Accumulation of polystyrene microplastics in juvenile Eriocheir sinensis and oxidative stress effects in the liver

Biodistribution of synthesized polyethylene terephthalate fibers in adult zebrafish, their sex hormone disruption effect, and mitigation using natural organic matter

Although polyethylene terephthalate (PET) fibers are a representative form of plastic pollutants, studies on their toxicity are currently limited compared to other plastic types. Moreover, the effect of natural organic matter (NOM) on their toxicity has not been investigated. In this study, female and male adult zebrafish were exposed to synthesized PET fibers at concentrations of 0.1, 1, 10, and 100 mg/L in the presence and absence of 10 mg/L of NOM for 10 d. Bioaccumulation of PET fibers in zebrafish intestine, liver, and gills was identified and expression levels of reactive oxygen species (ROS) generation, sex hormones, and oxidative stress and sex hormone-related genes were measured. In addition, the developmental stages of gonadal cells were examined through histological analysis. We found that PET fibers bioaccumulated in the intestine and liver of zebrafish. ROS generation significantly increased at 100 mg/L of PET fibers, the expression of oxidative stress-related genes decreased in female and increased in male zebrafish. Exposure to 100 mg/L of PET fibers did not affect 17-beta estradiol, but significantly decreased the testosterone levels in male zebrafish. Sex hormone-related genes significantly decreased in both female and male zebrafish, except for androgen receptor in female zebrafish. However, these changes were exacerbated by the removal of NOM, suggesting a protective effect of NOM against PET fibers toxicity. We demonstrated that the accumulated PET fibers may lead to oxidative stress and sex hormone alteration, and disrupt the development of gonadal cells. Additionally, the NOM coating did not alter bioaccumulation considerably, but mitigated the adverse effects at the hormone level in PET fiber-exposed zebrafish. Thus, this study provides a basis for further research on the toxicity assessment of PET fibers and interactions between NOM and PET fiber-related toxicity.

Potential harmful impacts of micro- and nanoplastics on the health of a tropical sea cucumber, Holothuria leucospilota, evidenced by changes of gut microflora, histology, immune and oxidative indexes

Nanoplastics (NPs) and microplastics (MPs) have emerged as pervasive environmental pollutants, and they ubiquitously distribute in ecosystems and accumulate within organisms, thereby posing a substantial threat to global ecology. Though the disruptive effects of NPs and MPs on physiology and behavior in some aquatic species have been extensively documented, the potential impacts of them on a widespread sea cucumber, Holothuria leucospilota, remain unexplored. In this study, we conducted a comprehensive investigation to reveal the effect of polyethylene NPs (200 nm) and MPs (20 μm) on the health of the sea cucumber. The results indicated that the exposure to NPs and MPs deeply altered the gut microbiota, wherein a substantial alternation of core gut microorganisms such as Rhodobacteraceae and Flavobacteriaceae was observed. NPs and MPs induced oxidative stress in the gut of sea cucumbers, which may be linked to intraspecific variations in the abundance of Rhodobacteraceae, Arcobacteraceae, and Spirochaetaceae, as well as an immune imbalance associated with shifts in Rhodobacteraceae and Arcobacteraceae populations within the gut microbiota. Notably, NPs exerting a more pronounced effect on oxidative stress levels compared to MPs. Additionally, obvious transmission and accumulation of plastic particles could be observed in the gut tissues, and therefore it likely contributed to histological damage, immunological dysregulation, and oxidative stress. These findings clearly demonstrated that NPs and MPs exert harmful impacts on the health of the sea cucumber. This study provides valuable and deep insights into the broader ecological hazards caused by the contamination of plastic particles in marine ecosystems.

MAPK signaling pathway enhances tolerance of Mytilus galloprovincialis to co-exposure of sulfamethoxazole and polyethylene microplastics

Microplastics (MPs) and antibiotics often coexist in complex marine environments, yet their combined detrimental effects on marine organisms remain underexplored. This study evaluated the effects of polyethylene microplastics (PE, 200 μg/L) and sulfamethoxazole (SMX, 50 μg/L), both individually and in combination, on Mytilus galloprovincialis. The exposure lasted 6 days, followed by a 6-day recovery period. Bioaccumulation, DNA damage, pollutants transport/metabolism related responses and responding alterations of mitogen-activated protein kinase (MAPK) signaling pathway were detected in gills and digestive glands. Bioaccumulation of SMX/PE in mussels occurred in a tissue-specific manner, co-exposure altered SMX contents in investigated tissues. Co-exposure did not induce extra DNA damage, elevated DNA damage was alleviated during the recovery period in all treated groups. The exposure of SMX/PE exerted different alterations in pollutants transport/metabolism related responses, characterized by multixenobiotic resistance and relative expression of key genes (cytochrome P450 monooxygenase, glutathione S-transferase, ATP-binding cassette transporters). Key molecules (p38 MAPK, c-jun N-terminal kinase, extracellular regulated protein kinase, nuclear factor-κB and tumor protein p53) in MAPK signaling pathway were activated at transcriptional and translational levels after SMX/PE and co-exposure. Co-regulation between MAPK members and pollutants transport/metabolism related factors was revealed, suggesting MAPK signaling pathway served as a regulating hub in exposed mussels to conquer SMX/PE stress. Overall, this study provides new insights on SMX/PE induced health risks in marine mussels and potential mechanism through MAPK cascades regulation.

The comparative toxicity of biobased, modified biobased, biodegradable, and petrochemical-based microplastics on the brackish water flea Diaphanosoma celebensis

The escalating production and improper disposal of petrochemical-based plastics have led to a global pollution issue with microplastics (MPs), which pose a significant ecological threat. Biobased and biodegradable plastics are believed to mitigate plastic pollution. However, their environmental fate and toxicity remain poorly understood. This study compares the in vivo effects of different types of MPs, poly(butylene adipate-co-terephthalate) as a biodegradable plastic, polylactic acid (PLA) as a biobased plastic, β-cyclodextrin-grafted PLA as a modified biobased plastic, and low density polyethylene as the reference petrochemical-based plastic, on the key aquatic primary consumer Diaphanosoma celebensis. Exposure to MPs resulted in significant reproductive decline, with comparable effects observed irrespective of MP type or concentration. Exposure to MPs induced distinct responses in redox stress, with transcriptional profiling revealing differential gene expression patterns that indicate varied cellular responses to different types of MPs. ATP-binding cassette transporter activity assays demonstrated altered efflux activity, mainly in response to modified biobased and biodegradable MPs. Overall, this study highlights the comparable in vivo and in vitro effects of biobased, biodegradable, and petrochemical-based MPs on aquatic primary consumers, highlighting their potential ecological implications.

The use of chitosan as an antioxidant in the feed of cultivated P. vannamei shrimp against oxidative stress induced by exposure to microplastics

Microplastics (MP) are omnipresent in aquaculture and can induce several toxic effects, mainly oxidative stress. Therefore, alternatives to minimize these effects are welcome. In this study, chitosan (1 and 3 g/kg) was supplemented through the feed of farmed shrimp P. vannamei for 30 days. After this period, the shrimp were exposed to MP (0.5 mg/L) for 7 days. The results showed the presence of MP in hepatopancreas, gills and muscle. Hepatopancreas morphological alterations, as well as lipid peroxidation, a decrease in GSH level, and an increase in SOD activity indicated an oxidative stress that was reversed by chitosan. The muscle was also affected by MP, showing decreased CAT activity and increased SOD activity, though no lipid peroxidation was observed. In muscle, chitosan reversed the SOD increase to basal activity. The results obtained showed that chitosan was more effective against oxidative stress than in preventing accumulation and histological damage.

The impacts of microplastics on zebrafish behavior depend on initial personality state

Microplastic pollution is associated with inflammation, gut dysbiosis and behavioral changes in fish. Fish have distinct personality traits but the role of personality in behavioral toxicology is rarely considered. We classified zebrafish on four behavioral axes: boldness, anxiety, sociability and exploration tendency then exposed them to low- or high- concentrations of two types of polyethylene microplastics (low- and high-density) for 28 days. Behaviors, antioxidant enzymes (catalase and superoxide dismutase), and gut microbiome were then measured. There were direct effects of microplastics on boldness, anxiety and sociability. However, fish retained their initial behavioral tendencies. Exposure to all microplastic treatments reduced average swimming speed and decreased the time spent motionless. Microplastic exposure did not affect antioxidant enzymes but did cause significant changes in the composition of the gut microbiome. This study demonstrates that environmentally realistic concentrations of microplastics can alter fish behavior, but much of the variance in response can be explained by personality.

