Adverse effects of microplastics and oxidative stress-induced MAPK/Nrf2 pathway-mediated defense mechanisms in the marine copepod Paracyclopina nana

Exposure to polystyrene microplastics induced gene modulated biological responses in zebrafish (Danio rerio)

The substantial increase in the occurrence of microplastics (MPs) in the aquatic ecosystem has been recognized as an emerging concern today. Studies have revealed the toxicity of microplastics on behavior, physiology, and reproduction of fishes. Despite several reports, there are inadequate literature reports on the impact of microplastics on aquatic forms at the molecular level. The present study was aimed to investigate the adverse effects of polystyrene microplastics (PS-MPs) in adult zebrafish model system. Healthy fishes were exposed to different concentrations (10 and 100 μg L^-1) of PS-MPs for 35 d. The results revealed that PS-MPs exposure induced ROS (Reactive oxygen species) generation disrupting the antioxidant defense system, hepatic enzymology, and neurotransmission. Correspondingly, the histological studies showed PS-MPs induced histopathological lesions, including inflammation, degeneration, necrosis, and hemorrhage, in the brain and liver tissues of zebrafish. Furthermore, PS-MPs exposure significantly upregulated the expressions of gstp1, hsp70l, and ptgs2a gene along with the downregulation of cat, sod1, gpx1a, and ache genes. Therefore, the present study illustrates the potential of PS-MPs to induce different grades of toxic impacts in fishes by altering its metabolic mechanism, histological architecture, and gene regulation pattern through ROS induced oxidative stress.

Glutathione S-Transferases in Marine Copepods

The glutathione S-transferase (GST) is a complex family of phase II detoxification enzymes, known for their ability to catalyze the conjugation of the reduced form of glutathione (GSH) to a wide variety of endogenous and exogenous electrophilic compounds for detoxification purposes. In marine environments, copepods are constantly exposed to multiple exogenous stressors, thus their capability of detoxification is key for survival. Full identification of the GST family in copepods has been limited only to few species. As for insects, the GST family includes a wide range of genes that, based on their cellular localization, can be divided in three classes: cytosolic, microsomal, and mitochondrial. The role of GSTs might have class-specific features, thus understanding the nature of the GST family has become crucial. This paper covers information of the GST activity in marine copepods based on studies investigating gene expression, protein content, and enzymatic activity. Using published literature and mining new publicly available transcriptomes, we characterized the multiplicity of the GST family in copepods from different orders and families, highlighting the possible role of these genes as biomarker for ocean health status monitoring.

Toxic effects of acute exposure to polystyrene microplastics and nanoplastics on the model insect, silkworm Bombyx mori

Microplastics and nanoplastics (MPs and NPs, respectively) are major contaminants of environmental concern due to their potentially detrimental effects on aquatic and terrestrial ecosystems. However, little is known about their potential toxicity in terrestrial organisms. Here, we used the model insect silkworm (Bombyx mori) to evaluate the potential hazardous effects of acute exposure (72 h) to polystyrene (PS) MPs and NPs at physiological, molecular, and biochemical levels as well as their impact on pathogen infection. Our results revealed no significant changes in larval body mass or survival. Nevertheless, exposure led to significant alterations in the expression of immunity-related genes (Cecropin A, Lysozyme, SOD, and GST) and antioxidant-mediated protective response (SOD, GST, and CAT enzymes) which differed in the PS-MP and PS-NP groups. Interestingly, PS-MPs induced a stronger immune response (higher expressions of Lysozyme, SOD, and GST genes along with increased activities of SOD, GST, and CAT enzymes) while the PS-NP response was more that of an inhibitory nature (decreased SOD activity and expression). As a result, upon infection with the natural pathogen Serratia marcescens Bm1, the PS-MP-exposed individuals survived the infection better whereas, PS-NP-exposed individuals exhibited significantly higher mortality. Thus, we infer that PS-MPs/NPs present ecological toxicity, which is closely related to their size, and that their exposure may render the organisms vulnerable or confer resistance to pathogen infections and ecotoxicants. Given the suitability of silkworm as a model organism, this study may promote its application for further investigation of the mechanism of adverse outcome pathways and in studies on bio-nano interactions.

Key mechanisms of micro- and nanoplastic (MNP) toxicity across taxonomic groups

Micro- and nanoplastics (MNPs) are ubiquitous in aquatic and terrestrial environments, and detrimental biological effects have been observed on a variety of organisms, from bacteria and alga to plants and animals. A fast-growing number of toxicological studies report diverse responses and wide species-dependent sensitivity upon MNP exposure. While studies are dominated by in vivo animal tests, our understanding of cellular toxicity and the corresponding toxicity mechanisms is still limited. This challenges the proper assessment of environmental hazards and health risks of MNPs. In this review, we gathered and analyzed the up-to-date studies on humans, animals, plants, alga, and bacteria, and identified the similarities and differences in key toxicity mechanisms of MNPs across different taxonomic groups. Particularly, human cell-based studies at the cellular level provide fundamental and valuable information on the key toxicity mechanisms, which are essential to answer the question of whether and how MNPs pose health threats. In general, toxicity mechanisms of MNPs depend on their size, surface characteristics, polymer type, as well as cell type. Plausible toxicity mechanisms mainly include membrane disruption, extracellular polymeric substance disruption, reactive oxygen species generation, DNA damage, cell pore blockage, lysosome destabilization, and mitochondrial depolarization. A deeper understanding of these key mechanisms in different taxonomic groups can also improve both in vivo and in vitro models useful for predictive impact assessments of plastic pollution on the environment and human health.

A Holistic Assessment of Polyethylene Fiber Ingestion in Larval and Juvenile Japanese Medaka Fish

Microplastic pollution is of public concern for global environmental health, aquaculture, and fisheries. Toxicity studies have shown that microplastic ingestion may cause intestinal damage, microbiota dysbiosis, and disturb the lipid and energy metabolism in fish. To determine the impact of environmentally relevant, chronic, low dose microplastic fibers on fish health, medaka larvae, and juveniles were exposed to five concentrations of polyethylene (PE) fibers for 21 days through the feed. Fish growth and condition were assessed to determine the overall impact on fish health. To identify impaired energy intake, the gastrointestinal tract (GIT) integrity was evaluated at the molecular and cellular levels. Microbiota analysis was performed by comparing the top seven most abundant phyla present in both larval and juvenile fish exposed to 0, 1.5, and 3 PE fibers/fish/day. A shift in the phyla Proteobacteria and Bacteroidetes were observed. Larval samples demonstrated decreased proteobacteria abundance, while juvenile samples displayed an increase in abundance. Relative gene expression of key digestive genes from GIT tissue was quantified using real time-quantitative polymerase chain reaction. An effect on digestive gene expression potentially affecting nutrient absorption and antioxidant production was indicated via a significant decrease of solute carrier family 6 member 6 expression in larvae exposed to 6 fibers/fish/day. No significant molecular changes were observed in juvenile GIT tissue, although a non-monotonous dose-response was observed. GIT morphology was analyzed using histomorphological observations of the GIT mucus and cell types. No significant impairment of the GIT epithelial layers was observed in larvae or juveniles. To assess growth and condition, Fulton's condition factor was measured. No differences were observed in larval or juvenile growth. Comparisons of different developmental stages allowed for identifying vulnerable developmental stages for microplastic exposure; larvae were more susceptible to molecular changes, while shifts in juvenile microbial communities were similar to changes reported post-polystyrene microplastic sphere exposure. This study is one of the first to provide toxicological data on the risk of PE fiber ingestion during fish development stages. Results indicate no imminent threat to fish condition at current measured environmental levels of microplastics; however, close monitoring of vital spawning grounds for commercially important fishes is recommended.

Ecotoxicological effects of different size ranges of industrial-grade polyethylene and polypropylene microplastics on earthworms Eisenia fetida

The effects of microplastics (MPs) on terrestrial organisms remain poorly understood, even though soil is an important MPs sink. In this study, the earthworms Eisenia fetida were exposed to 0.25% (w/w) of industrial-grade high-density polyethylene (HDPE, 28-145, 133-415 and 400-1464 μm) and polypropylene (PP, 8-125, 71-383 and 761-1660 μm) MPs in an agricultural soil for 28 d. The results showed that HDPE and PP MPs with different size ranges can be ingested by E. fetida. Exposure to different size ranges of HDPE and PP MPs altered the activities of superoxide dismutase, catalase and glutathione S-transferase and induced an increase in the 8-hydroxy-2'-deoxyguanosine level in E. fetida, suggesting that MPs-induced oxidative stress occurred in E. fetida. A size and type-dependent toxicity of MPs to E. fetida was demonstrated by the integrated biological response index. In addition, to obtain detailed molecular information on the responses of E. fetida to MPs exposure, transcriptomic analysis was conducted for E. fetida from HDPE (28-145 μm) and PP (8-125 μm) treatment groups. Transcriptomic analysis identified 34,937 and 28,494 differentially expressed genes in the HDPE and PP MPs treatments compared with the control, respectively. And, exposure to HDPE and PP MPs significantly disturbed several pathways closely related to neurodegeneration, oxidative stress and inflammatory responses in E. fetida. This study provides important information for the ecological risk assessment of different size ranges and types of industrial-grade MPs.

