A meta-analysis of the effects of exposure to microplastics on fish and aquatic invertebrates

Microplastic abundance and characteristics in bivalves from Tam Giang-Cau Hai and O Loan Lagoons, coastal regions in Central Vietnam: Implication on human health

Four common bivalves, including white clam (Meretrix lusoria), lined clam (Paratapes undulatus), oysters (Crassostrea gigas), and green mussels (Perna viridi), which are commonly consumed in Central Vietnam, were collected from Tam Giang-Cau Hai and O Loan Coastal Lagoons. The samples were investigated for the presence of microplastics (MPs) in their tissues. The average number of MPs determined in white clams, lined clams, oysters, and green mussels in Central Vietnam varies from 0.3 to 0.9 per g-ww and from 0.9 to 5.6 per individual. Fibers, fragments, and pellets were found with various proportions concerning. Fibers were the most common shape, making up 36-74 % of the total microplastics, followed by fragments accounting for 16-47 %. The most prevalent colors were white-transparent and black-grey, comprising 49-81 % of the MPs. Regarding the microplastics found in the bivalve tissues, 78-80 % were <500 μm. Given chemical analysis, rayon accounted for 38 % of the microplastics discovered in bivalve tissues; closely PET (13 %), PA (10 %), and PP (10 %) were followed. This study offers valuable insights into the microplastic contamination concerned by bivalve consumption in Thua Thien Hue and Phu Yen, Central Vietnam; the results estimate the annual intakes are between 5000 and 10,000 particles per person. Unprecedentedly addressed in the literature, these findings contribute to a better understanding of microplastic pollution in Vietnam. The results altogether provide solid shreds of evidence for the MP contamination in Vietnam-based seafood, thus encouraging further attempts for plausible socio-economical regulations and raising public awareness on the issue.

Microplastics bioaccumulation in fish: Its potential toxic effects on hematology, immune response, neurotoxicity, oxidative stress, growth, and reproductive dysfunction

After being exposed, microplastics mostly bioaccumulated in guts and gills of fish, then, through circulation, spread and bioaccumulated in other tissues. Circulatory system of fish is impacted by the microplastic bioaccumulation in their tissues, influencing a number of hematological indices that are connected with immunity, osmotic pressure, blood clotting, molecular transport and fat metabolism. Variables like size, dose, duration, food consumption and species, all affect the bioaccumulation and toxicity of the microplastic, rather than the exposure routes. Microplastics lead to an imbalance in the generation of ROS and antioxidant defense of fish, which resulting in oxidative injury. Moreover, microplastics affect immunological responses through physico-chemical damage, hence produce neurotoxicity and modifies the activity of the acetylcholine esterase. Exposure to microplastics caused damage to the hepatic and gut tissue, affect intestinal barrier function and dysbiosis of microbial composition, altered the metabolism of host, affecting the activities of the digestive enzymes, eventually affecting the growth performance of fish. Microplastics exposure target the HPG axis and interfere with the process of steroidogenesis, apoptosis of the gonadal tissue, ultimately causing reproductive dysfunction. Fish exposed to microplastics have a range of toxic effects viz. alteration to immune, antioxidant and hematological indices, bioaccumulation, neurotoxicity, growth and reproductive dysfunction, all were examined in this present review by using different indicators.

Acute and partial life-cycle toxicity of a tri-polymer blend of microplastics in the copepod Acartia tonsa

Microplastics are a prolific environmental contaminant that pose a risk to marine organisms. Ecotoxicological studies have identified microplastics can cause sub-lethal harm to aquatic biota. However, prior studies often lack comparability and environmental relevance, for example focussing upon monodisperse beads at extremely high concentrations. Copepods are keystone marine taxa that play vital roles in the marine food web and biogeochemical cycling. In this study, we adapted ISO methods to conduct acute and partial life-cycle toxicity tests exposing adult and juvenile life stages of the copepod Acartia tonsa to a fully characterised tri-polymer microplastic blend comprising cryoground polyethylene, polypropylene, and nylon particles (5-100 μm) at concentrations ranging 0-1000 μg L-1. The tests considered the toxicity of microplastics on a wide number of endpoints including adult survival, algal ingestion rates, egg production and size, larval development ratio and juvenile survival. Mortality, egg size and larval development ratio proved to be the most sensitive endpoints. The tri-polymer blend had an LC5072h value of 182 μg L-1 providing a baseline for future toxicity testing using this method.

Microplastic distribution in the surface water and potential fish uptake in an oligotrophic lake (Lake Mainit, Philippines)

Analyzing microplastic distribution patterns in freshwater ecosystems provides critical insights into pollution sources and accumulation zones, contributing to ecosystem health and functioning. Here, the surface water of Lake Mainit, an oligotrophic body of water in the Philippines, and the potential ingestion by Glossogobius giuris (15), a local fish species inhabiting the lake, were investigated. The surface water samples collected in ten sampling sites revealed an average microplastic concentration of 313.33 ± 252.11 particles/m3, with elevated levels in the northern part of the lake, likely due to adjacent industrial and agricultural activities. Fibers were the predominant microplastic morphology (58 %), with polyamide (28 %) as the most common polymer found in the surface water, suggesting primary sources from textiles and household waste. Size analysis showed that particles under 100 μm in size were most abundant, posing increased ingestion risks for aquatic organisms. All examined fish samples contained microplastics, averaging 0.7 particles per fish, primarily from the smallest particle class, indicating a potential risk of bioaccumulation. Risk assessment using the Polymer Hazard Index (PHI) and Pollution Load Index (PLI) indicated that polyvinyl chloride (PVC) and polyamide (PA) pose moderate to high pollution risks due to their persistence and toxicity potential. The PERI value for Lake Mainit was 34.63, classifying it as a minor risk. While current contamination levels are low, continued monitoring is essential to prevent future ecological risks. These results highlight the ecological threat of microplastics in Lake Mainit, with implications for biodiversity and human health, as the lake is an important local food source. To mitigate these risks, stricter pollution control, enhanced waste management, and public awareness initiatives are recommended. This study presents foundational data on microplastic pollution in an oligotrophic Philippine lake, emphasizing the need for further research to support protective management strategies.

Microplastic accumulation and histological effects on the Atlantic deep-sea scale-worm Laetmonice filicornis

Small benthic scavengers and carnivores, such as polychaetes, are very interesting to assess the accumulation and transfer of microplastics (MPs) to higher trophic levels in marine ecosystems. In this study we evaluate the presence, accumulation and impacts of MPs in the North-Atlantic deep-sea polychaete Laetmonice filicornis. Three types of MPs were identified: fishing lines, fibres and fragments, mostly black in colour, followed by red and blue ones. The average number of MPs was 4.10 ± 1.90 particles/g tissue. Fibres were the most abundant. They were composed of Polypropylene, Rayon, Polyethyleneimine Cellulose and Polyester. The histological analysis revealed the presence of microfibres embedded in muscles, peritoneum, nephridia, gonads and blood vessels, which can have a direct impact on vital functions, such as feeding and reproduction. This species occupies both predator and prey roles, bioaccumulate MPs and can transfer them to higher trophic links, representing a significant threat to all marine species, including humans.

Zooming in the plastisphere: the ecological interface for phytoplankton-plastic interactions in aquatic ecosystems

Phytoplankton is an essential resource in aquatic ecosystems, situated at the base of aquatic food webs. Plastic pollution can impact these organisms, potentially affecting the functioning of aquatic ecosystems. The interaction between plastics and phytoplankton is multifaceted: while microplastics can exert toxic effects on phytoplankton, plastics can also act as a substrate for colonisation. By reviewing the existing literature, this study aims to address pivotal questions concerning the intricate interplay among plastics and phytoplankton/phytobenthos and analyse impacts on fundamental ecosystem processes (e.g. primary production, nutrient cycling). This investigation spans both marine and freshwater ecosystems, examining diverse organisational levels from subcellular processes to entire ecosystems. The diverse chemical composition of plastics, along with their variable properties and role in forming the "plastisphere", underscores the complexity of their influences on aquatic environments. Morphological changes, alterations in metabolic processes, defence and stress responses, including homoaggregation and extracellular polysaccharide biosynthesis, represent adaptive strategies employed by phytoplankton to cope with plastic-induced stress. Plastics also serve as potential habitats for harmful algae and invasive species, thereby influencing biodiversity and environmental conditions. Processes affected by phytoplankton-plastic interaction can have cascading effects throughout the aquatic food web via altered bottom-up and top-down processes. This review emphasises that our understanding of how these multiple interactions compare in impact on natural processes is far from complete, and uncertainty persists regarding whether they drive significant alterations in ecological variables. A lack of comprehensive investigation poses a risk of overlooking fundamental aspects in addressing the environmental challenges associated with widespread plastic pollution.

