water

Carbapenem resistance poses a significant burden on healthcare systems worldwide. Microplastics (MPs) have emerged as potential contributors to antibiotic resistance spread in the environment. However, the link between MPs and carbapenem resistance remains unexplored. We investigated the prevalence of carbapenem-resistant bacteria colonizing MPs placed in a river. Three replicates of a mixture of polypropylene (PP), polyethylene (PE) and polyethylene terephthalate (PET) and of PET alone were placed both upstream and downstream a wastewater treatment plant (WWTP) discharge. Carbapenem-resistant Enterobacterales (CRE) were further characterized by phenotypic tests and whole-genome sequencing. The abundance of carbapenem-resistant bacteria on MPs increased significantly downstream the WWTP. Their prevalence was higher in the MPs mixture compared to PET alone. CRE strains colonizing MPs included Klebsiella pneumoniae (n = 3), Klebsiella quasipneumoniae (n = 3), Raoultella ornithinolytica (n = 2), Enterobacter kobei (n = 1) and Citrobacter freundii (n = 1), most (n = 8) recovered after the WWTP discharge. All strains exhibited at least one of the tested virulence traits (biofilm formation at 37 °C, haemolytic activity and siderophore production), were multi-drug resistant and carried carbapenemase-encoding genes [blaKPC-3 (n = 5), blaGES-5 (n = 2) or blaKPC-3 + blaGES-5 (n = 3)]. Uncommon phenotypes of resistance to imipenem/relebactam (n = 3) and ceftazidime/avibactam (n = 2) were observed. Two blaKPC-3-positive K. pneumoniae successfully transfer this gene trough conjugation. Genome analysis predicted all strains as human pathogens. The blaKPC-3 was associated with the Tn4401d transposon on a pBK30683-like plasmid in most of the isolates (n = 7). The blaGES-5 was mostly linked to class 3 integrons. A K. pneumoniae strain belonging to the outbreak-causing high-risk clone ST15 carried both blaKPC-3 and blaCTX-M-15. Two K. quasipneumoniae isolates carried the plasmid-mediated colistin resistance gene mcr-9. Our results underscore the role of MPs as vectors for CRE dissemination, particularly following WWTPs discharges. MPs may act as carriers, facilitating the dissemination of carbapenemase-encoding genes and potentially contributing to increased CRE incidence in the environment.

Potentially Toxic Elements' Accumulation in Relation to Sediment Physicochemical Attributes and Microplastic Content in Zayandeh-Rood River, Iran

Microplastics (MPs) are an emerging pollutant whose ability to adsorb potentially toxic elements (PTEs) poses a serious threat to aquatic ecosystems, including rivers. In highly developed basins, the abundance of MPs in river sediment is expected to be high, elevating the sedimentary accumulation of PTEs. This hypothesis was tested in the Zayandeh-Rood River, Central Iran, with 21 sediment sampling stations distributed along the entire river stretch. Results of sediment analysis showed significant variations in the abundance and size of MPs, with concentrations ranked as Ba (270.71 mg/kg) > Li (21.29 mg/kg) > Cs (2.50 mg/kg) > Be (1.44 mg/kg) > Sn (1.17 mg/kg) > Mo (1.06 mg/kg) > Ag (0.76 mg/kg), along with sediment physicochemical attributes such as EC, TOC, pH and grain size. MPs were identified in all sediment samples with a mean of 588 items/kg dry weight. Except for Ag, all other PTEs were classified as uncontaminated but exhibited increased enrichment downstream. According to the results of the generalized additive model (maximum R-sq of 0.766), the sedimentary concentration of the majority of PTEs is nonlinearly and positively associated with smaller and more abundant MPs. This study acknowledges that MPs might influence sediment porosity, permeability and structure, thereby directly affecting the settling dynamics of other particles, especially PTEs.

Abundance and risk assessment of microplastics in water, sediment, and aquatic insects of the Nile River

Microplastics (MPs) are a serious threat in freshwater environments. The ecological risk and abundance level of MPs in abiotic and biotic compartments of the Nile River haven't been systematically reported. Thus, these issues were highlighted in the present study during different seasons of the sampling year. The results showed that MP concentrations in the river ranged from 2.24 ± 0.6 to 3.76 ± 1.1 particles/L, 298 ± 63 to 520 ± 80 particles/kg dry weight, and 0.081 ± 0.051 to 4.95 ± 2.6 particles/individual in surface water, sediment, and different species of aquatic insects, respectively. All the extracted MPs are colored blue, red, and black. Fiber-shaped polyesters (<500-1500 μm) were the most common MPs in all the river compartments. MPs' dominance was observed during the summer in comparison with that in the other seasons. Environmental risk indicators indicate the high ecological risk of MPs, which are widely distributed in the Nile River. In conclusion, MP consumption by aquatic insects may not only be related to levels of environmental contamination, since other variables, such as taxon size, weight, and particular feeding behavior, may also be significant. Additionally, the presence of MPs in insects (at lower trophic levels) creates the potential for predation-based inter-trophic level transmission. Thus, higher trophic-level investigations of various feeding groups should be carried out to identify any possible harm that MPs cause to various aquatic organisms.

Coping with current impacts: The case of Scyliorhinus canicula in the NW Mediterranean Sea and implications for human consumption

The small-spotted catshark (Scyliorhinus canicula) is a bottom-dwelling elasmobranch that represents the most discarded catch in terms of biomass in the Catalan coast (NW Mediterranean). Potential impacts affecting its population and food safety implications have been assessed in three localities along the Catalan coast. Distinct indicators were integrated, such as biological data, ingested anthropogenic items (plastic and cellulose-like items), parasitological indices, trace metal concentrations and histopathology using liver as target organ. Although high ingestion rates of fibres and levels of some heavy metals, they do not seem negatively affected by any major pathology nor by the current levels of pollutants. Small-scale differences among localities and depths were found and discussed. No zoonotic parasites were found. Encysted larvae of Grillotia adenoplusia and, above all, the levels of Hg found in the musculature, that are well over the European Commission limits, rise concerns regarding human consumption of S. canicula in this region.

Systematic CFD-based evaluation of physical factors influencing the spatiotemporal distribution patterns of microplastic particles in lakes

Spatiotemporal distribution patterns of microplastic (MP) particles in lakes hinge on both the physical conditions in the lake and particle properties. Using numerical simulations, we systematically investigated the influence of lake depth and bathymetry, wind and temperature conditions, MP particle release location and timing, as well as particle diameter (10, 20, and 50 μm). Our results indicate that maximum lake depth had the greatest effect on the residence time in the water column, as it determines the settling timescale and occurrence of hydrodynamic complexity such as density-driven flows in the lake. Increasing particle size from 10 to 20 and 50 μm also significantly reduced the residence time making particle size the factor with the second strongest effect on the residence time and, in turn, on the availability of MP particles for uptake by organisms. Changing bathymetry from a uniform to a non-uniform had a less pronounced effect on particle residence time compared to maximum depth and particle size. Release location, wind conditions, and release time had comparably little effect on particle behavior but became more important as MP particle size decreased. The release of the 10 μm MP particles in the deeper lakes with uniform bathymetry during summer with stable thermal stratification, resulted in a nearly month-long turnover phase in the fall in which both settling and rising of particles occurred simultaneously. This was caused by convective heat and water transport during this period. In these scenarios about 2.6 to 5.4 % of the released MP particles were held in or returned to the water layers near the lake surface. While acknowledging the dominant role of lake depth and MP particle size on the particle residence time, this study further emphasizes that it is ultimately a particular combination of different factors and their interactions that shape MP distribution patterns in lakes.

