Effects of polyethylene microplastics on the microbiome and metabolism in larval zebrafish

Effects of 2-ethylhexyl diphenyl phosphate (EHDPP) on glycolipid metabolism in male adult zebrafish revealed by targeted lipidomic analyses

The present study aims to evaluate the effects of 2-ethylhexyldiphenyl phosphate (EHDPP) on glycolipid metabolism in vivo. Adult male zebrafish were exposed to various concentrations (0, 1, 10, 100 and 250 μg/L) of EHDPP for 28 days, and changes in lipid and glucose levels were measured. Results indicated significant liver damages in the 100 and 250 μg/L EHDPP groups, which both exhibited significant decreases in hepatic somatic index (HSI), elevated activities of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) in serum and liver, as well as hepatocyte vacuolation and nuclear pyknosis. Exposure to 100 and 250 μg/L EHDPP led to significant reductions in serum and liver cholesterol (TC), triglycerides (TGs), and lipid droplet deposition, indicating a significant inhibition of EHDPP on hepatic lipid accumulation. Lipidomic analyses manifested that 250 μg/L EHDPP reduced the levels of 103 lipid metabolites which belong to glycerides (TGs, diglycerides, and monoglycerides), fatty acyles (fatty acids), sterol lipids (cholesterol, bile acids), sphingolipids, and glycerophospholipids, and downregulated genes involved in de novo synthesis of fatty acids (fas, acc, srebp1, and dagt2), while upregulated genes involved in fatty acid β-oxidation (pparα and cpt1). KEGG analyses revealed that EHDPP significantly disrupted glycerolipid metabolism, steroid biosynthesis and fatty acid biosynthesis pathways. Collectively, the results showed that EHDPP induced lipid reduction in zebrafish liver, possibly through inhibiting lipid synthesis and disrupting glycerolipid metabolism. Our findings provide a theoretical basis for evaluating the ecological hazards and health effects of EHDPP on glycolipid metabolism.

Weathered polyethylene microplastics induced immunomodulation in zebrafish

Microplastics are pollutants of emerging concern and the aquatic biota consumes microplastics (MPs), which has a range of toxicological and environmental effects on aquatic organisms that are not the intended targets. The current study looked into how weathered polyethylene (wPE) MPs affected Danio albolineatus immunological and haematological markers. In this experiment, fish of both sexes were placed in control and exposure groups, and they were exposed for 40 d at the sublethal level (1 μg L-1) of fragmented wPE, which contained 1074 ± 52 MPs per litre. Similarly, fish exposed to wPE MPs showed significant modifications in lysozyme, antimicrobial, and antiprotease activity, as well as differential counts. Results of the present study show that the male fish were more susceptible than female fish after 40 d of chronic exposure. Further studies are needed to ascertain how the innate and humoral immune systems of the fish respond to MPs exposure.

Exploring developmental toxicity of microplastics and nanoplastics (MNPS): Insights from investigations using zebrafish embryos

Microplastics and nanoplastics (MNPs) have received increasing attention due to their high detection rates in human matrices and adverse health implications. However, the toxicity of MNPs on embryo/fetal development following maternal exposure remains largely unexplored. Zebrafish, sharing genetic similarities with human, boast a shorter life cycle, rapid embryonic development, and the availability of many transgenic strains, is a suitable model for environmental toxicology studies. This review comprehensively explores the existing research on the impacts of MNPs on zebrafish embryo development. MNPs exposure induces a wide array of toxic effects, encompassing neurodevelopmental toxicity, immunotoxicity, gastrointestinal effects, microbiota dysbiosis, cardiac dysfunctions, vascular toxicity, and metabolic imbalances. Moreover, MNPs disrupt the balance between reactive oxygen species (ROS) production and antioxidant capacity, culminating in oxidative damage and apoptosis. This study also offers insight into the current omics- and multi-omics based approaches in MNPs research, which greatly expedite the discovery of biochemical or metabolic pathways, and molecular mechanisms underlying MNPs exposure. Additionally, this review proposes a preliminary adverse outcome pathway framework to predict developmental toxicity caused by MNPs. It provides a comprehensive overview of pathways, facilitating a clearer understanding of the exposure and toxicity of MNPs, from molecular effects to adverse outcomes. The compiled data in this review provide a better understanding for MNPs effects on early life development, with the goal of increasing awareness about the risks posed to pregnant women by MNPs exposure and its potential impact on the health of their future generations.

Behavioral impairments and disrupted mitochondrial energy metabolism induced by polypropylene microplastics in zebrafish larvae

Polypropylene microplastics (PP-MPs) are emerging pollutant commonly detected in various environmental matrices and organisms, while their adverse effects and mechanisms are not well known. Here, zebrafish embryos were exposed to environmentally relevant concentrations of PP-MPs (0.08-50 mg/L) from 2 h post-fertilization (hpf) until 120 hpf. The results showed that the body weight was increased at 2 mg/L, heart rate was reduced at 0.08 and 10 mg/L, and behaviors were impaired at 0.4, 10 or 50 mg/L. Subsequently, transcriptomic analysis in the 0.4 and 50 mg/L PP-MPs treatment groups indicated potential inhibition on the glycolysis/gluconeogenesis and oxidative phosphorylation pathways. These findings were validated through alterations in multiple biomarkers related to glucose metabolism. Moreover, abnormal mitochondrial ultrastructures were observed in the intestine and liver in 0.4 and 50 mg/L PP-MPs treatment groups, accompanied by significant decreases in the activities of four mitochondrial electron transport chain complexes and ATP contents. Oxidative stress was also induced, as indicated by significantly increased ROS levels and significant reduced activities of CAT and SOD and GSH contents. All the results suggested that environmentally relevant concentrations of PP-MPs could induce disrupted mitochondrial energy metabolism in zebrafish, which may be associated with the observed behavioral impairments. This study will provide novel insights into PP-MPs-induced adverse effects and highlight need for further research.

Interactions between intestinal microbiota and metabolites in zebrafish larvae exposed to polystyrene nanoplastics: Implications for intestinal health and glycolipid metabolism

Previous studies have shown the harmful effects of nanoscale particles on the intestinal tracts of organisms. However, the specific mechanisms remain unclear. Our present study focused on examining the uptake and distribution of polystyrene nanoplastics (PS-NPs) in zebrafish larvae, as well as its toxic effects on the intestine. It was found that PS-NPs, marked with red fluorescence, primarily accumulated in the intestine section. Subsequently, zebrafish larvae were exposed to normal PS-NPs (0.2-25 mg/L) over a critical 10-day period for intestinal development. Histopathological analysis demonstrated that PS-NPs caused structural changes in the intestine, resulting in inflammation and oxidative stress. Additionally, PS-NPs disrupted the composition of the intestinal microbiota, leading to alterations in the abundance of bacterial genera such as Pseudomonas and Aeromonas, which are associated with intestinal inflammation. Metabolomics analysis showed alterations in metabolites that are primarily involved in glycolipid metabolism. Furthermore, MetOrigin analysis showed a significant correlation between bacterial flora (Pedobacter and Bacillus) and metabolites (D-Glycerate 2-phosphate and D-Glyceraldehyde 3-phosphate), which are related to the glycolysis/gluconeogenesis pathways. These findings were further validated through alterations in multiple biomarkers at various levels. Collectively, our data suggest that PS-NPs may impair the intestinal health, disrupt the intestinal microbiota, and subsequently cause metabolic disorders.

Effects of atrazine on movement, metabolism and gene expression in Pelophylax nigromaculatus larvae under global warming

Global warming and environmental pollutants both pose a threat to the behavior and physiology of animals, but research on the combined effects of the two is limited. Atrazine, a widely used herbicide, has toxic effects on organisms. In this study, the effects of environmental concentrations of atrazine exposure (100 μg/L) for seven days on the movement, metabolism and gene expression related to motility of Pelophylax nigromaculatus larvae (GS8) were investigated under global warming. The results showed that compared to the optimal growth temperature (18 °C), atrazine treatment under global warming (21 °C) significantly increased the average speed (about 11.2 times) and maximum acceleration (about 1.98 times) of P. nigromaculatus larvae, altered the relative abundance of 539 metabolites, including Formyl-5-hydroxykynurenamine, 2,4-Dihydroxybenzophenone, and FAPy-adenine, and changed the nucleotide metabolism, pyrimidine metabolism, glycerophospholipid metabolism, and purine metabolism, as well as increased the gene expression of SPLA2 (about 6.46 times) and CHK (about 3.25 times). In summary, atrazine treatment under global warming caused metabolic disorders in amphibian larvae and increased the expression of some movement-related genes in the brain, resulting in abnormally active.