Ecotoxicological effects of polystyrene nanoplastics on common carp: Insights into blood parameters, DNA damage, and gene expression

Plastics are ubiquitous in modern society due to their cost-effectiveness, lightweight nature, and versatility. However, their extensive use and inadequate recycling have led to a significant environmental challenge, with plastic waste accumulating rapidly and causing ecological and health problems, especially in aquatic environments. Nanoplastics, particles ranging from 1 to 100 nm, have emerged as a particularly concerning subset due to their ability to easily penetrate biological barriers and accumulate in tissues. In this study, we investigated the toxicity of carboxylate-modified polystyrene nanoplastics (PS-NPs) on common carp (Cyprinus carpio), a species often used in ecotoxicology research due to its ability to accumulate pollutants. The PS-NPs were characterized, and their effects on DNA damage gene expression related to oxidative stress and immunity were examined. PS-NPs with a diameter of 20-30 nm were found to possess a spherical shape and negatively charged surfaces. Exposure to PS-NPs led to significant DNA damage in the blood and brain cells of common carp, with higher concentrations resulting in more severe damage. Additionally, PS-NP exposure influenced the expression of genes related to antioxidative defense and stress response in the liver. Specifically, genes encoding superoxide dismutase (SOD), catalase (CAT), and heat shock protein 70 (Hsp70) showed upregulation, while glutathione peroxidase (GPx) and glutathione S-transferase (GST) exhibited downregulation at higher PS-NP concentrations. Furthermore, the immune-related genes interleukin-1ß (IL-1ß), interleukin-8 (IL-8), and tumor necrosis factor-α (TNF-α) displayed dose-dependent downregulation in the liver tissue. These findings suggest that exposure to PS-NPs induces oxidative stress, disrupts immune responses, and causes DNA damage in common carp. The results highlight the need for further research on the environmental impacts of PS-NPs and underscore the importance of proper waste management and recycling practices to mitigate plastic pollution.

Understanding and addressing microplastic pollution: Impacts, mitigation, and future perspectives

Improper disposal of household and industrial waste into water bodies has transformed them into de facto dumping grounds. Plastic debris, weathered on beaches degrades into micro-particles and releases chemical additives that enter the water. Microplastic contamination is documented globally in both marine and freshwater environments, posing a significant threat to aquatic ecosystems. The small size of these particles makes them susceptible to ingestion by low trophic fauna, a trend expected to escalate. Ingestion leads to adverse effects like intestinal blockages, alterations in lipid metabolism, histopathological changes in the intestine, contributing to the extinction of vulnerable species and disrupting ecosystem balance. Notably, microplastics (MPs) can act as carriers for pathogens, potentially causing impaired reproductive activity, decreased immunity, and cancer in various organisms. Studies have identified seven principal sources of MPs, including synthetic textiles (35%) and tire abrasion (28%), highlighting the significant human contribution to this pollution. This review covers various aspects of microplastic pollution, including sources, extraction methods, and its profound impact on ecosystems. Additionally, it explores preventive measures, aiming to guide researchers in selecting techniques and inspiring further investigation into the far-reaching impacts of microplastic pollution, fostering effective solutions for this environmental challenge.

Polystyrene microplastics facilitate renal fibrosis through accelerating tubular epithelial cell senescence

Microplastics (MPs), emerging contaminants, are easily transported and enriched in the kidney, suggesting the kidney is susceptible to the toxicity of MPs. In this study, we explored the toxicity of MPs, including unmodified polystyrene (PS), negative-charged PS-SO3H, and positive-charged PS-NH2 MPs, in mice models for 28 days at a human equivalent concentration. The results showed MPs significantly increased levels of UREA, urea nitrogen (BUN), creatinine (CREA), and uric acid (UA) levels in serum and white blood cells, protein, and microalbumin in urine. In the kidney, MPs triggered persistent inflammation and renal fibrosis, which was caused by the increased senescence of tubular epithelial cells. Moreover, we identified the critical role of the Klotho/Wnt/β-catenin signaling pathway in the process of MPs induced senescence of tubular epithelial cells, promoting the epithelial-mesenchymal transformation of epithelial cells. MPs supported the secretion of TGF-β1 by senescent epithelial cells and induced the activation of renal fibroblasts. On the contrary, restoring the function of Klotho can alleviate the senescence of epithelial cells and reverse the activation of fibroblasts. Thus, our study revealed new evidence between MPs and renal fibrosis, and adds an important piece to the whole picture of the plastic pollution on people's health.

Eco-toxicity assessment of polypropylene microplastics in juvenile zebrafish (Danio rerio)

In recent years, everyone has recognized microplastics as an emerging contaminant in aquatic ecosystems. Polypropylene is one of the dominant pollutants. The purpose of this study was to examine the effects of exposing zebrafish (Danio rerio) to water with various concentrations of polypropylene microplastics (11.86 ± 44.62 μm), including control (0 mg/L), group 1 (1 mg/L), group 2 (10 mg/L), and group 3 (100 mg/L) for up to 28 days (chronic exposure). The bioaccumulation of microplastics in the tract was noted after 28 days. From the experimental groups, blood and detoxifying organs of the liver and brain were collected. Using liver tissues evaluated the toxic effects by crucial biomarkers such as reactive oxygen species, anti-oxidant parameters, oxidative effects in protein & lipids, total protein content and free amino acid level. The study revealed that the bioaccumulation of microplastics in the organisms is a reflection of the oxidative stress and liver tissue damage experienced by the group exposed to microplastics. Also, apoptosis of blood cells was observed in the treated group as well as increased the neurotransmitter enzyme acetylcholine esterase activity based on exposure concentration-dependent manner. The overall results indicated bioaccumulation of microplastics in the gut, which led to increased ROS levels. This consequently affected antioxidant biomarkers, ultimately causing oxidation of biomolecules and liver tissue injury, as evidenced by histological analysis. This study concludes that chronic ingestion of microplastics causes considerable effects on population fitness in the aquatic environment, as well as other ecological complications, and is also critical to understand the magnitude of these contaminants' influence on ichthyofauna.

Combined effects of microplastics and benzo[a]pyrene on Asian sea bass Lates calcarifer growth and expression of functional genes

Microplastics (MPs) and polycyclic aromatic hydrocarbons (PAHs) are priority contaminants of marine environments. However, their combined toxic effects on aquatic organisms are still largely unclear. In this study, the toxicological effects of microplastics (MPs) and Benzo[a]pyrene (BaP), a representative PAH, on Asian sea bass Lates calcarifer was investigated. Juvenile Asian sea bass were exposed for 56 days to polyethylene MPs (0.1 and 1 mg/L) and BaP (20 and 80 μg/L) as single or combined environmental stressors. The effects of MPs and BaP exposure on fish were evaluated considering several biological indices such as growth and condition indices, the oxidative stress response in the liver, and the expression levels of genes related to the stress, immunomodulation, detoxification, and apoptosis. Exposure to MPs and BaP in single or combined experiments significantly (P < 0.05) decreased fish growth, and altered body protein content and food conversion ratio (FCR), but greater magnitudes of changes was observed in the combined experimental group of BaP80 + MP1. The activities of liver antioxidant enzymes: catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GPx) decreased; meanwhile, malondialdehyde (MDA) activity was dramatically enhanced (P < 0.05). The combined groups with higher concentrations (BaP80+ MP1) caused more severe alterations in enzyme levels compared to the single exposure groups and lower concentrations. MDA was the most affected among the studied enzymes. The expression levels of functional genes involved in stress response (GPX, HSP70, HSP90), pro-inflammation (LYZ, IL-1β, IL-8, and TNF-α), and detoxification (CYP1A) displayed significant alterations as the result of exposure to MPs and BaP single and in combination. The transcription levels of functional genes were more affected in fish exposed to BaP at 80 ng/mL when combined with MPs at 1 mg/mL. Additionally, MPs and BaP heightened the expression of apoptotic-related genes (p53 and caspase-3) on day 7 of exposure in a dose-dependent synergetic manner (P < 0.05). The results of this study demonstrate that exposure to MPs and BaP alone results in significant alterations in fish growth and condition factors, and could activate the stress response, stimulate the anti-oxidative defense system, immune transcriptomic response, and apoptosis in Asian sea bass; however, MPs can enhance the adverse effects of BaP on biological markers.

Effects of Microplastic Exposure against White Spot Syndrome Virus Infection in Pacific White Shrimp (Penaeus vannamei)

Plastic waste has emerged as a major environmental concern in recent years. As plastic waste discharged into the marine environment, it undergoes a breakdown process, eventually accumulating in aquatic organisms in the form of microplastics (MPs). To date, reduced food intake, nutritional absorption, and impaired immune system are known adverse effects of MPs-exposed aquatic organisms. This study aims to investigate whether MP exposure accelerated white spot syndrome virus (WSSV) infection in Pacific white shrimp (Penaeus vannamei) via laboratory tests. Briefly, experimental shrimp were divided into four groups; WSSV (group 1); MP (group 2); WSSV + MP (group 3); and Control (group 4). No mortality was observed in group 2, group 4, and even in group 1. However, group 3 showed a cumulative mortality of 50% during the experimental period. The PCR assay results showed no WSSV in the other three groups (groups 1, 2, and 4), but the dead and alive shrimp collected from group 3 were confirmed to be infected with the virus. Histopathological examination revealed normal structures in the hepatopancreas, gill, and muscle tissues of group 4, whereas numerous abnormally shaped nuclei were detected in the gill tissue of group 2. Moreover, group 1 showed minor WSSV-related lesions with few basophilic inclusion bodies in the gills, interestingly, group 3 exhibited severe lesions with numerous basophilic inclusion bodies in the gills. In conclusion, this study confirmed the correlation between the viral disease of shrimp and MPs, which can cause significant economic losses to the shrimp aquaculture industry.