Exploring the pathology of liver, kidney, muscle, and stomach of fledgling seabirds associated with plastic ingestion

There remain significant gaps in knowledge about 'sub-lethal' impacts of plastic ingestion, particularly chronic impacts on cells, tissues, or organs. Few studies have applied traditional animal health tools, such as histopathology, to assess physiological damage to wildlife, with fewer still providing information on the dosage or exposure to plastics needed to elicit negative effects. Our study seeks to investigate a common hypothesis in plastic pollution research; that an increasing plastics burden will have an impact on an animal's health, examining two wild species with high levels of environmental exposure to plastic through their diet. Here we assess the histopathology of the muscle, upper digestive tract, liver and kidney of two seabird species that are known to be commonly exposed to plastic, comparing exposed and non-exposed individuals. Fledgling seabirds showed histopathological evidence of cumulative pressures such as starvation, disease, and endoparasite burden. However, we observed no evidence of chronic harm that could be explicitly linked to the plastics. We found one case of haemorrhage, reaffirming that large/sharp plastic foreign bodies may cause acute physical damage. Given the numerous interacting pressures on the health of fledging seabirds, including exposure to plastic, this study highlights the need to scrutinise plastic-animal interactions and research though a One Health lens.

Analyzing species sensitivity distribution of evidently edible microplastics for freshwater biota

Assessing the ecological risks of microplastics is difficult because of the limited availability of reliable ecotoxicity data. Although freshwater is a valuable sink for microplastics, the current framework for ecological risk assessment using traditional toxicity data is not applicable to freshwater ecosystems. Herein, species sensitivity distribution (SSD) curves were compared for edible and all microplastics exposed to aquatic organisms based on traditional endpoint-based and all-endpoint-based databases. Freshwater toxicity data for microplastics were screened after verifying microplastic presence in test species (56 toxicity datapoints for one microalga, three water fleas, one fish, and one crab; 0.02-100 µm-sized microplastics). SSD and curve parameters were compared with or without non-traditional toxicity endpoints. The HC50 in all endpoint databases was more sensitive than that in the traditional endpoint database and showed a good fit. SSD curves derived from the database for all microplastics were compared and analyzed with edible microplastics. HCx increased for edible microplastics (0.02-100 µm-sized) than for all microplastics (0.02-200 µm-sized), and the size of edible microplastics was lower than of all microplastics. Thus, using non-traditional toxicity data, the SSD approach compensates for the limited ecotoxicity data on microplastics while considering the internalization of microplastics in biota.

Distribution characteristics and ecological risk assessment of microplastics in intertidal sediments near coastal water

Plastic products are widely distributed worldwide and continue to have a negative impact on the environment and organisms. Intertidal regions, which interface between upland and marine ecosystems, are regions of high ecological importance and serve as repositories for a variety of plastic wastes. However, ecological risk assessments of microplastics (MPs) in these transitional environments are still scarce. In this study, the morphological characteristics and spatial distribution of MPs in the intertidal surface sediments of Haizhou Bay were analyzed, and an ecological risk assessment framework for MPs was developed. Overall, the average abundance of MPs in the sediments was 2.31 ± 1.35 pieces/g dw. The size of the MPs was mainly less than 1 mm, and the main shape, color and polymer type of the MPs were mainly fibrous (58%), blue (30%), and PVC (22%), respectively. Cluster analyses showed that the sites could be well distinguished by size and polymer type but not by MP shape and color. According to the hazard scores, most of the sites in this area belonged to a risk level of IV, while the pollution loading index (PLI) showed that most of the sites belonged to a risk level of II. The ecological toxicity risk from the species-sensitive distribution (SSD) model showed that one-third of the sites had ecological MPs toxicity risks to marine organisms. We believe that normalized and standardized assessment methods should be implemented to monitor and manage the risk of MPs in the intertidal sediments. Particularly, the multiple dimensions, standard abundance of MPs, as well as MPs ingestion in the intertidal organisms, should be fully considered in the next step.

Occurrence of phthalic acid esters (PAEs) and active pharmaceutical ingredients (APIs) in key species of anthozoans in Mediterranean Sea

The Mediterranean Sea's biodiversity is declining due to climate change and human activities, with plastics and emerging contaminants (ECs) posing significant threats. This study assessed phthalic acid esters (PAEs) and active pharmaceutical ingredients (APIs) occurrence in four anthozoan species (Cladocora caespitosa, Eunicella cavolini, Madracis pharensis, Parazoanthus axinellae) using solid phase microextraction (SPME) and liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). All specimens were contaminated with at least one contaminant, reaching maximum values of 57.3 ng/g for the ∑PAEs and 64.2 ng/g (wet weight) for ∑APIs, with dibutyl phthalate and Ketoprofen being the most abundant. P. axinellae was the most contaminated species, indicating higher susceptibility to bioaccumulation, while the other three species showed two-fold lower concentrations. Moreover, the potential adverse effects of these contaminants on anthozoans have been discussed. Investigating the impact of PAEs and APIs on these species is crucial, given their key role in the Mediterranean benthic communities.

Probabilistic risk assessment of microplastics in Tai Lake, China

Microplastics are a global environmental concern, especially in freshwater ecosystems. Despite the studies in specific regions of Tai lake, a gap persists in understanding the comprehensive risk of MPs across the entire watershed. Therefore, this study offers an overview of MPs abundance and assesses ecotoxicological risk by employing acute and chronic species sensitivity distributions, which consider the effects triggered by MPs. The concentrations of MPs ranged from 0 to 18.6 particles/L within the lake, 1.56 to 1.42 × 102 particles/L in the rivers, and 0.16 to 0.7 particles/L in the estuaries. Certain areas, particularly the northwest and southeast regions, exhibit higher concentrations. Using existing toxicity data, this study calculated predicted no effect concentrations for acute and chronic exposure of MPs to freshwater species, resulting in values of 11.5 and 31.72 particles/L, respectively. The probabilistic risk assessment indicates that the average risk possibility of MPs in Tai lake was 16 %. Moreover, the risk characterization ratio indicated that 22 % of the locations in Tai lake showed an acute ecological risk, while 7.4 % exhibit a chronic ecological risk. The assessment concluded that MPs reported in the literature could pose a considerable risk to Tai lake biota. However, the risk associated with MPs followed descending order: river >lake > estuary waters. Our research supplies valuable insights for the assessment of ecological risks associated with MPs on a whole watershed scale.

The adsorption and its mechanism of venlafaxine by original and aged polypropylene microplastic and the changes of joint toxicity

Conjugation with the increment of consumption of polypropylene (PP) masks and antidepressants during pandemic, PP microplastics (MPs) and Venlafaxine (VEN) widely co-existed in surface waters. However, their environmental fate and the combined toxicity were unclear. Hence, we investigated the adsorption behaviors, and associated mechanisms of PP MPs for VEN. The impact factors including pH, salinity, and MPs aging were estimated. The results indicated PP MPs could adsorb amount of VEN within 24 h. The pseudo second-order kinetic model (R2 = 0.97) and Dubinin-Radushkevich model (R2 = 0.89) fitted well with the adsorption capacity of PP MPs for VEN, implying that chemical adsorption accompanied by electrostatic interaction might be the predominant mode for the interactions between PP MPs and VEN. Meanwhile, the adsorption capacity of PP MPs declined from pH of 2.5-4.5 and then increased from 4.5 to 9.5. The increased salinity (5-35 ppt) significantly suppressed the adsorption capacity. Aging by sunlight and UV triggered the formation of new functional group (carbonyl) on MPs, and then enhanced the adsorption capacity for VEN. Gaussian Model analysis further evidenced the electrostatic adsorption occurring in PP MPs and VEN. The combined exposure to PP MPs and VEN showed significantly antagonistic toxicity on Daphnia magna. The adsorption of VEN by PP MPs mitigated the lethal effects and behavioral function impairment posed by VEN on animals, implying the potential protective effects on zooplankton by PP MPs. This study for the first time provides perspective for assessing the environmental fate of MPs and antidepressants in aquatic system.