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

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

Micro-and nano-plastics induce kidney damage and suppression of innate immune function in zebrafish (Danio rerio) larvae

Aquatic environments serve as critical repositories for pollutants and have significantly accumulated micro- and nanoplastics (MNPs) due to the extensive production and application of plastic products. While the disease resistance and immunity of fish are closely linked to the condition of their aquatic habitats, the specific effects of nanoplastics (NPs) and microplastics (MPs) within these environments on fish immune functions are still not fully understood. The present study utilized zebrafish (Danio rerio) embryos and larvae as model organisms to examine the impacts of polystyrene NPs (100 nm) and MPs (5 μm) on fish immune responses. Our findings reveal that NPs and MPs tend to accumulate on the surfaces of embryos and within the intestines of larvae, triggering oxidative stress and significantly increasing susceptibility to Edwardsiella piscicida infection in zebrafish larvae. Transmission electron microscopy examined that both NPs and MPs inflicted damage to the kidney, an essential immune organ, with NPs predominantly inducing endoplasmic reticulum stress and MPs causing lipid accumulation. Transcriptomic analysis further demonstrated that both NPs and MPs significantly suppress the expression of key innate immune pathways, notably the C-type lectin receptor signaling pathway and the cytosolic DNA-sensing pathway. Within these pathways, the immune factor interleukin-1 beta (il1b) was consistently downregulated in both exposure groups. Furthermore, exposure to E. piscicida resulted in restricted upregulation of il1b mRNA and protein levels, likely contributing to diminished disease resistance in zebrafish larvae exposed to MNPs. Our findings suggest that NPs and MPs similarly impair the innate immune function of zebrafish larvae and weaken their disease resistance, highlighting the significant environmental threat posed by these pollutants.

Transcriptomic Responses and Larval-Stage Growth of Protandrous Yellowfin Seabream (Acanthopagrus Latus) to Different Polyethylene Microplastics Exposure

Polyethylene microplastics (PE-MPs) were widespread in the marine environment; thus, their influences on marine hermaphroditic fish cannot be ignored. This study intends to evaluate the adverse biological effects of two different sources of PE, identified by Raman spectroscopy, on protandrous yellowfin seabream (Acanthopagrus latus) larvae. Growth retardation, brain lesions, head/body length ratio increase, and neuroendocrine system disorders were found, and growth and neuroendocrine regulation-related genes such as sstr2, ghrb, irs1, UGT2B15, UGT2C1, drd4a, esr2b, hsd3b7, and hsd17b2 were identified. PE microbeads (100 μm) showed more severe tissue damage on fish, while environmental PE fibers (500-2500 μm) showed more imperceptible adverse effects. There were 218 DEGs up-regulated and 147 DEGs down-regulated in the environmental PE group, while 1284 (up) and 1267 (down) DEGs were identified in the virgin PE group. PE-MP stress influenced physiological processes like growth and neuroendocrine regulation and cholesterol-steroid metabolism, and caused tissue damage in the fish larvae. The study highlights the effects of environmental PE exposure on hermaphroditic protandrous fish.

Mind over Microplastics: Exploring Microplastic-Induced Gut Disruption and Gut-Brain-Axis Consequences

As environmental plastic waste degrades, it creates an abundance of diverse microplastic particles. Consequently, microplastics contaminate drinking water and many staple food products, meaning the oral ingestion of microplastics is an important exposure route for the human population. Microplastics have long been considered inert, however their ability to promote microbial dysbiosis as well as gut inflammation and dysfunction suggests they are more noxious than first thought. More alarmingly, there is evidence for microplastics permeating from the gut throughout the body, with adverse effects on the immune and nervous systems. Coupled with the now-accepted role of the gut-brain axis in neurodegeneration, these findings support the hypothesis that this ubiquitous environmental pollutant is contributing to the rising incidence of neurodegenerative diseases, like Alzheimer's disease and Parkinson's disease. This comprehensive narrative review explores the consequences of oral microplastic exposure on the gut-brain-axis by considering current evidence for gastrointestinal uptake and disruption, immune activation, translocation throughout the body, and neurological effects. As microplastics are now a permanent feature of the global environment, understanding their effects on the gut, brain, and whole body will facilitate critical further research and inform policy changes aimed at reducing any adverse consequences.

Integrated physiological, intestinal microbiota, and metabolomic responses of adult zebrafish (Danio rerio) to subacute exposure to antimony at environmentally relevant concentrations

The available information regarding the impact of antimony (Sb), a novel environmental pollutant, on the intestinal microbiota and host health is limited. In this study, we conducted physiological characterizations to investigate the response of adult zebrafish to different environmental concentrations (0, 30, 300, and 3000 µg/L) of Sb over a period of 14 days. Biochemical and pathological changes demonstrated that Sb effectively compromised the integrity of the intestinal physical barrier and induced inflammatory responses as well as oxidative stress. Analysis of both intestinal microbial community and metabolome revealed that exposure to 0 and 30 µg/L of Sb resulted in similar microbiota structures; however, exposure to 300 µg/L altered microbial communities' composition (e.g., a decline in genus Cetobacterium and an increase in Vibrio). Furthermore, exposure to 300 µg/L significantly decreased levels of bile acids and glycerophospholipids while triggering intestinal inflammation but activating self-protective mechanisms such as antibiotic presence. Notably, even exposure to 30 µg/L of Sb can trigger dysbiosis of intestinal microbiota and metabolites, potentially impacting fish health through the "microbiota-intestine-brain axis" and contributing to disease initiation. This study provides valuable insights into toxicity-related information concerning environmental impacts of Sb on aquatic organisms with significant implications for developing management strategies.

Microplastic contamination in salt-cured fish and commercial sea salts: an emerging food safety threat in relation to UN Sustainable Development Goals (SDGs)

Microplastic (MP) contamination in seafood, particularly processed varieties like dried and salt-cured fish, poses a significant threat to human health. This study investigated MP levels in 22 salt-cured fish species and commercial sea salts along the Indian east coast. Results showed substantially higher MP concentrations compared to global averages, with fragments and fibres (< 250 µm) composing 70% of identified MPs, primarily PVC and PS polymers (> 55%). Station 2 exhibited high pollution levels, with salt-cured fish averaging 54.06 ± 14.48 MP items/g and salt containing 23.53 ± 4.2 MP items/g, indicating a high hazard risk index. A modest correlation was observed between MP abundance, morphotypes, polymer composition in the salt, and their impact on fish products. Given the critical link between food safety, security, and public health, further research is imperative to mitigate MP contamination, aligning with UN Sustainable Development Goals (Goal 2, Goal 3, Goal 14, and Goal 15) for enhanced food safety and security.

Combined exposure with microplastics increases the toxic effects of PFOS and its alternative F-53B in adult zebrafish

Microplastics (MPs) can adsorb and desorb organic pollutants, which may alter their biotoxicities. Although the toxicity of perfluorooctane sulfonate (PFOS) and its alternative 6:2 chlorinated polyfluorinated ether sulfonate (F-53B) to organisms has been reported, the comparative study of their combined toxic effects with MPs on aquatic organisms is limited. In this study, adult female zebrafish were exposed to 10 μg/L PFOS/F-53B and 50 μg/L MPs alone or in combination for 14 days to investigate their single and combined toxicities. The results showed that the presence of MPs reduced the concentration of freely dissolved PFOS and F-53B in the exposure solution but did not affect their bioaccumulation in the zebrafish liver and gut. The combined exposure to PFOS and MPs had the greatest impact on liver oxidative stress, immunoinflammatory, and energy metabolism disorders. 16S rRNA gene sequencing analysis revealed that the combined exposure to F-53B and MPs had the greatest impact on gut microbiota. Functional enrichment analysis predicted that the alternations in the gut microbiome could interfere with signaling pathways related to immune and energy metabolic processes. Moreover, significant correlations were observed between changes in gut microbiota and immune and energy metabolism indicators, highlighting the role of gut microbiota in host health. Together, our findings demonstrate that combined exposure to PFOS/F-53B and MPs exacerbates liver immunotoxicity and disturbances in energy metabolism in adult zebrafish compared to single exposure, potentially through dysregulation of gut microbiota.

In Vivo Tissue Distribution of Polystyrene or Mixed Polymer Microspheres and Metabolomic Analysis after Oral Exposure in Mice

BACKGROUND

Global plastic use has consistently increased over the past century with several different types of plastics now being produced. Much of these plastics end up in oceans or landfills leading to a substantial accumulation of plastics in the environment. Plastic debris slowly degrades into microplastics (MPs) that can ultimately be inhaled or ingested by both animals and humans. A growing body of evidence indicates that MPs can cross the gut barrier and enter into the lymphatic and systemic circulation leading to accumulation in tissues such as the lungs, liver, kidney, and brain. The impacts of mixed MPs exposure on tissue function through metabolism remains largely unexplored.

OBJECTIVES

This study aims to investigate the impacts of polymer microspheres on tissue metabolism in mice by assessing the microspheres ability to translocate across the gut barrier and enter into systemic circulation. Specifically, we wanted to examine microsphere accumulation in different organ systems, identify concentration-dependent metabolic changes, and evaluate the effects of mixed microsphere exposures on health outcomes.

