Assimilation of polybrominated diphenyl ethers from microplastics by the marine amphipod, Allorchestes compressa

Insights into the synergistic toxicity mechanisms caused by nano- and microplastics with triclosan using a dose-dependent functional genomics approach in Saccharomyces cerevisiae

The emergence of polystyrene (PS) nano- and microplastics (NMPs) and triclosan (TCS) as environmental contaminants has raised concerns about their combined toxicities to organisms, but the complex toxicity arising from their interactions and the underlying molecular mechanisms remain obscure to us. In this study, we comprehensively detected the combined toxicity of PS-NMPs and TCS via the dose-dependent yeast functional genomics profiling. Firstly, our findings demonstrated that the combined exposure to PS-NMPs and TCS elicited a synergistic toxic effect in which the toxicity depended on the size of the PS-NMPs. Secondly, we found that TCS exposure, either alone or in combination with PS-NMPs, influenced lipid biosynthetic processes and ATP export pathways, while the unique responsive genes triggered by combined exposure to TCS and PS-NMPs are significantly enriched in mitochondrial translation, ribosomal small subunit assembly, and tRNA wobble uridine modification. Thirdly, our results demonstrated that point of departure (POD) at the pathway level was positively correlated with IC50, and POD was a more sensitive predictor of toxicity than the apical toxicity endpoints. More importantly, our findings suggested that the combined exposure of PS-NMPs in a size-dependent manner not only alleviated the harmful effects of TCS on glycerophospholipid metabolism, but also exacerbated its negative impact on oxidative phosphorylation. Collectively, our study not only provides new insights into the intricate molecular mechanisms that control the combined toxicity of PS-NMPs and TCS, but also confirms the effectiveness of the dose-dependent functional genomics approach in elucidating the molecular mechanisms of the combined toxicity of pollutants.

The role of iron materials in the abiotic transformation and biotransformation of polybrominated diphenyl ethers (PBDEs): A review

Polybrominated diphenyl ethers (PBDEs), widely used as flame retardants, easily enter the environment, thus posing environmental and health risks. Iron materials play a key role during the migration and transformation of PBDEs. This article reviews the processes and mechanisms of adsorption, degradation, and biological uptake and transformation of PBDEs affected by iron materials in the environment. Iron materials can effectively adsorb PBDEs through hydrophobic interactions, π-π interactions, hydrogen/halogen bonds, electrostatic interactions, coordination interactions, and pore filling interactions. In addition, they are beneficial for the photodegradation, reduction debromination, and advanced oxidation degradation and debromination of PBDEs. The iron material-microorganism coupling technology affects the uptake and transformation of PBDEs. In addition, iron materials can reduce the uptake of PBDEs in plants, affecting their bioavailability. The species, concentration, and size of iron materials affect plant physiology. Overall, iron materials play a bidirectional role in the biological uptake and transformation of PBDEs. It is necessary to strengthen the positive role of iron materials in reducing the environmental and health risks caused by PBDEs. This article provides innovative ideas for the rational use of iron materials in controlling the migration and transformation of PBDEs in the environment.

Microplastics in feed affect the toxicokinetics of persistent halogenated pollutants in Atlantic salmon

Microplastics (MPs) are carriers of persistent organic pollutants (POPs). The influence of MPs on the toxicokinetics of POPs was investigated in a feeding experiment on Atlantic salmon (Salmo salar), in which fish were fed similar contaminant concentrations in feed with contaminants sorbed to MPs (Cont. MPs); feed with virgin MPs and contaminated feed (1:1), and feed with contaminants without MPs (Cont.). The results showed that the salmon fillets accumulated more POPs when fed with a diet where contaminants were sorbed to the MPs, despite the 125-250 μm size MPs themselves passing the intestines without absorption. Furthermore, depuration was significantly slower for several contaminants in fish fed the diet with POPs sorbed to the MPs. Modelled elimination coefficients and assimilation efficiencies of lipophilic chlorinated and brominated contaminants correlated with contaminant hydrophobicity (log Kow) within the diets and halogen classes. The more lipophilic the contaminant was, the higher was the transfer from feed to salmon fillet. The assimilation efficiency for the diet without MPs was 50-71% compared to 54-89% for the contaminated MPs diet. In addition, MPs caused a greater proportional uptake of higher molecular weight brominated congeners. In the present study, higher assimilation efficiencies and a significantly higher slope of assimilation efficiencies vs log Kow were found for the Cont. MPs diet (p = 0.029), indicating a proportionally higher uptake of higher-brominated congeners compared to the Cont. diet. Multiple variance analyses of elimination coefficients and assimilation efficiencies showed highly significant differences between the three diets for the chlorinated (p = 2E-06; 6E-04) and brominated (p = 5E-04; 4E-03) congeners and within their congeners. The perfluorinated POPs showed low assimilation efficiencies of <12%, which can be explained by faster eliminations corresponding to half-lives of 11-39 days, as well as a lower proportional distribution to the fillet, compared to e.g. the liver.

Comparative impact of pristine and aged microplastics with triclosan on lipid metabolism in larval zebrafish: Unveiling the regulatory role of miR-217

The prevalence of microplastics (MPs), especially aged particles, interacting with contaminants like triclosan (TCS), raises concerns about their toxicological effects on aquatic life. This study focused on the impact of aged polyamide (APA) MPs and TCS on zebrafish lipid metabolism. APA MPs, with rougher surfaces and lower hydrophobicity, exhibited reduced TCS adsorption than unaged polyamide (PA) MPs. Co-exposure to PA/APA MPs and TCS resulted in higher TCS accumulation in zebrafish larvae, notably more with PA than APA. Larvae exposed to PA + TCS exhibited greater oxidative stress, disrupted lipid metabolism, and altered insulin pathway genes than those exposed to TCS. However, these negative effects were lessened in the APA + TCS group. Through miRNA-seq and miR-217 microinjection, it was revealed that PA + TCS co-exposure upregulated miR-217, linked to lipid metabolic disorders in zebrafish. Moreover, molecular docking showed stable interactions formed between PA, TCS, and the insulin signaling protein Pik3r2. This study demonstrated that PA and TCS co-exposure significantly inhibited the insulin signaling in zebrafish, triggering lipid metabolism dysregulation mediated by miR-217 upregulation, while APA and TCS co-exposure alleviated these disruptions. This research underscored the ecological and toxicological risks of aged MPs and pollutants in aquatic environments, providing crucial insights into the wider implications of MPs pollution.

Toxicity effects and mechanism of micro/nanoplastics and loaded conventional pollutants on zooplankton: An overview

Micro/nanoplastics in aquatic environments is a noteworthy environmental problem. Zooplankton, an important biological group in aquatic ecosystems, readily absorb micro/nanoplastics and produce a range of toxic endpoints due to their small size. This review summarises relevant studies on the effects of micro/nanoplastics on zooplankton, including combined effects with conventional pollutants. Frequently reported adverse effects include acute/chronic lethal effects, oxidative stress, gene expression, energetic homeostasis, and growth and reproduction. Obstruction by plastic entanglement and blockage is the physical mechanism. Genotoxicity and cytotoxicity are molecular mechanisms. Properties of micro/nanoplastics, octanol/water partition coefficients of conventional pollutants, species and intestinal environments are important factors influencing single and combined toxicity. Selecting a wider range of micro/nanoplastics, focusing on the aging process and conducting field studies, adopting diversified zooplankton models, and further advancing the study of mechanisms are the outstanding prospects for deeper understanding of impacts of micro/nanoplastics on aquatic ecosystem.

Research progress on the origin, fate, impacts and harm of microplastics and antibiotic resistance genes in wastewater treatment plants

Previous studies reported microplastics (MPs), antibiotics, and antibiotic resistance genes (ARGs) in wastewater treatment plants (WWTPs). There is still a lack of research progress on the origin, fate, impact and hazards of MPs and ARGs in WWTPs. This paper fills a gap in this regard. In our search, we used "microplastics", "antibiotic resistance genes", and "wastewater treatment plant" as topic terms in Web of Science, checking the returned results for relevance by examining paper titles and abstracts. This study mainly explores the following points: (1) the origins and fate of MPs, antibiotics and ARGs in WWTPs; (2) the mechanisms of action of MPs, antibiotics and ARGs in sludge biochemical pools; (3) the impacts of MPs in WWTPs and the spread of ARGs; (4) and the harm inflicted by MPs and ARGs on the environment and human body. Contaminants in sewage sludge such as MPs, ARGs, and antibiotic-resistant bacteria enter the soil and water. Contaminants can travel through the food chain and thus reach humans, leading to increased illness, hospitalization, and even mortality. This study will enhance our understanding of the mechanisms of action among MPs, antibiotics, ARGs, and the harm they inflict on the human body.