Changes in characteristics and risk of freshwater microplastics under global warming

Microplastics present a significant threat to freshwater ecosystems. However, the impact of global warming on their characteristics and associated risks remains uncertain. This study collected 2793 sample sites from literature and datasets to create a new risk assessment and rank methodology, known as the Multi-characteristics Potential Ecological Risk Index (MPERI), which incorporates various microplastic characteristics, such as concentration, size distribution, color, shape, and polymer diversity. Using regression random forest models (RRF), this study predicted that a 10 °C increase would raise microplastic concentration from 12,465.34 ± 68,603.87 to 13,387.17 ± 60,692.96 particles/m3. The percentage of small-size microplastics initially decreased (from 69.10 % to 68.72 %) and then increased (from 68.72 % to 68.78 %), while the diversity of color, shape, and polymer decreased by 0.29 %, 3.24 %, and 0.17 %, respectively. Furthermore, global warming could increase the rank of microplastic risks from high (405.25 ± 528.9) to dangerous (535.37 ± 582.03) based on the MPERI method. Most countries would experience an increase in risk values, with Indonesia and Vietnam transitioning from low to medium risk, and China and Malaysia transitioning from high to dangerous risk. The feature importance assessment of the RRF model indicated that concentration was the most influential variable in determining the change in risk values. While other microplastic characteristics had a lesser impact compared to concentration, they still influenced the risk ranking. This study highlights the role of global warming in shaping microplastic risks.

Combined effect and mechanism of microplastic with different particle sizes and levofloxacin on developing Rana nigromaculata: Insights from thyroid axis regulation and immune system

Microplastics (MPs) usually appear in the aquatic environment as complex pollutants with other environmental pollutants, such as levofloxacin (LVFX). After 45-day exposure to LVFX and MPs with different particle sizes at environmental levels, we measured the weight, snout-to-vent length (SVL), and development stages of Rana nigromaculata. Furthermore, we analyzed proteins and genes related to immune system and thyroid axis regulation, intestinal histological, and bioaccumulation of LVFX and MPs in the intestine and brain to further explore the toxic mechanism of co-exposure. We found MPs exacerbated the effect of LVFX on growth and development, and the order of inhibitory effects is as follows: LVFX-MP3>LVFX-MP1>LVFX-MP2. 0.1 and 1 μm MP could penetrate the blood-brain barrier, interact with LVFX in the brain, and affect growth and development by regulating thyroid axis. Besides, LVFX with MPs caused severer interference on thyroid axis compared with LVFX alone. However, 10 μm MP was prone to accumulating in the intestine, causing severe histopathological changes, interfering with the intestinal immune system and influencing growth and development through immune enzyme activity. Thus, we concluded that MPs could regulate the thyroid axis by interfering with the intestinal immune system.

Chronic Polystyrene Microplastic Exposure Reduces Testosterone Levels in Mice through Mitochondrial Oxidative Stress and BAX/BCL2-Mediated Apoptosis

Microplastics (MPs) have emerged as a major environmental issue. They have been found to cause significant reproductive toxicity and lower testosterone levels in adult males, though the exact mechanisms remain unclear. In this study, C57bl/6 mice were orally exposed to saline or varying doses (0.25, 0.5, and 1 mg/day) of 5 μm polystyrene MPs (PS-MPs) for 4 weeks, and TM3 mouse Leydig cells were treated with different concentrations of PS-MPs. Our results found that exposure to PS-MPs significantly reduced testosterone levels and impaired the synthesis function of testicular steroids. In vitro, PS-MPs reduced steroid synthesis in Leydig cells. Treatment with PS-MPs significantly increased the apoptosis rate and BAX/BCL2 ratio in Leydig cells. Additionally, GSH-px and SOD activities decreased, while MDA levels increased, along with a rise in mitochondrial ROS. In conclusion, chronic PS-MP exposure reduced testosterone levels in mice through mitochondrial oxidative stress and BAX/BCL2-mediated apoptosis. This study offers new insights into the health risks posed by MPs.

Impact of sub-chronic polystyrene nanoplastics exposure on hematology, histology, and endoplasmic reticulum stress-related protein expression in Nile tilapia (Oreochromis niloticus)

Nanoplastics (NPs) are one of the most hazardous marine litters, having the potential to cause far-reaching impacts on the environment and humankind. The effect of NPs on fish health has been studied, but their impact on the subcellular organelles remains unexplored. The present investigation studied the possible implications of polystyrene-nanoplastics (PS-NPs) on the hematology, tissue organization, and endoplasmic reticulum (ER) stress-related proteins in Nile tilapia (Oreochromis niloticus). Fish were exposed to ∼100 nm PS-NPs at environmentally relevant (0.1 mg/L), and sublethal (1, 10 mg/L) concentrations for 14 days through water exposure. The growth performance and hematological parameters such as erythrocytes, hemoglobin, hematocrit, and leucocytes decreased, while thrombocytes increased with PS-NPs dose-dependently. The gills, liver, kidney, and heart tissues displayed increasing degrees of pathology with increased concentrations of PS-NPs. The gills showed severe epithelial hyperplasia and lamellar fusion. The liver had an abstruse cellular framework, membrane breakage, and vacuolation. While glomerular and tubular atrophy was the most prominent pathology in the kidney tissue, the heart displayed extensive myofibrillar loss and disorderly arranged cardiac cells. The ER-stress-related genes such as bip, atf6, ire1, xbp1, pkr, and apoptotic genes such as casp3a, and bax were over-expressed, while, the anti-apoptotic bcl2 was under-expressed with increasing concentrations of PS-NPs. Immunohistochemistry and blotting results of GRP78, CHOP, EIF2S, and ATF6 in gills, liver, kidney, and heart tissues affirmed the translation to ER stress proteins. The results revealed the sub-lethal adverse effects and the activation of the ER-stress pathway in fish with sub-chronic exposure to PS-NPs.

Impact of aged and virgin polyethylene microplastics on multi end-points effects of freshwater fish tissues

The buildup of plastic waste in aquatic environments presents serious threats to the environment, wildlife, and ultimately to humans. Specifically, microplastics (MPs) ingestion by aquatic animals leads to adverse physiological and toxicological effects. In addition, discarded MPs undergo aging and degradation processes which affect their morphological properties and chemical composition, enhancing the absorption of environmental pollutants. Under this prism, the present research was conducted to investigate and compare the impact of 'aged' versus pristine low-density polyethylene microplastics (PE-MPs) on various toxicity endpoints as biochemical and molecular parameters in the muscle tissue and liver of the freshwater fish species Perca fluviatilis. In parallel, the morphological, physicochemical, and structural changes occurred in "aged" PE-MPs, (after being exposed to UV radiation for 120 days) were studied, significantly illustrating signs of oxidation and crack propagation at the surface of the studied MPs. Fish were exposed to artificial diet reached with virgin and "aged" PE-MPs, sized 100-180 μm, at concentrations of 1 mg/g of dry food for a period of 15-days. Thereafter, liver and muscle tissues were analyzed in relation to multi oxidative parameters. Compared to the control group, the observed changes in the examined fish included increased activities of antioxidant enzymes, as superoxide dismutase, catalase and glutathione reductase, enhanced concentrations of malondialdehyde, protein carbonylation, HSP70 levels, elevated MAPK phosphorylation, induction of ubiquitin-proteins, as well as heightened levels of Bax/Bcl-2 proteins, caspases and differentiated levels of LC3 II/I, SQSTM1/p62. From the studied biomarkers, apoptosis, ubiquitin and hsp70 levels, showed a more sensitive response against the ingested MPs, followed by autophagy, p38MAPK levels, antioxidant enzymes, MDA and carbonylation levels. The effect of "aged" PE-MPs was more pronounced compared to that of the virgin ones. When evaluating the response of all oxidative stress biomarkers across the studied tissues, the liver demonstrates the highest response for the majority of the biomarkers against both virgin and "aged" PE-MPs. These findings strongly indicate that "aged" MPs activate the antioxidant defence mechanisms and impact the cellular well-being of the examined fish species.

Microplastic from beach sediment to tissue: a case study on burrowing crab Dotilla blanfordi

Background

Microplastics (MPs) are pervasive pollutants in the marine environment, exhibiting persistence in coastal sediment over extended periods. However, the mechanism of their uptake by marine organisms and distribution in habitat is less understood. The objective of the present study was to investigate the presence of MP contamination in burrow sediment, feeding pellets, and tissue of Dotilla blanfordi in the Gulf of Kachchh, Gujarat State.

Methods

A total of 500 g of burrow sediment, 100 g of feeding pellets, and body tissue of 10 resident D. blanfordi were pooled as one replica. Such seven replicas from each site were analyzed for MP extraction from three sites, including Asharmata, Mandvi, and Serena, located in the Gulf of Kachchh. The standard protocol was used during the analysis of the collected samples in order to isolate MPs.