The links between soil and water pollution and cardiovascular disease

Soil and water pollution represent significant threats to global health, ecosystems, and biodiversity. Healthy soils underpin terrestrial ecosystems, supporting food production, biodiversity, water retention, and carbon sequestration. However, soil degradation jeopardizes the health of 3.2 billion people, while over 2 billion live in water-stressed regions. Pollution of soil, air, and water is a leading environmental cause of disease, contributing to over 9 million premature deaths annually. Soil contamination stems from heavy metals, synthetic chemicals, pesticides, and plastics, driven by industrial activity, agriculture, and waste mismanagement. These pollutants induce oxidative stress, inflammation, and hormonal disruption, significantly increasing risks for non-communicable diseases (NCDs) such as cardiovascular disease (CVD). Emerging contaminants like micro- and nanoplastics amplify health risks through cellular damage, oxidative stress, and cardiovascular dysfunction. Urbanization and climate change exacerbate soil degradation through deforestation, overfertilization, and pollution, further threatening ecosystem sustainability and human health. Mitigation efforts, such as reducing chemical exposure, adopting sustainable land-use practices, and advancing urban planning, have shown promise in lowering pollution-related health impacts. Public health initiatives, stricter pollution controls, and lifestyle interventions, including antioxidant-rich diets, can also mitigate risks. Pollution remains preventable, as demonstrated by high-income nations implementing cost-effective solutions. Policies like the European Commission's Zero-Pollution Vision aim to reduce pollution to safe levels by 2050, promoting sustainable ecosystems and public health. Addressing soil pollution is critical to combating the global burden of NCDs, particularly CVDs, and fostering a healthier environment for future generations.

Microplastic accumulation in respiratory and digestive systems of selected fish from Banten Bay, Indonesia

Microplastics pose a significant environmental threat as they can be consumed directly or indirectly by various marine organisms. This investigation explores the ecological hazards of microplastic pollution in marine life, with an emphasis on fish in Banten Bay, Indonesia. The sampling spots were in Banten Bay where traditional fishing gears known as "bubu" were used and nets. This study represents an inaugural examination of microplastic contamination in selected fish species including Gambusia affinis, Stolephorus indicus, Scatophagus argus, Epinephelus coioides, Rastrelliger sp., Parapenaeopsis sculptilis, and Leiognathus sp. As a result, microplastics were detected in each fish, with a notable increase in concentrations within the gills (7.85 ± 3.54 items/ind) as opposed to the digestive tract (4.95 ± 2.15 items/ind). Their presence indicated a significant difference (p < 0.01), primarily observed as fragments and filaments. Nine distinct polymer types were identified with FT-IR in fish samples collected from Banten Bay, including polyethylene terephthalate, polyvinyl chloride, polyester, polyurethane, ethylene propylene, polypropylene, polyethylene, polystyrene and polyphenylene sulfide. Microplastics were primarily detected within the size range of 20 to 4510 µm. Microplastic contamination in fish causes detrimental implications on aquatic ecosystems and human health, since the particles exist in the food chain, altering the biological activities of fish, and potentially posing hazards to consumers. Considering the closeness of Banten Bay to Indonesia's capital and economic hub, immediate preventive actions are essential to safeguard human health and the ecosystem. Additional investigation into plastic degradation and waste management is crucial for comprehending the origins of contamination. The results establish a foundation for continuous monitoring of microplastic risks in Banten Bay and other swiftly evolving coastal ecosystems in Northeast Asia.

Different impacts of oil-based and bio-based microplastics on isotopic composition and stoichiometry of a model freshwater grazer

Microplastic pollution has become a pervasive environmental challenge due to their global distribution and putatively harmful effects on organisms at different ecotoxicological endpoints. However, in some cases, the effects of microplastics are similar to, or even less harmful than those of naturally occurring particles. Bioplastics, developed as a more sustainable alternative to traditional plastics, still have unclear effects compared with oil-based microplastics. This study uses a laboratory-controlled experiment to compare the physical effects of oil-based high-density polyethylene (HDPE) and bio-based biodegradable polylactic acid (PLA) on the consumption rate, isotopic composition, respiration rate, stoichiometry, and growth rate of model freshwater snail Radix balthica. The experiment included a positive control using silica sand (Si) to simulate natural particles and a control with no experimental additions. It was hypothesised that exposure to microplastics affects the snails solely through the physical influence of the particles, and that the effects of microplastics depend on their composition. The results show that the effects of HDPE were attributable solely due to the physical presence of the particles, but this was not the case for PLA. Exposure to PLA led to increased growth (as final mass). Consumption, respiration, and growth rates were not significantly affected when exposed to the experimental additions. However, the isotopic composition and C:N of snails was altered after exposure to HDPE and Si compared with control. The isotopic composition of snails exposed to PLA did not show significant changes, but they did have higher phosphorous content in their tissues. In this study, HDPE microplastics were not more harmful than naturally occurring particles, and PLA microplastics appeared to influence growth patterns differently than expected. Further research is needed to confirm these observations and fully assess the environmental and biological implications of these contaminants.

Soil and water pollution and cardiovascular disease

Healthy, uncontaminated soils and clean water support all life on Earth and are essential for human health. Chemical pollution of soil, water, air and food is a major environmental threat, leading to an estimated 9 million premature deaths worldwide. The Global Burden of Disease study estimated that pollution was responsible for 5.5 million deaths related to cardiovascular disease (CVD) in 2019. Robust evidence has linked multiple pollutants, including heavy metals, pesticides, dioxins and toxic synthetic chemicals, with increased risk of CVD, and some reports suggest an association between microplastic and nanoplastic particles and CVD. Pollutants in soil diminish its capacity to produce food, leading to crop impurities, malnutrition and disease, and they can seep into rivers, worsening water pollution. Deforestation, wildfires and climate change exacerbate pollution by triggering soil erosion and releasing sequestered pollutants into the air and water. Despite their varied chemical makeup, pollutants induce CVD through common pathophysiological mechanisms involving oxidative stress and inflammation. In this Review, we provide an overview of the relationship between soil and water pollution and human health and pathology, and discuss the prevalence of soil and water pollutants and how they contribute to adverse health effects, focusing on CVD.

Assessing Hydrocyclone System's Efficiency in Water-Borne Microplastics Capture Using Online Microscopy Sensors

Plastic pollution has been a global concern. Microplastics are often referred to as plastic particulates whose sizes are within the range of 1 μm to 5 mm. To cost-effectively capture these tiny microplastics from open environments, such as from the air or aquatic/marine systems, is far from trivial. Not only is some innovative capturing technology demanded, but some online monitoring solutions are often requested as well to assess the capturing effectiveness and efficiency, as well as provide some feedback information to the control system to adapt to varying operating conditions. Inspired by the de-oiling treatment of the produced water in offshore oil & gas production, this paper explores the potential to apply the hydrocyclone technology to cost-effectively handle the water-borne microplastics, and its effectiveness is demonstrated based on reliably calibrated online microscopy measurements subject to artificial polyethylene particulates added to the water stream. The experimental work is carried out using a commercial de-oiling hydrocyclone system and a set of commercial optical microscopy sensors. A statistic-based calibration method is firstly proposed for the deployed microscopy sensors to select the best calibration parameters. Afterwards these sensors are installed at the inlet and water-outlet of the hydrocyclone system via a side-stream sampling mechanism to assess this system's (microplastics) separation efficiency subject to dynamical operating conditions, which are mimicked by manipulating its underflow and overflow control valves via PI-controlled loops. The separation efficiencies are calculated based on these volume concentration measurements and compared between the case with (statistically) optimal calibration parameters and the case with a set of non-optimal parameters. The best separation efficiency of 87.76% under the optimal calibration parameters is observed under a specific operating condition. The obtained result shows a promising potential to use these separation and sensing systems to cost-effectively handle aquatic microplastics collection, though it also indicates that a further higher efficiency could be achieved by some (microplastics) dedicated cyclone design combined with a dedicated process control system, and this is one part of our ongoing research work.

The ant that may well destroy a whole dam: a systematic review of the health implication of nanoplastics/microplastics through gut microbiota

Since the widespread usage of plastic materials and inadequate handling of plastic debris, nanoplastics (NPs) and microplastics (MPs) have become global hazards. Recent studies prove that NPs/MPs can induce various toxicities in organisms, with these adverse effects closely related to gut microbiota changes. This review thoroughly summarized the interactions between NPs/MPs and gut microbiota in various hosts, speculated on the potential factors affecting these interactions, and outlined the impacts on hosts' health caused by NPs/MPs exposure and gut microbiota dysbiosis. Firstly, different characteristics and conditions of NPs/MPs often led to complicated hazardous effects on gut microbiota. Alterations of gut microbiota composition at the phylum level were complex, while changes at the genus level exhibited a pattern of increased pathogens and decreased probiotics. Generally, the smaller size, the rougher surface, the longer shape, the higher concentration, and the longer exposure of NPs/MPs induced more severe damage to gut microbiota. Then, different adaptation and tolerance degrees of gut microbiota to NPs/MPs exposure might contribute to gut microbiota dysbiosis. Furthermore, NPs/MPs could be carriers of other hazards to generally exert more severe damage on gut microbiota. In summary, both pristine and contaminated NPs/MPs posed severe threats to hosts through inducing gut microbiota dysbiosis.