Psychrobacter species enrichment as potential microplastic degrader and the putative biodegradation mechanism in Shenzhen Bay sediment, China

Microplastic (MP) pollution has emerged as a pressing environmental concern due to its ubiquity and longevity. Biodegradation of MPs has garnered significant attention in combatting global MP contamination. This study focused on MPs within sediments near the sewage outlet of Shenzhen Bay. The objective was to elucidate the microbial communities in sediments with varying MPs, particularly those with high MP loads, and to identify microorganisms associated with MP degradation. The results revealed varying MP abundance, ranging from 211 to 4140 items kg-1 dry weight (d. w.), with the highest concentration observed near the outfall. Metagenomic analysis confirmed the enrichment of Psychrobacter species in sediments with high MP content. Psychrobacter accounted for ∼16.71% of the total bacterial community and 41.71% of hydrocarbon degrading bacteria at the S3 site, exhibiting a higher abundance than at other sampling sites. Psychrobacter contributed significantly to bacterial function at S3, as evidenced by the Kyoto Encyclopedia of Genes and Genomes pathway and enzyme analysis. Notably, 28 enzymes involved in MP biodegradation were identified, predominantly comprising oxidoreductases, hydrolases, transferases, ligases, lyases, and isomerases. We propose a putative mechanism for MP biodegradation, involving the breakdown of long-chain plastic polymers and subsequent oxidation of short-chain oligomers, ultimately leading to thorough mineralization.

No Effect of Realistic Concentrations of Polyester Microplastic Fibers on Freshwater Zooplankton Communities

Zooplankton are a conduit of energy from autotrophic phytoplankton to higher trophic levels, and they can be a primary point of entry of microplastics into the aquatic food chain. Investigating how zooplankton communities are affected by microplastic pollution is thus a key step toward understanding ecosystem-level effects of these global and ubiquitous contaminants. Although the number of studies investigating the biological effects of microplastics has grown exponentially in the last decade, the majority have used controlled laboratory experiments to quantify the impacts of microplastics on individual species. Given that all organisms live in multispecies communities in nature, we used an outdoor 1130-L mesocosm experiment to investigate the effects of microplastic exposure on natural assemblages of zooplankton. We endeavored to simulate an environmentally relevant exposure scenario by manually creating approximately 270 000 0.015 × 1- to 1.5-mm polyester fibers and inoculating mesocosms with zero, low (10 particles/L), and high (50 particles/L) concentrations. We recorded zooplankton abundance and community composition three times throughout the 12-week study. We found no effect of microplastics on zooplankton abundance, Shannon diversity, or Pielou's evenness. Nonmetric multidimensional scaling plots also revealed no effects of microplastics on zooplankton community composition. Our study provides a necessary and realistic baseline on which future studies can build. Because numerous other stressors faced by zooplankton (e.g., food limitation, eutrophication, warming temperatures, pesticides) are likely to exacerbate the effects of microplastics, we caution against concluding that polyester microfibers will always have no effect on zooplankton communities. Instead, we encourage future studies to investigate the triple threats of habitat degradation, climate warming, and microplastic pollution on zooplankton community health. Environ Toxicol Chem 2024;43:418-428. © 2023 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Comparison of concentration, shape, and polymer composition between microplastics and mesoplastics in Japanese river waters

While plastics are classified by size as microplastics (<5 mm), mesoplastics (5-25 mm), and macroplastics (>25 mm), research in rivers has centered on microplastics, followed by macroplastics, with limited research on mesoplastics (research gap). This study aims to clarify the concentration, shape, and polymer composition of microplastics and mesoplastics in Japanese river water. We conducted field surveys for microplastics and mesoplastics in 147 rivers and at 185 measurement stations. The novelty of this study is in the use of a large number of field data to minimize the effect of the spatial difference in the microplastics and mesoplastics on the data analysis. Microplastics and mesoplastics were found at 183 (99 %) and 136 (74 %) stations, respectively. The difference between the concentration of microplastics and mesoplastics increased significantly with the increase in the concentration of microplastics, showing that the concentration of both microplastics and mesoplastics should be monitored to prevent an underestimation of plastic pollution in rivers with the appropriate sampling. A 2-stage size classification with microplastics (<5 mm) and macroplastics (>5 mm) is not suitable because the mesoplastics may be substantially overlooked. The regression slopes between microplastics and mesoplastics concentrations significant decrease in variance with increasing data number, suggesting the necessity of the large number of samples used in this study. The predominant shapes and polymer types of microplastics and mesoplastics were found to be fragment and fiber and polyethylene and polyethylene terephthalate (PET), respectively, which were affected appreciably by many fiber clusters. The fiber and PET ratios were dominant at stations with small population densities and urban ratios and can be attributed to atmospheric deposition and the underdeveloped rate of wastewater treatment plants (WWTPs). Therefore, it is necessary to monitor the dynamics and fate of fiber clusters inside and outside the basin.

Selection for antimicrobial resistance in the plastisphere

Microplastics and antimicrobials are widespread contaminants that threaten global systems and frequently co-exist in the presence of human or animal pathogens. Whilst the impact of each of these contaminants has been studied in isolation, the influence of this co-occurrence in driving antimicrobial resistance (AMR)1 in microplastic-adhered microbial communities, known as 'the Plastisphere', is not well understood. This review proposes the mechanisms by which interactions between antimicrobials and microplastics may drive selection for AMR in the Plastisphere. These include: 1) increased rates of horizontal gene transfer in the Plastisphere compared with free-living counterparts and natural substrate controls due to the proximity of cells, co-occurrence of environmental microplastics with AMR selective compounds and the sequestering of extracellular antibiotic resistance genes in the biofilm matrix. 2) An elevated AMR selection pressure in the Plastisphere due to the adsorbing of AMR selective or co-selective compounds to microplastics at concentrations greater than those found in surrounding mediums and potentially those adsorbed to comparator particles. 3) AMR selection pressure may be further elevated in the Plastisphere due to the incorporation of antimicrobial or AMR co-selective chemicals in the plastic matrix during manufacture. Implications for both ecological functioning and environmental risk assessments are discussed, alongside recommendations for further research.

Microplastics as vectors of other contaminants: Analytical determination techniques and remediation methods

The ubiquitous and persistent presence of microplastics (MPs) in aquatic and terrestrial ecosystems has raised global concerns due to their detrimental effects on human health and the natural environment. These minuscule plastic fragments not only threaten biodiversity but also serve as vectors for contaminants, absorbing organic and inorganic pollutants, thereby causing a range of health and environmental issues. This review provides an overview of microplastics and their effects. This work highlights available analytical techniques for detecting and characterizing microplastics in different environmental matrices, assessing their advantages and limitations. Additionally, this review explores innovative remediation approaches, such as microbial degradation and other advanced methods, offering promising prospects for combatting microplastic accumulation in contaminated environments. The focus on environmentally-friendly technologies, such as the use of microorganisms and enzymes for microplastic degradation, underscores the importance of sustainable solutions in plastic pollution management. In conclusion, this article not only deepens our understanding of the microplastic issue and its impact but also advocates for the urgent need to develop and implement effective strategies to mitigate this critical environmental challenge. In this context, the crucial role of advanced technologies, like quantitative Nuclear Magnetic Resonance spectroscopy (qNMR), as promising tools for rapid and efficient microplastic detection, is emphasized. Furthermore, the potential of the enzyme PETase (polyethylene terephthalate esterase) in microplastic degradation is examined, aiming to address the growing plastic pollution, particularly in saline environments like oceanic ecosystems. These innovations offer hope for effectively addressing microplastic accumulation in contaminated environments and minimizing its adverse impacts.