Results

The abundance of MP was found higher in burrow sediment, feeding pellets and tissue of D. blanfordi at study site Mandvi, followed by Serena and Asharmata. The abundance of MP was found higher in D. blanfordi tissue, followed by burrow sediment and feeding pellet. A significant variation was observed in MP abundance among burrow sediment, feeding pellets, and tissue. MPs with various shapes (fiber, film, and fragment), sizes (1-2, 2-3, 3-4, and 4-5 mm), and colors (blue, green, black, pink, purple, red transparent) were recorded from all the study sites. Polyurethane and polyvinyl chloride were recognized as the chemical profile of the extracted MPs. The current investigation revealed greater accumulation of MPs in D. blanfordi's tissues compared to sediment and pellets, suggesting a risk of MP contamination in marine benthic fauna with a greater rate of bioaccumulation. D. blanfordi plays a significant role as a structuring agent for MP distribution in the intertidal flat through burrowing activity.

Combined effects of polyethylene terephthalate and abamectin on enzymatic activity and histopathology response in juvenile zebrafish (Danio rerio)

One of the most pressing global environmental issues is the widespread abundance and distribution of microplastics (MPs). MPs can act as vectors for other contaminants in the environment making these small plastic particles hazardous for ecosystems. The presence of MPs in aquatic environments may pose threats to aquatic organisms that ingest them. This study examined effects of abamectin (ABM) and polyethylene terephthalate (PET) MP fragments on histopathological and enzymatic biomarkers in zebrafish (Danio rerio). Zebrafish were exposed for 96 h to pristine PET-MPs at concentrations of 5 mg/L and 10 mg/L, ABM alone at 0.006 mg/L, and the same concentration of ABM in the presence of PET-MPs in aquaria. Histopathological analysis revealed tissue content changes in liver and kidney in the presence of ABM individually and in combination with MPs. Results of enzymatic analysis showed that MPs increased the bioavailability and toxicity of pesticides due to inhibition of catalase (CAT) and acid phosphatase (ACP) enzymes. However, MPs did not affect the toxicity of ABM for glutathione s-transferase (GST) enzyme. Despite the inhibition of acetylcholinesterase (AChE) in MPs or ABM treatments, and some neurotoxicity, no change in activity of this enzyme and neurotoxicity was observed in the combined MPs and ABM treatments, although toxicity effects of MPs and ABM on zebrafish require more detailed studies.

Single and combined toxicity of tadalafil (Cilais) and microplastic in Tilapia fish (Oreochromis niloticus)

The joint impact of tadalafil (Cilais) as a pharmaceutical residue and microplastics on fish is not well comprehended. The current study examined haematological, biochemical, and antioxidant parameters, along with immunohistochemical and histological indications in tilapia (Oreochromis niloticus) after being exposed to tadalafil, polyethylene microplastics (PE-MPs), and their mixtures for 15 days. The fish were distributed into 1st group control group (The fish was maintained in untreated water without any supplements); 2nd group exposed to 10 mg/L PE-MPs;3rd group exposed to 20 mg/l tadalafil (Cilais); 4th group exposed to 20 mg/l tadalafil (Cilais) + 10 mg/LPE-MPs (in triplicate). The levels of creatinine, uric acid, glucose, AST, ALT, and albumin in fish treated with tadalafil alone or in combination with PE-MPs were significantly higher than those in the control group. Fish exposed to PE-MPs, tadalafil, and tadalafil plus PE-MPs showed significantly lower levels of RBCs, Hb, Ht, neutrophils, and lymphocytes compared to the control group. Serum levels of total antioxidant capacity and reduced glutathione (GSH) were notably lowered in fish groups subjected to PE-MPs, tadalafil, and tadalafil + PE-MPs combinations in comparison to the control group. Malondialdehyde (MDA) serum levels were notably elevated in fish groups subjected to PE-MPs, tadalafil, and tadalafil + PE-MPs combinations compared to the control group. The most severe impact was observed in the tadalafil + PE-MPs combination group. Interleukin-6 (IL-6) levels were significantly increased in liver tissues following exposure to both tadalafil and microplastics compared to tissues exposed to only one substance or the control group. Changes in the gills, liver, and renal tissues were seen following exposure to PE-MPs, tadalafil, and tadalafil + PE-MPs combination in comparison to the control group of fish. Ultimately, the mixture of tadalafil and PE-MPs resulted in the most detrimental outcomes. Tadalafil and PE-MPs exhibited showed greater adverse effects, likely due to tadalafil being absorbed onto PE-MPs.

Toxicological review of micro- and nano-plastics in aquatic environments: Risks to ecosystems, food web dynamics and human health

The increase of micro- and nano-plastics (MNPs) in aquatic environments has become a significant concern due to their potential toxicological effects on ecosystems, food web dynamics, and human health. These plastic particles emerge from a range of sources, such as the breakdown of larger plastic waste, consumer products, and industrial outputs. This review provides a detailed report of the transmission and dangers of MNPs in aquatic ecosystems, environmental behavior, and interactions within aquatic food webs, emphasizing their toxic impact on marine life. It explores the relationship between particle size and toxicity, their distribution in different tissues, and the process of trophic transfer through the food web. MNPs, once consumed, can be found in various organs, including the digestive system, gills, and liver. Their consumption by lower trophic level organisms facilitates their progression up the food chain, potentially leading to bioaccumulation and biomagnification, thereby posing substantial risks to the health, reproduction, and behavior of aquatic species. This work also explores how MNPs, through their persistence and bioaccumulation, pose risks to aquatic biodiversity and disrupt trophic relationships. The review also addresses the implications of MNPs for human health, particularly through the consumption of contaminated seafood, highlighting the direct and indirect pathways through which humans are exposed to these pollutants. Furthermore, the review highlights the recommendations for future research directions, emphasizing the integration of ecological, toxicological, and human health studies to inform risk assessments and develop mitigation strategies to address the global challenge of plastic pollution in aquatic environments.

When antibiotics encounter microplastics in aquatic environments: Interaction, combined toxicity, and risk assessments

Antibiotics and microplastics (MPs), known as emerging pollutants, are bound to coexist in aquatic environments due to their widespread distribution and prolonged persistence. To date, few systematic summaries are available for the interaction between MPs and antibiotics in aquatic ecosystems, and a comprehensive reanalysis of their combined toxicity is also needed. Based on the collected published data, we have analyzed the source and distribution of MPs and antibiotics in global aquatic environments, finding their coexistence occurs in a lot of study sites. Accordingly, the presence of MPs can directly alter the environmental behavior of antibiotics. The main influencing factors of interaction between antibiotics and MPs have been summarized in terms of the characteristics of MPs and antibiotics, as well as the environmental factors. Then, we have conducted a meta-analysis to evaluate the combined toxicity of antibiotics and MPs on aquatic organisms and the related toxicity indicators, suggesting a significant adverse effect on algae, and inapparent on fish and daphnia. Finally, the environmental risk assessments for antibiotics and MPs were discussed, but unfortunately the standardized methodology for the risk assessment of MPs is still challenging, let alone assessment for their combined toxicity. This review provides insights into the interactions and environment risks of antibiotics and MPs in the aquatic environment, and suggests perspectives for future research.

Oral exposure to polystyrene nanoplastics altered the hypothalamic-pituitary-testicular axis role in hormonal regulation, inducing reproductive toxicity in albino rats

BACKGROUND

Nanoplastics can be considered a novel contaminant for the environment because of their extensive applications in modern society, which represents a possible threat to humans. Nevertheless, the negative effect of polystyrene nanoplastics (PS-NPs) on male reproduction, fertility, and progeny outcomes is not well known. Thus, the aim of the present work was to calculate the median lethal dose (LD50) and investigate the consequences of exposure to PS-NPs (25 nm) on male reproductive toxicity.

METHODS

This investigation first determined the LD50 of PS-NPs in male Wistar rats, and then in a formal study, 24 rats were distributed into three groups (n = 8): the control group; the low-dose group (3 mg/kg bw); and the high-dose group (10 mg/kg bw) of PS-NPs administered orally for 60 days. On the 50th day of administration, the fertility test was conducted.

RESULTS

The LD50 was determined to be 2500 mg/kg. PS-NP administration induced significant alternations, mainly indicating mortality in the high-dose group, a significant elevation in body weight gain, declined sperm quality parameters, altered reproductive hormonal levels, thyroid endocrine disruption, an alternation of the normal histo-architecture and the histo-morphometric analysis of the testes, and impaired male fertility.

CONCLUSION

Altogether, the current findings provide novel perspectives on PS-NP general toxicity with specific reference to male reproductive toxicity.

Bifenthrin induces changes in clinical poisoning symptoms, oxidative stress, DNA damage, histological characteristics, and transcriptome in Chinese giant salamander (Andrias davidianus) larvae

Bifenthrin (BF) is a broad-spectrum insecticide that has gained widespread use due to its high effectiveness. However, there is limited research on the potential toxic effects of bifenthrin pollution on amphibians. This study aimed to investigate the 50 % lethal concentration (LC50) and safety concentration of Chinese giant salamanders (CGS) exposed to BF (at 0, 6.25,12.5,25 and 50 μg/L BF) for 96 h. Subsequently, CGS were exposed to BF (at 0, 0.04, and 4 μg/L BF) for one week to investigate its toxic effects. Clinical poisoning symptoms, liver pathology, oxidative stress factors, DNA damage, and transcriptome differences were observed and analyzed. The results indicate that exposure to BF at 4 μg/L significantly decreased the adenosine-triphosphate (ATP), superoxide dismutase (SOD), glutathione (GSH), and catalase (CAT) contents in the brain, liver, and kidney of CGS. Additionally, the study found that the malondialdehyde (MDA), reactive oxygen species (ROS), and 8-hydroxydeoxyguanosine (8-OHdG) contents were increased. The liver tissue exhibited significant inflammatory reactions and structural malformations. RNA-seq analysis of the liver showed that BF caused abnormal antioxidant indices of CGS. This affected molecular function genes such as catalytic activity, ATP-dependent activity, metabolic processes, signaling and immune system processes, behavior, and detoxification, which were significantly upregulated, resulting in the differential genes significantly enriched in the calcium signaling pathway, PPARα signaling pathway and NF-kB signaling pathway. The results suggest that BF induces the abnormal production of free radicals, which overwhelms the body's self-defense system, leading to varying degrees of oxidative stress. This can result in oxidative damage, DNA damage, abnormal lipid metabolism, autoimmune diseases, clinical poisoning symptoms, and tissue inflammation. This work provides a theoretical basis for the rational application of bifenthrin and environmental risk assessment, as well as scientific guidance for the conservation of amphibian populations.