Phenotypic and transcriptomic responses of the rotifer Brachionus koreanus by single and combined exposures to nano-sized microplastics and water-accommodated fractions of crude oil

Sorption of organic pollutants on microplastics can be an alternative uptake route for organic pollutants in aquatic organisms. To assess the combined effects of microplastics and organic pollutants, we employed phenotypic and transcriptomic analyses to the responses of the marine rotifer Brachionus koreanus to environmentally relevant concentrations of nano-sized microplastic (0.05 µm), water-accommodated fractions of crude oil, and binary mixtures thereof. Our multigenerational in vivo experiments revealed more than additive effects on population growth of B. koreanus in response to combined exposure, while a single exposure to nano-sized microplastic did not induce observable adverse effects. Synergistic transcriptome deregulation was consistently associated with dramatically higher numbers of differentially expressed genes, and increased gene expression was associated with combined exposure. The majority of synergistic transcriptional alteration was related to metabolism and transcription, with impaired reproduction resulting from energetic reallocation toward adaptation. As further supported by chemistry analysis for polycyclic aromatic hydrocarbons sorption on microplastic, our findings imply that nano-sized microplastics can synergistically mediate the effects of organic pollutants in aquatic organisms.

Presence of airborne microplastics in human lung tissue

Plastics are ubiquitously used by societies, but most of the plastic waste is deposited in landfills and in the natural environment. Their degradation into submillimetre fragments, called microplastics, is a growing concern due to potential adverse effects on the environment and human health. Microplastics are present in the air and may be inhaled by humans, but whether they have deleterious effects on the respiratory system remain unknown. In this study, we determined the presence of microplastics in human lung tissues obtained at autopsies. Polymeric particles (n = 33) and fibres (n = 4) were observed in 13 of 20 tissue samples. All polymeric particles were smaller than 5.5 µm in size, and fibres ranged from 8.12 to 16.8 µm. The most frequently determined polymers were polyethylene and polypropylene. Deleterious health outcomes may be related to the heterogeneous characteristics of these contaminants in the respiratory system following inhalation.

Occurrence and characterization of microplastics in white shrimp, Metapenaeus affinis, living in a habitat highly affected by anthropogenic pressures, northwest Persian Gulf

Microplastics (MPs) are a modern societal concern and recognized as a growing environmental hazard by careless disposal. This study aimed to assess the MPs content in white shrimp (Metapenaeus affinis) inhabiting in a natural habitat affected by high anthropogenic pressures, and recognize if the shrimp could be a suitable bioindicator for MPs pollution. To assess spatial changes of MPs presence in shrimps, sampling was carried out by a trawl net from 13 stations across the entire Musa Bay. Tissues of shrimps were examined for MPs following floatation, digestion, microscopic observation and identified by Confocal Raman Spectroscopy. MPs were observed in the shrimps of all stations. The average MPs abundance was 1.02 items/g of digestive tissues. About 37% of recorded MPs in M. affinis samples exceeding 500 μm that could be related to surface area and stickiness as notable controls beyond ingestion. The dominant shape of MPs was fiber, followed by film. Five different colors were recorded in tissues of M. affinis samples, and the white/transparent MPs were the most abundant, followed by blue and black. In addition, a wide range of recorded colors of MPs in the study area could suggest a variety of sources of MPs. Confocal Raman Spectroscopy confirmed that polyethylene terephthalate (46%), polypropylene (27%) and polystyrene (27%) were dominant polymers. As the average annually consumption of shrimp in the region is 2.3 g/person/day, therefore each person could consume 857 MPs per year. In conclusion, the results of this research provide a detailed and useful information for a better understanding of MPs contamination in the region and suggest Jinga shrimp as a suitable species for monitoring MPs in marine ecosystems.

Microplastics intake and excretion: Resilience of the intestinal microbiota but residual growth inhibition in common carp

Aquatic animals can be influenced by exposure to microplastics (MPs), but little is known about their recovery capacity following MPs excretion. Here, common carp were exposed to environmentally relevant concentrations of MPs for 30 days and followed by MPs excretion for another 30 days. Growth, isotopic and elemental compositions and intestinal microbiota were investigated. We found that fish growth was not influenced by exposed to MPs but was significantly reduced following MPs excretion, indicating a delayed effect on growth. MPs intake and excretion, however, had no obvious effects on isotopic and elemental compositions. MPs altered the community structure and composition of intestinal microbiota and might reduce functional diversity. After MPs excretion, interestingly, bacterial community structures of MPs treatments were grouped together with the control, suggesting the general resilience of fish intestinal microbiota. Nevertheless, high abundance of pathogenic Shewanella, Plesiomonas and Flavobacterium was observed in MPs treatments but did not affect the functional potential of intestinal microbiota. The results of this study provide new information for the application of adverse outcome pathway (AOP) in MPs, suggesting the necessity of paying attention to recovery assay following MPs intake in the development of AOP frameworks.

Resolving the effects of environmental micro- and nanoplastics exposure in biota: A knowledge gap analysis

The pervasive spread of microplastics (MPs) and nanoplastics (NPs) has raised significant concerns on their toxicity in both aquatic and terrestrial environments. These polymer-based materials have implications for plants, wildlife and human health, threatening food chain integrity and ultimate ecosystem resilience. An extensive - and growing - body of literature is available on MP- and NP-associated effects, including in a number of aquatic biota, with as yet limited reports in terrestrial environments. Effects range from no detectable, or very low level, biological effects to more severe outcomes such as (but not limited to) increased mortality rates, altered immune and inflammatory responses, oxidative stress, genetic damage and dysmetabolic changes. A well-established exposure route to MPs and NPs involves ingestion with subsequent incorporation into tissues. MP and NP exposures have also been found to lead to genetic damage, including effects related to mitotic anomalies, or to transmissible damage from sperm cells to their offspring, especially in echinoderms. Effects on the proteome, transcriptome and metabolome warrant ad hoc investigations as these integrated "omics" workflows could provide greater insight into molecular pathways of effect. Given their different physical structures, chemical identity and presumably different modes of action, exposure to different types of MPs and NPs may result in different biological effects in biota, thus comparative investigations of different MPs and NPs are required to ascertain the respective effects. Furthermore, research on MP and NP should also consider their ability to act as vectors for other toxicants, and possible outcomes of exposure may even include effects at the community level, thus requiring investigations in mesocosm models.

Single and combined acute and subchronic toxic effects of microplastics and copper in zebrafish (Danio rerio) early life stages

The evaluation of the interaction between microplastics (MPs) and heavy metals is of special importance for risk assessment. In this study, zebrafish (Danio rerio) were exposed to MPs (2 mg/L), two sub-lethal concentrations of copper (Cu, 60 and 125 μg/L) and their mixtures (Cu60 + MPs, Cu125 + MPs), from 2-h post-fertilization (hpf) until 14-days post-fertilization (dpf). Lethal and sublethal endpoints were evaluated, along with a set of biochemical and genetic biomarkers between 2 and 14 dpf. Exposure to MPs and Cu, single or combined, induced high mortality and oxidative stress in zebrafish larvae, with data showing that the antioxidant enzymes were inhibited at 6 dpf, increasing thereafter until 14 dpf, due to the accumulation of reactive oxygen species. MPs and Cu, single or combined, caused neurotoxicity in larvae by inhibiting acetylcholinesterase activity. There was an increased and significant effect of Cu + MPs groups on the evaluated biomarkers, concerning the corresponding Cu groups, suggesting that MPs may have a synergistic effect in relation to Cu. The Integrated Biomarker Response (IBR) evidenced that a higher degree of stress occurred at the larval period. Our findings highlight that MPs can act as a vector for heavy metals, therefore, influencing their bioavailability and toxicity in the organisms.