N6-methyladenosine RNA methylation regulates microplastics-induced cell senescence in the rainbow trout liver

Microplastics are prevalent in aquatic ecosystems, impacting various forms of aquatic life, including fish. In this study, Rainbow trout (Oncorhynchus mykiss) were exposed to two concentrations of microplastics (0 and 500 μg/L) over a 14-day period, during which a comprehensive analysis was conducted to assess the liver accumulation of microplastics and their effects on oxidative stress, the liver response, and transcriptomics. Our findings indicated that microplastics significantly accumulated in the liver and activated the antioxidant system in fish by enhancing the activity of antioxidant enzymes. Histological lesions were also observed in the liver of the fish. Furthermore, microplastics induced alterations in the expression of hepatic N6-methyladenosine readers, specifically downregulating IGF2BP1 (encoding insulin like growth factor 2 mRNA binding protein 1) and upregulating YTHDF2 (encoding YTH N6-methyladenosine RNA binding protein F2), which in turn decreased mRNA stability and reduced the expression of C-myc and other regulatory factors involved in the cell cycle and proliferation. This sequence of events resulted in slowed cell proliferation, the induction of cell cycle arrest, and the promotion of cellular senescence. This study offers valuable insights into the toxicological mechanisms of microplastics and enhances our understanding of the threats that plastic pollution poses to freshwater organisms.

Microplastics versus natural mineral particles. How to create and test them while maintaining environmental relevance

Whether microplastics cause different effects than inert natural particles, and how to create relevant testing materials, are key questions in microplastics research. We prepared Environmentally Relevant Microplastic (ERMP) and Mineral Microparticle (ERMS) mixtures with similar levels of polydispersity and tested their 28-day chronic effects on the reproduction and growth of L. variegatus at two different organic matter (OM) contents (average and enriched). Additionally L. variegatus was exposed to ERMP and ERMS to study the particle egestion for 14 days. We observed no differences in growth or reproduction between ERMP and ERMS at particle concentrations of up to 10 % (v/v). In contrast, organisms exposed to enriched OM content increased their growth with 30 % and increased reproduction with 20 %. For ERMP with an enriched OM content, reproduction was reduced with an effect threshold EC50 of 13.68 ± 5.54 % (v/v). After 14 days of exposure to 5 % ERMP, the egestion of faecal pellets was higher compared to exposure to 5 % ERMS, suggesting that in order to acquire the same amount of nutrition, L. variegatus is spending more energy. With this study, we demonstrate that refinements in the manufacturing of environmentally diverse particle mixtures can contribute to a more realistic testing of particle effects.

Unlocking the combined impact of microplastics and emerging contaminants on fish: A review and meta-analysis

Microplastics (MPs) possess unique adsorptive properties that render their surfaces prone to absorbing other contaminants. When interacting with these emerging contaminants, MPs may have unpredictable negative impacts on fish. Prior studies have primarily concentrated on the impact of single contaminants, while investigations into combined pollution have not received adequate attention. Therefore, research on combined pollution holds greater practical significance. The physiological indicators of fish affected by emerging contaminants and the mechanisms behind these effects are not yet fully clear. To address this issue, a meta-analysis was performed to evaluate the impact of combined pollution of MPs-containing emerging contaminants on various aspects of fish health, encompassing behavior, consumption, development, and reproduction, along with the assessment of oxidative stress and neurotoxicity of fish. The results of the meta-analysis indicated that combined pollution adversely impacted fish reproduction, development, oxidative stress, and neurotoxicity. Importantly, significant differences were observed between fish species regarding their susceptibility to function and oxidative stress. Further investigation into the mechanisms of the impact of combined pollution on fish revealed that the magnitude of this impact is closely associated with the characteristics of the MPs themselves. MPs with higher adsorption capacities tend to lead to more severe consequences, while the impact of MPs with lower adsorption capacities relies more on their toxicity. Nevertheless, a close correlation between the duration of exposure to combined pollution and the level of oxidative stress in fish was not identified. Through a systematic analysis of existing studies, this review not only explored the cumulative effects of combined pollution on fish but also highlighted the intricate nature of such pollution within aquatic ecosystems. It contributes to the growing body of knowledge on the subject and emphasizes the need for further research to unravel the complexities associated with the combined impact of MPs-containing emerging contaminants on aquatic life.

Microplastics impair extracellular enzymatic activities and organic matter cycling in oligotrophic sandy marine sediments

Microplastics (MPs) are ubiquitous and constantly accumulating in the marine environment, especially sediments. Yet, it is not well clarified if and how their carbon backbone could interact with surrounding sediments, eventually impairing key benthic processes. We assessed the effects of a 'pulse' contamination event of MPs on sedimentary organic matter (OM) quantity, quality and extracellular enzymatic activities (EEAs), which are well established descriptors of benthic ecosystem functioning. Marine sediments were exposed for 30 days to environmentally relevant concentrations (∼0.2 % in weight) of naturally weathered particles (size range 70-210 μm) of polyurethane, polyethylene, and a mixture of the most common polymers that are documented to accumulate in marine sediments. Despite the low concentration, contaminated sediments showed significantly different composition of OM, showing a decrease in lipid content and increase in protein. Moreover, we document a significant decrease (over 25 %) in quantity of biopolymeric C already after 15 days of exposure, compared to controls. Contaminated sediments showed lower C degradation rates (up to -40 %) and altered EEAs, with alkaline phosphatase being ∼50 % enhanced and aminopeptidase being reduced over 35 % compared to control treatments. Overall, the effects generated by the mixture of polymers were smaller than those exerted by the same amount of a single polymer. Our results provide insights on how that MPs can significantly alter marine sedimentary biogeochemistry through altered benthic processes, that could cumulatively impair whole benthic trophic webs by enhancing the accumulation and possible longer-term storage of recalcitrant organic C in the seabed.

Impacts of microplastic ingestion on fish communities in Haizhou Bay, China

Microplastics are pervasive throughout aquatic ecological communities. While their negative impacts on the life history traits of aquatic species are well studied, the effects on community dynamics remain elusive. Consequently, community-level assessments of microplastic effects on marine food webs are largely lacking, creating significant knowledge gaps regarding marine ecosystem structure and dynamics in the context of microplastic contamination. Here we expand a multispecies size-spectrum model by incorporating microplastic impacts on individual life-history traits, ultimately allowing us to study microplastic-mediated structural and functional changes in fish communities. As expected, microplastic ingestion may drive species extinction, but the microplastic-to-food ratio threshold for extinction is species-specific, and not necessarily correlated with species' asymptotic weights. Interestingly, species responses to microplastics also propagate through the community as ingestion triggers both bottom-up and top-down effects on community dynamics. Which specific type of cascading effect is dominating depends on which species is ingesting microplastics as well as its trophic role in the community. Generally, low-trophic-level species ingesting microplastics can exert large detrimental effects on community biomass. Thus, this study highlights the necessity for a comprehensive risk assessment of species-specific responses to microplastic contamination as well as an understanding of individual species' role in their communities.

Review on the relationship between microplastics and heavy metals in freshwater near mining areas

Microplastics (MPs), degraded from plastic wastes, have drawn significant attention worldwide due to its prevalence and rapid transition. Contamination of freshwater with MPs has become an emerging global issue. Heavy metals (HMs), a prominent global pollutant, also garnered much attention due to their potential interaction with MPs, presenting a multifaceted environmental threat. The primary source of HM contamination in freshwater has been identified as mining sites. Additionally, the increasing use of plastic materials within mining areas raises concerns about MP release into the surrounding freshwater environments. Recent studies only provide information on the contamination of HMs status with MPs. However, studies on the mechanism responsible for MPs contamination from both external and internal sources of freshwater MPs and HMs are limited. The knowledge gaps in the deposition and fate of MPs in various mining situations and the possibility of combined impacts of heavy metals and MPs in the ecosystem raise ecological concerns. Here, we review the origins of MPs and HM pollution within mining sites and explore the potential combined detrimental impacts on plants and animal life. We found out that polystyrene (PS) and polyethylene (PE) have higher adsorption affinity to heavy metals, and the mingle toxic consequence of the MPs and HM can depend on the MP surface properties, pH, and salinity of the neighboring water solution. The Langmuir and Freundlich isotherm models enable the efficient design of adsorption systems. The Langmuir model describes single-layer adsorption at homogeneous sites, while the Freundlich model addresses multilayer adsorption on heterogeneous surfaces. The crucial mechanism of adsorption and desorption that underlies the occurrence of both MPs and heavy metals is a decisive matter in this issue.