Polystyrene microplastics induce male reproductive toxicity in mice by activating spermatogonium mitochondrial oxidative stress and apoptosis

Microplastics have emerged as environmental hazards in recent years. This study was intended to prove the toxic effects of microplastics on the male reproductive system and further elucidate its mechanism. C57bl/6 mice were exposed to ultrapure water or different doses (0.25, 0.5 and 1 mg/d) of 5 μm polystyrene microplastics (PS-MPs) for 4 weeks, and the GC-1 mouse spermatogonium was treated with different concentrations of PS-MPs. The results showed that sperm count and motility were decreased, and sperm deformity rate was increased after exposure to PS-MPs. The morphology of testes in PS-MPs groups exhibited pathological changes, such as abnormal development of spermatogenic tubules, and inhibited spermatogonium function. Furthermore, the fluorescence intensity of TUNEL staining and the BAX/BCL2 ratio were increased. Exposure to PS-MPs resulted in impaired mitochondrial morphology of spermatogonium, decreased activity of GSH-px and SOD, and increased the MDA level. In vitro, after treatment with PS-MPs, the cell apoptosis rate of spermatogonium was significantly increased, mitochondrial membrane potential was decreased, mitochondrial morphology was damaged, and exposure to PS-MPs increased mitochondrial reactive oxygen species, inducing an oxidative stress state in spermatogonia. In summary, PS-MPs induced a decrease in sperm quality by activating spermatogonium mitochondrial oxidative stress and apoptosis, offering novel insights into mitigating the reproductive toxicity of microplastics.

The combined toxicity of polystyrene nano/micro-plastics and triphenyl phosphate (TPHP) on HepG2 cells

Combined toxicity is a critical concern during the risk assessment of environmental pollutants. Due to the characteristics of strong hydrophobicity and large specific surface area, microplastics (MPs) and nanoplastics (NPs) have become potential carriers of organic pollutants that may pose a health risk to humans. The co-occurrence of organic pollutants and MPs would cause adverse effects on aquatic organism, while the information about combined toxicity induced by organophosphorus flame retardants and MPs on human cells was limited. This study aimed to reveal the toxicity effects of co-exposure to triphenyl phosphate (TPHP) and polystyrene (PS) particles with micron-size/nano-size on HepG2 cell line. The adsorption behaviors of TPHP on PS particles was observed, with the PS-NP exhibiting a higher adsorption capacity. The reactive oxygen species generation, mitochondrial membrane potential depolarization, lactate dehydrogenase release and cell apoptosis proved that PS-NPs/MPs exacerbated TPHP-induced cytotoxicity. The particle size of PS would affect the toxicity to HepG2 cells that PS-NP (0.07 μm) exhibited more pronounced combined toxicity than PS-MP (1 μm) with equivalent concentrations of TPHP. This study provides fundamental insights into the co-toxicity of TPHP and PS micro/nanoplastics in HepG2 cells, which is crucial for validating the potential risk of combined toxicity in humans.

Integration of transcriptome, gut microbiota, and physiology reveals toxic responses of the red claw crayfish (Cherax quadricarinatus) to imidacloprid

Imidacloprid enters the water environment through rainfall and causes harm to aquatic crustaceans. However, the potential chronic toxicity mechanism of imidacloprid in crayfish has not been comprehensively studied. In this study, red claw crayfish (Cherax quadricarinatus) were exposed to 11.76, 35.27, or 88.17 μg/L imidacloprid for 30 days, and changes in the physiology and biochemistry, gut microbiota, and transcriptome of C. quadricarinatus and the interaction between imidacloprid, gut microbiota, and genes were studied. Imidacloprid induced oxidative stress and decreased growth performance in crayfish. Imidacloprid exposure caused hepatopancreas damage and decreased serum immune enzyme activity. Hepatopancreatic and plasma acetylcholine decreased significantly in the 88.17 μg/L group. Imidacloprid reduced the diversity of the intestinal flora, increased the abundance of harmful flora, and disrupted the microbiota function. Transcriptomic analysis showed that the number of up-and-down-regulated differentially expressed genes (DEGs) increased significantly with increasing concentrations of imidacloprid. DEG enrichment analyses indicated that imidacloprid inhibits neurotransmitter transduction and immune responses and disrupts energy metabolic processes. Crayfish could alleviate imidacloprid stress by regulating antioxidant and detoxification-related genes. A high correlation was revealed between GST, HSPA1s, and HSP90 and the composition of gut microorganisms in crayfish under imidacloprid stress. This study highlights the negative effects and provides detailed sequencing data from transcriptome and gut microbiota to enhance our understanding of the molecular toxicity of imidacloprid in crustaceans.

The Role of Life Stages in the Sensitivity of Hediste diversicolor to Nanoplastics: A Case Study with Poly(Methyl)Methacrylate (PMMA)

The presence of plastic particles in oceans has been recognized as a major environmental concern. The decrease in particle size increases their ability to directly interact with biota, with particles in the nanometer size range (nanoplastics-NPs) displaying a higher ability to penetrate biological membranes, which increases with the decrease in particle size. This study aimed to evaluate the role of life stages in the effects of poly(methyl)methacrylate (PMMA) NPs on the polychaete Hediste diversicolor, a key species in the marine food web and nutrient cycle. Thus, behavioral (burrowing activity in clean and spiked sediment) and biochemical endpoints (neurotransmission, energy reserves, antioxidant defenses, and oxidative damage) were assessed in juvenile and adult organisms after 10 days of exposure to spiked sediment (between 0.5 and 128 mg PMMA NPs/Kg sediment). Overall, the results show that H. diversicolor is sensitive to the presence of PMMA NPs. In juveniles, exposed organisms took longer to burrow in sediment, with significant differences from the controls being observed at all tested concentrations when the test was performed with clean sediment, whereas in PMMA NP-spiked sediment, effects were only found at the concentrations 8, 32, and 128 mg PMMA NPs/Kg sediment. Adults displayed lower sensitivity, with differences to controls being found, for both sediment types, at 8, 32, and 128 mg PMMA NPs/Kg sediment. In terms of Acetylcholinesterase, used as a marker of effects on neurotransmission, juveniles and adults displayed opposite trends, with exposed juveniles displaying increased activity (suggesting apoptosis), whereas in adults, overall decreased activity was found. Energy-related parameters revealed a generally similar pattern (increase in exposed organisms) and higher sensitivity in juveniles (significant effects even at the lower concentrations). NPs also demonstrated the ability to increase antioxidant defenses (higher in juveniles), with oxidative damage only being found in terms of protein carbonylation (all tested NPs conditions) in juveniles. Overall, the data reveal the potential of PMMA NPs to affect behavior and induce toxic effects in H. diversicolor, with greater effects in juveniles.

Neurotoxic effects of polystyrene nanoplastics on memory and microglial activation: Insights from in vivo and in vitro studies

Nanoplastics, arising from the fragmentation of plastics into environmental pollutants and specialized commercial applications, such as cosmetics, have elicited concerns due to their potential toxicity. Evidence suggests that the oral ingestion of nanoplastics smaller than 100 nm may penetrate the brain and induce neurotoxicity. However, comprehensive research in this area has been hampered by technical challenges associated with the detection and synthesis of nanoplastics. This study aimed to bridge this research gap by successfully synthesizing fluorescent polystyrene nanoplastics (PSNPs, 30-50 nm) through the incorporation of IR-813 and validating them using various analytical techniques. We administered PSNPs orally (10 and 20 mg/kg/day) to mice and observed that they reached brain tissues and induced cognitive dysfunction, as measured by spatial and fear memory tests, while locomotor and social behaviors remained unaffected. In vitro studies (200 μg/mL) demonstrated a predominant uptake of PSNPs by microglia over astrocytes or neurons, leading to microglial activation, as evidenced by immunostaining of cellular markers and morphological analysis. Transcriptomic analysis indicated that PSNPs altered gene expression in microglia, highlighting neuroinflammatory responses that may contribute to cognitive deficits. To further explore the neurotoxic effects of PSNPs mediated by microglial activation, we measured endogenous neuronal activity using a multi-electrode array in cultured hippocampal neurons. The application of conditioned media from microglia exposed to PSNPs suppressed neuronal activity, which was reversed by inhibitors of microglial activation. Our findings offer detailed insights into the mechanisms by which nanoplastics damage the brain, particularly emphasizing the potential environmental risk factors that contribute to cognitive impairment in neurodegenerative diseases.