Eco-Interactions of Engineered Nanomaterials in the Marine Environment: Towards an Eco-Design Framework

Marine nano-ecotoxicology has emerged with the purpose to assess the environmental risks associated with engineered nanomaterials (ENMs) among contaminants of emerging concerns entering the marine environment. ENMs’ massive production and integration in everyday life applications, associated with their peculiar physical chemical features, including high biological reactivity, have imposed a pressing need to shed light on risk for humans and the environment. Environmental safety assessment, known as ecosafety, has thus become mandatory with the perspective to develop a more holistic exposure scenario and understand biological effects. Here, we review the current knowledge on behavior and impact of ENMs which end up in the marine environment. A focus on titanium dioxide (n-TiO₂) and silver nanoparticles (AgNPs), among metal-based ENMs massively used in commercial products, and polymeric NPs as polystyrene (PS), largely adopted as proxy for nanoplastics, is made. ENMs eco-interactions with chemical molecules including (bio)natural ones and anthropogenic pollutants, forming eco- and bio-coronas and link with their uptake and toxicity in marine organisms are discussed. An ecologically based design strategy (eco-design) is proposed to support the development of new ENMs, including those for environmental applications (e.g., nanoremediation), by balancing their effectiveness with no associated risk for marine organisms and humans.

Genotoxicity and oxidative stress induction by polystyrene nanoparticles in the colorectal cancer cell line HCT116

The potential risks of environmental nanoparticles (NPs), in particular Polystyrene Nanoparticles (PNPs), is an emerging problem; specifically, the interaction of PNPs with intestinal cells has not been characterized so far. The mechanism by which polystyrene particles are transferred to humans has not yet been clarified, whether directly through ingestion from contaminated food. We evaluated the interaction between PNPs and colorectal adenocarcinoma cells (HCT116). Cells were exposed to different concentrations of PNPs, metabolic activity and the consequent cytotoxic potential were assessed through viability test; we evaluated the PNP genotoxic potential through the Cytokinesis-Block Micronucleus cytome (CBMN cyt) assay. Finally, we detected Reactive Oxygen Species (ROS) production after NPs exposure and performed Western Blot analysis to analyze the enzymes (SOD1, SOD2, Catalase, Glutathione Peroxidase) involved in the cell detoxification process that comes into play during the cell-PNPs interaction. This work analyzes the cyto and genotoxicity of PNPs in the colorectal HCT116 cell line, in particular the potential damage from oxidative stress produced by PNPs inside the cells related to the consequent nuclear damage. Our results show moderate toxicity of PNPs both in terms of ROS production and DNA damage. Further studies will be needed on different cell lines to have a more complete picture of the impact of environmental pollution on human health in terms of PNPs cytotoxicity and genotoxicity.

Occurrence and ecological impact of microplastics in aquaculture ecosystems

Extensive applications of plastic in human life has caused substantial microplastic pollution in the global environment, which, due to plastic's ubiquitous nature and everlasting ecological impact, has caused worldwide concern. In aquatic ecosystems, microplastics are ingested by aquatic animals, affecting their growth and development and resulting in trophic transfer to higher organisms in the food chain. Therefore, consumption of aquatic products is a main primary source of human exposure to microplastics. Recently, aquaculture production has experienced tremendous growth and will exceed production from fish catch soon. Because they constitute an important source of protein in the human food supply, aquaculture products contaminated with microplastics directly affect food quality and safety. The present review summarizes documented studies regarding the occurrence and distribution of microplastics in various aquaculture systems and species and compares microplastic pollution in aquaculture species and captured species. Microplastics in aquaculture environments mainly come from exogenous imports, such as plastic waste and debris from the land, tourism, shipping transportation and atmospheric deposition. In addition, the use of plastic gear and equipment, aquaculture feed and health products, and special aquaculture environments contribute to a higher accumulation of microplastics. We also discuss the adverse effects of microplastics in aquaculture species and the potential health risks of microplastics to humans through the food chain. In summary, this review highlights the effects of microplastic pollution in aquaculture, particularly the ecological impacts on aquaculture species and associated human health implications, and calls for restricted control of microplastics in aquaculture ecosystems.

Effects of microplastics on marine copepods

Microplastic contamination has been considered as a global environmental problem in marine ecosystem. Due to small size (< 5 mm) in overlapping with that of microalgae, microplastics can easily be ingested by a wide range of marine copepods both in the laboratory and in situ. Although many studies have reported adverse effects of microplastics on marine copepods, it still lacks a systematic overview about the bioavailability of microplastics and their potential ecological consequences. As copepods dominate zooplankton biomass and provide an essential trophic link in marine ecosystem, this review indicates the bioavailability and toxicity of microplastics in such taxon depend on the shape, size, abundance, and properties of plastics. Also, ours is purposed to tease out the possible molecular mechanisms behind. Microplastic ingestion is prevalent; they impede food intake, block the digestive tract, and cause physiological stress in copepods (e.g., immune responses, metabolism disorders, energy depletion, behavioral alterations, growth retardation, and reproduction disturbance). Notably, in response to microplastic exposure, the copepods show both species- and stage-specificity. Furthermore, microplastics can serve as vectors of organic contaminants (e.g., triclosan, chlorpyrifos, and dibutyl phthalate) and thus increase their toxicity in marine copepods, consequently aggravating the adverse impacts of microplastics in marine ecosystem. Given that most previous studies have partially used pristine microplastics and their short-term exposure might have undervalued their negative effects, more multigenerational mechanistic researches (for example, via an integration of omics-based technology and phenotypic trait analysis) are urgently required for numerous marine copepods exposed to environmental-characteristics plastics as demonstrated by aged microplastics at environmentally realistic concentrations and added with other environmental pollutants; thus it will not only provide mechanistic insights into the biological impacts of microplastics, but also help make the seawater-benchmark setting and ecological assessment for microplastic pollution in marine environment.

Micro and Nano Plastics Distribution in Fish as Model Organisms: Histopathology, Blood Response and Bioaccumulation in Different Organs

Micro- and nano-plastic (MP/NP) pollution represents a threat not only to marine organisms and ecosystems, but also a danger for humans. The effects of these small particles resulting from the fragmentation of waste of various types have been well documented in mammals, although the consequences of acute and chronic exposure are not fully known yet. In this review, we summarize the recent results related to effects of MPs/NPs in different species of fish, both saltwater and freshwater, including zebrafish, used as model organisms for the evaluation of human health risk posed by MNPs. The expectation is that discoveries made in the model will provide insight regarding the risks of plastic particle toxicity to human health, with a focus on the effect of long-term exposure at different levels of biological complexity in various tissues and organs, including the brain. The current scientific evidence shows that plastic particle toxicity depends not only on factors such as particle size, concentration, exposure time, shape, and polymer type, but also on co-factors, which make the issue extremely complex. We describe and discuss the possible entry pathways of these particles into the fish body, as well as their uptake mechanisms and bioaccumulation in different organs and the role of blood response (hematochemical and hematological parameters) as biomarkers of micro- and nano-plastic water pollution.

Formation of Fiber Fragments during Abrasion of Polyester Textiles

Fiber fragments are one of the dominant types of microplastics in environmental samples, suggesting that synthetic textiles are a potential source of microplastics to the environment. Whereas the release of microplastics during washing of textiles is already well studied, much less is known about the release during abrasion processes. The abrasion of textiles may induce fibrillation of fibers and therefore result in the formation of much finer fiber fragments. The aim of this study was to investigate the influence of abrasion of synthetic textiles on the formation of microplastic fibers and fibrils. Fleece and interlock textile swatches made of polyester were abraded using abrasion tests with a Martindale tester. The microplastic fibers and fibrils formed during abrasion were extracted from the textiles and characterized in terms of number, length, and diameter. The microplastic fibers demonstrated the same diameter than the fibers found in the textiles (fleece: 12.3 μm; interlock: 12.7 μm), while fibrils with a much smaller diameter (fleece: 2.4 μm; interlock: 4.9 μm) were also found. The number of fibrils formed during abrasion in both textiles was higher than the number of microplastic fibers. The majority of the extracted microplastic fibers had a length between 200 and 800 μm, while most fibrils were between 30 and 150 μm, forming two distinct fiber fragment morphologies. The number of microplastic fibers formed during abrasion was 5 to 30 times higher than the number of microplastic fibers that could be extracted from non-abraded samples. The number of fibrils increased after abrasion by more than a factor of 200 for both fabric types. The fibrils formed during abrasion have diameters that fall within the inhalable size for airborne particles. The potential release of fibrils into air during wear of textiles thus raises questions about the human exposure to these materials. Since the Martindale tester can simulate a daily application scenario of textiles over a prolonged period only in a limited way, future studies are needed to establish the correlation between the test results with a real-world scenario.