Preferential deposition of buoyant small microplastics in surface sediments of the Three Gorges Reservoir, China: Insights from biomineralization

Sediments act as sinks of microplastics (MPs) derived from terrestrial ecosystems. However, the fate and transport of MPs at the zone of sediment-overlying water in reservoir environment are poorly understood. Here, the MPs distribution patterns in surface sediments of the Three Gorges Reservoir (TGR) and dominant mechanisms responsible for the sinking of MPs at the zone of sediment-overlying water were comprehensively investigated. The predominant occurrence of small microplastics (<300 µm, SMPs) in surface sediments of the TGR was found, with buoyant polyethene (PE) was dominant polymer types. Interestingly, the high abundance of SMPs in sediments correlated well with the Ca2+/Mg2+ in overlying water, suggesting that divalent cations in overlying water may enhance the preferential deposition of SMPs. Simulation sinking experiments under the presence of Microcystis aeruginosa and two divalent cations using different-sized PE MPs demonstrated that the greater deposition of SMPs was mainly the result of the formation of biogenic calcite on the surface of MPs rather than magnesium minerals, which provides stronger ballasting effects for SMPs than for large MPs. This study first highlights that the impact of biomineralization on preferential sinking of SMPs and enhances the understanding of the transport behaviour of MPs in aquatic environment.

Microplastics and nanoplastics: Source, behavior, remediation, and multi-level environmental impact

Plastics introduced into the natural environment persist, degrade, and fragment into smaller particles due to various environmental factors. Microplastics (MPs) (ranging from 1 μm to 5 mm) and nanoplastics (NPs) (less than 1 μm) have emerged as pollutants posing a significant threat to all life forms on Earth. Easily ingested by living organisms, they lead to ongoing bioaccumulation and biomagnification. This review summarizes existing studies on the sources of MPs and NPs in various environments, highlighting their widespread presence in air, water, and soil. It primarily focuses on the sources, fate, degradation, fragmentation, transport, and ecotoxicity of MPs and NPs. The aim is to elucidate their harmful effects on marine organisms, soil biota, plants, mammals, and humans, thereby enhancing the understanding of the complex impacts of plastic particles on the environment. Additionally, this review highlights remediation technologies and global legislative and institutional measures for managing waste associated with MPs and NPs. It also shows that effectively combating plastic pollution requires the synergization of diverse management, monitoring strategies, and regulatory measures into a comprehensive policy framework.

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.

The combined effects of microplastics and bisphenol-A on the innate immune system response and intestinal microflora of the swimming crab Portunus trituberculatus

Microplastics (MPs) and bisphenol-A (BPA) have been shown to have toxic effects on aquatic organisms. However, data on the combined effects of MPs and BPA on the innate immune system response and intestinal microorganisms of crabs are limited. Here, Portunus trituberculatus were exposed to BPA (at a concentration of 100 μg/L), MPs (microbeads of polystyrene with a particle size of 1 µm and at a concentration of 1 × 106 particles/L) or BPA+MPs for 21 days were tested at the tissue, cellular, and molecular levels. The results showed that neither the single nor combined exposure of MPs and BPA had a significant impact on the growth of crabs. However, intestinal histology study found that the intestinal villi of crabs in the BPA treated group, MP treated group and MP+BPA treated group appeared abnormal. Overall, compared with the control group and the single pollutant exposure group, co-exposure to the MP and BPA generally led to a significant increase in MDA and SOD activity and a significant decrease in CAT activity, and the activation of MyD88, Crustin-1, TARF6, Cu/Zn-SOD, Lyz, Toll-2 and NOX gene expression levels were significantly up-regulated. Co-exposure induced disorders of the intestinal microbial community of crabs, resulting in an increase in the abundance of harmful bacteria and a decrease in the abundance of beneficial bacteria. This study shows that the combined exposure of MPs and BPA can exacerbate the intestinal toxicity of a single pollutant to P. trituberculatus.

20 years of polybrominated diphenyl ethers on toxicity assessments

Polybrominated diphenyl ethers (PBDEs) serve as brominated flame retardants which continue to receive considerable attention because of their persistence, bioaccumulation, and potential toxicity. Although PBDEs have been restricted and phased out, large amounts of commercial products containing PBDEs are still in use and discarded annually. Consequently, PBDEs added to products can be released into our surrounding environments, particularly in aquatic systems, thus posing great risks to human health. Many studies and reviews have described the possible toxic effects of PBDEs, while few studies have comprehensively summarized and analyzed the global trends of their toxicity assessment. Therefore, this study utilizes bibliometrics to evaluate the worldwide scientific output of PBDE toxicity and analyze the hotspots and future trends of this field. Firstly, the basic information including the most contributing countries/institutions, journals, co-citations, influential authors, and keywords involved in PBDE toxicity assessment will be visualized. Subsequently, the potential toxicity of PBDE exposure to diverse systems, such as endocrine, reproductive, neural, and gastrointestinal tract systems, and related toxic mechanisms will be discussed. Finally, we conclude this review by outlining the current challenges and future perspectives in environmentally relevant PBDE exposure, potential carriers for PBDE transport, the fate of PBDEs in the environment and human bodies, advanced stem cell-derived organoid models for toxicity assessment, and promising omics technologies for obtaining toxic mechanisms. This review is expected to offer systematical insights into PBDE toxicity assessments and facilitate the development of PBDE-based research.

Microcosm study of the effects of polyester microfibers on the indigenous marine amphipod (Cyphocaris challengeri) in the Strait of Georgia (BC, Canada)

Microplastics (MP) remain contaminants of great concern in the ocean because of their abundance, prevalence, and threat to marine organisms. Still, there is a great need for studies on the impact of MP on marine zooplankton. Here, we investigated the effects of polyethylene terephthalate (PET) microfibers (Mf) on the survival, Mf ingestion and retention, predation, and fecal pellets (FP) of the marine amphipod (Cyphocaris challengeri) at environmentally relevant concentrations (0, 10, 100, 1000, 10,000 and 50,000 Mf·L-1) and varied exposure time (24, 48 and 72 h). Our study demonstrated that exposure of C. challengeri to PET Mf did not affect their survival. The average number of ingested Mf and the Mf ingestion rate increased significantly with Mf concentrations. Nonetheless, the Mf ingestion rates by C. challengeri decreased significantly between 24 and 72 h in the two highest Mf treatments (10,000 and 50,000 Mf·L-1), suggesting careful rejection of the Mf or reduced feeding activity. Indeed, PET Mf significantly reduced the copepod feeding rate of the amphipods at Mf concentrations ≥1000 Mf·L-1 after 24 and 48 h of exposure duration. Over time, prey intake reduction in amphipods due to Mf ingestion could affect their reproductive outcome, growth, development, and cellular and ecosystem function. The encapsulation of PET Mf into the FP of C. challengeri significantly increased the FP density and sinking velocities, ultimately doubling the transfer rate of the FP from the surface waters to the sediments in SoG. Conversely, ingesting PET microfibers and their incorporation in FP will potentially enhance the role of C. challengeri in the biological C pump and sequestration in SoG. Our study showed that changes in Mf concentration had a more significant effect on C. challengeri Mf ingestion and ingestion rate, prey consumption, FP density and sinking velocity than the exposure time.