Microplastics and Oxidative Stress-Current Problems and Prospects

Microplastics (MPs) are plastic particles between 0.1 and 5000 µm in size that have attracted considerable attention from the scientific community and the general public, as they threaten the environment. Microplastics contribute to various harmful effects, including lipid peroxidation, DNA damage, activation of mitogen-activated protein kinase pathways, cell membrane breakages, mitochondrial dysfunction, lysosomal defects, inflammation, and apoptosis. They affect cells, tissues, organs, and overall health, potentially contributing to conditions like cancer and cardiovascular disease. They pose a significant danger due to their widespread occurrence in food. In recent years, information has emerged indicating that MPs can cause oxidative stress (OS), a known factor in accelerating the aging of organisms. This comprehensive evaluation exposed notable variability in the reported connection between MPs and OS. This work aims to provide a critical review of whether the harmfulness of plastic particles that constitute environmental contaminants may result from OS through a comprehensive analysis of recent research and existing scientific literature, as well as an assessment of the characteristics of MPs causing OS. Additionally, the article covers the analytical methodology used in this field. The conclusions of this review point to the necessity for further research into the effects of MPs on OS.

New insights into changes in phosphorus profile at sediment-water interface by microplastics: Role of benthic bioturbation

Microplastics (MPs) have attracted increasing attention due to their ubiquitous occurrence in freshwater sediments and the detrimental effects on benthic invertebrates. However, a clear understanding of their downstream impacts on ecosystem services is still lacking. This study examines the effects of bio-based polylactic acid (PLA), fuel-based polyethylene terephthalate (PET), and biofilm-covered PET (BPET) MPs on the bioturbator chironomid larvae (Tanypus chinensis), and the influence on phosphorus (P) profiles in microcosms. The changes in biochemical responses and metabolic pathways indicated that MPs disrupted energy synthesis by causing intestinal blockage and oxidative stress in T. chinensis, leading to energy depletion and impaired bioturbation activity. The impairment further resulted in enhanced sedimentary P immobilization. For larval treatments, the internal-P loadings were respectively 11.4%, 8.6%, and 9.0% higher in the PLA, PET, and BPET groups compared to the non-MP control. Furthermore, the influence of bioturbation on P profiles was MP-type dependent. Both BPET and PLA treatments displayed more obvious impacts on P profiles compared to PET due to the changes in MP bioavailability or sediment microenvironment. This study connects individual physiological responses to broader ecosystem services, showing that MPs alter P biogeochemical processes by disrupting the bioturbation activities of chironomid larvae.

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

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

Impact of Polyethylene Terephthalate Microplastics on Drosophila melanogaster Biological Profiles and Heat Shock Protein Levels

Microplastics and nanoplastics are abundant in the environment. Further research is necessary to examine the consequences of microplastic contamination on living species, given its widespread presence. In our research, we determined the toxic effects of PET microplastics on Drosophila melanogaster at the cellular and genetic levels. Our study revealed severe cytotoxicity in the midgut of larvae and the induction of oxidative stress after 24 and 48 h of treatment, as indicated by the total protein, Cu-Zn SOD, CAT, and MDA contents. For the first time, cell damage in the reproductive parts of the ovaries of female flies, as well as in the accessory glands and testes of male flies, has been observed. Furthermore, a decline in reproductive health was noted, resulting in decreased fertility among the flies. By analyzing stress-related genes such as hsp83, hsp70, hsp60, and hsp26, we detected elevated expression of hsp83 and hsp70. Our study identified hsp83 as a specific biomarker for detecting early redox changes in cells caused by PET microplastics in all the treated groups, helping to elucidate the primary defense mechanism against PET microplastic toxicity. This study offers foundational insights into the emerging environmental threats posed by microplastics, revealing discernible alterations at the genetic level.

Vital role of oxidative stress in tadpole liver damage caused by polystyrene nanoparticles

Polystyrene nanoparticles are emerging as contaminants in freshwater environments, posing potential risks to amphibians exposed to extended periods of water contamination. Using tadpoles as a model, this study aimed to evaluate the toxicity of PS NPs. Pyrolysis-gas chromatography-tandem mass spectrometry (Py-GCMS) analysis revealed a concentration-dependent increase in polystyrene nanoparticles (PS NPs) levels in tadpoles with escalating exposure concentrations. Following exposure to 100 nm fluorescent microspheres, fluorescence was observed in the intestines and gills, peaking at 48 hours. Histopathological analysis identified degenerative necrosis and inflammation in the liver, along with atrophic necrosis of glomeruli and tubules in the kidneys. These results indicate a discernible impact of PS NPs on antioxidant levels, including reduced superoxide dismutase and catalase activities, elevated glutathione content, and increased malondialdehyde levels. Electron microscopy observations revealed the infiltration of PS NPs into Kupffer's cells and hepatocytes, leading to visible lesions such as nuclear condensation and mitochondrial disruption. The primary objective of this research was to elucidate the adverse effects of prolonged PS NPs exposure on amphibians.

Microplastics as an emerging threat to amphibians: Current status and future perspectives

Given their pervasiveness in the environment, particularly in aquatic ecosystems, plastics are posing a growing concern worldwide. Many vertebrates and invertebrates in marine, freshwater, and terrestrial ecosystems exhibit microplastic (MP) uptake and accumulation. Some studies have indicated the fatal impacts of MPs on animals and their possible transfer through food chains. Thus, it is crucial to study MP pollution and its impacts on environment-sensitive and globally threatened animal groups, such as amphibians, which also play an important role in the energy transfer between ecosystems. Unfortunately, research in this field is lacking and sources of organized information are also scarce. Hence, we systematically reviewed published literature on MPs in amphibians to fill the existing knowledge gap. Our review revealed that most of the previous studies have focused on MP bioaccumulation in amphibians, whereas, only a few research highlighted its impacts. We found that more than 80% of the studied species exhibited MP accumulation. MPs were reported to persist in different organs for a long time and get transferred to other trophic levels. They can also exhibit cytotoxic and mutagenic effects and may have fatal impacts. Moreover, they can increase the disease susceptibility of amphibians. Our study concludes the MPs as a potential threat to amphibians and urges increasing the scope and frequency of research on MP pollution and its impacts on this vulnerable animal group. We also provide a generalized method for studying MPs in amphibians with future perspectives and research directions. Our study is significant for extending the knowledge of MPs and their impacts on amphibians and guiding prospective research.

Chlorination-improved adsorption capacity of microplastics for antibiotics: A combined experimental and molecular mechanism investigation

Microplastics and antibiotics not only pollute aquatic environments and threaten human health, but are also tricky to remove. Microplastics adsorb antibiotics, and, before being released into the natural environment, most microplastics pass through some wastewater treatment and/or disinfection (such as chlorination) facilities. It is therefore necessary to understand how these treatment processes may affect or alter microplastics' properties, particularly their ability to adsorb antibiotics, and whether or not the two, when bound together, may present exacerbated harm to the environment. This study used both laboratory tests and molecular dynamics simulation to investigate the mechanism through which chlorinated microplastics (specifically polystyrene) adsorb the antibiotic tetracycline, and showed that chlorination gave the polystyrene a larger interaction area (> 21%) and more free energy (> 14%) to adsorb tetracycline. Van der Waals (vdW) forces played a more dominant role than electrostatics in facilitating tetracycline's adsorption. Moreover, a density functional theory analysis demonstrated that the vdW potentials of the microplastics decreased as more and more hydrogen atoms became replaced by chlorine, suggesting a facilitation of the adsorption of polycyclic antibiotic molecules. The experimental results confirmed the simulation's prediction that a higher degree of chlorination significantly increases the polystyrene's adsorption capacity, whereas pH and salinity had almost no effect on the adsorption. This study demonstrates that disinfection elevates the risk of antibiotics adhering to and accumulating on the surface of microplastics.

Hazards of microplastics exposure to liver function in fishes: A systematic review and meta-analysis

Microplastics (5 mm - 1 μm) have become one of the major pollutants in the environment. Numerous studies have shown that microplastics can have negative impacts on aquatic organisms, affecting their liver function levels. However, the extent of these effects and their potential toxicological mechanisms are largely unknown. In this study, a meta-analysis and systematic review were conducted to assess the effects of microplastics on fish liver function and summarize the potential toxicological mechanisms of microplastic-induced liver toxicity. The meta-analysis results indicate that compared to the control group, exposure to microplastics significantly affects fish liver indicators: aspartate aminotransferase (AST) (p < 0.001), alanine aminotransferase (ALT) (p < 0.001), alkaline phosphatase (ALP) (p < 0.001), total protein (TP) (p < 0.001), and lactate dehydrogenase (LDH) (p < 0.001), including oxidative stress indicators: superoxide dismutase (SOD) (p < 0.001), glutathione S-transferase (GST) (p < 0.001), glutathione (GSH) (p < 0.001), and malondialdehyde (MDA) (p < 0.001) in fish liver. For fish living in different environments, the potential toxicological mechanisms of microplastics exposure on fish liver may exhibit some differences. For freshwater fish, the mechanism may be that microplastics exposure causes overproduction of reactive oxygen species (ROS) in fish hepatocyte mitochondria. ROS promotes the expression of toll-like receptor 2 (TLR2) and activates downstream molecules myeloid differentiation factor 88 (MyD88) and tumor necrosis factor receptor-associated factor 6 (TRAF6) of the TLR2 signaling pathway, leading to phosphorylation of NF-κB p65. This leads to the release of inflammatory factors and oxidative stress and inflammation in fish liver. In addition, for seawater fish, the mechanism may be that microplastics exposure can cause damage or death of fish hepatocytes, leading to continuous pathological changes, inflammation, lipid and energy metabolism disorders, thereby causing significant changes in liver function indexes.