METHODS

To investigate the impact of ingested microspheres on target metabolic pathways, mice were exposed to either polystyrene (5 μ m ) microspheres or a mixture of polymer microspheres consisting of polystyrene (5 μ m ), polyethylene (1 - 4 μ m ), and the biodegradability and biocompatible plastic, poly-(lactic-co-glycolic acid) (5 μ m ). Exposures were performed twice a week for 4 weeks at a concentration of either 0, 2, or 4 mg / week via oral gastric gavage. Tissues were collected to examine microsphere ingress and changes in metabolites.

RESULTS

In mice that ingested microspheres, we detected polystyrene microspheres in distant tissues including the brain, liver, and kidney. Additionally, we report on the metabolic differences that occurred in the colon, liver, and brain, which showed differential responses that were dependent on concentration and type of microsphere exposure.

DISCUSSION

This study uses a mouse model to provide critical insight into the potential health implications of the pervasive issue of plastic pollution. These findings demonstrate that orally consumed polystyrene or mixed polymer microspheres can accumulate in tissues such as the brain, liver, and kidney. Furthermore, this study highlights concentration-dependent and polymer type-specific metabolic changes in the colon, liver, and brain after plastic microsphere exposure. These results underline the mobility within and between biological tissues of MPs after exposure and emphasize the importance of understanding their metabolic impact. https://doi.org/10.1289/EHP13435.

Co-exposure to polystyrene microplastics and cypermethrin enhanced the effects on hepatic phospholipid metabolism and gut microbes in adult zebrafish

Microplastics (MPs) can absorb environmental pollutants from the aquatic environment to cause mixed toxicity, which has received widespread attention. However, studies on the joint effects of MPs and insecticides are limited. As one of the most widely used pyrethroids, there was a large amount of residual cypermethrin (CYP) in water due to insufficient decomposition. Here, adult female zebrafish were exposed to MPs, CYP, and their mixtures for 21 days, respectively. After exposures, the MPs and CYP caused tissue damage to the liver. Hepatic triglyceride (TG) level increased significantly after MPs + CYP exposure, and the expression of genes about glycolipids metabolism was significantly altered. Furthermore, metabolome results suggested that MPs + CYP exposure resulted in increased content of some glycerophospholipid, affecting phospholipid metabolism-related pathways. In addition, through 16 s rDNA sequencing, it was found that MPs + CYP led to significant changes in the proportion of dominant phyla. Interestingly, Cetobacterium which increased in CYP and the co-exposure group was positively correlated with most lipid metabolites. Our results suggested that co-exposure to MPs and CYP enhanced the disturbances in hepatic phospholipid metabolism by affecting the gut microbial composition, while these changes were not observed in separate treatment groups. These results emphasized the importance of studying the joint toxicity of MPs and insecticides.

Impact of microplastics on nicosulfuron accumulation and bacteria community in soil-earthworms system

Microplastics (MPs) widely co-occur with various pollutants in soils. However, the data related to the impacts of MPs on terrestrial animal and microbial properties in pesticide-contaminated soils are few. In this study, the influence of MPs (0.01%, 0.1%, and 1%) on nicosulfuron concentrations in soil (10 µg/g) and earthworms were investigated, moreover, microbial community structure and diversity in soil and earthworm gut were also measured. After 30 days, the concentration of nicosulfuron in soil decreased to 1.27 µg/g, moreover, the residual concentration of nicosulfuron in soil (1%MPs and nicosulfuron) was only 44.8% of that in the single nicosulfuron treatment group. The accumulation of nicosulfuron in earthworms (1%MPs and nicosulfuron) was 7.37 µg/g, which was 1.82 times of that in the single nicosulfuron treatment group. In addition, 1% MPs decreased the richness and diversity of the soil and gut bacterial community in earthworms as well as altered microbial community composition, leading to the enrichment of specific microbial community. Our findings imply that MPs may change the migration of pesticides to terrestrial animal and as well as microbial diversity in earthworms and soil.

Simulated gastrointestinal digestion of two different sources of biodegradable microplastics and the influence on gut microbiota

Biodegradable plastics, were considered environmentally friendly, may produce more microplastic particles (MPs) within the same period and exert more pronounced adverse effects on human health than traditional non-biodegradable plastics. Thus, this study investigated the changes of two kinds of biodegradable MPs from different sources in the digestive tract by using simulated digestion and fermentation models in vitro, with particle size, scanning electron microscopy (SEM) and gel permeation chromatography (GPC) analysis, and their implications on the gut microbiota were detected by full-length bacterial 16S rRNA gene amplicon sequencing. Poly(ε-caprolactone) (PCL) MPs exhibited stability in the upper gastrointestinal tract, while poly(lactic acid) (PLA) MPs were degraded beginning in the small intestine digestion phase. Both PCL and PLA MPs were degraded and oligomerized during colonic fermentation. Furthermore, this study highlighted the disturbance of the gut microbiota induced by MPs and their oligomers. PCL and PLA MPs significantly changed the composition and reduced the α-diversity of the gut microbiota. PCL and PLA MPs exhibited the same inhibitory effects on key probiotics such as Bifidobacterium, Lactobacillus, Faecalibacterium, Limosilactobacillus, Blautia, Romboutsia, and Ruminococcus, which highlighted the potential hazards of these materials for human health. In conclusion, this study illuminated the potential biodegradation of MPs through gastrointestinal digestion and the complex interplay between MPs and the gut microbiota. The degradable characteristic of biodegradable plastics may cause more MPs and greater harm to human health.

Efficacy of Jiuzao polysaccharides in ameliorating alcoholic fatty liver disease and modulating gut microbiota

Jiuzao, the residue from Baijiu production, has shown radical scavenging properties in prior investigations, suggesting its potential as a hepatoprotective agent against acute liver damage. This study reveals that Jiuzao polysaccharides ameliorated liver morphological damage in zebrafish larvae afflicted with alcoholic fatty liver disease (AFLD), as evidenced by Oil red O, H&E, and Nile red staining. These polysaccharides notably modulated antioxidant enzyme levels and lipid peroxidation components. The real-time quantitative polymerase chain reactions analyses illustrated the significant impact of Jiuzao polysaccharides on genes integral to ethanol and lipid metabolism. The 16 S rRNA results showed that Jiuzao polysaccharides could improve the intestinal flora in zebrafish larvae exposed to ethanol. In summary, Jiuzao polysaccharides efficaciously mitigate liver lipid accumulation, enhance ethanol metabolism, and reduce oxidative stress by downregulating genes involved in AFLD development. They also regulate the changes in gut microbiota, providing further protection against acute alcoholic liver insult in zebrafish larvae.

Concurrent impacts of polystyrene nanoplastic exposure and Aeromonas hydrophila infection on oxidative stress, immune response and intestinal microbiota of grass carp (Ctenopharyngodon idella)

Research has demonstrated that polystyrene nanoplastics (PS-NPs) can have adverse effects on the immune responses of fish. NPs have the potential to increase the likelihood of infections in fish by pathogenic bacteria, such as the opportunistic pathogen Aeromonas hydrophila, potentially increasing the virulence of pathogenic bacteria infections in fish. The concurrent effects of PS-NPs and A. hydrophila on grass carp intestinal tissues were assessed by exposing grass carp to different concentrations of PS-NPs (10 μg/L, 100 μg/L, 1000 μg/L) after infection with A. hydrophila. As the concentration of PS-NPs in the exposure and the duration of A. hydrophila infection both escalated, intestinal tissues showed damage in the form of disordered breakage of intestinal villi, thinning of the intestinal wall, and reduced necrosis of the cells in the annulus muscle layer. The AHS-PS100 group and AHS-PS1000 group exhibited a substantial rise in the function of CAT, SOD, GST, and MPO, as well as increased MDA content and elevated ROS levels (p < 0.05). In the AHS-PS1000 group, the expression levels of IL-6, IL-8, IL-10, IL-1β, TNF-α, and IFN-γ2 experienced a significant upsurge (p < 0.05). In addition, exposure to PS-NPs and A. hydrophila infection induced modifications in the microbial composition of the grass carp gut, affecting both phylum and genus taxonomic categories. Moreover, an increase in the abundance of Spirochaetota and Bacteroidota was observed not only in the positive control group but also in the AHS-PS100 and AHS-PS1000 groups following A. hydrophila infection. These experimental results indicate that PS-NPs exposure will aggravate the oxidative stress and inflammatory response of grass carp intestinal tissue in response to A. hydrophila infection, and lead to changes in intestinal microbial diversity and abundance. Overall, this study provides valuable hints on the potential concurrent effects of PS-NPs exposure on grass carp's response to A. hydrophila infection.