Floating plastics as integrative samplers of organic contaminants of legacy and emerging concern from Western Mediterranean coastal areas

This study investigates the role of floating plastics as integrative samplers of organic contaminants. To this end, plastics items were collected in two Western Mediterranean coastal areas: the Mar Menor lagoon, and the last transect of Ebro river. Floating plastics were identified and characterized by attenuated total reflection Fourier-transform infrared spectrometry. Then, organic contaminants were extracted from plastic items by ultrasonic extraction with methanol, and the concentrations of 168 regulated and emerging contaminants were analysed. These compounds were analysed by stir bar sorptive extraction coupled to gas chromatography-mass spectrometry (GC-MS), except for bisphenol analogues, which were analysed with a ultraperformance liquid chromatography pump coupled to a triple quadrupole mass spectrometer (UHPLC-MS/MS), and pharmaceutical compounds, determined by UPLC coupled to hybrid triple quadrupole-linear ion trap mass spectrometer (UPLC-MS/MS). All the contaminants groups considered were detected in the samples, being particularly relevant the contribution of plastic additives. The most frequently detected contaminants were UV-filters, PAHs, pharmaceuticals and synthetic musks. Apart from plasticizers, the individual contaminants octocrylene, homosalate, galaxolide, salycilic acid and ketoprofen were frequently detected in plastics items. The results pointed out to urban and touristic activities as the main sources of pollution in the coastal areas investigated. The utility of floating plastics as integrative samplers for the detection of organic contaminants in aquatic ecosystems has been demonstrated.

UV Light Causes Structural Changes in Microplastics Exposed in Bio-Solids

Bio-solids (biological sludge) from wastewater treatment plants are a significant source of the emission of microplastics (MPs) into the environment. Weakening the structure of MPs before they enter the environment may accelerate their degradation and reduce the environmental exposure time. Therefore, we studied the effect of UV-A and UV-C, applied at 70 °C, on three types of MPs, polypropylene (PP), polyethylene (PE), and polyethylene terephthalate (PET), that are commonly found in sewage sludge, using three shapes (fibers, lines, granules). The MPs were exposed to UV radiation in bio-solid suspensions, and to air and water as control. The structural changes in and degradation of the MPs were investigated using Attenuated Total Reflectance-Fourier Transform Infrared Spectrometry (ATR-FTIR) and surface morphology was performed with SEM analysis. UV exposure led to the emergence of carbonyl and hydroxyl groups in all of the PP samples. In PE and PET, these groups were formed only in the bio-solid suspensions. The presence of carbonyl and hydroxyl groups increased with an increasing exposure time. Overall, UV radiation had the greatest impact on the MPs in the bio-solids suspension. Due to the surface-to-volume ratio of the tested samples, which influences the degradation rate, the fibers were more degraded than the other two plastic shapes. UV-A was slightly more effective at degrading the MPs than UV-C. These findings show that ultraviolet radiation in combination with an elevated temperature affects the structure of polymers in wastewater bio-solids, which can accelerate their degradation.

Co-exposure of microplastics and heavy metals in the marine environment and remediation techniques: a comprehensive review

Microplastics (MPs) and heavy metals are significant pollutants in the marine environment, necessitating effective remediation strategies to prevent their release into the sea through sewage and industrial effluent. This comprehensive review explores the current understanding of the co-exposure of MPs and heavy metal-enriched MPs, highlighting the need for effective remediation methods. Various mechanisms, including surface ion complexation, hydrogen bonding, and electrostatic forces, contribute to the adsorption of heavy metals onto MPs, with factors like surface area and environmental exposure duration playing crucial roles. Additionally, biofilm formation on MPs alters their chemical properties, influencing metal adsorption behaviors. Different thermodynamic models are used to explain the adsorption mechanisms of heavy metals on MPs. The adsorption process is influenced by various factors, including the morphological characteristics of MPs, their adsorption capacity, and environmental conditions. Additionally, the desorption of heavy metals from MPs has implications for their bioavailability and poses risks to marine organisms, emphasizing the importance of source reduction and remedial measures. Hybrid approaches that combine both conventional and modern technologies show promise for the efficient removal of MPs and heavy metals from marine environments. This review identifies critical gaps in existing research that should be addressed in future studies including standardized sampling methods to ensure accurate data, further investigation into the specific interactions between MPs and metals, and the development of hybrid technologies at an industrial scale. Overall, this review sheds light on the adsorption and desorption mechanisms of heavy metal-enriched MPs, underscoring the necessity of implementing effective remediation strategies.

Plastic debris, persistent organic pollutants and their toxicity impacts in coastal areas in Central Chile

The chemical components of plastic wastes have made their disposal a major economic, social, and environmental problem worldwide. This study evaluated the acute toxicity and genotoxicity of marine plastic debris on the beaches of Concepción Bay, Central Chile, taken during three periods (spring, summer, and winter). An integrated approach was used, including chemical and toxicological data, using the Microtox® test with Vibrio fischeri and SOS chromotest with Escherichia coli and concentrations of polychlorinated biphenyls (PCBs), Organochlorine Pesticides (OCPs) and polybrominated diphenyl ethers (PBDEs). The results presented here exclusively include the novel data obtained from the winter campaign, revealing high concentrations of PBDEs (238 ± 521 ng g-1). In addition, the genotoxicity and acute toxicity tests were sensitive for most of the samples studied. This investigation is the first attempt to analyse the toxicity of plastic debris in coastal areas along the Chilean coast.

The carrier effect mechanism of butachlor in water by three typical microplastics

Butachlor (BUT) is a widely used herbicide that can cause environmental problems when used excessively. BUT has been found to exist in large quantities in the water environment so far. As an agricultural pre-emergent herbicide, BUT can enter the water environment through multiple channels and cause pollution. This study investigated the mechanism of three types of microplastics (MPs): polyethylene (PE), polypropylene (PP), and polyvinyl chloride (PVC) to remove BUT from water. The adsorption behavior between MPs and BUT under different factors, namely pH, salt ion concentration, and aging, was investigated. This study further investigated the desorption and aging of BUT-adsorbed MPs. In this research, the adsorption capacity of BUT by PE, PP, and PVC are 13.65 μg/g, 14.82 μg/g, and 18.88 μg/g, respectively, and the order of carrier effect was: PVC>PP>PE. Experiments show that MPs have low adsorption performance on the microgram level for BUT. The adsorption behavior of PE, PP, and PVC on BUT conformed to pseudo-second-order kinetics, indicating the presence of physical and chemical adsorption. The Langmuir isotherm model fits well, indicating that the adsorption is a single-layer adsorption process. The pH value causes slight fluctuations in the overall carrier effect. Low concentration of salt ions can inhibit the carrier effect, and high concentration will promote the interaction between MPs and BUT. Aging experiments show that the carrier effect of the original materials was higher than the adsorption capacity of hydrogen peroxide and MPs after acid aging, and acid aging can cause the adsorption capacity to drop significantly.

Effect of Microplastic Types on the In Vivo Bioavailability of Polychlorinated Biphenyls

As MPs are released into the soil, various equilibrium statuses are expected. MPs could play roles as a "source," a "cleaner," or a "sink" of HOCs. Three types of MPs (LDPE, PLA, and PS) were selected to study their effect on polychlorinated biphenyl (PCBs) relative bioavailability (RBA) measured by a mouse model. As a "source" of HOCs, exposure to MP-sorbed PCBs resulted in their accumulation in adipose tissue with PCB RBA as 101 ± 6.73% for LDPE, 76.2 ± 19.2% for PLA, and 9.22 ± 2.02% for PS. The addition of 10% MPs in PCB-contaminated soil led to a significant (p < 0.05) reduction in PCB RBA (52.2 ± 16.7%, 49.3 ± 4.85%, and 47.1 ± 5.99% for LDPE, PLA, and PS) compared to control (75.0 ± 4.26%), implying MPs acted as "cleaner" by adsorbing PCBs from the digestive system and reducing PCB accumulation. MPs acted as a "sink" for PCBs in contaminated soil after aging, but the sink effect varied among MP types with more pronounced effect for LDPE than PLA and PS. Therefore, the role played by MPs in bioavailability of HOCs closely depended on the MP types as well as the equilibrium status among MPs, soil, and HOCs.

Interactive effects of microplastics and benzo[a]pyrene on two species of marine invertebrates

This study aimed to evaluate B[a]P and low-density polyethylene microplastics (MPs) toxicty, alone and in mixture (0.03 to 30 μg L-1 of B[a]P; and 5, 50 and 500 mg L-1 for MPs). Five mg L-1 of MPs is considerably higher than commonly reported environmental concentrations, although it has been reported for marine environments. Individual (sea urchin embryo-larval development and mortality of mysids) and sub-individual responses (LPO and DNA damage in mysids) were assessed. The toxicity increased as the B[a]P concentration increased, and microplastics alone did not cause toxicity. B[a]P toxicity was not modified by the lowest concentration of MPs (5 mg L-1), but at higher MPs concentrations (50 and 500 mg L-1), the effects of B[a]P on sea urchin development and in biomarkers in mysids were diminished. Microplastics interacted with B[a]P in seawater, reducing its toxicity, probably due to adsorption of B[a]P to the surface of microplastics.