Enhancing polyethylene degradation: a novel bioprocess approach using Acinetobacter nosocomialis pseudo-resting cells

Despite the discovery of several bacteria capable of interacting with polymers, the activity of the natural bacterial isolates is limited. Furthermore, there is a lack of knowledge regarding the development of bioprocesses for polyethylene (PE) degradation. Here, we report a bioprocess using pseudo-resting cells for efficient degradation of PE. The bacterial strain Acinetobacter nosocomialis was isolated from PE-containing landfills and characterized using low-density PE (LDPE) surface oxidation when incubated with LDPE. We optimized culture conditions to generate catalytic pseudo-resting cells of A. nosocomialis that are capable of degrading LDPE films in a bioreactor. After 28 days of bioreactor operation using pseudo-resting cells of A. nosocomialis, we observed the formation of holes on the PE film (39 holes per 217 cm2, a maximum diameter of 1440 μm). This study highlights the potential of bacteria as biocatalysts for the development of PE degradation processes. KEY POINTS: • New bioprocess has been proposed to degrade polyethylene (PE). • Process with pseudo-resting cells results in the formation of holes in PE film. • We demonstrated PE degradation using A. nosocomialis as a biocatalyst.

Hazard assessment of microplastics and heavy metals contamination in Levant frogs (Pelophylax bedriagae): A bioindicator in Western Iran

The increasing pollution of aquatic ecosystems caused by microplastics (MPs) and heavy metal ions worldwide threatens the life of aquatic organisms, including amphibians. In this study, we investigated the presence and accumulation of MPs and heavy metal ions in the upper gastrointestinal tract (GIT) of the Levant frog (Pelophylax bedriagae) as a bioindicator in contaminated sites of Western Iran. A total of 192 adult frogs from 16 locations in the west and northwest of Iran were collected. We measured the accumulation of MPs and heavy metal ions in the collected frogs and determined the characteristics of MPs in the samples. Our findings revealed widespread MPs and heavy metal ions contamination in the frog GIT across all sampled stations. We found 742 MP particles in the digestive system of frogs, with the highest (7.09 MP/individual) and lowest (2.37 MP/individual) number observed in stations 10 and 9, respectively. Fibers were the most common MPs and polyester (PES) (42.5%) and polyethylene terephthalate (PET) (17.2%) were found to be the most common polymers in the GIT of frogs. The average accumulation of heavy metal ions showed significant differences (P < 0.05) among 16 sampling stations, and zinc (II) and mercury (II) showed the highest and lowest concentrations in frogs. We also found moderate to strong positive correlations between the detected MPs and heavy metal ions in the frog samples across all sampling stations. Our findings confirm the contamination of frogs by MPs and heavy metal ions and the potential capacity of MPs to increase the toxicity of heavy metals in P. bedriagae as a bioindicator in contaminated sites.

Oxidative Stress in Mussel Mytilus trossulus Induced by Different-Sized Plastics

Polyethylene and polystyrene are massively used around the world in various applications and are the most abundant plastic waste. Once in the marine environment, under the influence of physical and chemical factors, plastic products degrade, changing from the size category of macroplastics to microplastics. In order to study the effect of plastic on marine organisms, we modeled the conditions of environmental pollution with different-sized plastic-polystyrene microparticles of 0.9 µm and macro-sized polyethylene fragments of 10 cm-and compared their effect on biochemical parameters in the tissues of the bivalve mollusk Mytilus trossulus. Using biomarkers, it was found that regardless of the size and type of polymer, polystyrene microparticles and polyethylene macrofragments induced the development of oxidative stress in mussels. A significant decrease in the level of lysosomal stability in mussel hemocytes was observed. Increases in the level of DNA damage and the concentration of malonic dialdehyde in the cells of gills and the digestive gland were also shown. The level of total antiradical activity in cells varied and had a tissue-specific character. It was shown that both ingested polystyrene particles and leachable chemical compounds from polyethylene are toxic for mussels.

Are microplastics a new cardiac threat? A pilot study with wild fish from the North East Atlantic Ocean

Global environmental contamination by microplastics (MPs) is a growing problem with potential One Health impacts. The presence of MPs in vital organs, such as the heart, is of particular concern, but the knowledge is still limited. The goal of the present pilot study was to investigate the potential presence of MPs in the heart of wild specimens of three commercial fish species (Merluccius merluccius, Sardina pilchardus, and Trisopterus luscus) from the North East Atlantic Ocean. Heart samples from 154 fish were analysed for MP content (one heart sample per fish). A total of 44 MPs were recovered from heart samples from the three species. MPs had varied chemical composition (5 polymers), shapes (4) and colours (5). Differences in the profile of the MPs among species was observed (p ≤ 0.05). Thirty fish (19%) had MPs in their hearts, with a total mean (±SD) concentration of 0.286 ± 0.644 MPs/fish. S. pilchardus had the highest heart contamination (p ≤ 0.05). There were no significant (p > 0.05) differences between M. merluccius and T. luscus. These findings in fish with different biological and ecological traits together with literature data suggest that heart contamination likely is a disseminated phenomenon. Therefore, further research on the presence of MPs in the cardiovascular system and its potential health effects is very much needed.

Determination of microplastics in sediment, water, and fish across the Orange-Senqu River basin

Microplastics are increasingly recognised as posing a significant environmental threat across systems. Their pervasive presence in freshwater poses a serious concern, given the heavy reliance of both humans and biodiversity on healthy, functioning freshwater ecosystems. Acknowledgment of the potential risks led the transboundary Orange-Senqu River Commission (ORASECOM) to include sampling for microlitter (primarily microplastics) in riverine sediment, surface water, and fishes, across Southern Africa as part of the third Joint Basin Survey (JBS3) in 2021. The aim was to establish a first, basin-wide estimate of microlitter contamination across compartments, setting a baseline for further monitoring. The survey showed that the abundance of microlitter in riverine sediment (0 - 4000 particles.kg-1 dry weight (dw)) and riverine water (1.00 ± 0.71 - 69.75 ± 68.55 SD items.L-1) varied considerably between sample sites, with no correlation between the two. The abundance of microlitter in fishes was low (average of 0.7 ± 0.4 items.individual-1). Course resolution analyses suggested that microlitter concentrations in riverine sediment and riverine water at each site did not correlate with land use directly upstream, though variation in microlitter abundance did isolate some hotspots of contamination. Discharge data collected from nine gauging stations near sampling sites confirmed that low flows prevailed in the system during the study, with high flows occurring approximately 5 months prior during the summer months. There is some variation in river flow across the catchment which is a likely driver of microlitter transport. This was evident in the polymer composition for sediment and water samples. Based on the average discharge at each gauging station and microlitter concentrations measured in riverine water, the estimated microlitter load ranged from ∼889 particles.s-1 to ∼17.9 million particles.s-1, with a substantial amount ending likely up in the mudbelt adjacent to the Orange River mouth. This assessment provides a first insight into the characterisation and distribution of microlitter in multiple compartments across the Orange-Senqu River basin. Overall, the findings highlight the need for continued monitoring across compartments at catchment scales to improve our understanding of microplastic pathways into and within riverine systems.

Effect of biodegradable and conventional microplastic exposure in combination with seawater inundation on the coastal terrestrial plant Plantago coronopus

Coastal ecosystems face a multitude of pressures including plastic pollution and increased flood risk due to sea level rise and the frequency and severity of storms. Experiments seldom examine multiple stressors such as these, but here we quantified the effect of microplastics (polyethylene terephthalate (PET): a durable plastic and polybutylene adipate terephthalate (PBAT): a biodegradable polymer), in combination with simulated seawater inundation on the coastal species Plantago coronopus. After 35-days exposure to plastic (0.02 g.Kg-1, <300 μm diameter), P. coronopus were flooded to pot height with artificial seawater for 72-h, drained and grown for a further 24-days. Plant mortality, necrosis and photosynthetic efficiency (Fv/Fm) were recorded throughout, with root:shoot biomass and scape production (flower stalks) quantified at harvest. There were significant interactions between microplastics and seawater on the root:shoot ratio; a measure of resource allocation. The allocation to belowground biomass increased significantly under the PET + inundation treatment compared to the PBAT + inundation and the no plastic + inundation treatments, with potential consequences on the capture of water, nutrients and sunlight, which can affect plant performance. Plant necrosis significantly increased, and Fv/Fm declined as a result of seawater inundation. While not significant, plant Fv/Fm responses were influenced by microplastics (17% and 7% reduction in PBAT and PET exposure respectively compared to the no plastic control). Plants mediated this stress response with no discernible treatment-specific effects detected in Fv/Fm 14-days after seawater introduction. Plastic exposure significantly influenced potential reproductive output, with lower average scape numbers across PBAT treatments, but higher in PET treatments. This study highlights the complex interactions and potential for microplastics to present an elevated risk when in combination with additional stressors like seawater flooding; establishing the threat presented to ecosystem resilience in a changing world is a priority.