The potential toxicity of microplastics on human health

Microplastics are plastic particles, films, and fibers with a diameter of < 5 mm. Given their long-standing existence in the environment and terrible increase in annual emissions, concerns were raised about the potential health risk of microplastics on human beings. In particular, the increased consumption of masks during the COVID-19 pandemic has dramatically increased human contact with microplastics. To date, the emergence of microplastics in the human body, such as feces, blood, placenta, lower airway, and lungs, has been reported. Related toxicological investigations of microplastics were gradually increased. To comprehensively illuminate the interplay of microplastic exposure and human health, we systematically reviewed the updated toxicological data of microplastics and summarized their mode of action, adverse effects, and toxic mechanisms. The emerging critical issues in the current toxicological investigations were proposed and discussed. Our work would facilitate a better understanding of MPs-induced health hazards for toxicological evaluation and provide helpful information for regulatory decisions.

Intracellular Protein Adsorption Behavior and Biological Effects of Polystyrene Nanoplastics in THP-1 Cells

Micro(nano)plastics (MNPs) are emerging pollutants that can adsorb pollutants in the environment and biological molecules and ultimately affect human health. However, the aspects of adsorption of intracellular proteins onto MNPs and its biological effects in cells have not been investigated to date. The present study revealed that 100 nm polystyrene nanoplastics (NPs) could be internalized by THP-1 cells and specifically adsorbed intracellular proteins. In total, 773 proteins adsorbed onto NPs with high reliability were identified using the proteomics approach and analyzed via bioinformatics to predict the route and distribution of NPs following cellular internalization. The representative proteins identified via the Kyoto Encyclopedia of Genes and Genomes pathway analysis were further investigated to characterize protein adsorption onto NPs and its biological effects. The analysis revealed that NPs affect glycolysis through pyruvate kinase M (PKM) adsorption, trigger the unfolded protein response through the adsorption of ribophorin 1 (RPN1) and heat shock 70 protein 8 (HSPA8), and are chiefly internalized into cells through clathrin-mediated endocytosis with concomitant clathrin heavy chain (CLTC) adsorption. Therefore, this work provides new insights and research strategies for the study of the biological effects caused by NPs.

Exploring the impact of antibiotics, microplastics, nanoparticles, and pesticides on zebrafish gut microbiomes: Insights into composition, interactions, and health implications

This review addresses the impact of various chemical entities like pesticides, antibiotics, nanoparticles and microplastic on gut microbiota of zebrafish. Gut microbiota plays a vital role in metabolic regulation in every organism. As majority of metabolic pathways coordinated by microbiota, small alterations associated with mild to serious outcomes. Because of their unstoppable usage in day-to-day life, the present-day research on gut microbiota is mostly comprising aforementioned chemicals. It is better to understand how gut microbiome is dysbiosed by various environmental factors, to keep our microbiota safe. We tried to delineate the natural flora of zebrafish gut microbiome and the metabolic and other pathways associated and what are the common flora that was dysbiosed during the treatment. Based on the existing literature, we reviewed pesticides like Imazalil, Difenoconazole, Chlorpyrifos, Metamifop, Carbendazim, Imidacloprid, Phoxim, Niclosamide, Dieldrin, and antibiotics like Oxytetracycline, Enrofloxacin, Florfenicol, Sulfamethoxazole, Tetracycline, Streptomycin, Doxycycline, and in the category of nanoparticles, Titanium dioxide nanoparticles (nTiO2), Abalone viscera hydrolysates decorated silver nanoparticles (AVH-AgNPs), Lead-halide perovskite nanoparticles (LHP NPs), Copper nanoparticles (Cu-NPs), silver nanoparticles (Ag-NPs) and microplastic types like polyethylene and polystyrene microplastic. Other studies with miscellaneous chemical entities on zebrafish gut microbiome include Ferulic acid, Polychlorinated biphenyls, Cadmium, Disinfection by-products, Triclosan, microcystin-LR, Fluoride, and Amitriptyline.

Resveratrol ameliorates intestinal lipid metabolism through the PPAR signaling pathway in high-fat diet-fed red tilapia (Oreochromis niloticus)

Feeding high-fat (HF) diets has been shown to cause hepatic and intestinal impairment in fish species, but the mode of action, especially the pathways involved in the intestine, has not been determined yet. In this study, the effects of resveratrol (RES) supplementation on the intestinal structure, microbial flora, and fat metabolism in red tilapia (Oreochromis niloticus) were determined. The results showed RES maintained the structural integrity of the intestine and significantly increased the number of goblet cells in the midgut. RES significantly induced interferon (IL)-1β, IL-6, IL-10, and tumor necrosis factor (TNF)-α, serumal and fecal trimetlylamine oxide (TMAO) and lipopolysaccharides (LPS), intestinal acetic acid levels. However, the concentrations of bound bile acids increased in HF-fed red tilapia. Atp5fa1 and Pafah1b3 significantly increased, Pmt and Acss2 significantly decreased, respectively, with RES supplementation, which was alleviated and retained at the same level in the selisistat (EX527) group. While for transcriptome and proteomics results, RES was found to promote fatty acid β-oxidation and arachidonic acid metabolism associated with the peroxisome proliferator-activated receptor (PPAR) signaling pathway. The next validation experiment showed some genes related to apoptosis and fatty acid metabolism pathways were altered by RES supplementation. Namely, sn6, loc100702698, new_14481, and prkaa1 were upregulated, while ffrs1, ap3s1, and loc100705861 were downregulated. RES significantly increased Planctomycetes and Verrucomicrobia while decreased Moonvirus, Citrobacter, and Pseudomonas. Akkermansia and Fusobacterium significantly increased and Aeromonas significantly decreased. Thus, unsaturated fatty acid biosynthesis significantly increased and carbohydrate/energy metabolism decreased. To conclude, RES enabled the body to complete fatty acid β-oxidation and arachidonic acid metabolism, whereas the addition of inhibitors increased the expression of the phagosome transcriptome and reduced fatty acid β-oxidative metabolism.

Inhibitory Effects of Jiuzao Polysaccharides on Alcoholic Fatty Liver Formation in Zebrafish Larvae and Their Regulatory Impact on Intestinal Microbiota

The liver is critical in alcohol metabolism, and excessive consumption heightens the risk of hepatic damage, potentially escalating to hepatitis and cirrhosis. Jiuzao, a by-product of Baijiu production, contains a rich concentration of naturally active polysaccharides known for their antioxidative properties. This study investigated the influence of Laowuzeng Jiuzao polysaccharide (LJP) on the development of ethanol-induced alcoholic fatty liver. Zebrafish larvae served as the model organisms for examining the LJPs hepatic impact via liver phenotypic and biochemical assays. Additionally, this study evaluated the LJPs effects on gene expression associated with alcoholic fatty liver and the composition of the intestinal microbiota through transcriptomic and 16 S rRNA gene sequencing analyses, respectively. Our findings revealed that LJP markedly mitigated morphological liver damage and reduced oxidative stress and lipid peroxidation in larvae. Transcriptome data indicated that LJP ameliorated hepatic fat accumulation and liver injury by enhancing gene expression involved in alcohol and lipid metabolism. Furthermore, LJP modulated the development of alcoholic fatty liver by altering the prevalence of intestinal Actinobacteriota and Firmicutes, specifically augmenting Acinetobacter while diminishing Chryseobacterium levels. Ultimately, LJP mitigated alcohol-induced hepatic injury by modulating gene expression related to ethanol metabolism, lipid metabolism, and inflammation and by orchestrating alterations in the intestinal microbiota.

Organ-specific distribution and size-dependent toxicity of polystyrene nanoplastics in Australian bass (Macquaria novemaculeata)

Micro- and nano-plastics (MNPs) are emerging contaminants found in air, water, and food. Ageing and weathering processes convert aquatic plastics into MNPs which, due to their small size, can be assimilated by organisms. The accumulation of MNPs in aquatic life (e.g., fish, oysters, and crabs) will, in turn, pose risks to the health of ecosystems and human. This study focuses on the uptake, biodistribution, and size-dependent toxicity of polystyrene nano-plastics (PS-NPs) in a commercially important food web, the Australian Bass (Macquaria novemaculeata). Fish were fed artemia containing PS-NPs of various sizes (ranging from 50 nm to 1 μm) for durations of 5 and 7 days. The findings revealed that smaller NPs (50 nm) accumulated in the brain and muscle tissues at higher concentrations, whereas larger NPs (1 μm) were primarily found in the gills and intestines. In addition, an inverse correlation was observed between the size of NPs and the rate of trophic transfer, with smaller PS-NPs resulting in a higher transfer rate from artemia to fish. Polystyrene NPs caused both activation of the enzyme superoxide dismutase and damage to the DNA of fish tissues. These effects were size dependent. Metabolomic analysis revealed that indirect exposure to different-sized PS-NPs resulted in altered metabolic profiles within fish intestines, potentially impacting lipid and energy metabolism. These results offer novel perspectives on the size-specific toxic impacts of NPs on fish and the transfer of plastics through the food chain.