The synergetic effects of 4-nonylphenol and polyethylene microplastics in Cyprinus carpio juveniles using blood biomarkers

Microplastics are widely distributed in aquatic ecosystems along with other chemical pollutants. Therefore, it is vital to study the health-hazardous effects of MPs in combination with 4-nonylphenol (4-NP), which is a highly abundant industrial waste and a critical alkylphenol endocrine disruptor. We investigated the effects of the exposure to polyethylene microplastics (PE-MPs), 4-NP, and their combination on blood biomarkers in Cyprinus carpio juveniles. Four study groups were treated for 15 consecutive days: (1) control group, (2) 10 mg/L PE-MP group, (3) 10 mg/L PE-MPs + 200 µg/L 4-NP group, and (4) 200 µg/L 4-NP group, followed by 15 days of recovery. Biochemical analyses showed that creatine kinase, lactate dehydrogenase, glucose, liver enzymes, total protein, and A/G ratios were significantly increased after exposure to PE-MPs, 4-NP, and the combination. Hematological parameters (RBC's, Hb, Ht, neutrophil percentage, and WBC's) were significantly decreased in the three exposure groups, whereas mean corpuscular volume and lymphocyte percentages were significantly increased. The 15-day recovery period improved most hematobiochemical parameters and PE-MP accumulation indices. Taken together, we demonstrated the hazardous effects of PE-MP and 4-NP combinations on C. carpio blood parameters and highlighted their potential risk to human health.

Use of a Dual-Labeled Bioaccumulation Method to Quantify Microplastic Vector Effects for Hydrophobic Organic Contaminants in Soil

Although in vitro simulation and in vivo feeding experiments are commonly used to evaluate the carrier role of microplastics in the bioaccumulation of toxic chemicals, there is no direct method for quantitatively determining their vector effect. In this study, we propose a dual-labeled method based on spiking unlabeled hydrophobic organic contaminants (HOCs) into soils and spiking their respective isotope-labeled reference compounds into microplastic particles. The bioaccumulation of the unlabeled and isotope-labeled HOCs in Eisenia fetida earthworms was compared. Earthworms can assimilate both unlabeled and isotope-labeled HOCs via three routes: dermal uptake, soil ingestion, and microplastic ingestion. After 28 days of exposure, the relative fractions of bioaccumulated isotope-labeled HOCs in the soil treated with 1% microplastics ranged from 15.5 to 55.8%, which were 2.9-47.6 times higher than those in the soils treated with 0.1% microplastics. Polyethylene microplastics were observed to have higher relative fractions of bioaccumulated isotope-labeled HOCs, potentially because of their surface hydrophobicity and amorphous rubbery state. The general linear models suggested that the vector effects were mainly due to the microplastic concentration, followed by polymer properties and HOC hydrophobicity. This proposed method and the derived empirical formula contribute to a more comprehensive understanding of the vector effects of microplastics for HOC bioaccumulation.

Abundance, characteristics, and removal of microplastics in the Cihu Lake-wetland microcosm system

Sewage treatment plants (STPs) are significant routes through which microplastics (MPs) are released into the aquatic environment. Constructed wetland is an effective facility for deep treatment of tailwater. At present, research on the removal of MPs in the tailwater of STPs by multi-stage constructed wetlands is limited. This work investigated and analyzed the removal characteristics of MPs in the tailwater treatment system of Cihu wetland park in Huangshi, Hubei Province of China. The abundance/removal of MPs in the Cihu Lake-wetland microcosm system was investigated. The results showed that the multi-stage constructed wetlands achieved a total removal rate of 94.7% for MPs with 2.2 particles/L MPs in the effluent. The removal rates of MPs reached 89 and 37.5%, respectively, in the (horizontal/vertical) subsurface flow constructed wetland and surface flow constructed wetland. The abundance of MPs in receiving water of Cihu Lake substantially decreased due to the dilution of wetland effluents. This study partially bridged the knowledge gap hypothesis on the treatment of MPs in tailwater by multi-stage constructed wetlands.

Effects of microplastics on the growth, photosynthetic efficiency and nutrient composition in freshwater algae Chlorella vulgaris Beij

Microplastics, plastic particles and fragments smaller than 5 mm are ubiquitous in various aquatic environments, but the hazards of microplastics with different particle sizes, concentrations and materials are not well understood. This study investigated the toxicity of polyethylene microplastics (PE-MPs) with different concentrations and particle sizes or polystyrene microplastics (PS-MPs) on freshwater algae Chlorella vulgaris Beij (C. vulgaris) for 11 days. Results indicated that the growth, colony formation, photosynthetic pigment contents and soluble intracellular polysaccharides were unaffected, whereas the photosynthetic efficiency and the total soluble protein (TSP) contents were remarkably decreased at 11 d with the increased concentration of PE-MP exposure. The growth, photosynthetic efficiency, soluble intracellular polysaccharides and TSP contents were unaffected after exposure to PE-MPs with different particle sizes or PS-MPs. By contrast, the colony formation and photosynthetic pigment contents were remarkably decreased after exposure to PS-MPs compared with the control or PE-MPs with the same particle size. The C. vulgaris colonization on microplastics was proven by scanning electron microscopy, indicating that the adsorption effects were the main harmful pathways of different microplastics to algal. Our results suggested that microplastics have limited harmful effects on algae, mainly in adsorption and shading.

Recent analytical techniques, and potential eco-toxicological impacts of textile fibrous microplastics (FMPs) and associated contaminates: A review

Despite of our growing understanding of microplastic's implications, research on the effects of fibrous microplastic (FMPs) on the environment is still in its infancy. Some scientists have hypothesized the possibility of natural textile fibres, which may act as one of the emerging environmental pollutants prevalent among microplastic pollutants in the environment. Therefore, this review aims to critically evaluate the toxic effects of emerging FMPs, the presence, and sources of FMPs in the environment, identification and analytical techniques, and the potential impact or toxicity of the FMPs on the environment and human health. About175 publications (2011-2023) based on FMPs were identified and critically reviewed for transportation, analysis and ecotoxicological behaviours of FMPs in the environment. Textile industries, wastewater treatment plants, and household washing of clothes are significant sources of FMPs. In addition, various characterization techniques (e.g., FTIR, SEM, RAMAN, TGA, microscope, and X-Ray Fluorescence Spectroscopy) commonly used for the identification and analysis of FMPs are also discussed, which justifies the novelty aspects of this review. FMPs are pollutants of emerging concern due to their prevalence and persistence in the environment. FMPs are also found in the food chain, which is an alarming situation for living organisms, including effects on the nervous system, digestive system, circulatory system, and genetic alteration. This review will provide readers with a comparison of different analytical techniques, which will be helpful for researchers to select the appropriate analytical techniques for their study and enhance their knowledge about the harmful effects of FMPs.

Liquid Crystals as Multifunctional Interfaces for Trapping and Characterizing Colloidal Microplastics

Identifying and removing microplastics (MPs) from the environment is a global challenge. This study explores how the colloidal fraction of MPs assemble into distinct 2D patterns at aqueous interfaces of liquid crystal (LC) films with the goal of developing surface-sensitive methods for identifying MPs. Polyethylene (PE) and polystyrene (PS) microparticles are measured to exhibit distinct aggregation patterns, with addition of anionic surfactant amplifying differences in PS/PE aggregation patterns: PS changes from a linear chain-like morphology to a singly dispersed state with increasing surfactant concentration whereas PE forms dense clusters at all surfactant concentrations. Statistical analysis of assembly patterns using deep learning image recognition models yields accurate classification, with feature importance analysis confirming that dense, multibranched assemblies are unique features of PE relative to PS. Microscopic characterization of LC ordering at the microparticle surfaces leads to predict LC-mediated interactions (due to elastic strain) with a dipolar symmetry, a prediction consistent with the interfacial organization of PS but not PE. Further analysis leads to conclude that PE microparticles, due to their polycrystalline nature, possess rough surfaces that lead to weak LC elastic interactions and enhanced capillary forces. Overall, the results highlight the potential utility of LC interfaces for rapid identification of colloidal MPs based on their surface properties.