Long-term nanoplastics exposure results in multi and trans-generational reproduction decline associated with germline toxicity and epigenetic regulation in Caenorhabditis elegans

The environmental risk from long-term plastic pollution is growing. We investigated the multi and trans-generational reproductive toxicity of nanoplastics (NPs) in Caenorhabditis elegans and the underlying mechanisms over five generations. Following a single maternal exposure (F0) to NPs (100 nm; 1, 10, 50, or 100 mg/L) for 72 h, the subsequent generations (F1-F4) were cultured under NPs-free conditions. We showed that the total brood size was significantly reduced across all offspring generations (F1-F4). NPs accumulated in the intestine of C. elegans in the F0 generation, but not in the germline system, and not observed in subsequent generations. Chromosomal aberrations in oocytes and germline cell apoptosis were significantly elevated in the NPs-exposed F0 generation and in subsequent unexposed generations. Likewise, the expression of ced-3 was increased across generations, regulated by hypomethylation in the promoter region of ced-3 after maternal NPs exposure. Finally, NPs exposure reduced the expression of epigenesis-related genes met-2, set-2, and spr-5 and the trans-generational effects of maternal NPs exposure were not observed in met-2, set-2, and spr-5 RNAi worms. We demonstrate that a single long-term maternal NPs exposure can cause multi and trans-generational reproduction decline in C. elegans, which may be associated with germline toxicity and epigenetic regulation.

Redox-sensitive Nrf2 and MAPK signaling pathways contribute to trichloroethene-mediated autoimmune disease progression

Trichloroethene (TCE) exposure is associated with the induction of autoimmune diseases (ADs). Although oxidative stress plays a major role in TCE-mediated autoimmunity, the underlying molecular mechanisms still need to be delineated. Dysregulation of redox-sensitive nuclear factor (erythroid-derived 2)-like2 (Nrf2), resulting in uncontrolled antioxidant and cytoprotective genes, and pro-inflammatory MAPK signaling pathways could be critical in TCE-mediated disease progression. This study was, therefore, focused on establishing status and contribution of Nrf2 and MAPK signaling in TCE-mediated inflammatory and autoimmune responses, especially during disease progression. To achieve these objectives, time-response studies were conducted by treating female MRL+/+ mice with TCE (0.5 mg/mL, a dose relevant to human exposure) for 24, 36 and 52 wks. TCE exposure led to reduction in Nrf2 expression, but increased phos-NF-κB (p65) and iNOS along with increased phosphorylation of MAPKs (p38, ERK and JNK) and downstream pro-inflammatory cytokines IL-12, TNF-α and RANTES in the livers in a time-dependent manner. These changes were also associated with time-dependent increases in liver protein carbonyls and induction of serum anti-dsDNA antibodies (marker of systemic lupus erythematosus disease), further supporting the role of oxidative stress and Nrf2/MAPK signaling in TCE-mediated autoimmune response progression. The mechanistic role of MAPK in TCE-mediated autoimmunity was further established by treating MRL+/+ mice with sulforaphane (SFN; 8 mg/kg, i.p., every other day) along with TCE (10 mmol/kg, i.p., every 4th day) for 6 wks using an established protocol, and by in vitro treatment of T cells with dichloroacetyl chloride (a TCE metabolite) with/without p38 MAPK inhibitor. SFN treatment attenuated the TCE-mediated phosphorylation of p38 MAPK. More importantly, treatment with SFN or p38 inhibitor led to suppression of downstream pro-inflammatory cytokines IL-12 and TNF-α. These findings thus support the contribution of Nrf2 and MAPK signaling pathways and help in delineating novel potential therapeutic targets against TCE-mediated autoimmunity.

Impact of Microbial Colonization of Polystyrene Microbeads on the Toxicological Responses in the Sea Urchin Paracentrotus lividus

The sea urchin Paracentrotus lividus (P. lividus) was exposed to either virgin or biofilm-covered polystyrene microbeads (micro-PS, 45 μm) in order to test the effect of microbial colonization on the uptake, biodistribution, and immune response. The biofilm was dominated by bacteria, as detected by scanning electron microscopy and 16S rRNA sequencing. A higher internalization rate of colonized micro-PS inside sea urchins compared to virgin ones was detected, suggesting a role of the plastisphere in the interaction. Colonized and virgin micro-PS showed the same biodistribution pattern by accumulating mainly in the digestive system with higher levels and faster egestion rates for the colonized. However, a significant increase of catalase and total antioxidant activity was observed only in the digestive system of colonized micro-PS-exposed individuals. Colonized micro-PS also induced a significant decrease in the number of coelomocytes with a significant increase in vibratile cells, compared to control and virgin micro-PS-exposed animals. Moreover, a general time-dependent increase in the red/white amoebocytes ratio and reactive oxygen species and a decrease in nitrogen ones were observed upon exposure to both colonized and virgin micro-PS. Overall, micro-PS colonization clearly affected the uptake and toxicological responses of the Mediterranean sea urchin P. lividus in comparison to virgin micro-PS.

Effects of polystyrene in the brackish water flea Diaphanosoma celebensis: Size-dependent acute toxicity, ingestion, egestion, and antioxidant response

Owing to the increasing usage of plastics, their debris is continuously deposited in marine environments, resulting in deleterious effects on aquatic organisms. Although it is known that microplastics disturb the cellular redox status, knowledge of molecular in marine cladocerans is still lacking. In the present study, we investigated the acute toxicity of different-sized polystyrene (PS) beads (0.05, 0.5, and 6-μm diameter), ingestion and egestion patterns, their distribution in the tissues, and their effects on the antioxidant systems in the brackish water flea Diaphanosoma celebensis. All different-sized PS beads showed no mortality at the concentrations used in this study. After 48 h of exposure to PS beads of different sizes, all microbeads were retained in the digestive tract, but the retention time varied according to the bead size. In particular, the group that was exposed to 0.05-μm beads showed widely distributed fluorescence (e.g., in the embryo, and probably in lipid droplets as well as the digestive tract). The transcriptional level and enzyme activities of antioxidants were modulated depending on the size of the PS beads, and lipid peroxidation was induced in groups exposed to 0.05 and 0.5-μm beads. These findings suggest that the size of PS beads is an important factor for cellular toxicity, and can induce size-dependent oxidative stress in this species. This study provides a better understanding of the molecular modes of action of microplastics in marine zooplankton.

Impact of polyethylene terephthalate microfiber length on cellular responses in the Mediterranean mussel Mytilus galloprovincialis

Many studies have investigated the toxic effects of microplastics in marine organisms, but most studied nano-sized round microplastics at high concentrations and were not environmentally relevant. To understand the cellular toxicity of polyethylene terephthalate microfibers (PET-MFs) by length (50 and 100 μm), Mediterranean mussels (Mytilus galloprovincialis) were exposed to environmental (0.5 μg/L) and high (100 mg/L) MF concentrations for four days. Short PET-MFs accumulated in the lower intestinal organs of the mussels, but long PET-MFs were only observed in the upper intestinal organs. Both sized PET-MFs affected necrosis, DNA damage, reactive oxygen species, nitric oxide, and acetylcholinesterase (AChE) activity. Significant MF length-dependent effects occurred at environmentally relevant concentrations for DNA damage (100 μm MFs) and AChE activity (50 μm MFs). However, length effects disappeared at the higher exposure concentration. The current study provides potentially sensitive indicators to detect MFs exposure and the ecotoxicological implications of MFs in marine ecosystems.

Effects of environmentally relevant levels of polyethylene microplastic on Mytilus galloprovincialis (Mollusca: Bivalvia): filtration rate and oxidative stress

The objective of the present study was to evaluate the potential toxic effects of polyethylene microplastics (PE-MPs) (40-48 μm) on the Mediterranean mussel Mytilus galloprovincialis in controlled laboratory conditions. The exposure was carried out for 14 days with three environmentally relevant PE-MPs concentrations of 1, 10, and 100 and a high concentration of 1000 μg/L. Effects of PE-MPs were assessed by evaluating the filtration rate (FR) after 7 and 14 days of exposure and by analyzing biochemical biomarkers of oxidative stress (catalase - CAT, glutathione S-transferase - GST, and the levels of lipid peroxidation - LPO) in the M. galloprovincialis digestive gland after 14 days of exposure. Results showed that M. galloprovincialis does not accumulate PE-MPs of 40-48 μm size in its whole tissues. The filtration rate was significantly reduced with the increase of PE-MPs concentrations. The biochemical biomarkers indicated that PE-MPs induced oxidative damage (LPO) at low concentrations (1 and 10 μg/L) with a significant reduction in females of 1000 μg/L treated group and inactivate antioxidative system (CAT and GST) in the digestive gland of both sexes at high concentrations (100 and 1000 μg/L). This study demonstrates that PE-MPs have biological effects on M. galloprovincialis at environmentally relevant concentrations thus brings new insights on the potential impacts of PE-MPs in marine bivalves.