Effects of nanoplastics on the gut microbiota of Pacific white shrimp Litopenaeus vannamei

Nanoplastics (NPs) are an abundant, long-lasting, and widespread type of environmental pollution that is of increasing concern because of the serious threats they might pose to ecosystems and species. Identifying the ecological effects of plastic pollution requires understanding the effects of NPs on aquatic organisms. Here, we used the Pacific white shrimp (Litopenaeus vannamei) as a model species to investigate whether ingestion of polystyrene NPs affects gut microbes and leads to metabolic changes in L. vannamei. The abundance of Proteobacteria increased and that of Bacteroidota decreased after NPs treatment. Specifically, Vibrio spp., photobacterium spp., Xanthomarina spp., and Acinetobacter spp. increased in abundance, whereas Sulfitobacter spp. and Pseudoalteromonas spp. decreased. Histological observations showed that L. vannamei exposed to NP displayed a significantly lower intestinal fold height and damaged intestinal structures compared with the control group. Exposure to NPs also stimulated alkaline phosphatase, lysozyme, and acid phosphatase activity, resulting in an immune response in L. vannamei. In addition, the content of triglycerides, total cholesterol, and glucose were significantly altered after NP exposure. These results provided significant ecotoxicological data that can be used to better understand the biological fate and effects of NPs in L. vannamei.

PLASTAMINATION: Outcomes on the Central Nervous System and Reproduction

BACKGROUND

Environmental exposures to non-biodegradable and biodegradable plastics are unavoidable. Microplastics (MPs) and nanoplastics (NPs) from the manufacturing of plastics (primary sources) and the degradation of plastic waste (secondary sources) can enter the food chain directly or indirectly and, passing biological barriers, could target both the brain and the gonads. Hence, the worldwide diffusion of environmental plastic contamination (PLASTAMINATION) in daily life may represent a possible and potentially serious risk to human health.

OBJECTIVE

This review provides an overview of the effects of non-biodegradable and the more recently introduced biodegradable MPs and NPs on the brain and brain-dependent reproductive functions, summarizing the molecular mechanisms and outcomes on nervous and reproductive organs. Data from in vitro, ex vivo, non-mammalian and mammalian animal models and epidemiological studies have been reviewed and discussed.

RESULTS

MPs and NPs from non-biodegradable plastics affect organs, tissues and cells from sensitive systems such as the brain and reproductive organs. Both MPs and NPs induce oxidative stress, chronic inflammation, energy metabolism disorders, mitochondrial dysfunction and cytotoxicity, which in turn are responsible for neuroinflammation, dysregulation of synaptic functions, metabolic dysbiosis, poor gamete quality, and neuronal and reproductive toxicity. In spite of this mechanistic knowledge gained from studies of non-biodegradable plastics, relatively little is known about the adverse effects or molecular mechanisms of MPs and NPs from biodegradable plastics.

CONCLUSION

The neurological and reproductive health risks of MPs/NPs exposure warrant serious consideration, and further studies on biodegradable plastics are recommended.

Simulated gastrointestinal digestion of polylactic acid (PLA) biodegradable microplastics and their interaction with the gut microbiota

The accumulation of microplastics (MPs) in the environment as well as their presence in foods and humans highlight the urgent need for studies on the effects of these particles on humans. Polylactic acid (PLA) is the most widely used bioplastic in the food industry and medical field. Despite its biodegradability, biocompatibility, and "Generally Recognized As Safe" (GRAS) status, recent animal model studies have shown that PLA MPs can alter the intestinal microbiota; however, to date, no studies have been reported on the possible gut and health consequences of its intake by humans. This work simulates the ingestion of a realistic daily amount of PLA MPs and their pass through the gastrointestinal tract by combining the INFOGEST method and the gastrointestinal simgi® model to evaluate possible effects on the human colonic microbiota composition (16S rRNA gene sequencing analysis) and metabolic functionality (lactic acid and short-chain fatty acids (SCFA) production). Although PLA MPs did not clearly alter the microbial community homeostasis, increased Bifidobacterium levels tended to increase in presence of millimetric PLA particles. Furthermore, shifts detected at the functional level suggest an alteration of microbial metabolism, and a possible biotransformation of PLA by the human microbial colonic community. Raman spectroscopy and field emission scanning electron microscopy (FESEM) characterization revealed morphological changes on the PLA MPs after the gastric phase of the digestion, and the adhesion of organic matter as well as a microbial biofilm, with surface biodegradation, after the intestinal and colonic phases. With this evidence and the emerging use of bioplastics, understanding their impact on humans and potential biodegradation through gastrointestinal digestion and the human microbiota merits critical investigation.

Impacts of Nile Tilapia (Oreochromis niloticus) exposed to microplastics in bioflocs system

Microplastics (MPs) are abundant in aquaculture water, including in bioflocs aquaculture systems. Compared with other aquaculture systems, biofloc technology systems have the richest microbes and are beneficial to cultivated organisms. Therefore, this study provides a comprehensive assessment of the potential effects of MPs on aquaculture organisms in bioflocs systems. Here, Nile Tilapia (Oreochromis niloticus) were exposed to MPs (polystyrene; 32-40 μm diameter) with 0, 80 items/L (30 μg/L), and 800 items/L (300 μg/L) for 28 days in a bioflocs aquaculture system. The results showed that the MPs generally had no apparent effect on water quality, tilapia growth, or digestive enzyme activity. However, MPs accumulated the most in the liver (5.65 ± 0.74 μg/mg) and significantly increased the hepato-somatic index of tilapia and reduced the crude protein and lipid of tilapia muscle (p < 0.05). The levels of the antioxidant enzymes catalase and glutathione S-transferase increased significantly in response to MPs (p < 0.05). In contrast, MPs did not affect the content of glutathione, glutathione peroxidase, oxidized glutathione, and malondialdehyde, or the enzyme activity of Na+/K+-ATPase. Moreover, using an improved integrated biomarker response index, growth performance was found to be less responsive to MPs than to oxidative stress and digestive activity. Exposure to MPs did not significantly influence the microbial communities of the bioflocs and tilapia guts (p < 0.05). These results suggest that MPs barely affected tilapia in the bioflocs system. This study contributes to the evaluation of the ecological risk of MPs in aquaculture systems and a better understanding of the integrated response of cultivated vertebrates to MPs in biofloc technology systems.

Nano- and micro-polystyrene plastics interfered the gut barrier function mediated by exosomal miRNAs in rats

Microplastics (MPs) are widely distributed in the global environment, entering and accumulating in organisms in various ways and posing health threats. MPs can damage intestine; however, the mechanism by which MPs cause intestinal damage in rats is unclear. Here, rats were exposed to 50 nm PS-NPs or 5 μm PS-MPs for 4 weeks to evaluate the possible effects on intestinal barrier function and exosomal miRNAs expressions. The results showed that PS-NPs or PS-MPs disrupted the gut microbiota and affected gut barrier function at the biological level. In addition, PS-NPs and PS-MPs altered the composition of exosomal miRNAs in the intestinal and serum. Both PS-NPs and PS-MPs decreased the expression of miR-126a-3p in the intestinal and serum exosomes, which is an important signalling molecule involved in MPs induced gut barrier function disorder. More importantly, both in vitro and in vivo experiments indicated that miR-126a-3p was closely related to oxidative damage of intestinal cells through the PI3K-Akt pathway and eventually promote cell apoptosis by regulating the target gene of PIK3R2. Our study suggested that PS-NPs and PS-MPs could affect rat intestinal barrier function through an exosomal miRNA mediated pathway.

Synergistic adverse effects of microfibers and freshwater acidification on host-microbiota interactions in the water flea Daphnia magna

Microfibers are the most common type of microplastics in freshwater environments. Anthropogenic climate stressors, such as freshwater acidification (FA), can interact with plastic pollution to disrupt freshwater ecosystems. However, the underlying mechanisms responsible for the interactive effects of microfibers and FA on aquatic organisms remain poorly understood. In this study, we investigated individual Daphnia magna-microbiota interactions affected by interactions between microfibers and FA (MFA). We found that the accumulated amount of microfibers in pH-treatment groups was significantly higher than in the control groups, resulting in negative consequences on reproduction, growth, and sex ratio. We also observed that MFA interactions induced immunity- and reproduction-related biological processes. In particular, the abundance of pathogenic bacteria increased only in MFA groups, indicating that MFA interactions can cause intestinal damage. Our integrated analysis of microbiomes and host transcriptomes revealed that synergistic adverse effects of MFAs are closely related to changes in microbial communities, suggesting that D. magna fitness and the microbial community are causally linked. These finding may help elucidate the toxicity mechanisms governing the responses of D. magna to microfibers and acidification interactions, and to host-microbiome-environment interactions.