Influence of synthetic and natural microfibers on the growth, substance exchange, energy accumulation, and oxidative stress of field-collected microalgae compared with microplastic fragment

Synthetic microfibers (MFs), which are Microplastics (MPs), have not received attention commensurate with their abundance in the environment. Currently, limited studies on MFs have focused on their effects on marine organisms. It is therefore necessary to conduct exposure experiments of MFs on freshwater organisms to provide reference data for the ecological risk assessment of MFs. As a primary producer in freshwater ecosystems, microalgae have an ecological niche that is highly overlapping with that of MFs. In this study, we examined the effects of MFs on the growth of Chlorella and indicators of oxidative stress to examine their potential risk on the microalgae population. The results showed that inhibition rate of microalgae increased with MF concentration in the range of 0.01-100 mg/L. Compared with natural fibers such as cotton and wool, PET and PP fibers showed significant growth inhibition, but less so when in fragment form with the same material and concentration. PP and PET particles, whether fibers or fragments, increased the total antioxidant capacity of microalgal cells and caused oxidative damage. To determine the influence of MFs on the interaction of cells in the environment, the exchanged substances and accumulated energy of microalgae cells were also detected. The results indicated that PP and PET fibers, as well as fragments, increased the diameter and membrane permeability of microalgae cell, thus interfering with the cell division and substance exchange processes. PET fibers and fragments showed different interactions at the level of individual cells and populations. This suggests that the evaluation of MPs should consider examinations from cells to population and even community levels in the future.

Microplastics exposure: implications for human fertility, pregnancy and child health

Plastics found in our everyday environment are becoming an increasing concern for individual and population-level health, and the extent of exposure and potential toxic effects of these contaminants on numerous human organ systems are becoming clear. Microplastics (MPs), tiny plastic particles, appear to have many of the same biological effects as their plastic precursors and have the compounded effect of potential accumulation in different organs. Recently, microplastic accumulation was observed in the human placenta, raising important questions related to the biological effects of these contaminants on the health of pregnancies and offspring. These concerns are particularly heightened considering the developmental origins of health and disease (DOHaD) framework, which postulates that in utero exposure can programme the lifelong health of the offspring. The current review examines the state of knowledge on this topic and highlights important avenues for future investigation.

Microplastic Removal in Wastewater Treatment Plants (WWTPs) by Natural Coagulation: A Literature Review

Urban industrialization has caused a ubiquity of microplastics in the environment. A large percentage of plastic waste originated from Southeast Asian countries. Microplastics arising from the primary sources of personal care items and industrial uses and the fragmentation of larger plastics have recently garnered attention due to their ubiquity. Due to the rising level of plastic waste in the environment, the bioaccumulation and biomagnification of plastics threaten aquatic and human life. Wastewater treatment plant (WWTP) effluents are one of the major sources of these plastic fragments. WWTPs in Southeast Asia contribute largely to microplastic pollution in the marine environment, and thus, further technological improvements are required to ensure the complete and efficient removal of microplastics. Coagulation is a significant process in removing microplastics, and natural coagulants are far superior to their chemical equivalents due to their non-toxicity and cost-effectiveness. A focused literature search was conducted on journal repository platforms, mainly ScienceDirect and Elsevier, and on scientific databases such as Google Scholar using the keywords Wastewater Treatment Plant, Coagulation, Microplastics, Marine Environment and Southeast Asia. The contents and results of numerous papers and research articles were reviewed, and the relevant papers were selected. The relevant findings and research data are summarized in this paper. The paper reviews (1) natural coagulants for microplastic removal and their effectiveness in removing microplastics and (2) the potential use of natural coagulants in Southeast Asian wastewater treatment plants as the abundance of natural materials readily available in the region makes it a feasible option for microplastic removal.

Exposure of Mytilus galloprovincialis to Microplastics: Accumulation, Depuration and Evaluation of the Expression Levels of a Selection of Molecular Biomarkers

Microplastic contamination is a growing marine environmental issue with possible consequences for seafood safety. Filter feeders are the target species for microplastic (MPs) pollution because they filter large quantities of seawater to feed. In the present study, an experimental contamination of Mytilus galloprovincialis was conducted using a mixture of the main types of MPs usually present in the seawater column (53% filaments, 30% fragments, 3% granules) in order to test the purification process as a potential method for removing these contaminants from bivalves intended for human consumption. A set of molecular biomarkers was also evaluated in order to detect any variations in the expression levels of some genes associated with biotransformation and detoxification, DNA repair, cellular response, and the immune system. Our results demonstrate that: (a) the purification process can significantly reduce MP contamination in M. galloprovincialis; (b) a differential expression level has been observed between mussels tested and in particular most of the differences were found in the gills, thus defining it as the target organ for the use of these biomarkers. Therefore, this study further suggests the potential use of molecular biomarkers as an innovative method, encouraging their use in next-generation marine monitoring programs.

Effects of microplastics mixed with natural particles on Daphnia magna populations

The toxicity of microplastics on Daphnia magna as a key model for freshwater zooplankton is well described. While several studies predict population-level effects based on short-term, individual-level responses, only very few have validated these predictions experimentally. Thus, we exposed D. magna populations to irregular polystyrene microplastics and diatomite as natural particle (both ≤63 μm) over 50 days. We used mixtures of both particle types at fixed particle concentrations (50,000 particles mL-1) and recorded the effects on overall population size and structure, the size of the individual animals, and resting egg production. Particle exposure adversely affected the population size and structure and induced resting egg production. The terminal population size was 28-42 % lower in exposed compared to control populations. Interestingly, mixtures containing diatomite induced stronger effects than microplastics alone, highlighting that natural particles are not per se less toxic than microplastics. Our results demonstrate that an exposure to synthetic and natural particles has negative population-level effects on zooplankton. Understanding the mixture toxicity of microplastics and natural particles is important given that aquatic organisms will experience exposure to both. Just as for chemical pollutants, better knowledge of such joint effects is essential to fully understand the environmental impacts of complex particle mixtures. ENVIRONMENTAL IMPLICATIONS: While microplastics are commonly considered hazardous based on individual-level effects, there is a dearth of information on how they affect populations. Since the latter is key for understanding the environmental impacts of microplastics, we investigated how particle exposures affect the population size and structure of Daphnia magna. In addition, we used mixtures of microplastics and natural particles because neither occurs alone in nature and joint effects can be expected in an environmentally realistic scenario. We show that such mixtures adversely affect daphnid populations and highlight that population-level and mixture-toxicity designs are one important step towards more environmental realism in microplastics research.