Enhanced hepatic cytotoxicity of chemically transformed polystyrene microplastics by simulated gastric fluid

Microplastics pollution has emerged as one of the top-ranked global environmental issues, receiving worldwide attention in recent years. However, knowledge about the detrimental effects of microplastics on human health is still limited. In real-world settings, the physicochemical characteristics of microplastics were modified by environmental and biological transformation, largely changing their ultimate toxicity. Nonetheless, the toxicity change related to transformation of microplastics has not been considered in most published studies thus far. In the current study, we investigated the cytotoxicity of transformed polystyrene microplastics in hepatocytes. Our results revealed that 500 nm polystyrene microplastics, which were chemically transformed by simulated gastricfluid, exacerbated their adverse effects on SMMC-7721 cells at 20 μg/mL for 24 h treatment, including morphological alteration, membrane damage and increased cell apoptosis via oxidative stress. This exacerbated cytotoxicity could be at least partially explained by the degradation, changed surface charge and altered surface chemistry of these polystyrene microplastics after transformation. In conclusion, our study demonstrates that the hepatic cytotoxicity of polystyrene microplastics is enhanced after transformation.

The joint effect of parental exposure to microcystin-LR and polystyrene nanoplastics on the growth of zebrafish offspring

The coexistence of nanoplastics (NPs) and various pollutants in the environment has become a problem that cannot be ignored. In order to identify the microcystin-LR (MCLR) bioaccumulation and the potential impacts on the early growth of F1 zebrafish (Danio rerio) offspring in the presence of polystyrene nanoplastics (PSNPs), PSNPs and MCLR were used to expose adult zebrafish for 21days. The exposure groups divided into MCLR (0, 0.9, 4.5 and 22.5μgL^-1) alone groups and PSNP (100μgL^-1) and MCLR co-exposure groups. F1 embryos were collected and developed to 120 h post-fertilization (hpf) in clear water. Compared with the exposure to MCLR only, the combined exposure increased the parental transfer of MCLR to the offspring and subsequently exacerbated the growth inhibition of F1 larvae. Further research clarified that combined exposure of PSNPs and MCLR could reduce the levels of thyroxine (T4) and 3, 5, 3'-triiodothyronine (T3) by altering the expression of hypothalamus-pituitary-thyroid (HPT) axis-related genes, eventually leading to growth inhibition of F1 larvae. Our results also exhibited combined exposure of PSNPs and MCLR could change the transcription of key genes of the GH/IGF axis compared with MCLR single exposure, suggesting the GH/IGF axis was a potential target for the growth inhibition of F1 larvae in PSNPs and MCLR co-exposure groups. The present study highlights the potential risks of coexistence of MCLR and PSNPs on development of fish offspring, and the environmental risks to aquatic ecosystems.

Algal density affects the influences of polyethylene microplastics on the freshwater rotifer Brachionus calyciflorus

Most previous researches focused on the toxicity of polystyrene microplastics (MPs) to marine organisms, but less on polyethylene MPs and freshwater zooplanktons. The present study aims to elucidate the toxicity of polyethylene (PE) MPs (diameter = 10-22 μm) to the typical freshwater rotifer Brachionus calyciflorus. Firstly, fluorescent microscope observation showed that rotifers could ingest PE MPs and accumulate them in their digestive tracts. Life-table experiments revealed that exposure to 0.5 × 10³, 2.5 × 10³, and 1.25 × 10⁴ particles/mL PE MPs significantly reduced net reproductive rate and intrinsic rate of pollution increase of rotifers under algal densities (Scenedesmus obliquus) of 0.1 × 10⁶, and 0.5 × 10⁶ cells/mL, but no significant effects were observed under 2.5 × 10⁶ cells/mL algal density. These results showed that PE MPs suppressed the reproduction of rotifer and this negative effect could be alleviated by increasing food supply. The swimming linear speed of rotifers significantly decreased with increasing MP concentrations. The activities of superoxide dismutase and Na⁺-K⁺-ATPase significantly decreased in treatments with high concentration of PE MPs under 0.1 × 10⁶ cells/mL algal density, but did not change significantly in MP treatments under 0.5 × 10⁶ and 2.5 × 10⁶ cells/mL, compared to the control. Glutathione peroxidase activity significantly increased in treatments with 1.25 × 10⁴ particles/mL and 2.5 × 10³ particles/mL under 0.1 × 10⁶ and 0.5 × 10⁶ cells/mL algal density, respectively, but did not change significantly in all MP treatments under 2.5 × 10⁶ cells/mL. Exposure to PE MPs might lower the gathering capacity of algae, induce oxidative stress, trigger cell membrane damages and disturb energy metabolism in rotifers, which can explain the PE MPs toxicity to rotifer reproduction.

A preliminary study of the association between colonization of microorganism on microplastics and intestinal microbiota in shrimp under natural conditions

The microplastics pollution in wild aquatic organisms has been described by many studies. However, few studies focused on the farmed ones and MPs impacts on their gut microbiota under natural conditions. Here, we present the first detection of MPs in shrimp ponds and Litopenaeus vannamei. We also globally, firstly and preliminarily investigate the association between colonization of microorganism on MPs and intestinal microbiota under natural conditions. Microplastics (5129 ± 1176 items/kg d.w.) in sediments were mainly pellets, mostly white and blue, and in size less than 1 mm. Microplastics (14.08 ± 5.70 items/g w.w.) in shrimps were higher than that in mostly wild aquatic organisms and positively correlated with that in sediments. Blue fibers in small size (<0.5 mm) were dominant in shrimps. The bacterial communities and their microbial function on MPs were similar with that in shrimp gut, with higher diversity and richness in bacteria communities colonized on MPs. Network analysis demonstrated that the colonization of microorganism on MPs were associated with shrimp intestinal microbiota. Results suggest that except for toxicity reported previously, the effects on intestinal microbiota induced by MPs were possibly because of the biofilm on their surfaces as well, causing notable impacts on aquatic animals.

The Influence of Polystyrene Microspheres Abundance on Development and Feeding Behavior of Artemia salina (Linnaeus, 1758)

In the present study, it has been evaluated how 10 µm of polyethylene microspheres can be ingested by Artemia salina (Linnaeus, 1758) larvae within the first 7 days of the life cycle, and the impact on their health. Twelve A. salina larvae (instar I) groups were exposed to different microplastics (MPs) concentrations (0-1-10-102-103-104 MPs/mL), with and without Dunaliella salina as a food source. The results highlighted that A. salina larvae ingest MPs in relation to the exposure times in a dose-dependent manner and are significantly influenced by food availability. The highest contamination found was 306.2 MPs/individual at 104 MPs/mL exposure without a food source. No MPs were found in the presence of the food source from 1 to 102 MPs/mL, while contamination was detected at all concentrations of MPs without a food source. The worst effect on the developmental stages was evaluated at 168 h with a food source, with a delay compared to the control of I and II instars at 103 and 104 MPs/mL, respectively. Furthermore, microalgal feeding was significantly reduced for about 50% in the presence of 104 MPs/mL. These results highlight that aquatic microplastics pollution could affect the A. salina’s feeding behavior and life cycle.

Effect of microplastics in water and aquatic systems

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

Arsenic exposure combined with nano- or microplastic induces different effects in the marine rotifer Brachionus plicatilis

Besides the adverse biological effects induced by microplastics (MPs), the effects associated with sorption of ambient pollutants on MPs are considered as an emerging environmental problem as MPs act as a mediator of pollutants. The present study examines the combined effects of nano(micro)plastics (NMPs) and arsenic (As) by exposing the marine rotifer Brachionus plicatilis to MP particles at the micro-scale (6 μm) and nano-scale (nanoplastics, NPs) (50 nm) along with As. In vivo toxicity, bioaccumulation, and biochemical reactions were used to examine the effects of combined exposure. The results of in vivo experiments showed that As toxicity increased with NP exposure, whereas toxicity was alleviated by MPs, indicating a different mode of action between NPs and MPs in combination with As. The highest level of As bioaccumulation was detected in NP + As groups, and followed by MP + As and As-only exposure groups, whereas no significant difference between groups was shown for As metabolites. In addition, the activity of several ATP-binding cassette proteins that confer multixenobiotic resistance, which is responsible for efflux of As, was activated by As but significantly inhibited by NP exposure, supporting the findings of in vivo experiments. Our results show that the effects of combining exposure to As with NP and MPs differ depending on particle size and provide an in-depth understanding of both environmental pollutants.