Bioaccumulation and metabolism of polybrominated diphenyl ethers (PBDEs) in coenobitid hermit crabs from marine litter-polluted beaches in remote islands

Plastic litter containing additives is potentially a major source of chemical contamination in remote areas. We investigated polybrominated diphenyl ethers (PBDEs) and microplastics in crustaceans and sand from beaches with high and low litter volumes on remote islands that were relatively free of other anthropogenic contaminants. Significant numbers of microplastics in the digestive tracts, and sporadically higher concentrations of rare congeners of PBDEs in the hepatopancreases were observed in coenobitid hermit crabs from the polluted beaches than in those from the control beaches. PBDEs and microplastics were detected in high amounts in one contaminated beach sand sample, but not in other beaches. Using BDE209 exposure experiments, similar debrominated products of BDE209 in field samples were detected in the hermit crabs. The results showed that when hermit crabs ingest microplastics containing BDE209, BDE209 leaches out and migrates to other tissues where it is metabolized.

Changes in metabolic profiles of amphipods Allorchestes compressa after acute exposures to copper, pyrene, and their mixtures

Amphipods are ideal indicators for biomonitoring and ecotoxicological studies of environmental contaminants because they are extensively distributed in aquatic environments, are easy to collect and are important in nutrient cycling. Marine amphipods (Allorchestes compressa) were exposed to two concentrations of copper and pyrene, and their mixtures, for 24 and 48 h. Changes in polar metabolites were assessed using Gas Chromatography Mass Spectrometry (GC-MS)-based untargeted metabolomics. Generally, limited metabolite changes were observed for copper and pyrene single exposures (eight and two significant metabolites, respectively), while 28 metabolites had changed following exposures to mixtures. Furthermore, changes were mainly observed after 24 h but had seemingly returned to control levels after 48 h. Multiple types of metabolites were affected including amino acids, Tricarboxylic acid (TCA) cycle intermediates, sugars, fatty acids, and hormones. This study highlights the sensitivity of metabolomics in assessing the impacts of low concentrations of chemicals compared to traditional ecotoxicological endpoints.

A review of microplastic pollution in commercial fish for human consumption

Today microplastics (MPs) have received worldwide attention as an emerging environmental pollution which is one of the four major global environmental threat and health hazard to human as well. Unfortunately, MPs have been founded in the all environments and media include air, water resources, sediments, and soil. It should not be forgotten MPs have also been detected in food and processing products like tuna. MPs can be ingested by marine organisms such as zooplankton, fish and birds. Accumulation and distribution of MPs by commercially important aquatic organisms is expected to lead to greater exposure risk for human populations with possible adverse effects over time. The aim of this work was to review the published literature regarding the contamination of commercial fish muscle for human consumption. Furthermore, a short revision of the environmental contamination and human health effects by MPs are included. We also estimated human daily intake considering the worldwide contamination of commercial fish muscle ranged from 0.016 items/g muscle of fish to 6.06 items/g muscle of fish. MPs have been found in 56.5% of the commercial fish samples analysed here. As fish is used in human food table across the word, they constitute a long-term exposure route for all humans and raise the concern about the potential public health risk.

Microplastics (MPs) in marine food chains: Is it a food safety issue?

The enormous usage of plastic over the last seven decades has resulted in a massive quantity of plastic waste, much of it eventually breaking down into microplastic (MP) and nano plastic (NP). The MPs and NPs are regarded as emerging pollutants of serious concern. Both MPs and NPs can have a primary or secondary origin. Their ubiquitous presence and ability to sorb, desorb, and leach chemicals have raised concern over their presence in the aquatic environment and, particularly, the marine food chain. MPs and NPs are also considered vectors for pollutant transfer along with the marine food chain, and people who consume seafood have began significant concerns about the toxicity of seafood. The exact consequences and risk of MP exposure to marine foods are largely unknown and should be a priority research area. Although several studies have documented an effective clearance mechanism by defecation, significant aspect has been less emphasized for MPs and NPs and their capability to translocate in organs and clearance is not well established. The technological limitations to study these ultra-fine MPs are another challenge to be addressed. Therefore, this chapter discusses the recent findings of MPs in different marine food chains, their translocation and accumulations potential, MPs as a critical vector for pollutant transfer, toxicology impact, cycling in the marine environment and seafood safety. Besides, the concerns and challenges that are overshadowed by findings for the significance of MPs were covered.

Abundance and characterization of microplastics in amphipods from the Japanese coastal environment

Microplastics can be ingested by tiny detritivores such as amphipods, with potential consequences on the food chain. The present study characterizes the abundance, chemical composition, and size of microplastics in amphipods found in the Japan Sea coastal environment, which is a hotspot for microplastic accumulation. High amounts of microplastic ingestion and a large discrepancy by amphipod species, Talorchestia nipponensis, Ampithoe valida, and Trinorchestia trinitatis, were observed (between 0.2 and 76.3 particles/individual) which may be due to differences in habitat preference and background contamination. This result indicates that coastal amphipods in particular may ingest large amounts of microplastics. The average microplastic particle size in amphipods was 59 ± 8.6 µm, with 83% of particles smaller than 90 µm, and polyethylene was dominant. This study provides insights into microplastic abundance in coastal amphipods and the context for further studies on coastal amphipod microplastic ingestion.

A Systematic Review of Nano- and Microplastic (NMP) Influence on the Bioaccumulation of Environmental Contaminants: Part I-Soil Organisms

Nano- and microplastics (NMPs) are a group of contaminants that cause concern due to their abundance in the environment, high persistence, and interaction with other contaminants. This review aims to understand the role of NMP in the bioaccumulation of environmental contaminants. For that, a comprehensive literature search was conducted to identify publications that compared the uptake of contaminants in the presence and absence of NMP. In this part I, twenty-eight publications of the terrestrial compartment were analyzed. Two main taxonomic groups were studied, namely, earthworms and terrestrial plants. In earthworms, most studies observed an increase in the bioaccumulation of the contaminants, while in plants, most studies observed a decrease in the bioaccumulation. Changes in bioavailable fractions of contaminants due to NMP presence was the main reason pointed out by the authors for their outcomes. Moreover, biological aspects were also found to be important in defining how NMPs affect bioaccumulation. Dermal damage and changes in contaminant-degrading bacteria in the gut of earthworms caused an increase in bioaccumulation, and root pore blockage was a common reason for the decrease in the bioaccumulation of contaminants in plants. Nevertheless, such effects were mainly observed at high, unrealistic NMP concentrations. Finally, knowledge gaps were identified, and the limitations of this systematic review were presented.

Caenorhabditis elegans: a model organism in the toxicity assessment of environmental pollutants

The unfavorable effects of environmental pollutants are becoming increasingly evident. In recent years, Caenorhabditis elegans (C. elegans) has been used as a powerful terrestrial model organism for environmental toxicity studies owing to its various advantages, including ease of culture, short lifespan, small size, transparent body, and well-characterized genome. In vivo bioassays and field studies can analyze and evaluate various toxic effects of the toxicants on the model organism, while emerging technologies allow profound insights into molecular disturbances underlying the observed phenotypes. In this review, we discuss the applications of C. elegans as a model organism in environmental toxicity studies and delineate apical assays such as lifespan, growth rate, reproduction, and locomotion, which are widely used in toxicity evaluation. In addition to phenotype assays, a comprehensive understanding of the toxic mode of action and mechanism can be achieved through a highly sensitive multi-omics approach, including the expression levels of genes and endogenous metabolites. Recent studies on environmental toxicity using these approaches have been summarized. This review highlights the practicality and advantages of C. elegans in evaluating the toxicity of environmental pollutants and presents the findings of recent toxicity studies performed using this model organism. Finally, we propose crucial technical considerations to escalate the appropriate use of C. elegans in examining the toxic effects of environmental pollutants.