Microplastic Effect Tests Should Use a Standard Heterogeneous Mixture: Multifarious Impacts among 16 Benthic Invertebrate Species Detected under Ecologically Relevant Test Conditions

Microplastics require a risk assessment framework that takes their multidimensionality into account while exclusively considering robust data. Therefore, effect tests should use a diverse, environmentally relevant microplastic (ERMP) standard material that adheres to high-quality requirements. In this study, we provide chronic dose-effect relationships and effect thresholds for 16 benthic species exposed to ERMP. The ERMP was created from plastic items collected from natural sources and cryogenically milled to represent the diversity of microplastics. The test design met 20 previously published quality assurance and quality control criteria. Adverse effect thresholds (EC10) were determined at ERMP concentrations of 0.11 ± 0.17% sediment dry weight (Gammarus pulex, growth), 0.49 ± 0.68% sediment dry weight (Lumbriculus variegatus, growth), and 1.90 ± 1.08% sediment dry weight (L. variegatus, reproduction). A positive effect of microplastics, such as decreased mortality, was observed for Cerastoderma edule (EC10 = 0.021 ± 0.027% sediment dry weight) and Sphaerium corneum (EC10 = 7.67 ± 3.41% sediment dry weight), respectively. Several of these laboratory-based single-species effect thresholds for ERMP occurred at concentrations lower than those found in the environment. For other species, no significant effects were detected up to an ERMP dose of 10% dry weight.

Microplastic burden in marine benthic invertebrates depends on species traits and feeding ecology within biogeographical provinces

The microplastic body burden of marine animals is often assumed to reflect levels of environmental contamination, yet variations in feeding ecology and regional trait expression could also affect a species' risk of contaminant uptake. Here, we explore the global inventory of individual microplastic body burden for invertebrate species inhabiting marine sediments across 16 biogeographic provinces. We show that individual microplastic body burden in benthic invertebrates cannot be fully explained by absolute levels of microplastic contamination in the environment, because interspecific differences in behaviour and feeding ecology strongly determine microplastic uptake. Our analyses also indicate a degree of species-specific particle selectivity; likely associated with feeding biology. Highest microplastic burden occurs in the Yellow and Mediterranean Seas and, contrary to expectation, amongst omnivores, predators, and deposit feeders rather than suspension feeding species. Our findings highlight the inadequacy of microplastic uptake risk assessments based on inventories of environmental contamination alone, and the need to understand how species behaviour and trait expression covary with microplastic contamination.

Forecasting global plastic production and microplastic emission using advanced optimised discrete grey model

Plastic pollution has become a prominent and pressing environmental concern within the realm of pollution. In recent times, microplastics have entered our ecosystem, especially in freshwater. In the contemporary global landscape, there exists a mounting apprehension surrounding the manifold environmental and public health issues that have emerged as a result of the substantial accumulation of microplastics. The objective of the current study is to employ an enhanced grey prediction model in order to forecast global plastic production and microplastic emissions. This study compared the accuracy level of the four grey prediction models, namely, EGM (1,1, α, θ), DGM (1,1), EGM (1,1), and DGM (1,1, α) models, to evaluate the accuracy levels. As per the estimation of the study, DGM (1,1, α) was found to be more suitable with higher accuracy levels to predict microplastic emission. The EGM (1,1, α, θ) model has slightly better accuracy than the DGM (1,1, α) model in predicting global plastic production. Various accuracy measurement tools (MAPE and RMSE) were used to determine the model's efficiency. There has been a gradual growth in both plastic production and microplastic emission. The current study using the DGM (1,1, α) model predicted that microplastic emission would be 1,084,018 by 2030. The present study aims to provide valuable insights for policymakers in formulating effective strategies to address the complex issues arising from the release of microplastics into the environment and the continuous production of plastic materials.

Using eRNA/eDNA metabarcoding to detect community-level impacts of nanoplastic exposure to benthic estuarine ecosystems

Plastic particles are ubiquitous in marine systems and fragment into smaller pieces, such as nanoplastics (NPs). The effects of NPs on marine organisms are of growing concern but are not well understood. Marine sediments act as a sink for many contaminants, like microplastics, and are rich habitats for benthic micro- and meiofauna which are ecologically-important components of marine food webs; however, little is known about the sensitivities of specific organisms to NPs or the effects on community diversity and composition. Utilizing molecular methods, such as metabarcoding of environmental DNA/RNA, allows for the rapid and comprehensive detection of microscopic organisms via high-throughput sequencing to assess adverse effects at the community level. The objective of this study was to use a metabarcoding approach to investigate the effects of NPs on benthic micro- and meiofaunal community diversity. Mesocosms were created with sediment cores collected from the Narrow River estuary (Rhode Island, USA) and exposed to 900 nm diameter weathered polystyrene beads at concentrations of 0.1, 1, 10, or 100 mg/kg dry weight in sediment for two weeks. Following exposure, RNA and DNA were co-extracted from the sediment, RNA was reverse-transcribed, 18S and COI markers were PCR-amplified, and amplicons were sequenced on an Illumina MiSeq. Using the 18S marker and eRNA template, increases to α-diversity and significant differences to β-diversity were observed in the highest NP exposures relative to the control. Observed differences in community composition were driven by the differential abundance of several types of protists and arthropods. Significant dose-dependent shifts in composition were observed in β-diversity Jaccard and Unweighted-Unifrac metrics with the 18S marker using the RNA template. To our knowledge, this is the first demonstration of a dose-response relationship for NPs at a community level, and it highlights the value of using community-level endpoints to assess environmental impacts of nanoparticles.

Seasonal variations of microplastic in sediment, Chironomus sp. larvae, and chironomid tubes in two wastewater sites in Sohag Governorate, Egypt

Microplastic (MP) contamination is an acknowledged global problem that poses a severe risk to aquatic ecosystem biota. Nevertheless, little is known about their prevalence in animal construction. The main objective of our study was to reduce the gap information of seasonal abundance, distribution, composition, and risk assessment of MP contamination. The concentrations of MPs in sediment, Chironomus sp. larvae, and their tubes were found to be higher in site 2 (S2) than in site 1 (S1) during the four seasons of the year. However, MP concentrations ranged from 312 ± 64.7 to 470 ± 70 items/kg dry weight, 0.79 ± 0.16 to 1.1 ± 0.3 particles/individual, and 0.5 ± 0.04 to 0.9 ± 0.04 particles/tube in sediment, Chironomus, and chironomid tubes, respectively. Blue and red polyester fibers are the most dominant MPs which are distributed in sediment, Chironomus, and chironomid tubes. The length of the dominant fiber accumulates in Chironomus, and their tubes are highly varied compared to that of the substrate. Additionally, we found that the mean number of MPs/individual larvae in the fourth instar was significantly higher than that in the second instar. Risk indicators for the environment, polymer risk assessment, and pollution load were estimated, where they were higher in S2 than in S1 correlated to MPs abundance and polymer type. The seasonal fluctuation in MP concentration, characterization, and risk in the two sites could depend on the amount of sewage effluent discharged into the wastewater treatment plants (WWTPs), which was reflected by Chironomus sp. larvae. Therefore, further research should be done to adopt the applicability of Chironomus as MP bioindicators in various freshwater environments throughout the world.