Microplastics meet micropollutants in a central european river stream: Adsorption of pollutants to microplastics under environmentally relevant conditions

Microplastics have emerged as pervasive pollutants in aquatic environments, and their interaction with organic contaminants poses a significant environmental challenge. This study aimed to explore the adsorption of micropollutants onto microplastics in a river, examining different plastic materials and the effect of aging on adsorption capacity. Microplastics (low-density polyethylene (LDPE), polyethylene terephthalate (PET), and polyvinyl chloride (PVC)) were introduced into a river stream, and a comprehensive analysis involving 297 organic pollutants was conducted. Passive samplers were deployed to monitor micropollutant presence in the river. Sixty-four analytes were identified in the river flow, with telmisartan being the most prevalent. Nonaged PVC showed the highest telmisartan concentration at 279 ng/g (168 ng/m2 regarding the microplastic surface), while aged PVC exhibited a fourfold decrease. Conversely, aged LDPE preferentially adsorbed metoprolol and tramadol, with concentrations increasing 12- and 3-fold, respectively, compared to nonaged LDPE. Azithromycin and clarithromycin, positively charged compounds, exhibited higher sorption to PET microplastics, regardless of aging. Diclofenac showed higher concentrations on nonaged PVC compared to aged PVC. Aging induced structural changes in microplastics, including color alterations, smaller particle production, and increased specific surface area. These changes influenced micropollutant adsorption, with hydrophobicity, dissociation constants, and the ionic form of pollutants being key factors. Aged microplastics generally showed different sorption properties. A comparison of microplastics and control sand particles indicated preferential micropollutant sorption to microplastics, underscoring their role as vectors for contaminant transport in aquatic ecosystems. Analysis of river sediment emphasized the significance of contact time in pollutant accumulation. Overall, this study provides insights into the complex interactions between microplastics and organic pollutants under environmental conditions and contributes to a better understanding of the fate and behavior of these two types of contaminants in aquatic ecosystems.

Changes in global methylation patterns of Mytilus galloprovincialis exposed to microplastics

Microplastics (MPs) disturb the normal activity of aquatic organisms at different levels, causing physiological stress and altering feeding, growth, and reproduction. Alterations of epigenetic patterns due to exposure to MPs have scarcely been studied in invertebrates. In this study, Mytilus galloprovincialis mussels (N = 61) were intermittently exposed to different concentrations of pure polystyrene microbeads for three weeks. The concentrations used in this research were similar to those currently found in certain polluted environments (E1), as well as higher doses to which mussels could be further exposed (E2 and E3). After exposure period, the global methylation patterns were investigated using Amplified Fragment Length Polymorphism (AFLPs). Significantly lower methylation was found in exposed groups compared to the control group. The level of hypomethylation increased with the concentration of microbeads. Similar results were found from field samples inhabiting two sites differentially MPs-polluted. The implications of this discovery were analysed and discussed, noting the already known effects of MPs on metabolism and cell division. Further studies on this and other sentinel organisms are recommended to understand the response of the aquatic species to the currently increasing MPs pollution.

Microplastics predominantly affect gut microbiota by altering community structure rather than richness and diversity: A meta-analysis of aquatic animals

The impacts of microplastics on the gut microbiota, a crucial component of the health of aquatic animals, remain inadequately understood. This phylogenetically controlled meta-analysis aims to identify general patterns of microplastic effects on the alpha diversity (richness and Shannon index), beta diversity, and community structure of gut microbiota in aquatic animals. Data from 63 peer-reviewed articles on the Web of Science were synthesized, encompassing 424 observations across 31 aquatic species. The analysis showed that microplastics significantly altered the community structure of gut microbiota, with between-group distances being 87.75% higher than within-group distances. This effect was significant even at environmentally relevant concentrations (≤1 mg L-1). However, their effects on richness, Shannon index, and beta diversity (community variation) were found to be insignificant. The study also indicated that the effects of microplastics were primarily dependent on their concentration and size, while the phylogeny of tested species explained limited heterogeneity. Furthermore, variations in gut microbiota alpha diversity, beta diversity, and community structure were correlated with changes in antioxidant enzyme activities from the liver and hepatopancreas. This implies that gut microbiota attributes of aquatic animals may provide insights into host antioxidant levels. In summary, this study illuminates the impacts of microplastics on the gut microbiota of aquatic animals and examines the implications of these effects for host health. It emphasizes that microplastics mainly alter the community structure of gut microbiota rather than significantly affecting richness and diversity.

The impact of microplastics on lake communities: A mesocosm study

Plastics are pervasive pollutants that are being produced at an increasing rate to meet consumer demands. After entering the environment, plastics can break down, creating smaller fragments, including secondary microplastics. Microplastic contamination in lakes has been recorded worldwide, and the ingestion of microplastics has been documented in zooplankton, macroinvertebrates, and fish. Microplastic ingestion and exposure can cause varying deleterious effects on these organism groups, but the impact of realistic microplastic concentrations on whole freshwater food webs requires further study. We addressed these knowledge gaps by conducting an 8-week experiment factorially crossing microplastic addition at a concentration of 1.5 particles/L with a fish predator (perch, Perca fluviatilis) presence in 1200-L outdoor mesocosms. Microplastic exposure had time-varying effects on zooplankton abundance, with a lower abundance of zooplankton in plastic treatments at the end of the experiment. Although microplastics had no impact on total macroinvertebrate abundance, there were effects on individual taxa. In the presence of microplastics, the cased caddisfly Triplectides spp. had a significantly lower abundance, which may have led to an increase in the snail Gyraulus spp. in week eight. Across the benthic and pelagic invertebrate communities, there were near-significant compositional differences between control and plastic treatments. These findings indicate that microplastic exposure may negatively impact freshwater invertebrate communities, even at low, field-realistic concentrations representative of the densities currently found in lakes.

Depuration kinetics and accumulation of microplastics in tissues of mussel Mytilus galloprovincialis

Microplastics (MPs) constitute the predominant plastic type in marine environments. Since they occupy the same size fraction of sediment particles and planktonic organisms they are potentially bioavailable to a broad scope of organisms, such as filter feeders, which are particularly vulnerable to MP ingestion. To understand the potential impact of MPs in filter feeders it is essential to clarify the uptake, accumulation patterns and elimination rates with time of MPs. The aim of this study was to determine the depuration dynamics and accumulation in tissues of mussels Mytilus galloprovincialis exposed during 24 h to different size polystyrene MPs (1 μm and 10 μm), and depurated for a maximum of 7 days (T = 24 h, T = 48 h and T = 7 d). Mussels were chemically digested with KOH 10% and filtered to quantify the number of MP ingested, and they were cryostat sliced for MP localization in tissues. Both MP sizes were quantified in all depuration times, but mussels accumulated significantly higher quantities of 10 μm MP throughout depuration compared to 1 μm MP. A significant decrease was observed after 7 d depuration in mussels exposed to 10 μm. Mussels removed the same amount of 1 and 10 μm MP after 7 days depuration. However, the depuration dynamics differed for each size-MPs and showed to be size-dependent. Most of both size MPs were eliminated in the first 24 h, but 1 μm MP showed to pass faster through the digestive tract than 10 μm MP. MPs of 1 μm and 10 μm were localized mainly in the lumen and a few in the epithelium of the digestive tract (stomach, intestine and digestive gland) during the depuration and in the gills after the exposure; as confirmed by Raman spectroscopy. The usage of chemical digestion and histological analysis as complementary techniques show to be suitable to infer the depuration dynamics of MPs in mussels.

Microplastic Transport and Accumulation in Rural Waterbodies: Insights from a Small Catchment in East China

Microplastic (MP) pollution in agricultural ecosystems is an emerging environmental concern, with limited knowledge of its transport and accumulation in rural waterbodies. This study investigates the distribution and sources of MP in drainage ditches influenced by pond connectivity, land use, and soil properties within a small catchment in Nanjing, East China. Sediment was collected from ditches in 18 sites across forest, agricultural, horticultural, and urban areas. Using laser-directed infrared spectroscopy (LDIR), 922 MP particles were identified. Six materials were dominant: fluororubber (FR), polyethylene terephthalate (PET), polyurethane (PU), acrylonitrile (ACR), chlorinated polyethylene (CPE), and polyethylene (PE). MP concentrations varied by land use and pond connectivity, with ditches above ponds exhibiting higher counts (1700 particles/kg) than those below (1050 particles/kg), indicating that ponds act as MP sinks. The analysis revealed site-specific MP sources, with FR linked to road runoff and PET associated with agricultural practices. Correlations between MP shape and soil properties showed that more compact and filled shapes were more commonly associated with coarser soils. PE particle size was negatively correlated with organic matter. This study highlights the need for targeted strategies to reduce MP pollution in rural landscapes, such as reducing plastic use, ditch maintenance, and improved road runoff management.