Toxic effect of chronic exposure to polyethylene nano/microplastics on oxidative stress, neurotoxicity and gut microbiota of adult zebrafish (Danio rerio)

The rapid development of aquaculture industry has provided a large amount of high-quality animal protein, while the food safety caused by microplastics and nanoplastics (MP/NPs) has become a major concern. In addition, recent evidence has shown the potential toxic effect of PE-MP/NPs, highlighting the need for further research into their environmental and health impacts. Chronic exposure of polyethylene microplastics (PE-MPs) and nanoplastics (PE-NPs) on adult zebrafish were conducted in the present study for 21 d. Organ-dependent oxidative damage induced by MP/NPs was observed. Insignificant differences in neurotoxicity and dysbiosis of gut microbiota were found between MPs and NPs. Changes in glutathione S-transferase (GST), glutathione (GSH), catalase (CAT), lipid peroxidation (LPO), and superoxide dismutase (SOD) showed that MP/NPs induced oxidative damage in gill and intestinal cells of zebrafish. The inhibited AChE activity suggested the potential neurotoxicity of microplastics and nanoplastics (MP/NPs). In addition, chronic exposure increased the alpha-diversity of intestinal microbiota. At the phylum level, the average relative abundance of Proteobacteria increased from 29.73% (control group) to 66.10% (microplastics), 54.84% (nanoplastics) and 60.03% (combined exposure), respectively. Tenericutes decreased from 55.43% (control group) to 20.02% (microplastics), 22.44% (nanoplastics) and 31.77% (combined exposure), respectively. Overall, this study provides new insights and objective evidence for the toxicity assessment of PE-MPs.

Probiotics mitigate kidney damage after exposure to Sri Lanka's local groundwater from chronic kidney disease with uncertain etiology (CKDu) prevalent area in zebrafish

Groundwater in Sri Lanka, contaminated with environmental toxins, is suspected to potentially induce chronic kidney disease of uncertain etiology (CKDu) in humans. This study aims to elucidate the potential mitigating effects of probiotics on kidney damage induced by exposure to this local groundwater (LW) in zebrafish. We used zebrafish as a model organism and exposed them to local groundwater to evaluate the risk of CKDu. Probiotics were then added at a concentration of 108 colony-forming units per milliliter (CFU/mL). Our findings revealed that exposure to local groundwater resulted in abnormalities, such as tail deletion and spinal curvature in zebrafish larvae. However, the addition of probiotics mitigated these effects, improving the hatching rate, heart rate, length, weight, deformity rate, survival rate, and abnormal behavior of zebrafish. It also positively influenced the differential expression levels of kidney development and immunity-related genes (dync2h1, foxj1, pkd2, gata3, slc20a1, il1β, and lyso). Furthermore, exposure to LW decreased both the diversity and abundance of microbiota in zebrafish larvae. However, treatment with probiotics, such as L. plantarum and L. rhamnosus partially restored the disrupted gut microbiota and significantly impacted the cellular process pathways of the microbial community, as determined by KEGG (Kyoto Encyclopedia of Genes and Genomes) analysis. In conclusion, this study highlights the risks associated with Sri Lanka's local groundwater from a CKDu prevalent area and confirms the beneficial effects of different probiotics. These findings may provide new insights into bacterial function in host kidney health.

Enantioselective effects of paclobutrazol and its enantiomers on glycolipid metabolism in zebrafish (Danio rerio)

Paclobutrazol is a plant growth inhibitor widely used in agricultural production. However, toxicology studies of paclobutrazol enantiomers towards aquatic organisms are limited. Herein, effects of paclobutrazol and its two enantiomers (2R, 3R; 2S, 3S) on glycolipid metabolism of zebrafish have been systemically explored at the concentration of 10 mg/L through biochemical analyses, LC-MS/MS, molecular dynamics simulation, and gene expression. In all treatments, the contents of glucose, citric acid and lactate significantly were increased while the glycogen and pyruvate contents were decreased, in which (2R, 3R)-paclobutrazol exhibited a greater effect than the (2S, 3S)-enantiomer (P < 0.05). Then, activities of hexokinase and lactate dehydrogenase in (2R, 3R)-paclobutrazol treatment were 0.74- and 1.18-fold higher than (2S, 3S)-enantiomer treatment, respectively (P < 0.001), and the results of molecular dynamics simulation revealed that the binding free energy of hexokinase 1 to (2R, 3R)-paclobutrazol was higher than that to the antipode. Moreover, lipids including triglycerides, total cholesterol, fatty acids, bile acids and glycerophospholipids in zebrafish were strikingly affected after paclobutrazol exposure. The (2R, 3R)-paclobutrazol-treated group showed the most obvious changes, indicating that it possessed much stronger disruption ability on the lipid metabolism of zebrafish. Furthermore, qRT-PCR analysis results revealed that (2R, 3R)-enantiomer significantly impacted expressions of glycolipid metabolism-related genes (hk1, g6pc, pck1, pk, aco, cebpa, cyp51, fasn and ppara) in zebrafish than (2S, 3S)-enantiomer (P < 0.05). Briefly, this study provides new evidences for the toxicity of paclobutrazol to aquatic organisms and the potential risk to human health at the chiral level.

Sex-specific metabolic dysregulation in digestive glands of green mussels following exposure to triazophos

As a ubiquitous environmental pollutant in China, triazophos (TP) is known to have neurotoxicity, oxidative stress, and reproductive toxicity to mussels. To investigate the molecular mechanisms of TP toxicity, metabolic changes in the digestive glands of Perna viridis in different sexes were examined after treated with 35 μg/L TP. Notably, 158 significant different metabolites (SDMs) were detected in TP-treated mussels and more than half of the SDMs were lipids and lipid-like molecules, which suggested that TP disturbed the lipid metabolism of P. viridis. In addition, metabolites associated with neurotoxicity and reproductive disturbance were also detected in female and male mussels. Moreover, a larger number of SDMs were found in male mussels (120 SDMs) than females (99 SDMs), and 60 common metabolites exhibited consistent variation tendency and similar magnitude in both sexes. The metabolic alternations in female and male mussels displayed similar protective mechanisms and also sex-specific responses, male mussels were more sensitive to TP exposure. This research provided new data about the molecular mechanisms of TP toxicity and the gender specific changes in mussels after treated by chemicals.

The impact of amine and carboxyl functionalised microplastics on the physiology of daphnids

Plastic waste is considered a major threat for terrestrial, marine and freshwater ecosystems. Ingestion of primary or secondary microparticles resulting from plastic degradation can lead to their trophic transfer raising serious health concerns. In this study, the effect of amine and carboxy functionalized polystyrene microparticles on the physiology of daphnids was investigated with a combination of phenotypic and metabolic endpoints. Carboxy functionalized microparticles showed higher toxicity in acute exposures compared to their amine counterparts. Accumulation of both microparticles in animal gut was confirmed by stereo-microscopy as well as fluorescent microscopy which showed no presence of particles in the rest of the animal. Fluorescence based quantification of microparticles extracted from animal lysates validated their concentration-dependent uptake. Additionally, exposure of daphnids to amine and carboxy functionalized microparticles resulted in increased activities of key enzymes related to metabolism and detoxification. Finally, significant metabolic perturbations were discovered following exposure to microplastics. These findings suggest that polystyrene microparticles can hinder organism performance of the freshwater species and highlight the importance of seeking for holistic and physiological endpoints for pollution assessment.

Potential effects of natural aging process on the characteristics and toxicity of facial masks: A zebrafish-based study

The use of facial masks has increased and is therefore being recognized as a large source of environmental microplastics. Herein, we naturally aged disposable masks in a lake for eight weeks and compared the toxicity of mask-derived microplastics depending on the aging process using zebrafish (Danio rerio). Zebrafish were exposed to virgin and aged mask fragments (VF and AF, respectively) for eight weeks. The aging process induced cracks on the surface of mask fragments and chemical adsorption. Both VF and AFs damaged the zebrafish's liver, gills, and intestine and adversely affected their digestive ability, and their movement-aggression was decreased. These observations highlight the consequences of indiscriminately discarding masks or AFs following consumption. In conclusion, personal protective equipment waste in the environment should be appropriately managed to prevent negative impacts on aquatic organisms and, consequently, on humans via the food chain.

Adverse effects of polystyrene nanoplastics on sea cucumber Apostichopus japonicus and their association with gut microbiota dysbiosis

The mariculture environment is a sink of microplastics (MPs) due to its enclosed nature and mass use of plastics. Nanoplastics (NPs) are MPs with a diameter <1 μm that have a more toxic effect on aquatic organisms than other MPs. However, little is known about the underlying mechanisms of NP toxicity on mariculture species. Here, we performed a multi-omics investigation to explore gut microbiota dysbiosis and associated health problems induced by NPs in juvenile sea cucumber Apostichopus japonicus, a commercially and ecologically important marine invertebrate. We observed significant differences in gut microbiota composition after 21 days of NP exposure. Ingestion of NPs significantly increased core gut microbes, especially Rhodobacteraceae and Flavobacteriaceae families. Additionally, gut gene expression profiles were altered by NPs, especially those related to neurological diseases and movement disorders. Correlation and network analyses indicated close relationships between transcriptome changes and gut microbiota variation. Furthermore, NPs induced oxidative stress in sea cucumber intestines, which may be associated with intraspecies variation in Rhodobacteraceae in the gut microbiota. The results suggested that NPs were harmful to the health of sea cucumbers, and they highlighted the importance of the gut microbiota in the responses to NP toxicity in marine invertebrates.