Incidence and exposure to microplastics in table salt present in the Iran market

Plastics and microplastics (MPs) are toxic, pervasive and threatening the biotic and abiotic components of the earth, and they threaten food safety and food security by moving in the food chain. In this study, the amounts and characteristics of 40 table salt samples with different brands, including sea salt (No = 13), rock (No = 13), bulk (No = 8) and non-standard (No = 6), were investigated with a combination of sieving, filtration, observation and FTIR, Micro-Raman and SEM techniques. The results showed that all the salts were contaminated with MPs. In general, the abundance range of detected particles was 700-5470 MPs/kg. The abundance of MPs was higher in counterfeit and non-standard salts (1825 ± 1808 MPs/kg). Investigating the relationship between the effect of the purification process (Kruskal-Wallis Test, P = 0.841), the type of packaging (Kruskal-Wallis Test, P = 0.609), and the type of salt (Kruskal-Wallis Test, P = 0.942), on the abundance of MPs using a comparison test Kruskal-Wallis was not significant. However, the numerical difference was recognizable. The most identified polymer in the salts was cellulose acetate, which probably causes by unmanaged plastic litter in the environment (especially cigarette butts). The dominant form of particles was fragment-shaped, which is the most abundant form of identified MPs in the environment. Both environmental pollution and secondary pollution (during production and packaging), respectively, contribute to the contamination of salts with MPs. The estimated human dietary intake (EDI) and the amount of estimated annual intake (EAI) for different ages in Iran were obtained EDI = 5-59 MPs/capita/day and EAI = 1967-21563 MPs/capita/year. The surface morphology of the particles showed that the MPs were affected by continuous weathering, mechanical fracture and oxidation. MPs are a threat to human health due to the absorption and transmission of dangerous pollutants and their inherent toxicity. Therefore, a solution must be thought of to prevent the contamination of the food chain through salts by MPs, (with protective measures at the salt source, and by improving its production processes.

Atmospheric microplastic transport and deposition to urban and pristine tropical locations in Southeast Asia

Atmospheric microplastic transport is an important delivery pathway with the deposition of microplastics to ecologically important regions raising environmental concerns. Investigating atmospheric delivery pathways and their deposition rates in different ecosystems is necessary to understanding its global impact. In this study, atmospheric deposition was collected at three sites in Malaysia, two urban and one pristine, covering the Northeast and Southwest monsoons to quantify the role of this pathway in Southeast Asia. Air mass back trajectories showed long-range atmospheric transport of microplastics to all sites with atmospheric deposition varying from 114 to 689 MP/m2/day. For the east coast of Peninsular Malaysia, monsoonal season influenced microplastic transport and deposition rate with peak microplastic deposition during the Northeast monsoon due to higher wind speed. MP morphology combined with size fractionation and plastic type at the coastal sites indicated a role for long-range marine transport of MPs that subsequently provided a local marine source to the atmosphere at the coastal sites.

Water, Water Everywhere, but Every Drop Unique: Challenges in the Science to Understand the Role of Contaminants of Emerging Concern in the Management of Drinking Water Supplies

The protection and management of water resources continues to be challenged by multiple and ongoing factors such as shifts in demographic, social, economic, and public health requirements. Physical limitations placed on access to potable supplies include natural and human-caused factors such as aquifer depletion, aging infrastructure, saltwater intrusion, floods, and drought. These factors, although varying in magnitude, spatial extent, and timing, can exacerbate the potential for contaminants of concern (CECs) to be present in sources of drinking water, infrastructure, premise plumbing and associated tap water. This monograph examines how current and emerging scientific efforts and technologies increase our understanding of the range of CECs and drinking water issues facing current and future populations. It is not intended to be read in one sitting, but is instead a starting point for scientists wanting to learn more about the issues surrounding CECs. This text discusses the topical evolution CECs over time (Section 1), improvements in measuring chemical and microbial CECs, through both analysis of concentration and toxicity (Section 2) and modeling CEC exposure and fate (Section 3), forms of treatment effective at removing chemical and microbial CECs (Section 4), and potential for human health impacts from exposure to CECs (Section 5). The paper concludes with how changes to water quantity, both scarcity and surpluses, could affect water quality (Section 6). Taken together, these sections document the past 25 years of CEC research and the regulatory response to these contaminants, the current work to identify and monitor CECs and mitigate exposure, and the challenges facing the future.

Ecotoxicological effects of antibiotic adsorption behavior of microplastics and its management measures

Microplastics adsorb heavy metals and organic pollutants to produce combined pollution. Recently, the adsorption behavior of antibiotics on microplastics has received increasing attention. Exploring the sorption behavior of pollutants on microplastics is an important reference in understanding their ecological and environmental risk studies. In this paper, by reviewing the academic literature in recent years, we clarified the current status of research on the adsorption behavior of antibiotics on microplastics, discussed its potential hazards to ecological environment and human health, and summarized the influence of factors on the adsorption mechanisms. The results show that the adsorption behavior of antibiotics on microplastics is controlled by the physical and chemical properties of antibiotics, microplastics, and water environment. Antibiotics are adsorbed on microplastics through physical and chemical interactions, which include hydrophobic interaction, partitioning, electrostatic interaction, and other non-covalent interactions. Intensity of adsorption between them is mainly determined by their physicochemical properties. The basic physicochemical properties of the aqueous environment (e.g., pH, salinity, ionic strength, soluble organic matter content, and temperature) will affect the physicochemical properties of microplastics and antibiotics (e.g., particle size, state of dispersibility, and morphology), leading to differences in the type and strength of their interactions. This paper work is expected to provide a meaningful perspective for better understanding the potential impacts of antibiotic adsorption behavior of microplastics on aquatic ecology and human health. In the meantime, some indications for future related research are provided.

Toxicity assessment of microplastics within the Loire River in the clam Corbicula fluminea exposed to environmentally relevant exposure conditions

The dispersed pollution caused by microplastics (MPs) represents a current and global concern. While the fragmentation of plastic debris into smaller particles occurs in rivers, little MP research is done on freshwater species and is published compared to the marine environment. The Loire River is the longest river in France and is subject to moderate to high anthropic pressure while it represents major societal and economic issues. However, there are not many studies that have been put forward with regards to the effect of environmental MPs (EMPs) on aquatic organisms and no policies have been enacted to monitor the plastic pollution. In this study, freshwater bivalves, Corbicula fluminea, were exposed for 21 days to environmentally relevant concentrations of a mixture of <200 µm MPs generated from plastic litter collected directly along the banks of the Loire River. This mixture was composed of 40% polyethylene (PE), 40% polypropylene (PP), 10% polyethylene terephthalate (PET) and 10% polyvinylchloride (PVC) (mass percentage). Ecotoxicological effects were assessed from the individual to the molecular levels on several endpoints: condition index, filtration efficiency, enzyme activities, lipid peroxidation, energy reserves and gene expression. The ingestion of EMPs caused damages at the biochemical level. Indeed, we reported an increase in catalase activity in gills and digestive mass, a decrease in TBARs in gills, a decrease in acetylcholinesterase activity in the digestive mass, a decrease of glycogen and lipid contents in the whole organisms and a significant induction of the expression of gst, cat, mp, acp genes. The current results suggest therefore that long-term exposure to realistic doses of EMPs causes toxicity towards freshwater benthic biota. The analysis of biomarker activities and the analysis of gene expression are complementary to prevent the effects of a plastic contamination at higher biological levels in aquatic organisms.

Microplastics in Cetaceans Stranded on the Portuguese Coast

This study characterises microplastics in small cetaceans on the coast of Portugal and assesses the relationship between several biological variables and the amount of detected microplastics. The intestines of 38 stranded dead cetaceans were processed in the laboratory, with digestion methods adapted to the amount of organic matter in each sample. The influence of several biological and health variables (e.g., species, sex, body condition) on the amount of microplastics was tested in all analysed species and particularly in common dolphins, due to the larger number of available samples. Most of the analysed individuals had microplastics in the intestine (92.11%), with harbour porpoises revealing a significantly higher median number of microplastics than common dolphins, probably due to their different diets, use of habitat and feeding strategies. None of the other tested variables significantly influenced the number of microplastics. Moreover, the microplastics found should not be enough to cause physical or chemical sublethal effects, although the correlation between microplastic ingestion and plastic additive bioaccumulation in cetacean tissues requires further investigation. Future monitoring in biota should rely on improved and standardised protocols for microplastic analyses in complex samples to allow for accurate analyses of larger samples and spatio-temporal comparisons.