From marine to freshwater environment: A review of the ecotoxicological effects of microplastics

Microplastics (MPs) have been widely detected in the world's water, which may pose a significant threat to the ecosystem as a whole and have been a subject of much attention because their presence impacts seas, lakes, rivers, and even the Polar Regions. There have been numerous studies that report direct adverse effects on marine organisms, but only a few have explored their ecological effects on freshwater organisms. In this field, there is still a lack of a systematic overview of the toxic effects and mechanisms of MPs on aquatic organisms, as well as a consistent understanding of the potential ecological consequences. This review describes the fate and impact on marine and freshwater aquatic organisms. Further, we examine the toxicology of MPs in order to uncover the relationship between aquatic organism responses to MPs and ecological disorders. In addition, an overview of the factors that may affect the toxicity effects of MPs on aquatic organisms was presented along with a brief examination of their identification and characterization. MPs were discussed in terms of their physicochemical properties in relation to their toxicological concerns regarding their bioavailability and environmental impact. This paper focuses on the progress of the toxicological studies of MPs on aquatic organisms (bacteria, algae, Daphnia, and fish, etc.) of different trophic levels, and explores its toxic mechanism, such as behavioral alternations, metabolism disorders, immune response, and poses a threat to the composition and stability of the ecosystem. We also review the main factors affecting the toxicity of MPs to aquatic organisms, including direct factors (polymer types, sizes, shapes, surface chemistry, etc.) and indirect factors (persistent organic pollutants, heavy metal ions, additives, and monomer, etc.), and the future research trends of MPs ecotoxicology are also pointed out. The findings of this study will be helpful in guiding future marine and freshwater rubbish studies and management strategies.

Total organic carbon content as an index to estimate the sorption capacity of micro- and nano-plastics for hydrophobic organic contaminants

The worldwide existing micro- and nano-plastics (MNPs) showed high sorption capacity for hydrophobic organic contaminants (HOCs), and thus leading to change of the environmental behaviors and fates of HOCs. However, there is a lack of general index for evaluating the sorption capacity of MNPs for HOCs. Herein, we investigated the sorption of chlorobenzene, naphthalene and phenanthrene to 10 MNPs of different polymer types with and without UV-aging, respectively. It was found that the sorption was well fitted by Freundlich isotherm model with coefficients R² in the range of 0.892-1.00, and aging of most MNPs resulted in decreased sorption capacity for naphthalene and phenanthrene but slightly increased sorption capacity for chlorobenzene. More importantly, for the 8 MNPs commonly present in the environment and with measured total organic carbon (TOC) covering the range of 23.0-91.9%, the logarithm sorption constant (logK_d) values of the studied HOCs positively correlated with TOC contents of MNPs, with a good determination coefficient (R²) of 0.923 for naphthalene, 0.694 for chlorobenzene, and 0.565 for phenanthrene. Our study demonstrated that the TOC content of MNPs is a good index for estimating the contribution of total MNPs to the sorption of nonpolar HOCs in the environmental media.

Microplastics: A Real Global Threat for Environment and Food Safety: A State of the Art Review

Microplastics are small plastic particles that come from the degradation of plastics, ubiquitous in nature and therefore affect both wildlife and humans. They have been detected in many marine species, but also in drinking water and in numerous foods, such as salt, honey and marine organisms. Exposure to microplastics can also occur through inhaled air. Data from animal studies have shown that once absorbed, plastic micro- and nanoparticles can distribute to the liver, spleen, heart, lungs, thymus, reproductive organs, kidneys and even the brain (crosses the blood-brain barrier). In addition, microplastics are transport operators of persistent organic pollutants or heavy metals from invertebrate organisms to other higher trophic levels. After ingestion, the additives and monomers in their composition can interfere with important biological processes in the human body and can cause disruption of the endocrine, immune system; can have a negative impact on mobility, reproduction and development; and can cause carcinogenesis. The pandemic caused by COVID-19 has affected not only human health and national economies but also the environment, due to the large volume of waste in the form of discarded personal protective equipment. The remarkable increase in global use of face masks, which mainly contain polypropylene, and poor waste management have led to worsening microplastic pollution, and the long-term consequences can be extremely devastating if urgent action is not taken.

Impact of face mask microplastics pollution on the aquatic environment and aquaculture organisms

Microplastic pollution in our environment, especially water bodies is an emerging threat to food security and human health. Inevitably, the outbreak of Covid-19 has necessitated the constant use of face masks made from polymers such as polypropylene, polyurethane, polyacrylonitrile, polystyrene, polycarbonate, polyethylene, or polyester which eventually will disintegrate into microplastic particles. They can be broken down into microplastics by the weathering action of UV radiation from the sun, heat, or ocean wave-current and precipitate in natural environments. The global adoption of face masks as a preventive measure to curb the spread of Covid-19 has made the safe management of wastes from it cumbersome. Microplastics gain access into aquaculture facilities through water sources and food including planktons. The negative impacts of microplastics on aquaculture cannot be overemphasized. The impacts includes low growth rates of animals, hindered reproductive functions, neurotoxicity, low feeding habit, oxidative stress, reduced metabolic rate, and increased mortality rate among aquatic organisms. With these, there is every tendency of microplastic pollution to negatively impact fish production through aquaculture if the menace is not curbed. It is therefore recommended that biodegradable materials rather than plastics to be considered in the production of face mask while recycle of already produced ones should be encouraged to reduce waste.

Accumulation of microplastics and Tcep pollutants in agricultural soil: Exploring the links between metabolites and gut microbiota in earthworm homeostasis

Agricultural soil contamination with plastic film has become a critical global environmental problem, requiring greater research on the possible occurrence and biological risk of microplastics (MPs) and their additives in soil ecosystems. The presence of MPs and tris (2-chloroethyl) phosphate (Tcep) in agricultural soil was investigated at nine sites in the present study. Polyethylene MPs (PE-MPs) and Tcep were found at all nine sites. To study co-exposure effects on soil microbiota and earthworms, and to mimic a realistic exposure scenario, 0.05 % (w/w) PE-MPs with three particle size ranges were combined with Tcep (1.0 mg/kg). After 28 days of exposure, there was no indication that added PE-MPs and/or Tcep significantly affected the soil microbial community structure. In earthworms, size-selective intake, digestion and egestion of PE-MPs may occur, with Tcep co-exposure affecting the residual Tcep concentration in earthworm intestines (3.52-9.31 μg/g dw). Long-term earthworm PE-MPs intake caused intestinal damage, and Tcep co-exposure increased oxidative stress, thereby influencing their feeding behavior and growth, resulting in weight loss (3.42 %-14.96 %), especially for the most common PE-MPs sizes (0-300 μm). High performance liquid chromatography-mass spectrometry (LC-MS) was used for metabolomic analysis, revealing the significant up-regulation of citrate (p < 0.001) and down-regulation of l-glutamate (p < 0.05) in co-exposure groups. Co-exposure resulted in the alteration of most metabolic pathways, thereby impairing nervous, digestive and excretory systems in the earthworm, with an associated decrease in amino acid metabolism and changes in tricarboxylic acid (TCA) cycle intermediates. Gut microbiota, such as Proteobacteria (Verminephrobacter and Bradyrhizobium) and Firmicutes (Bacillus), are critically important in maintaining earthworm metabolic homeostasis, particularly for the TCA cycle and amino acid metabolism. Overall, MPs and Tcep co-exposure in agricultural soil enhanced their toxicity to earthworms and may potentially endanger the development of agricultural sustainability.

Adsorption of pesticides and personal care products on pristine and weathered microplastics in the marine environment. Comparison between bio-based and conventional plastics

The hydrophobicity of persistent organic pollutants (POPs) makes them adsorb on microplastics in the marine environment, affecting their distribution, persistence, or their transfer to the trophic chain. Fragrances and non-polar pesticides can be adsorbed by microplastics in the marine environment because of their physico-chemical characteristics. In this work, the adsorption of two pesticides (α-endosulfan and chlorpyrifos) and 6 musk fragrances (musk xylene, musk ketone, musk moskene, galaxolide, tonalide, and celestolide) on polyamide (PA6) (a petroleum based polymer) and on polyhydroxybutyrate (PHB) (biopolymer) in seawater was studied, considering also the effect of water temperature and plastic weathering. Results show higher adsorption of the selected pollutants for PHB than PA, being PA more affected by the water temperature and the plastic weathering. The highest percentage of adsorption was achieved in most cases at 24 h. In addition, this process was irreversible, as it showed the leaching assays. Besides, this work revealed that plastics mitigate the degradation of α-endosulfan in aquatic media (hydrolysis), showing that plastics can act as inhibitors of degradation of POPs, increasing its persistence in the environment.