Size matters either way: Differently-sized microplastics affect amphibian host and symbiotic microbiota discriminately

Concerns about the implications of microplastics (MPs) on aqueous animals have gained widespread attention. It has been postulated that the magnitude of MPs can influence its toxicity. However, little is known about how MPs toxicity changes with particle size. Amphibians are reliable bioindicators of ecosystem health due to their complex life cycles. In this study, we compared the influences of two sizes nonfunctionalized polystyrene microspheres (1 and 10 μm) on the metamorphosis of Asiatic toad (Bufo gargarizans). Acute exposure to MPs at high concentrations led to bioaccumulation in the digestive track and internal organs (i.e., liver and heart) of tadpoles. Long-term exposure to either size, at environmentally-related concentrations (1 and 4550 p/mL), led to growth and development delay in pro-metamorphic tadpoles. Remarkably, developmental plasticity mitigated these deleterious effects prior to the onset of metamorphic climax without compromising survival rate in later stages. MPs with a diameter of 10 μm dramatically altered the gut microbiota (e.g., abundance of Catabacter and Desulfovibrio) of pro-metamorphic tadpoles, whereas MPs with a diameter of 1 μm induced much more intensive transcriptional responses in the host tissues (e.g., upregulation of protein synthesis and mitochondrial energy metabolism, and downregulation of neural functions and cellular responses). Given that the two MPs sizes induced similar toxic outcomes, this suggests that their principal toxicity mechanisms are distinct. Small-sized MPs can travel easily across the intestinal mucosa and cause direct toxicity, while large-sized MPs accumulate in gut and affect the host by changing the homeostasis of digestive track. In conclusion, our findings indicate that MPs can affect the growth and development of amphibian larvae, but their developmental plasticity determines the ultimate detrimental effects. Multiple pathways of toxicity may contribute to the size-dependent toxicity of MPs. We anticipate that these findings will increase our understanding of the ecological effects of MPs.

The detrimental effects of micro-and nano-plastics on digestive system: An overview of oxidative stress-related adverse outcome pathway

With the massive manufacture and use of plastics, plastic pollution-related environmental impacts have raised great concern in recent years. As byproducts of plastic fragmentation and degradation, microplastics (MPs) and nanoplastics (NPs) have been identified as novel pollutants that posed a threat to the ecosystem and humans. Since MPs/NPs could be transported via the food chain and retained in the water, the digestive system should be one of the major targets of MPs/NPs-related toxicity. Although considerable evidence has supported the digestive toxicity of MPs/NPs, the proposed mechanisms remained ambiguous due to the variety of study types, models, and endpoints. This review provided a mechanism-based perspective on MPs/NPs-induced digestive effects by adopting the adverse outcome pathway framework as a promising tool. The overproduction of reactive oxygen species was identified as the molecular initiating event in MPs/NPs-mediated injury to the digestive system. A series of detrimental effects including oxidative stress, apoptosis, inflammation, dysbiosis, and metabolic disorders were summarized as key events. Finally, the occurrence of these effects eventually led to an adverse outcome, suggesting a possible increase in the incidence of digestive morbidity and mortality.

Effects of microplastics and lead exposure on gut oxidative stress and intestinal inflammation in common carp (Cyprinus carpio L.)

Microplastics (MPs) are increasingly being detected in freshwater environments, which have the potential to cause combined toxicity with other contaminants on aquatic organisms. To reveal the ecological risks, the combined effects of lead (Pb) and polyvinyl chloride microplastics (MPs) were explored in the gut of common carp (Cyprinus carpio L.). The results confirmed that exposure of Pb alone accelerated Pb accumulation, increased oxidative stress, and activated the inflammation response of the gut. However, the aforementioned effects all decreased under the co-exposure of Pb and MPs. In addition, MPs altered intestinal microbial community of common carp, especially the abundance of immune system-related species. All measured variables were organized for partial least square path modeling, which revealed the combined effects of Pb and MPs on inflammation response. The results implied that MPs reduced inflammation response in two ways, including the reduction of intestinal Pb accumulation and the alteration of the intestinal microbial community. Overall, this study provides a novel aspect of ecological effects on aquatic animals from Pb and MPs exposure. The interesting results remind us that when exploring the ecological risks of MPs, combined effects from other toxic substances must be considered simultaneously.

Are Microplastics Toxic? A Review from Eco-Toxicity to Effects on the Gut Microbiota

Emerging studies have presented an initial picture of the toxic effects of exposure to environmental micro- and nanoplastics. They have indicated that micro- and nanoplastics may induce toxicity by leading to oxidative stress, energy metabolism disorders, gene damage, and so forth in environmental organisms, marine invertebrates and vertebrates, and laboratory mouse models. In recent years, micro- and nanoplastics have been discovered in human fecal samples, placentas, lung tissue, and even blood; thus, micro- and nanoplastics pose an alarming and ever-increasing threat to global public health. However, current research on the health effects of micro- and nanoplastics and the possible adverse outcomes in humans has only presented the tip of the iceberg. More robust clinical data and basic experiments are still warranted to elucidate the specific relationships and mechanisms. In this paper, we review studies on micro- and nanoplastic toxicity from the perspectives of eco-toxicity, the adverse effects on invertebrates and vertebrates, and the impact of micro- and nanoplastics on the gut microbiota and its metabolites. In addition, we evaluate the toxicological role of micro- and nanoplastic exposure and its potential implications in respect to human health. We also summarize studies regarding preventive strategies. Overall, this review provides insights on micro- and nanoplastic toxicity and its underlying mechanisms, opening up scientific avenues for future in-depth studies.

In Vivo Tissue Distribution of Microplastics and Systemic Metabolomic Alterations After Gastrointestinal Exposure

Global plastic use has consistently increased over the past century with several different types of plastics now being produced. Much of these plastics end up in oceans or landfills leading to a substantial accumulation of plastics in the environment. Plastic debris slowly degrades into microplastics (MPs) that can ultimately be inhaled or ingested by both animals and humans. A growing body of evidence indicates that MPs can cross the gut barrier and enter into the lymphatic and systemic circulation leading to accumulation in tissues such as the lungs, liver, kidney, and brain. The impacts of mixed MPs exposure on tissue function through metabolism remains largely unexplored. To investigate the impact of ingested MPs on target metabolomic pathways, mice were subjected to either polystyrene microspheres or a mixed plastics (5 µm) exposure consisting of polystyrene, polyethylene and the biodegradability and biocompatible plastic, poly-(lactic-co-glycolic acid). Exposures were performed twice a week for four weeks at a dose of either 0, 2, or 4 mg/week via oral gastric gavage. Our findings demonstrate that, in mice, ingested MPs can pass through the gut barrier, be translocated through the systemic circulation, and accumulate in distant tissues including the brain, liver, and kidney. Additionally, we report on the metabolomic changes that occur in the colon, liver and brain which show differential responses that are dependent on dose and type of MPs exposure. Lastly, our study provides proof of concept for identifying metabolomic alterations associated with MPs exposure and adds insight into the potential health risks that mixed MPs contamination may pose to humans.

Mitochondrial dysfunction in metabolic disorders induced by per- and polyfluoroalkyl substance mixtures in zebrafish larvae

Several per- and polyfluoroalkyl substances (PFAS) have been linked to metabolic disorders in organisms. However, few studies have considered their combined effects, which would be more representative of PFAS occurring in the environment. In this study, zebrafish embryos were exposed to a mixture of 18 PFAS at three environmentally relevant concentrations for 5 days to assess their bioconcentration and metabolic consequences. The burdens of ∑PFAS in zebrafish larvae were 0.12, 1.58, and 9.63 mg/kg in the 0.5, 5, and 50 μg/L treatment groups, respectively. Exposure to the PFAS mixture accelerated hatching and larval heart rates, increased energy expenditure, and reduced ATP levels and glucose contents due to decreased feed intake and glucose uptake. Metabolomic analysis revealed that exposure to the PFAS mixture enhanced glycolysis but inhibited phospholipid synthesis, and significantly increased the expression of lipid metabolism related genes (srebf1, acox, and pparα), which indicated enhanced β-oxidation. The significant changes in mitochondrial membrane potential, mitochondrial content, and the transcription of genes involved in the mitochondrial respiratory chain (mfn2, ndufs1, atp5fa1, and mt-nd1) and mitochondrial DNA replication and transcription (18rs-rrn, and polg1) suggested that exposure to the PFAS mixture could cause mitochondrial dysfunction and further disrupt glucose and lipid metabolic pathways, ultimately causing metabolic disorders in zebrafish larvae. These findings demonstrate the importance of assessing the metabolic effects of PFAS mixtures on early development in wildlife and humans.