Tissue damage, antioxidant capacity, transcriptional and metabolic regulation of red drum Sciaenops ocellatus in response to nanoplastics exposure and subsequent recovery

Nanoplastics are recognized as emerging contaminants that can cause severe toxicity to marine fishes. However, limited researches were focusing on the toxic effects of nanoplastics on marine fish, especially the post-exposure resilience. In this study, red drum (Sciaenops ocellatus) were exposed to 5 mg/L polystyrene nanoplastics (100 nm, PS-NPs) for a 7-day exposure experiment, and a 14-day recovery experiment that followed. The aim was to evaluate the dynamic alterations in hepatic and branchial tissue damage, hepatic antioxidant capacity, as well as hepatic transcriptional and metabolic regulation in the red drum during exposure and post-exposure to PS-NPs. Histopathological observation found that PS-NPs primarily triggered hepatic lipid droplets and branchial epithelial liftings, a phenomenon persistently discernible up to the 14 days of recovery. Although antioxidant capacity partially recovered during recovery periods, PS-NPs resulted in a sustained reduction in hepatic antioxidant activity, causing oxidative damage throughout the entire exposure and recovery phases, as evidenced by decreased total superoxide dismutase activities and increased malondialdehyde content. At the transcriptional and metabolic level, PS-NPs primarily induced lipid metabolism disorders, DNA damage, biofilm disruption, and mitochondrial dysfunction. In the gene-metabolite correlation interaction network, numerous CcO (cytochrome c oxidase) family genes and lipid metabolites were identified as key regulatory genes and metabolites in detoxification processes. Among them, the red drum possesses one additional CcO6B in comparison to human and zebrafish, which potentially contributes to its enhanced capacity for maintaining a stable and positive regulatory function in detoxification. This study revealed that nanoplastics cause severe biotoxicity to red drum, which may be detrimental to the survival of wild populations and affect the economics of farmed populations.

Microplastic contamination in wastewater: Sources, distribution, detection and remediation through physical and chemical-biological methods

Microplastics are tiny plastic particles smaller than 5 mm. that have been widely detected in the environment, including in wastewater. They originate from various sources including breakdown of larger plastic debris, release of plastic fibres from textiles, and microbeads commonly used in personal care products. In wastewater, microplastics can pass through the treatment process and enter the environment, causing harm to biodiversity by potentially entering the food chain. Additionally, microplastics can act as a vector for harmful pollutants, increasing their transport and distribution in the environment. To address this issue, there is a growing need for effective wastewater treatment methods that can effectively remove microplastics. Currently, several physical and chemical methods are available, including filtration, sedimentation, and chemical degradation. However, these methods are costly, low efficiency and generate secondary pollutants. Furthermore, lack of standardization in the measurement and reporting of microplastics in wastewater, makes it difficult to accurately assess microplastic impact on the environment. In order to effectively manage these issues, further research and development of effective and efficient methods for removing microplastics from wastewater, as well as standardization in measurement and reporting, are necessary to effectively manage these detrimental contaminants.

Impact of microplastics and nanoplastics on liver health: Current understanding and future research directions

With continuous population and economic growth in the 21st century, plastic pollution is a major global issue. However, the health concern of microplastics/ nanoplastics (MPs/NPs) decomposed from plastic wastes has drawn public attention only in the recent decade. This article summarizes recent works dedicated to understanding the impact of MPs/NPs on the liver-the largest digestive organ, which is one of the primary routes that MPs/NPs enter human bodies. The interrelated mechanisms including oxidative stress, hepatocyte energy re-distribution, cell death and autophagy, as well as immune responses and inflammation, were also featured. In addition, the disturbance of microbiome and gut-liver axis, and the association with clinical diseases such as metabolic dysfunction-associated fatty liver disease, steatohepatitis, liver fibrosis, and cirrhosis were briefly discussed. Finally, we discussed potential directions in regard to this trending topic, highlighted current challenges in research, and proposed possible solutions.

Science-based evidence on pathways and effects of human exposure to micro- and nanoplastics

Human exposure to plastic particles has raised great concern among all relevant stakeholders involved in the protection of human health due to the contamination of the food chain, surface waters, and even drinking water as well as due to their persistence and bioaccumulation. Now more than ever, it is critical that we understand the biological fate of plastics and their interaction with different biological systems. Because of the ubiquity of plastic materials in the environment and their toxic potential, it is imperative to gain reliable, regulatory-relevant, science-based data on the effects of plastic micro- and nanoparticles (PMNPs) on human health in order to implement reliable risk assessment and management strategies in the circular economy of plastics. This review presents current knowledge of human-relevant PMNP exposure doses, pathways, and toxic effects. It addresses difficulties in properly assessing plastic exposure and current knowledge gaps and proposes steps that can be taken to underpin health risk perception, assessment, and mitigation through rigorous science-based evidence. Based on the existing scientific data on PMNP adverse health effects, this review brings recommendations on the development of PMNP-specific adverse outcome pathways (AOPs) following the AOP Users' Handbook of the Organisation for Economic Cooperation and Development (OECD).

Individual and combined impact of microplastics and lead acetate on the freshwater shrimp (Caridina fossarum): Biochemical effects and physiological responses

Microplastics and heavy metals pollution is recognised as a major problem affecting aquatic ecosystems. For this reason, this study aims to assess the toxicity of different concentrations of polyethylene microplastics (PE-MPs) (0.0, 500, and 1000 μg L-1) with a mean size of 15-25 μm and lead acetate Pb(C2H3O2)2 (0.0, 2.5, and 5 mg L-1), both individually and in combination, through the exposure of the freshwater grass shrimp, Caridinia fossarum for 15 days, focusing on microplastic interaction with co-occurring contaminants. After being exposed to both contaminants, either individually or in combination, significant alterations in numerous biochemical markers were observed. Specifically, exposure to lead acetate alone resulted in significant changes across ALP, AST, ALT, LDH, GGT, and BChE enzyme activity levels indicating hepatotoxicity and neurotoxicity. Also, Pb exposure led to alterations in total antioxidant capacity, MDA, total lipids, and glycogen contents, signalling the onset of oxidative stress. Exposure to PE-MPs alone led to changes in ALP, LDH, GGT, and BChE enzyme levels, and in MDA, total lipids, and glycogen samples' contents. Remarkably, the study observed increased bioaccumulation of lead acetate in samples treated with the combination, emphasizing the synergistic impact of PE-MPs on the toxicity of lead acetate. This synergy was also evident in AST and ALT enzyme activity levels and MDA contents. This underscores the necessity for measures to address both microplastic pollution and heavy metal contamination, taking into account the synergistic behaviour of MPs in the presence of concurrent contaminants.

Polystyrene microplastics induced disturbances in neuronal arborization and dendritic spine density in mice prefrontal cortex

An increasing use of plastics in daily life leads to the accumulation of microplastics (MPs) in the environment, posing a serious threat to the ecosystem, including humans. It has been reported that MPs cause neurotoxicity, but the deleterious effect of polystyrene (PS) MPs on neuronal cytoarchitectural morphology in the prefrontal cortex (PFC) region of mice brain remains to be established. In the present study, Swiss albino male mice were orally exposed to 0.1, 1, and 10 ppm PS-MPs for 28 days. After exposure, we found a significant accumulation of PS-MPs with a decreased number of Nissl bodies in the PFC region of the entire treated group compared to the control. Morphometric analysis in the PFC neurons using Golgi-Cox staining accompanied by Sholl analysis showed a significant reduction in basal dendritic length, dendritic intersections, nodes, and number of intersections at seventh branch order in PFC neurons of 1 ppm treated PS-MPs. In neurons of 0.1 ppm treated mice, we found only decrease in the number of intersections at the seventh branch order. While 10 ppm treated neurons decreased in basal dendritic length, dendritic intersections, followed by the number of intersections at the third and seventh branch order were observed. As well, spine density on the apical secondary branches along with mRNA level of BDNF was significantly reduced in all the PS-MPs treated PFC neurons, mainly at 1 ppm versus control. These results suggest that PS-MPs exposure affects overall basal neuronal arborization, with the highest levels at 1 and 10 ppm, followed by 0.1 ppm treated neurons, which may be related to the down-regulation of BDNF expression in PFC.