Abundance and characteristics of microplastic in some commercial species from the Persian Gulf, Iran

Global production of plastics has increased dramatically in recent decades and is considered a major threat to marine life and human health due to their stability, persistence, and potential to move through food chains. The study was conducted to detect, identify and quantify microplastics (MP) in the gastrointestinal tract (GI) of some commercial fish species in the North Persian Gulf in Bushehr Province: Psettodes erumei, Sphyraena jello, Sillago sihama, Metapenaeus affinis and Portunus segnis. A total of 216 plastic particles were collected from 102 individuals (72.68% of all sampled individuals; MP prevalence of 85.1% for M. affinis, 80% for P. segnis, 70% for P.erumei, 60.3% for S.sihama, 45.2% for S.jello). The average number of microplastics per organism was 2.26 ± 0.38 MP/ind (considering only species that ingested plastic, n = 102) and 1.51 ± 0.40 pieces/ind (considering all species studied, n = 140). Microfibers accounted for 58.49% of the total microplastics, followed by fragments (33.02%) and pellets (8.49%). The most common color of microplastic was black (52.83%), followed by blue (22.64%) and transparent (15.09%). The length of microplastic ranged from 100 to 5000 μm with an average of 854 ± 312 μm. Microplastics were significantly (p < 0.05) abundant in two shrimp studied: M. affinis and P. segnis (plastic in 80% of individuals studied) and to a lesser extent in the pelagic barracuda fish S. jello (plastic in 45% of individuals studied). The main synthetic polymers identified by Fourier transform infrared spectroscopy (FTIR) were polyethylene (38%), polypropylene (24%), polystyrene (17%), polyethylene terephthalate (11%) and polyamide (10%). The pollutant load index and lifetime accumulation index were calculated to identify the most polluted species and their toxicity to human health. The white shrimp M. affinis was identified as the most polluted and toxic species for MP based on PLI. The present study can provide valuable data for further research and a background for the control and monitoring of this pollutant in the coastal environment of Bushehr province.

Microplastics in marine mammal blubber, melon, & other tissues: Evidence of translocation

Marine mammals consume large quantities of microplastic particles, likely via trophic transfer (i.e., through prey who have consumed plastic) and direct consumption from seawater or sediment. Microplastics have been found in the stomachs, gastro-intestinal tracts, and feces of cetaceans and pinnipeds. Translocation of ingested microplastics has been documented in other organs of several aquatic species, but has not been examined in marine mammals. Marine mammals have highly specialized lipid-rich tissues which may increase susceptibility to lipophilic microplastics. Here we demonstrate the occurrence of microplastics, ranging in size, mass concentration, and particle count concentration from 24.4 μm - 1387 μm, 0.59 μg/g - 25.20 μg/g, and 0.04 - 0.39 particles/g, respectively, in four tissues (acoustic fat pad, blubber, lung, & melon) from twelve marine mammal species inclusive of mysticetes, odontocetes, and phocids. Twenty-two individuals were examined for microplastics using a combination of Raman spectroscopy and pyrolysis gas chromatography with mass spectrometry. Overall, 68% of individuals had at least one microplastic particle in at least one of the four tissue types, with the most common polymer and shape observed being polyethylene and fibers, respectively. These findings suggest some proportion of ingested microplastics translocate throughout marine mammal bodies posing an exposure risk to both marine mammals and people. For people, exposure could be directly through consumption for those who rely on marine mammals as food and indirectly to peoples globally who consume the same prey resources as marine mammals. Some individuals examined represent samples obtained over two decades ago, suggesting that this process, and thus exposure risk, has occurred for some time.

Non-traditional species sensitivity distribution approaches to analyze hazardous concentrations of microplastics in marine water

Owing to their ubiquitous nature, microplastics are a major environmental concern. This study reviewed the toxicity data of microplastics in marine water, and analyzed their species sensitivity distribution (SSD) curves and hazardous concentrations (HCs). Toxicity database of no-observed effect concentration (NOEC), 50% effect concentration (EC50), and highest observed no-effect concentration (HONEC), and lethal, developing, reproductive, biochemical, and behavioral toxicity endpoints was used. Using 169 chronic NOEC databases, all non-traditional toxicity endpoint databases showed stronger HC values, better fit, and more variable toxicity sensitivity than those derived from traditional values. Moreover, using 426 chronic NOEC, EC50, and HONEC data points, HC values calculated from traditional plus HONEC toxicity values showed weaker HC values, slightly better fit, and more variable toxicity sensitivity than those derived from traditional toxicity values. The SSD approach using non-traditional toxicity and marine water toxicity data can expand the marine water toxicity database, including information on SSD curves and HCs of diverse microplastics.

Microplastics could be marginally more hazardous than natural suspended solids - A meta-analysis

Microplastics (MP) are perceived as a threat to aquatic ecosystems but bear many similarities to suspended sediments which are often considered less harmful. It is, therefore pertinent to determine if and to what extent MP are different from other particles occurring in aquatic ecosystems in terms of their adverse effects. We applied meta-regressions to toxicity data extracted from the literature and harmonized the data to construct Species Sensitivity Distributions (SSDs) for both types of particles. The results were largely inconclusive due to high uncertainty but the central tendencies of our estimates still indicate that MP could be marginally more hazardous compared to suspended sediments. In part, the high uncertainty stems from the general lack of comparable experimental studies and dose-dependent point estimates. We therefore argue that until more comparable data is presented, risk assessors should act precautionary and treat MP in the 1-1000 µm size range as marginally more hazardous to aquatic organisms capable of ingesting such particles.

Effects of virgin and BaP-adsorbed microplastics ingestion by Manila clams (Ruditapes philippinarum)

Numerous microplastic-related studies have investigated the impact of plastic materials on the marine food chain. In this study, Manila clams were exposed to microplastic (MP) of various polymer types, shapes, and concentrations to determine the ingestion selectivity and adverse effects caused. Benzo[a]pyrene was introduced as the second stressor to investigate the role of MP as a vector of contaminant. The result of a 2-day acute exposure showed that clams are more likely to ingest those in sphere shapes due to their similarity to microalgae. The feeding rate continuously declined when clams were exposed to at least 2to/L particles. Additionally, co-exposure of MP and B[a]P resulted in higher DNA fragmentation but lower catalase activity compared to single exposure to MP. Our study revealed that the uptake of MP by clams is not only determined by its shape and concentration but also by the presence of existing contaminants.

Distribution, abundance, and risks posed by microplastics in surface waters of the Yangtze River Basin, China

Microplastic (MP) pollution in the Yangtze River Basin, China, has become an environmental issue of great concern. However, most studies on MPs have focused on a part of the Yangtze River Basin, and still lack knowledge on the risk of MPs exposure in surface waters of the whole basin. This study overviews the differences in abundance and spatial distribution of MPs in surface waters basin-wide and comprehensively assesses the ecological risk of MPs exposure in surface waters of the Yangtze River Basin by considering the abundance and toxicity effects. The results showed that the MP abundance at the collected sampling sites ranged from 0 to 44,080 particles/m3, with a mean of 3441 particles/m3. MPs were unevenly distributed throughout the basin, with hotspots such as Three Gorges Reservoir, Yangtze River estuary, and some urban lakes showing relatively higher abundance than the surroundings. Based on the available toxicity data, chronic and acute predicted no-effect concentrations (PNECs) of 12.3 particles/L and 21 particles/L were derived for freshwater MPs exposure using constructed species sensitivity distributions (SSDs). The hazard quotient (HQ) method was used to compare the environmental exposure concentrations of MPs with PNECs, and the results showed that 71.8% of the sampling sites in the Yangtze River Basin had moderate chronic ecological risk, while 43% of the sampling sites had moderate acute ecological risk. Overall, the ecological risk of MPs in lake and reservoir water was higher than that in river water. Joint probability curves (JPCs) showed that the overall risk probability of MPs in the surface water of the Yangtze River Basin was lower than that of other basins in China and other countries. This research provides valuable information for the ecological risk assessment of MPs at the watershed scale.