Microplastic-stressor responses are rarely synergistic in freshwater fishes: A meta-analysis

Microplastic exposure can cause a range of negative effects on the biochemistry, condition and ecology of freshwater fishes depending on aspects of the exposure and the exposed fish. However, fishes are typically exposed to microplastics and additional multiple stressors simultaneously, for which the combined effects are poorly understood and may have important management consequences. Additive effects are those where the combined effect is equal to the sum, antagonistic where combined effects are less than the sum and for synergistic effects the combined effect is greater to the sum of the individual effects. Here, we performed a meta-analysis of studies recording freshwater fish responses to microplastic-stressor exposures to test if interactions were primarily non-additive (synergistic or antagonistic), and factors impacting the net response. Individual responses were classified (antagonistic/additive/synergistic) and the fit of net responses to a null additive model determined for 838 responses (36 studies) split by categorical variables for the microplastic exposure (environmental relevance, interacting stressor, microplastic morphology and response category measured), as well as the exposed fish (lifestage, ecology and family). Most responses were classified as antagonistic (48 %) and additive (34 %), with synergistic effects least frequent (17 %). Net responses fitted null additive models for all levels of interacting stressor, fish family and microplastic morphology. In contrast, net antagonism was present for biochemical responses, embryo lifestages, environmentally relevant microplastic exposures and fish with benthopelagic ecology, while synergism was identified for fishes with demersal ecology. While substantial knowledge gaps remain and are discussed, the data thus far suggest microplastic-stressor responses in freshwater fishes are rarely synergistic and, therefore, addressing either or both stressors will likely result in positive management and biological outcomes.

Nationwide evaluation of microplastic properties in municipal wastewater treatment plants in South Korea

Wastewater treatment plants (WWTPs) are considered a significant microplastic discharge source. To evaluate the amount and characteristics of microplastics discharged from WWTPs in South Korea, we selected 22 municipal WWTPs nationally and investigated microplastics at each treatment stage. The mean microplastic removal efficiency by WWTPs was >99%, and most of the microplastics were removed by sedimentation with the second clarifier during wastewater treatment. Consequently, the microplastic removal efficiency of WWTPs did not significantly differ from that of the adopted wastewater treatment technology because a second clarifier was applied in most WWTPs. However, for WWTPs operating a tertiary treatment process, the removal efficiency was enhanced compared with that of WWTPs discharging after a second clarifier. Although the microplastic removal efficiency was high by WWTP, the discharge contribution to the water environment could not be ignored because of the amount of treated wastewater, resulting in an increase of 5.8-270.9 items/m3 of microplastics in the receiving water. The characteristics of microplastics in WWTPs, including their components, shape, and size, were also evaluated. The most detected components included polytetrafluoroethylene and polyester. Most microplastics detected were categorized as fragments and fibers, while other types were hardly detected. The size of more than 70% of the microplastics detected in WWTPs was under 300 μm, implying that the size of microplastics required to control in WWTPs was much smaller than the defined size of microplastics. An evaluation of the correlation between other pollution factors and microplastic abundance did not reveal positive correlations, and microplastic occurrence was not affected by changing seasons, which may need to be evaluated with further studies. Research should also be performed on the effect of influent sources on the level of microplastic abundance and fate of ultrafine plastics in WWTPs.

Seasonal variability of microplastic contamination in marine fishes of the state of Gujarat, India

Seasonal variation in microplastics abundance, occurrence, and distribution in pelagic and demersal fishes was observed in this study during December 2021 to November 2022. One hundred percent presence of microplastic in inedible (gut and gills) tissue, while 82% and 54% in edible tissue (muscle) of pelagic and demersal fishes respectively were seen. Post-monsoon period showed high prevalence of microplastics followed by monsoon and the least during pre-monsoon in both pelagic and demersal fishes. In pelagic fishes, the edible tissue had microplastics abundance of 1.56 to 13.34 numbers per 10 g of tissue whereas inedible tissue had 3.36 to 16.67 numbers per 10 g of tissue. In demersal fishes, the edible tissue had microplastics abundance of 1.04 to 5.26 numbers per 10 g of tissue while it was 2.67 to 8.34 numbers per 10 g of inedible tissue. There was significant variation in abundance of microplastic in edible and inedible tissue of all the fishes (Mann-Whitney test, p < 0.05). The most dominant microplastics size was 0.005-0.05 mm followed by 0.05-0.5 mm and the least of greater than 0.5 mm in pelagic and demersal fishes respectively. Taking microplastic shape into consideration, the most dominant was fiber followed by fragment and the film in inedible tissue of all the fishes. The edible tissue of all the fishes had only fiber in them (100% occurrence). The dominance of blue color microplastics was observed followed by red, green, yellow, and orange at least in edible as well as inedible tissues of the fishes. More than 99% microplastics polymer observed in this study include polyethylene (PE), polypropylene (PP), and polystyrene (PS); only less than 1% was unidentified. This is the first study done on seasonal variation of microplastic in the marine fish population of Gujarat waters, Northeast Arabian Sea. The study highlights the nature of micro-pollutant in marine environments, emphasizing the need for comprehensive monitoring and management strategies.

Exploring the trophic transfer and effects of microplastics in freshwater ecosystems: A focus on Bellamya aeruginosa to Mylopharyngodon piceus

Microplastics (MPs) can enter aquatic food webs through direct ingestion from the environment or indirectly via trophic transfer, but their fate and biological effects within local freshwater food chains remain largely unexplored. In this study, we conducted the first investigation on the trophic transfer and impacts of fluorescently labeled polystyrene microplastics (PS-MPs) (100-nm and 10-μm) in a model freshwater food chain consisting of the snail Bellamya aeruginosa and the commercially important fish Mylopharyngodon piceus, both prevalent in Chinese freshwater ecosystems. Quantitative analysis revealed substantial accumulation of MPs in B. aeruginosa, reaching an equilibrium state within 12 h of exposure. While steady-state was not observed, a pronounced time-dependent bioaccumulation of MPs was evident in M. piceus over a five-week period following dietary exposure through the consumption of contaminated B. aeruginosa. Notably, MPs of both sizes underwent translocation from the gastrointestinal tract to the muscle tissue in M. piceus. High-throughput sequencing of the gut microbiota revealed that exposure to 100-nm MPs significantly altered the microbial community composition in M. piceus, and both particle sizes led to increased relative abundance of potentially pathogenic bacterial genera. Our findings provide novel insights into the trophic transfer, tissue accumulation, and biological impacts of MPs in a model freshwater food chain, highlighting the need for further research to assess the ecological and food safety risks associated with microplastic pollution in freshwater environments.

Effect of parasitic infection on microplastic ingestion in a native leuciscid hybrid species (Alburnus derjugini x Squalius orientalis) from Kürtün Dam Lake, Türkiye

Microplastic (MP) pollution is currently one of the most serious environmental issues. MPs were investigated in the Kürtün Dam Lake in healthy individuals of the native leuciscid hybrid (Alburnus derjugini x Squalius orientalis) species and individuals infected with the Ligula intestinalis parasite. Although MP abundance appeared to be higher in non-infected fish (NIF) than in L. intestinalis (L) and infected fish (IF), the MP abundance in IF was higher, because the parasite theoretically belongs to IF. In addition to the observation of MPs in the gastrointestinal tract (GIT) of fish, the diffusion of MPs by parasites settled in the body cavity indicates that MPs are not only present in the GIT. Therefore, predation on existing fish by birds causes MP dispersion. In the present study, the most common MP shape was fiber (100% for NIF and IF, 85.7% for L), the MP color was black (57.1% for IF and L) and orange (50% for NIF), and the polymer type was polyamide (57.1% for IF, 50% for NIF) and polyethylene terephthalate (28.5% for L). These MP compositions led us to believe that textile effluents and aquaculture operations in dam lakes could be sources of pollution. Therefore, this study provides insights for future research to elucidate the connection between MP consumption and parasite infection.

Negligible additive effect of environmental concentrations of fragmented polyethylene terephthalate microplastics on the growth and reproductive performance of Java medaka exposed to 17β-estradiol and bisphenol A

To investigate whether environmental concentrations of fragmented polyethylene terephthalate (PET) microplastics (MPs) have additional or combined effects on endocrine-disrupting activity, Java medaka (Oryzias javanicus) were exposed to 17β-estradiol (E2; 5, 10, 50, and 100 ng L-1), bisphenol A (BPA; 5, 10, 50, and 100 µg L-1), and E2 and BPA combined with PET MPs (1 and 100 particles L-1) for 200 days. The growth parameters, such as body length and weight, were significantly decreased by the highest concentrations of E2 and BPA. A significant reduction in egg production was observed in female fish exposed to BPA, with an additive toxic effect of PET MPs. A female-biased sex ratio was observed in fish exposed to both chemicals. Exposure to E2 significantly increased the hepatosomatic index (HSI) in both sexes, while no significant effect was observed in the gonadosomatic index (GSI). Exposure to BPA significantly increased the HSI in female fish and decreased the GSI in both sexes of fish. An additive effect of PET MPs was observed on the GSI value of female exposed to BPA. Significant elevations in vitellogenin (VTG) levels were observed in both sexes due to exposure to E2 and BPA. Additive effects of PET MPs were observed on VTG levels in males exposed to E2 and BPA. Taken together, even long-term treatment with PET MPs induced only a negligible additive effect on the endocrine-disrupting activity in Java medaka at environmentally relevant concentrations.