Exposure to polystyrene nanoplastics induced physiological and behavioral effects on the brittle star Ophiactis virens

Nanoplastic contamination has become an issue of environmental concern but the information on the potential adverse effects of nanoplastics on marine ecosystems is still limited. Therefore, the aim of this work was to investigate the effects of the exposure to polystyrene nanoplastics (PS-NPs; 0.05, 0.5 and 5 μg/mL) on the brittles star Ophiactis virens. Diverse endpoints at different levels of biological organization were considered, including behavior, arm regeneration capacity and oxidative stress. PS-NPs were observed on the brittle star body surface but not in inner tissues. Accumulation of PS-NPs was observed in the pre-buccal cavity of animals exposed to 5 μg/mL PS-NPs which also displayed delayed righting activity and an oxidative stress condition. Nevertheless, no effect was observed on arm regeneration efficiency at any tested PS-NPs concentration. Overall, our results highlighted that prolonged exposure to high amounts of PS-NPs could interfere at least partially with the physiology of O. virens.

Prevalence of microplastics in Peruvian mangrove sediments and edible mangrove species

Mangrove ecosystems have been hypothesised as a potential sink of microplastic debris, which could pose a threat to mangrove biota and ecological function. In this field-study we establish the prevalence of microplastics in sediments and commercially-exploited Anadara tuberculosa (black ark) and Ucides occidentalis (mangrove crab) from five different zones in the mangrove ecosystem of Tumbes, Peru. Microplastic were evident in all samples, with an average of 726 ± 396 microplastics/kg for the sediment, although no differences between the different zones of the mangrove ecosystem were observed. Microplastic concentrations were 1.6± 1.1 items/g for the black ark and 1.9 ± 0.9 microplastics/g for the mangrove crab, with a difference in the microplastic abundance between species (p < 0.05), and between the gills and stomachs of the crab (p < 0.01). Human intake of microplastics from these species, for the population in Tumbes, is estimated at 431 items per capita per year. The outcomes of this work highlight that the mangrove ecosystem is widely contaminated with microplastics, presenting a concern for the marine food web and food security.

Insight into microplastics in the aquatic ecosystem: Properties, sources, threats and mitigation strategies

Globally recognized as emergent contaminants, microplastics (MPs) are prevalent in aquaculture habitats and subject to intense management. Aquaculture systems are at risk of microplastic contamination due to various channels, which worsens the worldwide microplastic pollution problem. Organic contaminants in the environment can be absorbed by and interact with microplastic, increasing their toxicity and making treatment more challenging. There are two primary sources of microplastics: (1) the direct release of primary microplastics and (2) the fragmentation of plastic materials resulting in secondary microplastics. Freshwater, atmospheric and marine environments are also responsible for the successful migration of microplastics. Until now, microplastic pollution and its effects on aquaculture habitats remain insufficient. This article aims to provide a comprehensive review of the impact of microplastics on aquatic ecosystems. It highlights the sources and distribution of microplastics, their physical and chemical properties, and the potential ecological consequences they pose to marine and freshwater environments. The paper also examines the current scientific knowledge on the mechanisms by which microplastics affect aquatic organisms and ecosystems. By synthesizing existing research, this review underscores the urgent need for effective mitigation strategies and further investigation to safeguard the health and sustainability of aquatic ecosystems.

Physiological and histopathological effects of polystyrene nanoparticles on the filter-feeding fish Hypophthalmichthys molitrix

Excessive use of plastics in daily life is causing plastic pollution in aquatic environment and threatening the aquatic life. Therefore, research on the plastic pollution in aquatic environment is crucial to understand its impact and develop effective solution for safeguarding aquatic life and ecosystem. The current study investigated the effects of water borne polystyrene nanoparticles (PS-NPs) on hemato-immunological indices, serum metabolic enzymes, gills, and liver antioxidant parameters, plasma cortisol level and histopathological changes in liver and gill tissues of the widely distributed fish Hypophthalmichthys molitrix. The fingerlings of H. molitrix were exposed to different concentrations (T1-0.5, T2-1.0, and T3-2.0 mg/L) of PS-NPs respectively for 15 days consecutively. Our results indicated the dose dependent negative effects of PS-NPs on the physiology and histopathology of H. molitrix. Immuno-hematological indices showed significant increase in WBCs count, phagocytic activity, and lysozyme activity, while decreased RBC count, Hct%, Hb level, total proteins, IgM, and respiratory burst activity were observed. The levels of antioxidant enzymes like SOD, CAT and POD showed the decreasing trends while metabolic enzymes (AST, ALT, ALP and LDH), LPO, ROS activities and relative expressions of SOD1, CAT, HIF1-α and HSP-70 genes increased with increased concentrations of PS-NPs. Moreover, blood glucose and cortisol levels also showed significant increasing trends with dose dependent manner. Histopathological examination indicated moderate to severe changes in the gills and liver tissues of the group treated with 2.0 mg/L of PS-NPs. Overall, the results showed the deleterious effects of PS-NPs on physiology, immunity, metabolism, and gene expressions of H. molitrix. It is concluded that particulate plastic pollution has deleterious effects on filter feeding fish, which might affect human health through food chain and particulate chemical toxicity.

Assessing microplastics contamination in unviable loggerhead sea turtle eggs

Sea turtles, in comparison with marine mammals, sea birds, and fishes, are the most affected by microplastics in terms of number of individuals impacted and concentration within each organism. The ubiquitous nature and persistence of microplastics in the environment further compromises sea turtles as many species are currently vulnerable, endangered, or critically endangered. The objective of this study was to quantify microplastic contamination in unviable loggerhead sea turtle eggs (Caretta caretta). Eggs were collected from seven locations along the northwest coast of Florida. A total of 70 nests and 350 eggs were examined. Microplastics (n = 510) were found in undeveloped loggerhead sea turtle eggs across all seven sites, suggesting that maternal transference and/or exchange between the internal and external environment were possible. The frequency found was 7.29 ± 1.83 microplastic pieces per nest and 1.46 ± 0.01 per egg. Microplastics were categorized based on color, shape, size, and type of polymer. The predominant color of microplastics were blue/green (n = 236), shape was fibers (n = 369), and length was 10-300 μm (n = 191). Identified fragments, films, beads and one foam (n = 187) had the most common area of 1-10 μm2 (n = 45). Micro-Fourier Transform Infrared (μ-FTIR) spectroscopy analysis demonstrated that polyethylene (11 %) and polystyrene (7 %) were the main polymer types. For the first time microplastics were found in unviable, undeveloped loggerhead sea turtle eggs collected in northwest Florida. This work provides insight into the distribution patterns of microplastic pollutants in loggerhead sea turtle eggs and may extend to other species worldwide.

A comprehensive review on the source, ingestion route, attachment and toxicity of microplastics/nanoplastics in human systems

Microplastics (MPs)/nanoplastics (NPs) are widely found in the natural environment, including soil, water and the atmosphere, which are essential for human survival. In the recent years, there has been a growing concern about the potential impact of MPs/NPs on human health. Due to the increasing interest in this research and the limited number of studies related to the health effects of MPs/NPs on humans, it is necessary to conduct a systematic assessment and review of their potentially toxic effects on human organs and tissues. Humans can be exposed to microplastics through ingestion, inhalation and dermal contact, however, ingestion and inhalation are considered as the primary routes. The ingested MPs/NPs mainly consist of plastic particles with a particle size ranging from 0.1 to 1 μm, that distribute across various tissues and organs within the body, which in turn have a certain impact on the nine major systems of the human body, especially the digestive system and respiratory system, which are closely related to the intake pathway of MPs/NPs. The harmful effects caused by MPs/NPs primarily occur through potential toxic mechanisms such as induction of oxidative stress, generation of inflammatory responses, alteration of lipid metabolism or energy metabolism or expression of related functional factors. This review can help people to systematically understand the hazards of MPs/NPs and related toxicity mechanisms from the level of nine biological systems. It allows MPs/NPs pollution to be emphasized, and it is also hoped that research on their toxic effects will be strengthened in the future.

Efficient and accurate microplastics identification and segmentation in urban waters using convolutional neural networks

Microplastics (MPs), measuring less than 5 mm, pose threats to ecological security and human health in urban waters. Additionally, they act as carriers, transporting pollutants from terrestrial systems into oceanic circulation, contributing to global pollution. Recognizing the significance of identifying MPs in urban waters, one potential solution to the time-consuming and labor-intensive manual identification process is the application of a convolutional neural network (CNN). Therefore, having a reliable CNN model that efficiently and accurately identifies MPs is essential for extensive research on MPs pollution in urban waters. In this work, an MPs dataset with complex background was acquired from urban waters in southern China. The dataset was used to train and validate CNN models, including UNet, UNet2plus, and UNet3plus. Subsequently, the computational and inference performance of the three models was evaluated using a newly collected MPs dataset. The results showed that UNet, UNet2plus, UNet3plus, after being trained for 120 epochs, provided efficient inferences within less than 1 s, 2 s, and 3 s for 100 MPs images, respectively. Accurate segmentation with mIoU of 91.45 ± 5.93 % and 91.08 ± 6.18 % was achieved using UNet and UNet2plus, respectively, while UNet3plus exhibited a lower performance with only 82.21 ± 10.33 % mIoU. This work demonstrated that UNet and UNet2plus deliver efficient and accurate identification of MPs in urban waters. Developing CNN models that efficiently and accurately identify MPs is crucial for reducing manual time, especially in large-scale investigations of MPs pollution in urban waters.