Review on the ecotoxicological impacts of plastic pollution on the freshwater invertebrate Daphnia

The environmental impacts of plastic pollution have recently attracted universal attention, especially in the aquatic environment. However, research has mostly been focused on marine ecosystems, even though freshwater ecosystems are equally if not more polluted by plastics. In addition, the mechanism and extent to which plastic pollution affects aquatic biota and the rates of transfer to organisms through food webs eventually reaching humans are poorly understood, especially considering leaching hazardous chemicals. Several studies have demonstrated extreme toxicity in freshwater organisms such Daphnia. When such keystone species are affected by ambient pollution, entire food webs are destabilized and biodiversity is threatened. The unremitting increase in plastic contaminants in freshwater environments would cause impairments in ecosystem functions and structure, leading to various kinds of negative ecological consequences. As various studies have reported the effects on daphnids, a consolidation of this literature is critical to discuss the limitations and knowledge gaps and to evaluate the risk posed to the aquatic environment. This review was undertaken due to the evident need to evaluate this threat. The aims were to provide a meaningful overview of the literature relevant to the potential impact of plastic pollution and associated contaminants on freshwater daphnids as primary consumers. A critical evaluation of research gaps and perspectives is conducted to provide a comprehensive risk assessment of microplastic as a hazard to aquatic environments. We outlined the challenges and limitations to microplastic research in hampering better-focused investigations that could support the development of new plastic materials and/or establishment of new regulations.

Entrainment and vertical mixing of aquatic microplastics in turbulent flow: The coupled role of particle size and density

Diversity in microplastics' characteristics, including their size, affects their transport and distribution in aquatic systems. Furthermore, turbulent induced mixing is often considered dominant in the dispersion of sediments and contaminants in marine and freshwater systems, which is also affected by particle size. The aim of this study is to investigate the effect of microplastics' size and polymer density on their mixing behaviour in response to turbulent structures. Using sediment analogy, several parameters are defined to describe entrainment patterns of microplastic particles of common polymers. Our results indicate that the level of mixing of microplastics in turbulent flow can vary several orders of magnitude. While large particles' vertical motion may be dominated by gravitational settling or rising, the motion of fine microplastics is mainly governed by the ambient turbulent flow. Our findings provide a plausible explanation for the presence of fine microplastics in remote areas.

Polyvinyl Chloride Microplastics Leach Phthalates into the Aquatic Environment over Decades

Phthalic acid esters (phthalates) have been detected everywhere in the environment, but data on leaching kinetics and the governing mass transfer process into aqueous systems remain largely unknown. In this study, we experimentally determined time-dependent leaching curves for three phthalates di(2-ethylhexyl) phthalate, di(2-ethylhexyl) terephthalate, and diisononyl phthalate from polyvinyl chloride (PVC) microplastics and thereby enabled a better understanding of their leaching kinetics. This is essential for exposure assessment and to predict microplastic-bound environmental concentrations of phthalates. Leaching curves were analyzed using models for intraparticle diffusion (IPD) and aqueous boundary layer diffusion (ABLD). We show that ABLD is the governing diffusion process for the continuous leaching of phthalates because phthalates are very hydrophobic (partitioning coefficients between PVC and water log K_PVC/W were higher than 8.6), slowing down the diffusion through the ABL. Also, the diffusion coefficient in the polymer D_PVC is relatively high (∼8 × 10^-14 m² s^-1) and thus enhances IPD. Desorption half-lives of the studied PVC microplastics are greater than 500 years but can be strongly influenced by environmental factors. By combining leaching experiments and modeling, our results reveal that PVC microplastics are a long-term source of phthalates in the environment.

Coagulation and Flocculation before Primary Clarification as Efficient Solutions for Low-Density Microplastic Removal from Wastewater

Microplastic (MP) removal from wastewater was investigated using various types and doses of commercial coagulants (PIX, PAX) and flocculants (FPM, PEL, FCT) before primary clarification in a wastewater treatment plant (WWTP). Dosing with FPM, PIX, and PEL caused small MPs (180-212 µm) to be transferred mainly to the settled sludge (up to 86.4% of MP at a dose of 5 mL FMP/m³), while dosing of FCT and PAX caused these MPs to be transferred to the floated sludge (up to 64% MP at a dose of 5 mL PAX/m³). The efficiency of MP removal from wastewater was the highest (90%) with 2.5 mL PAX/m³; the generated primary sludge had a low MP content and could be safely managed in subsequent stages of sludge treatment. At the highest doses, PIX significantly increased the removal of P-PO₄ (up to 94%) and COD (up to 73%). FPM and FCT resulted in over 40% efficiency of ammonium removal-such disturbance in wastewater composition may negatively affect further biological treatment. Effective removal of MP in the mechanical part of WWTP resulting from coagulation and flocculation enables the safe use of the excess sludge for agricultural purposes.

Interactions of Ingested Polystyrene Microplastics with Heavy Metals (Cadmium or Silver) as Environmental Pollutants: A Comprehensive In Vivo Study Using Drosophila melanogaster

Living organisms are now constantly exposed to microplastics and nanoplastics (MNPLs), and besides their toxic potential, they can also act as carriers of various hazardous elements such as heavy metals. Therefore, this study explored possible interactions between polystyrene microplastics (PSMPLs) and two metal pollutants: cadmium chloride (CdCl₂) and silver nitrate (AgNO₃). To better understand the extent of biological effects caused by different sizes of PSMPLs, we conducted in vivo experiments with five doses (from 0.01 to 10 mM) that contained polystyrene particles measuring 4, 10, and 20 µm in size on Drosophila larvae. Additional experiments were performed by exposing larvae to two individual metals, CdCl₂ (0.5 mM) and AgNO₃ (0.5 mM), as well as combined exposure to PSMPLs (0.01 and 10 mM) and these metals, in an attempt to gain new insight into health risks of such co-exposure. Using transmission electron microscopy imaging, we managed to visualize the biodistribution of ingested PSMPLs throughout the fly's body, observing the interactions of such plastics with Drosophila intestinal lumen, cellular uptake by gut enterocytes, the passage of plastic particles through the intestinal barrier to leak into the hemolymph, and cellular uptake by hemocytes. Observations detected size and shape changes in the ingested PSMPLs. Egg-to-adult viability screening revealed no significant toxicity upon exposure to individual doses of tested materials; however, the combined exposure to plastic and metal particles induced aggravated genotoxic effects, including intestinal damage, genetic damage, and intracellular oxidative stress (ROS generation), with smaller sized plastic particles + metals (cadmium and silver) causing greater damage.

Ecotoxic effects of microplastics and contaminated microplastics - Emerging evidence and perspective

The high prevalence and persistence of microplastics (MPs) in pristine habitats along with their accumulation across environmental compartments globally, has become a matter of grave concern. The resilience conferred to MPs using the material engineering approaches for outperforming other materials has become key to the challenge that they now represent. The characteristics that make MPs hazardous are their micro to nano scale dimensions, surface varied wettability and often hydrophobicity, leading to non-biodegradability. In addition, MPs exhibit a strong tendency to bind to other contaminants along with the ability to sustain extreme chemical conditions thus increasing their residence time in the environment. Adsorption of these co-contaminants leads to modification in toxicity varying from additive, synergistic, and sometimes antagonistic, having consequences on flora, fauna, and ultimately the end of the food chain, human health. The resulting environmental fate and associated risks of MPs, therefore greatly depend upon their complex interactions with the co-contaminants and the nature of the environment in which they reside. Net outcomes of such complex interactions vary with core characteristics of MPs, the properties of co-contaminants and the abiotic factors, and are required to be better understood to minimize the inherent risks. Toxicity assays addressing these concerns should be ecologically relevant, assessing the impacts at different levels of biological organization to develop an environmental perspective. This review analyzed and evaluated 171 studies to present research status on MP toxicity. This analysis supported the identification and development of research gaps and recommended priority areas of research, accounting for disproportionate risks faced by different countries. An ecological perspective is also developed on the environmental toxicity of contaminated MPs in the light of multi-variant stressors and directions are provided to conduct an ecologically relevant risk assessment. The presented analyses will also serve as a foundation for developing environmentally appropriate remediation methods and evaluation frameworks.