Gut microbiota composition of the isopod Ligia in South Korea exposed to expanded polystyrene pollution

Plastics pose a considerable challenge to aquatic ecosystems because of their increasing global usage and non-biodegradable properties. Coastal plastic debris can persist in ecosystems; however, its effects on resident organisms remain unclear. A metagenomic analysis of the isopoda Ligia, collected from clean (Nae-do, ND) and plastic-contaminated sites (Maemul-do, MD) in South Korea, was conducted to clarify the effects of microplastic contamination on the gut microbiota. Ligia gut microbiota's total operational taxonomic units were higher in ND than in MD. Alpha diversity did not differ significantly between the two Ligia gut microbial communities collected from ND and MD, although richness (Observed species) was lower in MD than in ND. Proteobacteria (67.47%, ND; 57.30%, MD) and Bacteroidetes (13.63%, ND; 20.76%, MD) were the most abundant phyla found at both sites. Significant different genera in Ligia from EPS-polluted sites were observed. Functional gene analysis revealed that 19 plastic degradation-related genes, including those encoding hydrogenase, esterase, and carboxylesterase, were present in the gut microbes of Ligia from MD, indicating the potential role of the Ligia gut microbiota in plastic degradation. This study provides the first comparative field evidence of the gut microbiota dynamics of plastic detritus consumers in marine ecosystems.

The Duration of Dry Events Promotes PVC Film Fragmentation in Intermittent Rivers

The majority of microplastics (MPs) found in the environment originate from plastic fragmentation occurring in the environment and are influenced by environmental factors such as UV irradiation and biotic interactions. However, the effects of river drying on plastic fragmentation remain unknown, despite the global prevalence of watercourses experiencing flow intermittence. This study investigates, through laboratory experiments, the coupled effects of drying duration and UV irradiation on PVC film fragmentation induced by artificial mechanical abrasion. This study shows that PVC film fragmentation increases with drying duration through an increase in the abundance and size of formed MPs as well as mass loss from the initial plastic item, with significant differences for drying durations >50% of the experiment duration. The average abundance of formed MPs in treatments exposed to severe drying duration was almost two times higher than in treatments nonexposed to drying. Based on these results, we developed as a proof of concept an Intermittence-Based Plastic Fragmentation Index that may provide insights into plastic fragmentation occurring in river catchments experiencing large hydrological variability. The present study suggests that flow intermittence occurring in rivers and streams can lead to increasing plastic fragmentation, unraveling new insights into plastic pollution in freshwater systems.

Physiological and transcriptomic analysis reveals the toxicological mechanisms of polystyrene micro- and nano-plastics in Chlamydomonas reinhardtii

With the accumulation of plastic waste in the environment, the toxicity of micro- and nano-plastics (MNPs) to microalgae has attracted increasing attention. However, the underlying toxic mechanisms of MNPs remain to be elucidated. In this study, we synthesized micro- and nano-scale of polystyrene MNPs (PS MNPs) to investigate their toxicity and toxic mechanisms in Chlamydomonas reinhardtii. We found that PS MNPs significantly inhibit the production of photosynthetic pigments and increase soluble protein content. The detailed analysis of results shows that both materials affect photosynthetic efficiency by damaging the donor side, reaction center, and electron transfer of photosystem II. Moreover, compared to PS MPs, PS NPs have a greater negative impact on algal cells. Analyzing the transcriptome of cells suggests that the most sensitive metabolic pathways in response to PS MNPs involve oxidative phosphorylation, biosynthesis of secondary metabolites, and photosynthesis. Especially, genes related to photosynthesis and oxidative phosphorylation showed significant changes in expression after exposure to PS MNPs. This study provided molecular-level insights into the toxic mechanisms of PS MNPs on microalgae.

Investigation into the characteristics of electron beam-aged microplastics and adsorption behavior of dibutyl phthalate

Microplastics are increasingly prevalent in the environment, and their ability to adsorb various organic additives, posing harm to organisms, has attracted growing attention. Currently, there are no effective methods to age microplastics, and there is limited discussion on the subsequent treatment of aged microplastics. This study focuses on micro polyethylene (PE) and employs electron beam technology for aging treatment, investigating the adsorption and leaching behavior between PE and dibutyl phthalate (DBP) before and after aging. Experimental results indicate that with increasing doses of electron beam irradiation, the surface microstructure of PE worsens, inducing the generation of oxygen-containing functional groups on the surface of polyethylene. Comparative evaluations between electron beam aging and existing methods show that electron beam technology surpasses existing aging methods, achieving a level of aging exceeding 0.7 within an extremely short period of 1 min at doses exceeding 350 kGy. Adsorption experiments demonstrate that the adsorption between PE and DBP conforms to pseudo-second-order kinetics and the Freundlich model both before and after aging. The adsorption capacity of microplastics for DBP increases from 76.8 mg g-1 to 167.0 mg g-1 after treatment, exceeding that of conventional DBP adsorbents. Electron beam irradiation causes aging of microplastics mainly through the generation of ·OH, which lead to the formation of oxygen-containing functional groups on the microplastics' surface, thereby enhancing their adsorption capacity for DBP. This provides a new perspective for the degradation of aged microplastics and composite pollutants.

Advances of microplastics ingestion on the morphological and behavioral conditions of model zebrafish: A review

Concerns have been conveyed regarding the availability and hazards of microplastics (MPs) in aquatic biota due to their widespread presence in aquatic habitats. Zebrafish (Danio rerio) are widely used as a model organism to study the adverse impacts of MPs due to their several compelling advantages, such as their small size, ease of breeding, inexpensive maintenance, short life cycle, year-round spawning, high fecundity, fewer legal restrictions, and genetic resemblances to humans. Exposure of organisms to MPs produces physical and chemical toxic effects, including abnormal behavior, oxidative stress, neurotoxicity, genotoxicity, immune toxicity, reproductive imbalance, and histopathological effects. But the severity of the effects is size and concentration-dependent. It has been demonstrated that smaller particles could reach the gut and liver, while larger particles are only confined to the gill, the digestive tract of adult zebrafish. This thorough review encapsulates the current body of literature concerning research on MPs in zebrafish and demonstrates an overview of MPs size and concentration effects on the physiological, morphological, and behavioral characteristics of zebrafish. Finding gaps in the literature paves the way for further investigation.

Understanding Human Health Impacts Following Microplastic Exposure Necessitates Standardized Protocols

Microplastics (MPs; 1 µm to 5 mm) are a persistent and pervasive environmental pollutant of emergent and increasing concern. Human exposure to MPs through food, water, and air has been documented and thus motivates the need for a better understanding of the biological implications of MP exposure. These impacts are dependent on the properties of MPs, including size, morphology, and chemistry, as well as the dose and route of exposure. This overview offers a perspective on the current methods used to assess the bioactivity of MPs. First, we discuss methods associated with MP bioactivity research with an emphasis on the variety of assays, exposure conditions, and reference MP particles that have been used. Next, we review the challenges presented by common instrumentation and laboratory materials, the lack of standardized reference materials, and the limited understanding of MP dosimetry. Finally, we propose solutions that can help increase the applicability and impact of future studies while reducing redundancy in the field. The excellent protocols published in this issue are intended to contribute toward standardizing the field so that the MP knowledge base grows from a reliable foundation. © 2024 Wiley Periodicals LLC.

Do Antarctic bivalves present microdebris? The case of Livingston Island

Marine microdebris (MD) seem to be widespread in benthic invertebrates, even in the most remote areas of the planet such as Antarctica, although the information available is still very scarce. Here we provide a detailed quantification and characterization of the MD found on three common bivalve species (Aequiyoldia eightsii, Thracia cf. meridionalis, and Cyclocardia astartoides) inhabiting shallow areas in Johnsons' Bay, Livingston Island (South Shetland Islands, Antarctica) as a snapshot of the MD present. On average, these bivalves contained 0.71 ± 0.89 items per individual and 1.49 ± 2.35 items per gram, being comparable to the few previous existing studies in other Antarctic areas. Nearly half of the organisms analysed here (45.6 %), contained at least one item. No significant differences were found in the three bivalve species. As far as we know, this is the first study to analyse and compare MD in three bivalve species in the Antarctic Peninsula. Although our results indicate bivalves are as not as polluted as in other areas of the planet, this is remarkable since this is considered one of the last pristine areas of the world. Our results point to local activities as the main source of MD pollution in Livingston Island, although global pollution cannot be discarded. We believe this research provides a useful baseline for future studies and will contribute to develop policies and strategies to preserve Antarctic marine ecosystems from MD pollution.