Polystyrene microplastics lead to pyroptosis and apoptosis of ovarian granulosa cells via NLRP3/Caspase-1 signaling pathway in rats

Microplastics (MPs) considered as a new persistent environmental pollutant could enter into the circulatory system and result in decrease of sperm quantity and quality in mice. However, the effects of Polystyrene MPs (PS MPs) on the ovary and its mechanism in rats remained unclear. In this present study, thirty-two healthy female Wistar rats were exposed to different concentrations of 0.5 µm PS MPs dispersed in deionized water for 90 days. Using hematoxylin-eosin (HE) staining, the number of growing follicles was decreased compared to the control group. In addition, the activity of glutathione peroxidase (GSH-Px), catalase (CAT) and superoxide dismutase (SOD) were decreased while the expression level of malondialdehyde (MDA) was increased in ovary tissue. Confirmed by immunohistochemistry, the integrated optical density of NLRP3 and Cleaved-Caspase-1 had been elevated by 13.9 and 14 in granulosa cells in the 1.5 mg/kg/d group. Furthermore, compared to the control group, the level of AMH had been decreased by 23.3 pg/ml while IL-1β and IL-18 had been increased by 32 and 18.5 pg/ml in the 1.5 mg/kg/d group using the enzyme-linked immune sorbent assay (ELISA). Besides, the apoptosis of granulosa cells was elevated measured by terminal deoxyribonucleotide transferase-mediated nick end labeling (TUNEL) staining and flow cytometry. Moreover, western blot assays showed that the expressions of NLRP3/Caspase-1 signaling pathway related factors and Cleaved-Caspase-3 were increased. These results demonstrated that PS MPs could induce pyroptosis and apoptosis of ovarian granulosa cells via the NLRP3/Caspase-1 signaling pathway maybe triggered by oxidative stress. The present study suggested that exposure to microplastics had adverse effects on ovary and could be a potential risk factor for female infertility, which provided new insights into the toxicity of MPs on female reproduction.

Different effects of nano- and microplastics on oxidative status and gut microbiota in the marine medaka Oryzias melastigma

Plastic is regarded as a major environmental concern. In particular, nanoplastics and microplastics (NMPs) are attracting global attention due to their potential impact on aquatic organisms. Here, we examined the effects of NMPs (50 nm polystyrene microbead nanoplastics [NPs] and 45 µm microplastics [MPs]) on oxidative status and gut microbiota in the marine medaka Oryzias melastigma. The NP-exposed group exhibited stronger oxidative stress with higher activation levels of antioxidants compared to the MP-exposed group. However, the MP-exposed group demonstrated induction of intestinal damage (e.g., increased mucus ratio) with further alterations of gut microbiota, compared to the NP-exposed group. In particular, MPs caused more significant alterations of microbiota composition at both phylum and genus levels. Thus, in this study we show distinct toxicity pathways of NPs and MPs, an oxidative stress-mediated pathway (e.g., antioxidants) induced by NP exposure and dysbiosis of gut microbiota in association with immune dysfunction induced by MP exposure. Our results are helpful for expanding our knowledge about the impacts of NMPs as potentially harmful substances in the aquatic environment.

Micro and Nanoplastics Identification: Classic Methods and Innovative Detection Techniques

Micro and nanoplastics are fragments with dimensions less than a millimeter invading all terrestrial and marine environments. They have become a major global environmental issue in recent decades and, indeed, recent scientific studies have highlighted the presence of these fragments all over the world even in environments that were thought to be unspoiled. Analysis of micro/nanoplastics in isolated samples from abiotic and biotic environmental matrices has become increasingly common. Hence, the need to find valid techniques to identify these micro and nano-sized particles. In this review, we discuss the current and potential identification methods used in microplastic analyses along with their advantages and limitations. We discuss the most suitable techniques currently available, from physical to chemical ones, as well as the challenges to enhance the existing methods and develop new ones. Microscopical techniques (i.e., dissect, polarized, fluorescence, scanning electron, and atomic force microscopy) are one of the most used identification methods for micro/nanoplastics, but they have the limitation to produce incomplete results in analyses of small particles. At present, the combination with chemical analysis (i.e., spectroscopy) overcome this limit together with recently introduced alternative approaches. For example, holographic imaging in microscope configuration images microplastics directly in unfiltered water, thus discriminating microplastics from diatoms and differentiates different sizes, shapes, and plastic types. The development of new analytical instruments coupled with each other or with conventional and innovative microscopy could solve the current problems in the identification of micro/nanoplastics.

Metabolomic profiling reveals the intestinal toxicity of different length of microplastic fibers on zebrafish (Danio rerio)

To explore the intestinal toxicity of microplastic fibers, zebrafish larvae and adults were exposed to different length of microplastic fibers (50 ± 26 μm and 200 ± 90 μm). After exposure, microplastic fibers were observed in the gut of zebrafish even at the early life stage, causing length-dependent intestinal damage and toxicities manifested by histopathological changes and biomarker responses. Long microplastic fibers induced more serious effects. They significantly decreased the food intake of zebrafish by 54 %-67 % compared with short microplastic fibers. Metabolomics was conducted to further reveal the metabolic alterations induced by microplastic fibers in zebrafish. A total of 124 and 123 metabolites were significantly changed by short and long microplastic fibers. At the meanwhile, 41 significantly changed metabolites were shared between short and long fibers treatment groups and were further investigated to reveal the influence of fiber length on the toxicity. The results demonstrate that microplastic fibers can up-regulate glycerophospholipids metabolism which exacerbates oxidative damage and inflammation and down-regulate fatty acyls metabolism related to nutritional deficiency. These novel findings enhance our understanding of the intestinal toxicity of microplastic fibers and demonstrate that metabolomics is powerful to unravel the underlying mechanisms of microplastics (MPs) toxicity.

Eye-glass polishing wastewater as significant microplastic source: Microplastic identification and quantification

Microplastics (MPs) and nanoplastics (NPs) seriously contaminate environments by adsorbing environmentally hazardous chemicals. NPs (<1 µm) are not removed by conventional wastewater treatment processes, and have strong sorption capacity for the environmentally hazardous chemicals because of their high surface area. This study revealed that large amounts of MPs are generated in the eye-glass lens polishing process. Qualitative analyses of MPs were performed via Fourier-transform infrared (FTIR) and Raman spectroscopy. Particle size distribution was measured through particle size analysis based on light diffraction. MPs were quantified in the wastewater by measuring the mass balance using membrane filtration with polyaluminum chloride coagulation. One liter of wastewater contained 1380-62,539 mg MPs [corrected] and 0.0136-0.0324 mg NPs. Wastewater from 140,000 eye-glass shops in South Korea is discharged into wastewater plants, and about 57 g NPs per day pass through the wastewater treatment process. The amount of NPs that accumulate daily is likely to increase dramatically. Increased heavy metal concentrations after acid digestion confirmed that MPs in the wastewater adsorbed heavy metals. Detection of various types of volatile organic compounds in the wastewater indicated that workers in eye-glass shops are exposed to the significantly hazardous environments.

Toxicity of polystyrene microplastics on juvenile Oncorhynchus mykiss (rainbow trout) after individual and combined exposure with chlorpyrifos‎

Microplastic (MP) sorption and transfer of chemical contaminants has been widely reported, yet few studies have investigated combined effects of contaminant-loaded MPs on organisms. This study examined effects of pristine or chlorpyrifos (CPF)-loaded polystyrene (PS)‎ fragments on histopathological and histomorphometrical biomarkers in rainbow trout (Onchorhynchus mykiss)‎. In laboratory, O. mykiss were exposed for 96 h to pristine PS-MPs concentrations (30 or 300 µg/L), concentrations of CPF ‎alone (2 or ‎‎6 µg/L), and the same concentrations of CPF in the presence of PS-MPs in aquaria‎. Results showed the highest histopathological alterations in both CPF concentrations and when combined with PS-MPs in fish gills. Alternatively, high histopathological lesions including massive necrosis, infiltration of inflammatory cells, and shed of villi tips were observed in fish gut in high CPF concentrations combined with high PS-MP concentrations of ‎(6 μg/L CPF+300 μg/L PS-‎MPs). Individual CPF and PS-MP concentrations or combined together showed significant changes in histomorphometrical biomarkers in fish gills, gut and skin. Findings highlight that pristine PS-MPs cause toxicity and increase adverse effects of CPF in O. mykiss, especially in gill tissue. We present evidence that pristine short-term exposure to even low concentrations of PS-MPs has a significant impact on biomarker responses in O. mykiss.