Integrated numerical modeling to quantify transport and fate of microplastics in the hyporheic zone

Despite the significance of rivers and streams as pathways for microplastics (MP) entering the marine environment, limited research has been conducted on the behavior of MP within fluvial systems. Specifically, there is a lack of understanding regarding the infiltration and transport dynamics of MP across the streambed interface and within the hyporheic sediments. In this study, transport and retention of MP are investigated using a new numerical modeling approach. The model is built as a digital twin of accompanying flume experiments, which are used to validate the simulation results. The model accurately represents particle transport in turbulent water flow and within the hyporheic zone (HZ). Simulations for transport and infiltration of 1 µm MP particles into a sandy streambed demonstrate that the advection-dispersion equation can be used to adequately represent particle transport for pore-scale sized MP within the HZ. To assess the applicability of the modeling framework for larger MP, the experiment was repeated using 10 µm particles. The larger particles exhibited delayed infiltration and transport behavior, and while the model successfully represented the spatial extent of particle transport through the HZ, it was unable to fully replicate hyporheic transit times. This study is the first to combine explicit validation against experimental data, encompassing qualitative observations of MP concentration patterns and quantification of fluxes. By that, it significantly contributes to our understanding of MP transport processes in fluvial systems. The study also highlights the advantages and limitations of employing a fully integrated modeling approach to investigate the transport and retention behavior of MP in rivers and streams.

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.

Rethinking plastic recycling: A comparison between North America and Europe

In this article, we identify the problem of plastic proliferation, the consequent expansion of plastic waste in our society, the inadequacies of current attempts to recycle plastic, and the urgency to address this problem in the light of the microplastic threat. It details the problems with current efforts to recycle plastic and the particularly poor recycling rates in North America (NA) when compared to certain countries in the European Union (EU). The obstacles to plastic recycling are overlapping economic, physical and regulatory problems spanning fluctuating resale market prices, residue and polymer contamination and offshore export which often circumvents the entire process. The primary differences between the EU and NA are the costs of end-of-life disposal methods with most EU citizens paying much higher prices for both landfilling and Energy from Waste (incineration) costs compared with NA. At the time of writing, some EU states are either restricted from landfilling mixed plastic waste or the cost is significantly greater than in NA ($80 to 125 USD/t vs $55 USD/t). This makes recycling a favourable option in the EU, and, in turn, has led to more industrial processing and innovation, more recycled product uptake, and the structuring of collection and sorting methods that favour cleaner polymer streams. This is a self-re-enforcing cycle and is evident by EU technologies and industries that have emerged to process "problem plastics", such as mixed plastic film wastes, co-polymer films, thermosets, Polystyrene, (PS) Polyvinyl Chloride (PVC), and others. This is in contrast with NA recycling infrastructure, which has been tailored to shipping low-value mixed plastic waste abroad. Circularity is far from complete in any jurisdiction as export of plastic to developing countries is an opaque, but often used disposal method in the EU as it is in NA. Proposed restrictions on off-shore shipping and regulations requiring minimum recycled plastic content in new products will potentially increase plastic recycling by increasing both supply and demand for recycled product.

Microplastics in gastrointestinal tracts of gentoo penguin (Pygoscelis papua) chicks on King George Island, Antarctica

Microplastics (< 5 mm) have been found in marine ecosystems worldwide, even in Antarctic ecosystems. In this study, the stomach and upper intestines of 14 dead gentoo penguin (Pygoscelis papua) chicks were collected and screened for microplastics on King George Island, a gateway to Antarctic research and tourism. A total of 378 microplastics were identified by Fourier-transform infrared spectroscopy, with 27.0 ± 25.3 microplastics per individual. The detected number of microplastics did not increase with the mass of penguin chicks, suggesting no permanent accumulation of microplastics. However, the concentration of microplastics was much higher (9.1 ± 10.8 microplastics per individual within the size range 100-5000 μm) than the previously reported concentration in the penguin feces, and a greater number of smaller microplastics were found. Marine debris surveys near the breeding colony found various plastic (79.3%) to be the most frequent type of beached debris, suggesting that local sources of marine plastic waste could have contributed to microplastic contamination of penguin chicks being fed by parents that forage in nearby seas. This finding confirms the presence of microplastics in an Antarctic ecosystem and suggests the need for stronger waste management in Antarctica and a standardized scheme of microplastic monitoring in this once-pristine ecosystem.

Aquatic worms: relevant model organisms to investigate pollution of microplastics throughout the freshwater-marine continuum

Plastic pollution has become a global and emergency concern. Degradation processes of plastic macrowaste, either at the millimetre- and micrometre-size scales (microplastics, MP) or a nanometre one (nanoplastic, NP), is now well documented in all environmental compartments. It is hence necessary to study the environmental dynamic of MNP (micro(nano)plastic) on aquatic macrofauna considering their dispersion in different compartments. In this context, worms, having a large habitat in natural environments (soil, sediment, water) represent a relevant model organism for MNP investigations. In aquatic systems, worms could be used to compare MNP contamination between freshwater and seawater. The aim of this review was to discuss the relevance of using worms as model species for investigating MNP pollution in freshwater, estuarine, and marine systems. In this context, studies conducted in the field and in laboratory, using diverse classes of aquatic worms (polychaete and clitellate, i.e. oligochaete and hirudinea) to assess plastic contamination, were analysed. In addition, the reliability between laboratory exposure conditions and the investigation in the field was discussed. Finally, in a context of plastic use regulation, based on the literature, some recommendations about model species, environmental relevance, and experimental needs related to MNP are given for future studies.

Toxicity of mixture of polyethylene microplastics and Up Grade® pesticide on Oreochromis niloticus juvenile: I. Hemato-biochemical and histopathological alterations

Acute toxicity experiments were conducted to determine the lethal concentration 50 (LC50) of the Up Grade®46% SL for Oreochromis niloticus. Our results showed that the 96-h LC50 value of UPGR for O. niloticus was 29.16 mg L-1. To study hemato-biochemical effects, fish were exposed for 15 days to individual UPGR at 2.916 mg L-1, individual polyethylene microplastics (PE-MPs) at 10 mg L-1, and to their combinations UPGR+PE-MPs. UPGR exposure induced significant decrease in account of red blood cells (RBCs) and white blood cells (WBCs), platelets, monocytes, neutrophils, eosinophils, and the concentrations of hemoglobin (Hb), hematocrit (Hct), and mean corpuscular hemoglobin concentration (MCHC) than other treatments, compared to the control group. Sub-acute UPGR exposure significantly increase lymphocytes, mean corpuscular volume (MCV), and mean corpuscular hemoglobin (MCH), compared to the control group. In conclusion, UPGR and PE-MPs displayed antagonistic toxic effects due to maybe the sorption of UPGR onto PE-MPs.