A perspective on the impacts of microplastics on mosquito biology and their vectorial capacity

Microplastics (plastic particles <5 mm) permeate aquatic and terrestrial ecosystems and constitute a hazard to animal life. Although much research has been conducted on the effects of microplastics on marine and benthic organisms, less consideration has been given to insects, especially those adapted to urban environments. Here, we provide a perspective on the potential consequences of exposure to microplastics within typical larval habitat on mosquito biology. Mosquitoes represent an ideal organism in which to explore the biological effects of microplastics on terrestrial insects, not least because of their importance as an infectious disease vector. Drawing on evidence from other organisms and knowledge of the mosquito life cycle, we summarise some of the more plausible impacts of microplastics including physiological, ecotoxicological and immunological responses. We conclude that although there remains little experimental evidence demonstrating any adverse effect on mosquito biology or pathogen transmission, significant knowledge gaps remain, and there is now a need to quantify the effects that microplastic pollution could have on such an important disease vector.

Developmental and biochemical markers of the impact of pollutant mixtures under the effect of Global Climate Change

This study investigates the combined impact of microplastics (MP) and Chlorpyriphos (CPF) on sea urchin larvae (Paracentrotus lividus) under the backdrop of ocean warming and acidification. While the individual toxic effects of these pollutants have been previously reported, their combined effects remain poorly understood. Two experiments were conducted using different concentrations of CPF (EC10 and EC50) based on previous studies from our group. MP were adsorbed in CPF to simulate realistic environmental conditions. Additionally, water acidification and warming protocols were implemented to mimic future ocean conditions. Sea urchin embryo toxicity tests were conducted to assess larval development under various treatment combinations of CPF, MP, ocean acidification (OA), and temperature (OW). Morphometric measurements and biochemical analyses were performed to evaluate the effects comprehensively. Results indicate that combined stressors lead to significant morphological alterations, such as increased larval width and reduced stomach volume. Furthermore, biochemical biomarkers like acetylcholinesterase (AChE), glutathione S-transferase (GST), and glutathione reductase (GRx) activities were affected, indicating oxidative stress and impaired detoxification capacity. Interestingly, while temperature increase was expected to enhance larval growth, it instead induced thermal stress, resulting in lower growth rates. This underscores the importance of considering multiple stressors in ecological assessments. Biochemical biomarkers provided early indications of stress responses, complementing traditional growth measurements. The study highlights the necessity of holistic approaches when assessing environmental impacts on marine ecosystems. Understanding interactions between pollutants and environmental stressors is crucial for effective conservation strategies. Future research should delve deeper into the impacts at lower biological levels and explore adaptive mechanisms in marine organisms facing multiple stressors. By doing so, we can better anticipate and mitigate the adverse effects of anthropogenic pollutants on marine biodiversity and ecosystem health.

Microplastics in aquaculture - Potential impacts on inflammatory processes in Nile tilapia

Aquaculture is essential for meeting the growing global demand for fish consumption. However, the widespread use of plastic and the presence of microplastics in aquaculture systems raise concerns about their impact on fish health and the safety of aquaculture products. This study focused on the Nile tilapia (Oreochromis niloticus), one of the most important aquaculture fish species globally. The aim of this study was to investigate the effects of dietary exposure to a mixture of four conventional fossil fuel-based polymers (microplastics) on the health of adult and juvenile Nile tilapia. Two experiments were conducted, with 36 juvenile tilapia (10-40 g weight) exposed for 30 days and 24 adult tilapia (600-1000 g) exposed for 7 days, the former including a natural particle (kaolin) treatment. In the adult tilapia experiment, no significant effects on intestinal health (Ussing chamber method), oxidative stress, or inflammatory pathways (enzymatic and genetic biomarkers) were observed after exposure to the microplastic mixture. However, in the juvenile tilapia experiment, significant alterations in inflammatory pathways were observed following 30 days of exposure to the microplastic mixture, indicating potential adverse effects on fish health. These results highlight the potential negative impacts of microplastics on fish health and the economics and safety of aquaculture.

A critical review on male-female reproductive and developmental toxicity induced by micro-plastics and nano-plastics through different signaling pathways

It is widely accepted that humans are constantly exposed to micro-plastics and nano-plastics through various routes, including inhalation of airborne particles, exposure to dust, and consumption of food and water. It is estimated that humans may consume thousand to millions of micro-plastic particles, equating to several milligrams per day. Prolonged exposure to micro-plastics and nano-plastics has been linked to negative effects on different living organisms, including neurotoxicity, gastrointestinal toxicity, nephrotoxicity, and hepatotoxicity, and developmental toxicities. The main purpose of this review is to explore the effect of micro-plastics and nano-plastics on the male and female reproductive system, as well as their offspring, and the associated mechanism implicated in the reproductive and developmental toxicities. Micro-plastics and nano-plastics have been shown to exert negative effects on the reproductive system of both male and female mammals and aquatic animals, including developmental impacts on gonads, gametes, embryo, and their subsequent generation. In addition, micro-plastics and nano-plastics impact the hypothalamic-pituitary axes, leading to oxidative stress, reproductive toxicity, neurotoxicity, cytotoxicity, developmental abnormalities, poor sperm quality, diminishes ovarian ovulation and immune toxicity. This study discusses the so many different signaling pathways associated in the male and female reproductive and developmental toxicity induced by micro-plastics and nano-plastics.

Polyester microfiber impacts on coastal sediment organic matter consumption

As plastic pollution continues to accumulate at the seafloor, concerns around benthic ecosystem functionality heightens. This research demonstrates the systematic effects of polyester microfibers on seafloor organic matter consumption rates, an important benthic ecosystem function connected to multiple reactions and processes. We used a field-based assay to measure the loss of organic matter, both with and without polyester microfiber contamination. We identified sediment organic matter content, mud content, and mean grain size as the main drivers of organic matter consumption, however, polyester microfiber contamination decoupled ecosystem relationships and altered observed organic matter cycling dynamics. Organic matter consumption rates varied across horizontal and vertical spaces, highlighting that consumption and associated plastic effects are dependent on environmental heterogeneity at both small (within sites) and larger (between sites) scales. Our results emphasize the important role habitat heterogeneity plays in seafloor organic matter consumption and the associated effects of plastic pollution on ecosystem function.

Identifying potential high-risk zones for land-derived plastic litter to marine megafauna and key habitats within the North Atlantic

The pervasive use of plastic in modern society has led to plastic litter becoming ubiquitous within the ocean. Land-based sources of plastic litter are thought to account for the majority of plastic pollution in the marine environment, with plastic bags, bottles, wrappers, food containers and cutlery among the most common items found. In the marine environment, plastic is a transboundary pollutant, with the potential to cause damage far beyond the political borders from where it originated, making the management of this global pollutant particularly complex. In this study, the risks of land-derived plastic litter (LDPL) to major groups of marine megafauna - seabirds, cetaceans, pinnipeds, elasmobranchs, turtles, sirenians, tuna and billfish - and a selection of productive and biodiverse biogenic habitats - coral reefs, mangroves, seagrass, saltmarsh and kelp beds - were analysed using a Spatial Risk Assessment approach. The approach combines metrics for vulnerability (mechanism of harm for megafauna group or habitat), hazard (plastic abundance) and exposure (distribution of group or habitat). Several potential high-risk zones (HRZs) across the North Atlantic were highlighted, including the Azores, the UK, the French and US Atlantic coasts, and the US Gulf of Mexico. Whilst much of the modelled LDPL driving risk in the UK originated from domestic sources, in other HRZs, such as the Azores archipelago and the US Gulf of Mexico, plastic originated almost exclusively from external (non-domestic) sources. LDPL from Caribbean islands - some of the largest generators of marine plastic pollution in the dataset of river plastic emissions used in the study - was noted as a significant input to HRZs across both sides of the Atlantic. These findings highlight the potential of Spatial Risk Assessment analyses to determine the location of HRZs and understand where plastic debris monitoring and management should be prioritised, enabling more efficient deployment of interventions and mitigation measures.

Field and laboratory microplastics uptake by a freshwater shrimp

Microplastics are widespread pollutants, but few studies have linked field prevalence in organisms to laboratory uptakes. Aquatic filter feeders may be particularly susceptible to microplastic uptake, with the potential for trophic transfer to higher levels, including humans. Here, we surveyed microplastics from a model freshwater shrimp, common caraidina (Caridina nilotica) inhabiting the Crocodile River in South Africa to better understand microplastic uptake rates per individual. We then use functional response analysis (feeding rate as a function of resource density) to quantify uptake rates by shrimps in the laboratory. We found that microplastics were widespread in C. nilotica, with no significant differences in microplastic abundances among sampled sites under varying land uses, with an average abundance of 6.2 particles per individual. The vast majority of microplastics found was fibres (86.1%). Shrimp microplastic accumulation patterns were slightly higher in the laboratory than the field, where shrimp exhibited a hyperbolic Type II functional response model under varying exposure concentrations. Maximum feeding rates of 20 particles were found over a 6 h feeding period, and uptake evidenced at even the lowest laboratory concentrations (~10 particles per mL). These results highlight that microplastic uptake is widespread in field populations and partly density dependent, with field concentrations corroborating uptake rates recorded in the laboratory. Further research is required to elucidate trophic transfer from these taxa and to understand potential physiological impacts.