Time-dependent metabolic disorders induced by short-term exposure to polystyrene microplastics in the Mediterranean mussel Mytilus galloprovincialis

In the modern society, plastic has achieved a crucial status in a myriad of applications because of its favourable properties. Despite the societal benefits, plastic has become a growing global concern due to it is persistence and bioavailability as microplastics (MPs) to aquatic biota. In order to provide mechanistic insights into the early toxicity effects of MPs on aquatic invertebrates, a short-term (up to 72 h) exposure to 3 µm red polystyrene MPs (50 particles/mL) was conducted on marine mussels Mytilus galloprovincialis, selected as model organism for their ability to ingest MPs and their commercial relevance. The use of protonic Nuclear Magnetic Resonance (¹H NMR)-based metabolomics, combined with chemometrics, enabled a comprehensive exploration at fixed exposure time-points (T24, T48, T72) of the impact of MPs accumulated in mussel digestive glands, chosen as the major site for pollutants storage and detoxification processes. In detail, ¹H NMR metabolic fingerprints of MP-treated mussels were clearly separated from control and grouped for experimental time-points by a Principal Component Analysis (PCA). Numerous metabolites, including amino acids, osmolytes, metabolites involved in energy metabolism, and antioxidants, participating in various metabolic pathways significantly changed over time in MP-exposed mussel digestive glands related to control, reflecting also the fluctuations in MPs accumulation and pointing out the occurrence of disorders in amino acid metabolism, osmotic equilibrium, antioxidant defense system and energy metabolism. Overall, the present work provides the first insights into the early mechanisms of toxicity of polystyrene MPs in marine invertebrates.

Keap1-Nrf2 pathway up-regulation via hydrogen sulfide mitigates polystyrene microplastics induced-hepatotoxic effects

Microplastics, which are new types of environmental pollutants, are recently receiving widespread attention worldwide. Hydrogen sulfide (H₂S) as the third endogenous gaseous mediator had protective effects in multiple physiological and pathological conditions. However, the protective role of H₂S in microplastics-induced hepatotoxocity remain unclear. In this study, our data showed that H₂S significantly suppressed inflammation, apoptosis and oxidative stress induced by polystyrene microplastics (mic-PS) (20 mg/kg b.w.) in the liver. Strikingly, although mic-PS exposure increased the expression of nuclear factor-E2-related factor (Nrf2), it did not influence the levels of heme oxygenase-1 (HO-1) and NAD(P)H: quinone oxidoreductase 1 (NQOl) in the L02 hepatocytes. Immunofluorescence assay showed that sodium hydrosulfide (NaHS) reduced micro-Ps-induced hepatic apoptosis by facilitating nuclear accumulation of Nrf2. Simultaneously, flow cytometry also showed that NaHS could prevent mic-PS-induced accumulation of reactive oxygen species (ROS) by increasing the expression of HO-1 and NQO1. Furthermore, inhibition of HO-1 could reverse the hepatic protective effects of NaHS during mic-PS exposure. Mechanistically, H₂S elevating the HO-1 and NQO1 expression by facilitating nuclear accumulation of Nrf2, and consequently reducing mic-PS-induced hepatic apoptosis and inflammation. This study unveils the hepatotoxic effects of MPs and suggest NaHS have protective effects on mic-PS-induced liver damage.

Oxidative damage and decreased aerobic energy production due to ingestion of polyethylene microplastics by Chironomus riparius (Diptera) larvae

Riverine sediments are major sinks of microplastics from inland anthropogenic activities, imposing a threat to freshwater benthic invertebrates. This study investigated the ingestion of three size-classes (SC) of irregularly shaped polyethylene microplastics (PE-MPs; SC I: 32-63 μm; II: 63-250 μm; III: 125-500 μm) after 48 h by dipteran larvae (detritivore/collector) Chironomus riparius, and the consequent effects on neurotransmission, energy allocation and oxidative stress. The tested PE-MPs concentrations (1.25; 5; 20 g kg^-1) were within the range of concentrations reported in riverbanks from highly urbanised areas (1 - 9 g kg^-1), except for 20 g kg^-1 representing the worst-case scenario. After exposure to SC I, larvae presented high amounts (up to ∼2400 particles/organism) of PE-MPs in their guts, with an average size-range of 30-60 μm. In the SC II and III, larvae presented PE-MPs of higher diameter (up to 125 μm) and a visible gut obstruction. The high number of particles in the larval gut (SC I) and/or difficulties for their egestion (SC I, II and III) induced oxidative damage and reduced aerobic energy production. In addition, larvae exposed to SC II and III revealed depletion in their total lipid reserves as a consequence of lacking nutrients, and the ones exposed to SC III presented a decrease in their detoxification capacity. These results highlight that freshwater detritivores with low selective feeding behaviour (e.g., chironomids) are more prone to ingest microplastics, with potentially adverse effects on cellular metabolism, redox status and antioxidant-detoxification defences. These harmful effects at lower levels of the biological organisation may ultimately affect organisms' physiology and fitness.

Polystyrene nanoparticles trigger the activation of p38 MAPK and apoptosis via inducing oxidative stress in zebrafish and macrophage cells

Polystyrene nanoparticles (PS NPs), originated from breakdown of large plastic wastes, have already caused much concern for their environmental risks on health. This current study was aimed to reveal the toxicological mechanism of PS NPs on developing zebrafish and macrophage cells. To fulfill this purpose, 42 nm PS NPs were exposed to the early development stage of zebrafish for 5 days, the decreased heart rate and locomotor activity of zebrafish larvae were observed. The fluorescent PS NPs were used to precisely assess the accumulation of PS NPs in zebrafish larvae, and the results indicated that PS NPs not only accumulated in digestive system, but also infiltrated into the liver. More importantly, the transcriptomic analysis revealed that a total of 356 genes were differentially expressed and the KEGG class map showed significant differences in the MAPK pathway upon PS NPs treatment. Meanwhile, the induction of oxidative stress and inflammation were also observed in zebrafish larvae. Furthermore, PS NPs also induced oxidative damage and inflammatory response in RAW 264.7 cells, which activated p38 MAPK signal pathway and finally induced cell apoptosis. Our study provides a new understanding of MAPK signaling pathway involved in toxicity mechanism.

Lumbriculus variegatus (oligochaeta) exposed to polyethylene microplastics: biochemical, physiological and reproductive responses

Freshwater sediments are a repository of microplastics (MPs) resulting from inland anthropogenic activities. Benthic invertebrates, particularly endobenthic sediment-ingesting species such as the annelid Lumbriculus variegatus (blackworm), are commonly found in contaminated sediments where they likely find and ingest MPs. In the present study, L. variegatus was exposed to concentrations between 0.51 and 20 g kg^-1 dry sediment of four size-classes of irregularly-shaped polyethylene MPs (PE-MPs; size-class A: 32-63, B: 63-125, C: 125-250 and D: 250-500 μm) for 48 h to assess their sub-cellular responses to particles ingested, and for 28 days to determine chronic effects on worm's reproduction and biomass. After the short-term exposure (48 h), number of PE-MPs in blackworms' gut were related to MPs concentration in the sediment. In general, PE-MPs ingestion by blackworms induced depletion of their energy reserves (e.g., sugars in all size classes and lipids in the size-classes of PE-MPs > 125 μm), concomitant with the activation of antioxidant and detoxification mechanisms (increased level of total glutathione in all size-classes, and increased glutathione-S-transferase activity in PE-MPs > 250 μm), preventing lipid peroxidation. In addition, it was observed a reduction of aerobic energy production (decreased activity of the electron transport system) and a slight increase in neurotransmission (cholinesterase activity). After a long-term exposure (28 d), the presence and ingestion of PE-MPs did not affect reproduction and biomass of L. variegatus. The activation and efficiency of the antioxidant and detoxification mechanisms allied with the anatomy and physiology of L. variegatus, its feeding strategy and potentially dynamic ingestion/egestion capacity seem to be key features preventing MP deleterious effects under short- and chronic-exposures. Considering the MPs levels reported for freshwater sediments, and despite evidence of MPs ingestion and some sub-organismal effects, our results suggest no adverse impacts of PE-MPs contamination on L. variegatus populations fitness. This study applies an integrative approach in which data concerning the ingestion of different sized MPs and subsequent sub-cellular and apical responses are delivered, raising knowledge on endobenthic invertebrates' strategies to potentially overcome MP toxicity in field contaminated sites.

The gut retention time of microplastics in barnacle naupliar larvae from different climatic zones and marine habitats

Microplastic ingestion has been widely documented in marine zooplankton, but the retention time of microplastics in their digestive gut are still poorly studied, especially among species from different climatic zones and marine habitats. This study evaluated the ingestion and gut retention time of four sizes of fluorescent microplastic beads (1.3, 7.3, 10.6, and 19.0 μm) in stage II naupliar larvae of nine barnacle species from different habitats (epibiotic on turtles, mangroves, coral reefs, and rocky shores) and climatic zones (subtropical/tropical and temperate). Microbeads were not lethal to all species (climatic zones/habitats) tested from the four sizes of non-fluorescent virgin microbeads (1.7, 6.8, 10.4 and 19.0 μm, each at concentrations 1, 10, 100, and 1000 beads mL^-1). Gut retention time of microplastic beads in barnacle naupliar larvae significantly increased with decreasing size. Microbeads resided in digestive tracts generally 3-4 times longer in rocky shore and coral reef barnacles than in muddy shore and epibiotic ones. However, species from different climatic zone did not differ in retention time. Our results suggested nauplius larvae from rocky shore and coral reef barnacles appear to be more susceptible to the impacts of longer retained microplastics (e.g., toxic chemicals present on the surface).