The legacy effect of microplastics on aquatic animals in the depuration phase: Kinetic characteristics and recovery potential

The prevalence of microplastics (MPs) in global aquatic environments has received considerable attention. Currently, concerns have been raised regarding reports that the adverse effect of MPs on aquatic animals in the exposure phase may not be (completely) reversed in the depuration phase. In order to provide insights into the legacy effect of MPs from the depuration phase, this study evaluated the kinetic characteristics and recovery potential of aquatic animals after the exposure to MPs. More specifically, a total of 68 depuration kinetic curves were highly fitted to estimate the retention time of MPs. It was shown that the retention time ranged from 1.26 to 3.01 days, corresponding to the egestion of 90 % to 99 % of ingested MPs. The retention time decreased with the increased retention rate. Furthermore, variables potentially affecting the retention time were ranked by the decision tree-based eXtreme Gradient Boosting (XGBoost) algorithm, suggesting that the particle size and tested species were of great importance for explaining the difference in retention time of MPs. Moreover, a biomarker profile was recompiled to determine the toxic changes. Results indicated that the MPs-induced toxicity significantly reduced in the depuration phase, evidenced by the recovery of energy reserves and metabolism, hepatotoxicity, immunotoxicity, hematological parameters, neurotoxicity and oxidative stress. However, the continuous detoxification and remarkable genotoxicity implied that the toxicity was not completely alleviated. In addition, the current knowledge gaps are also highlighted, with recommendations proposed for future research.

Influence of microplastics on triclosan bioaccumulation and metabolomics variation in Tilapia fish tissues

Microplastics (MPs) and chemical pollutants usually coexist in aquatic environments. The bioaccumulation and metabolism of pollutants in aquatic organisms can be influenced by MPs. In this study, the bioaccumulation of triclosan (TCS) in tilapia tissues was determined, and metabolomics in the liver, gills, and gut were investigated after 10-day exposure to micro-sized polystyrene (PS) and TCS in water. The results showed that TCS bioaccumulated in various tissues, with the highest average concentration of 2728 ± 577 ng g^-1 in the gut. The log bioaccumulation factors (BAFs) for TCS in these tissues were in the range of 0.99-3.56. Compared to the TCS treatment alone, MPs showed enhancement on the bioaccumulation of TCS in tilapia skin, liver, gut, gills, and stomach tissues in the TCS plus MP exposure. Especially in the skin and liver, the TCS concentrations were up to 2.06 and 1.38 times higher in the co-exposure of TCS and MPs, respectively. Based on the metabolomic analysis, MPs mainly disturbed the lipid and energy metabolism in tilapia fish. The altered metabolites between treatment with TCS alone and TCS + MPs were consistent, indicating that TCS has stronger disturbance in lipid and energy metabolism than MPs. This implies that the metabolism influence by the mixture of MPs and compounds is complicated in fish tissues.

Recent advances in the breakdown of microplastics: strategies and future prospectives

Microplastics pollution is becoming a major environmental issue, and exposure to microplastics has been associated with numerous adverse results to both the ecological system and humans. This work summarized the state-of-the-art developments in the breakdown of microplastics, including natural weathering, catalysts-assisted breakdown and biodegradation. Characterization techniques for microplastic breakdown involve scanning electron microscopy, Fourier infrared spectroscopy, X-ray photoelectron spectroscopy, etc. Bioavailability and adsorption capacity of microplastics may change after they are broken down, therefore leading to variety in microplastics toxicity. Further prospectives for should be focused on the determination and toxicity evaluation of microplastics breakdown products, as well as unraveling uncultivable microplastics degraders via cultivation-independent approaches. This work benefits researchers interested in environmental studies, particularly the removal of microplastics from environmental matrix.

The ecotoxicological consequences of microplastics and co-contaminants in aquatic organisms: a mini-review

Microplastics (MPs, <5 mm in size) are a grave environmental concern. They are a ubiquitous persistent pollutant group that has reached into all parts of the environment - from the highest mountain tops to the depths of the ocean. During their production, plastics have added to them numerous chemicals in the form of plasticizers, colorants, fillers and stabilizers, some of which have known toxicity to biota. When released into the environments, MPs are also likely to encounter chemical contaminants, including hydrophobic organic contaminants, trace metals and pharmaceuticals, which can sorb to plastic surfaces. Additionally, MPs have been shown to be ingested by a wide range of organisms and it is this combination of ingestion and chemical association that gives weight to the notion that MPs may impact the bioavailability and toxicity of both endogenous and exogenous co-contaminants. In this mini-review, we set the recent literature within what has been previously published about MPs as chemical carriers to biota, with particular focus on aquatic invertebrates and fish. We then present a critical viewpoint on the validity of laboratory-to-field extrapolations in this area. Lastly, we highlight the expanding 'microplastic universe' with the addition of anthropogenic particles that have gained recent attention, namely, tire wear particles, nanoplastics and, bio-based or biodegradable MPs, and highlight the need for future research in their potential roles as vehicles of co-contaminant transfer.

Effects of nano- and microplastics on the bioaccumulation and distribution of phenanthrene in the soil feeding earthworm Metaphire guillelmi

Microplastics (MPs) and nanoplastics (NPs), are collectively referred to as fine plastic particles (FPs), have been reported for both the "vector" effect and "dilution" effect which alters the bioaccumulation of organic contaminants. However, which effect plays a dominant role, especially in terrestrial ecosystems, remains unknown. In the present study, we used ¹⁴C-radioactive labeling tracing technique to assess the sorption of a typical polycyclic aromatic hydrocarbon, phenanthrene on soil particles and FPs, as well as the contribution of vector effects of FPs on the bioaccumulation and distribution of phenanthrene by the geophagous earthworm Metaphire guillelmi. The results showed that the presence of FPs in soil decreased the bioaccumulation of ¹⁴C-Phenanthrene in M. guillelmi by decreasing the bioavailable fraction of phenanthrene in soil, and the decreasing effect was more dramatic for NPs treatments. In all cases, bioaccumulation of ¹⁴C-Phenanthrene in M. guillelmi was still determined by the free concentration of ¹⁴C-Phenanthrene in soil and limited vector effects was observed. Moreover, the different correlation coefficients between the free concentration of ¹⁴C-Phe in two soils and bioaccumulated ¹⁴C-Phenanthrene in earthworms indicated that soil properties remained a dominant factor that determines the bioaccumulation efficiency of ¹⁴C-Phenanthrene in the FPs-soil system. Although the total ¹⁴C-Phenanthrene bioaccumulation in earthworms did not increase, vector effects may be responsible for the increased relative distribution of ¹⁴C-phenanthrene in the organ region, compared with skin and gut regions, leading to unknown risks to organs that are sensitive to these contaminants.

The exposure to polyvinyl chloride microplastics and chrysene induces multiple changes in the structure and functionality of marine meiobenthic communities

The effects of microplastics and sorbed polycyclic aromatic hydrocarbons at community levels were rarely assessed in laboratory experiments, despite their obvious advantage in reflecting better the natural conditions compared to traditionally single species-focused toxicological experiments. In the current study, the multifaceted effects of polyvinyl chloride and chrysene, acting alone or combined, on general marine meiobenthos, but with a special focus on free-living marine nematode communities were tested in a laboratory experiment carried in microcosms. The meiobenthos was exposed to two polyvinyl chloride (5 and 10 mg.kg^-1 Dry Weight 'DW') and chrysene (37.5 and 75 ng.g^-1 DW) concentrations, respectively, as well as to a mixture of both compounds, for 30 days. The results highlighted a significant decrease in the abundance of all meiobenthic generic groups, including nematodes, directly with increasing dosages of these compounds when added alone. The addition of chrysene adheres to microplastics, making the sediment matrix glueyer, hence inducing greater mortality among generic meiobenthic groups. Moreover, the nematofauna went through a strong restructuring phase following the exposure to both compounds when added alone, leading to the disappearance of sensitive nematodes and their replacement with tolerant taxa. However, the similarity in nematofauna composition between control and polyvinyl chloride and chrysene mixtures suggests that the toxicity of the latter could be attenuated by its physical bonding to the former pollutant. Other changes in the functional traits within the nematode communities were a decline in the fertility of females and an increase of the pharyngeal pumping power following exposure to both pollutants for the dominant species. The latter results were also supported by additional toxicokinetics analyses and in silico modeling.