Environmental fate and impacts of microplastics in aquatic ecosystems: a review

Wide usage of plastic products leads to the global occurrence of microplastics (MPs) in the aquatic environment. Due to the small size, they can be bio-ingested, which may cause certain health effects. The present review starts with summarizing the main sources of various types of MPs and their occurrences in the aquatic environment, as well as their transportation and degradation pathways. The analysis of migration of MPs in water environments shows that the ultimate fate of most MPs in water environments is cracked into small fragments and sinking into the bottom of the ocean. The advantages and disadvantages of existing methods for detection and analysis of MPs are summarized. In addition, based on recent researches, the present review discusses MPs as carriers of organic pollutants and microorganisms, and explores the specific effects of MPs on aquatic organisms in the case of single and combined pollutants. Finally, by analysing the causes and influencing factors of their trophic transfer, the impact of MPs on high-level trophic organisms is explored.

The sources, fate and impacts of microplastics in aquatic ecosystems.

Exposure to polystyrene microplastics impairs gonads of zebrafish (Danio rerio)

Microplastic contamination poses a great threat to the health of aquatic species, which may affect their reproduction and result in ecological consequences. There is a need to further elucidate the potential impact microplastics can impose on aquatic species. In this study, the effects of exposure to polystyrene microplastics on reproductive organs, and the underlying response mechanisms, were investigated using zebrafish Danio rerio. After 21 days of continuous waterborne exposure, no significant difference was observed at the lower concentration of 10 μg/L. At concentrations above 100 μg/L, significantly enhanced reactive oxygen species (ROS) level was found in both male and female liver and gonads. At the concentration of 1000 μg/L, significantly increased apoptosis levels were observed in male testes, triggering increased expression of p53-mediated apoptotic pathways; histological alteration in the form of a significant decrease in testis basement membrane thickness was also observed. This study demonstrated that exposure to microplastics can induce molecular responses and histological alterations in fish gonads, implying potential adverse impact on fish reproductive organs. This work provided new insights on the reproductive damage microplastics can cause in fish and have implications in fields of freshwater ecology and environmental toxicology.

Probabilistic environmental risk assessment of microplastics in marine habitats

Microplastics are ubiquitous in the environment and given the large number of published hazard and exposure studies, quantitative environmental risks assessments of microplastics become feasible. We present here the first environmental risk assessment for marine waters based only on measured concentrations. The Thevariability and uncertainty of the measured data was accounted for in the exposure assessment, while probabilistic species sensitivity distributions were used for hazard assessment, from which a probability distribution was extracted for the predicted no-effect concentration (PNEC). By dividing the exposure distribution by the PNEC-distribution, we were able to calculate probabilistic risk characterisation ratios for each water body in which measurements were performed. Results show a good coverage of the world's major water bodies by measured exposure concentrations (MECs), while the hazard assessment could be improved by aligning the type of particles tested in hazard studies (size, form, polymer) to those actually found in the oceans. Overall, the mean predicted no-effect concentration (PNEC) is 3.84·10⁶ part m^-3, with Oryzias melastigma being the most sensitive species (calculated mean NOEC of 3.90·10⁶ part m^-3). Interestingly, the only type of dose descriptor that could be extracted from the literature for particles above 10-20 μm was the highest observed no effect concentration (HONEC), which indicates a very low or null toxicity of these larger MPs towards marine organisms. The mean MEC is 1.5·10³ part m^-3, the highest concentrations being measured in the Atlantic and Pacific Ocean. Although there is a very small overlap of the probability distribution associated with the RCR (0.00002 % of the data points), the mean RCR is 4·10^-4 and therefore risks are unlikely given the available data. However, as increasing amounts of plastic reach the environment, RCRs can be expected to increase in the future.

Microplastics in the Food Chain: Food Safety and Environmental Aspects

Plastic has been an incredibly useful and indispensable material in all aspects of human life. Without it many advances in medicine, technology or industry would not have been possible. However, its easy accessibility and low cost have led to global misuse. Basically, the production of the plastics from different chemical agents is very easy but unfortunately difficult to reuse or recycle, and it is thrown away as litter, incinerated or disposed of in landfill. Plastic once in the environment begins to degrade to very small sizes. Thus, many animals mistake them for food, so plastic enters a marine, terrestrial or freshwater food web. These microplastics although chemically inert have been shown to act as tiny "bio-sponges" for harmful chemicals found in the environment changing the nature of a plastic particle from chemically harmless to potentially toxic. It was believed that microparticles would simply pass through the gastrointestinal tract of animals and humans with no biological effect. However, studies have shown that they are sometimes taken up and distributed throughout the circulatory and lymphatic system and may be stored in the fatty tissues of different organisms. The result of the uptake of them showed potential carcinogenic effects, liver dysfunction and endocrine disruption. This review focuses on micro- and nanoplastics and their way entering marine and freshwater food webs, with particular attention to microplastic trophic transfer, their toxic side effects and influence to the human consumer in health and safety in the future.

Molecular and cellular responses to short exposure to bisphenols A, F, and S and eluates of microplastics in C. elegans

Bisphenol F (BPF) and bisphenol S (BPS) have been developed as an alternative to bisphenol A (BPA), a well-known endocrine disruptor, leading to their detection in the aquatic environment. In this work, we used the animal model Caenorhabditis elegans to improve our understanding of their potential effects on the biota and the environment. Our findings demonstrated that, after 24 h exposure, all the bisphenols examined increased the number of apoptotic corpses and the expression of the detoxifying enzymes SOD-3 and GST-4, without affecting the ROS levels, while BPA and BPS significantly enhanced DNA fragmentation. Furthermore, similarly to BPA, BPF and BPS did not alter the lifespan through the activation of SEK-1 and SKN-1 pathways. Thus, this study raises the attention of the risks associated with exposure to BPA alternatives. We also examined the effects of microplastic (MP) eluates on C. elegans. Aqueous extracts of weathered microplastic samples, both at high and low degradation state and pellets, have been evaluated for their effects on lifespan, DNA fragmentation, germline apoptosis, and oxidative stress response. Overall, our findings showed that eluates of low degraded plastics exert a greater toxic effect on the nematode C. elegans compared with the aqueous sample of high degraded plastic fragments and pellets.

Polystyrene microplastics cause granulosa cells apoptosis and fibrosis in ovary through oxidative stress in rats

Microplastics (MPs) are receiving increased attention as a harmful environmental pollutant. Studies have investigated that MPs have reproductive toxicity, but the mechanism is little known. Here, we aimed to investigate the effects of polystyrene microplastics (PS-MPs) on ovary in rats and the underlying molecular mechanisms. in vivo, thirty-two female Wistar rats were exposed to 0.5 μm PS-MPs at different concentrations (0, 0.015, 0.15 and 1.5 mg/d) for 90 days. And then, all animals were sacrificed, ovaries and blood were collected for testing. in vitro, granulosa cells (GCs) were separated from rat ovary and treated with 0、1、5、25 μg/mL PS-MPs and reactive oxygen species (ROS) inhibitor N-Acetyl-l-cysteine (NAC) respectively. Our results showed that PS-MPs could enter into GCs and result in the reducing of growing follicles number. And the Enzyme-linked immunosorbent assay (ELISA) manifested that PS-MPs could obviously decrease the level of anti-Müllerian hormone (AMH). In addition, PS-MPs induced oxidative stress, apoptosis of GCs and ovary fibrosis evidenced by assay kits, flow cytometry, immunohistochemistry, Masson's trichrome and Sirius red staining. Moreover, the western blot assay manifested that PS-MPs exposure significantly increased the expression levels of Wnt/β-Catenin signaling pathways-related proteins (Wnt, β-catenin, p-β-catenin) and the main fibrosis markers (transforming growth factor-β (TGF-β), fibronectin, α-smooth muscle actin (α-SMA). Additionally, the expression levels of Wnt and p-β-catenin, apoptosis of GCs decreased after NAC treatment. In summary, polystyrene microplastics cause fibrosis via Wnt/β-Catenin signaling pathway activation and granulosa cells apoptosis of ovary through oxidative stress in rats, both of which ultimately resulted in decrease of ovarian reserve capacity.