Advances in the Utilization of Zebrafish for Assessing and Understanding the Mechanisms of Nano-/Microparticles Toxicity in Water

A large amount of nano-/microparticles (MNPs) are released into water, not only causing severe water pollution, but also negatively affecting organisms. Therefore, it is crucial to evaluate MNP toxicity and mechanisms in water. There is a significant degree of similarity between the genes, the central nervous system, the liver, the kidney, and the intestines of zebrafish and the human body. It has been shown that zebrafish are exceptionally suitable for evaluating the toxicity and action mechanisms of MNPs in water on reproduction, the central nervous system, and metabolism. Providing ideas and methods for studying MNP toxicity, this article discusses the toxicity and mechanisms of MNPs from zebrafish.

Nanoplastics affect the growth of sea urchins (Strongylocentrotus intermedius) and damage gut health

Nanoplastics (NPs) are abundant and widespread throughout the ocean, not only causing severe environmental pollution, but also worsening the aquatic organisms. To elucidate the mechanism of biological toxic effects underlying the responses of marine invertebrates to NPs, Strongylocentrotus intermedius was stressed with three different NPs concentrations (0 particles/L, 10² particles/L and 10⁴ particles/L). Specific growth rates, enzyme activity, gut tissue section observation and structural characteristics of the gut bacterial community were analyzed. After 28 days of exposure, the specific growth rate of S. intermedius decreased significantly with NPs groups. Further, both lysozyme, pepsin, lipase and amylase activities decreased, while the superoxide dismutase activity increased, indicating that NPs negatively affected digestive enzyme and immune enzyme activity. The analysis of gut tissue sections revealed that NPs caused atrophy and cytoplasmic reduction in the epithelial cells of the S. intermedius intestine. Moreover, the structural characterization of the gut bacterial community indicated significant changes in the abundances of members from Campylobacterota, Chlamydiae, and Firmicutes. Members from Arcobacteraceae, Christensenellaceae and Clostridia were endemic to the NPs treatment. The KEGG database analysis demonstrated that the metabolic pathways specific to the NPs treatment group were significantly associated with growth, energy metabolism, and immunity. In summary, NPs have negatively affected on physiological response and altered gut microecological environment.

Joint effects of micro-sized polystyrene and chlorpyrifos on zebrafish based on multiple endpoints and gut microbial effects

Microplastics often co-occur with a variety of organic contaminants in aquatic environment and pose combined risks to aquatic wildlife. Here, we investigated joint effects of micro-sized polystyrene (mPS, 5 µm) and an organophosphate pesticide chlorpyrifos on zebrafish, using multiple endpoints at both fish individual and gut microbiota levels. It was revealed that mPS ingested by zebrafish accumulated in gut and liver, and caused oxidative stress, hyperactive swimming performance and histological damages in fish, and induced disorders and diversity alterations of the gut microbial community. More importantly, mPS exhibited considerable adsorption capacity against chlorpyrifos, and those adsorbing chlorpyrifos presented greater effects on fish individuals but no different effects on gut microbiota compared to single mPS exposure. Together with body residues of chlorpyrifos in zebrafish, it was proposed that the joint effects between mPS and chlorpyrifos were attributed to the chlorpyrifos released from mPS within zebrafish. The present results provided a comprehensive understanding of joint effects of mPS and contaminants co-occurring in the environment and emphasized the importance of considering the adsorbed chemicals in toxicological studies of microplastics.

The Minderoo-Monaco Commission on Plastics and Human Health

Background

Plastics have conveyed great benefits to humanity and made possible some of the most significant advances of modern civilization in fields as diverse as medicine, electronics, aerospace, construction, food packaging, and sports. It is now clear, however, that plastics are also responsible for significant harms to human health, the economy, and the earth's environment. These harms occur at every stage of the plastic life cycle, from extraction of the coal, oil, and gas that are its main feedstocks through to ultimate disposal into the environment. The extent of these harms not been systematically assessed, their magnitude not fully quantified, and their economic costs not comprehensively counted.

Goals

The goals of this Minderoo-Monaco Commission on Plastics and Human Health are to comprehensively examine plastics' impacts across their life cycle on: (1) human health and well-being; (2) the global environment, especially the ocean; (3) the economy; and (4) vulnerable populations-the poor, minorities, and the world's children. On the basis of this examination, the Commission offers science-based recommendations designed to support development of a Global Plastics Treaty, protect human health, and save lives.

Report Structure

This Commission report contains seven Sections. Following an Introduction, Section 2 presents a narrative review of the processes involved in plastic production, use, and disposal and notes the hazards to human health and the environment associated with each of these stages. Section 3 describes plastics' impacts on the ocean and notes the potential for plastic in the ocean to enter the marine food web and result in human exposure. Section 4 details plastics' impacts on human health. Section 5 presents a first-order estimate of plastics' health-related economic costs. Section 6 examines the intersection between plastic, social inequity, and environmental injustice. Section 7 presents the Commission's findings and recommendations.

Plastics

Plastics are complex, highly heterogeneous, synthetic chemical materials. Over 98% of plastics are produced from fossil carbon- coal, oil and gas. Plastics are comprised of a carbon-based polymer backbone and thousands of additional chemicals that are incorporated into polymers to convey specific properties such as color, flexibility, stability, water repellence, flame retardation, and ultraviolet resistance. Many of these added chemicals are highly toxic. They include carcinogens, neurotoxicants and endocrine disruptors such as phthalates, bisphenols, per- and poly-fluoroalkyl substances (PFAS), brominated flame retardants, and organophosphate flame retardants. They are integral components of plastic and are responsible for many of plastics' harms to human health and the environment.Global plastic production has increased almost exponentially since World War II, and in this time more than 8,300 megatons (Mt) of plastic have been manufactured. Annual production volume has grown from under 2 Mt in 1950 to 460 Mt in 2019, a 230-fold increase, and is on track to triple by 2060. More than half of all plastic ever made has been produced since 2002. Single-use plastics account for 35-40% of current plastic production and represent the most rapidly growing segment of plastic manufacture.Explosive recent growth in plastics production reflects a deliberate pivot by the integrated multinational fossil-carbon corporations that produce coal, oil and gas and that also manufacture plastics. These corporations are reducing their production of fossil fuels and increasing plastics manufacture. The two principal factors responsible for this pivot are decreasing global demand for carbon-based fuels due to increases in 'green' energy, and massive expansion of oil and gas production due to fracking.Plastic manufacture is energy-intensive and contributes significantly to climate change. At present, plastic production is responsible for an estimated 3.7% of global greenhouse gas emissions, more than the contribution of Brazil. This fraction is projected to increase to 4.5% by 2060 if current trends continue unchecked.

Plastic Life Cycle

The plastic life cycle has three phases: production, use, and disposal. In production, carbon feedstocks-coal, gas, and oil-are transformed through energy-intensive, catalytic processes into a vast array of products. Plastic use occurs in every aspect of modern life and results in widespread human exposure to the chemicals contained in plastic. Single-use plastics constitute the largest portion of current use, followed by synthetic fibers and construction.Plastic disposal is highly inefficient, with recovery and recycling rates below 10% globally. The result is that an estimated 22 Mt of plastic waste enters the environment each year, much of it single-use plastic and are added to the more than 6 gigatons of plastic waste that have accumulated since 1950. Strategies for disposal of plastic waste include controlled and uncontrolled landfilling, open burning, thermal conversion, and export. Vast quantities of plastic waste are exported each year from high-income to low-income countries, where it accumulates in landfills, pollutes air and water, degrades vital ecosystems, befouls beaches and estuaries, and harms human health-environmental injustice on a global scale. Plastic-laden e-waste is particularly problematic.

Environmental Findings

Plastics and plastic-associated chemicals are responsible for widespread pollution. They contaminate aquatic (marine and freshwater), terrestrial, and atmospheric environments globally. The ocean is the ultimate destination for much plastic, and plastics are found throughout the ocean, including coastal regions, the sea surface, the deep sea, and polar sea ice. Many plastics appear to resist breakdown in the ocean and could persist in the global environment for decades. Macro- and micro-plastic particles have been identified in hundreds of marine species in all major taxa, including species consumed by humans. Trophic transfer of microplastic particles and the chemicals within them has been demonstrated. Although microplastic particles themselves (>10 µm) appear not to undergo biomagnification, hydrophobic plastic-associated chemicals bioaccumulate in marine animals and biomagnify in marine food webs. The amounts and fates of smaller microplastic and nanoplastic particles (MNPs <10 µm) in aquatic environments are poorly understood, but the potential for harm is worrying given their mobility in biological systems. Adverse environmental impacts of plastic pollution occur at multiple levels from molecular and biochemical to population and ecosystem. MNP contamination of seafood results in direct, though not well quantified, human exposure to plastics and plastic-associated chemicals. Marine plastic pollution endangers the ocean ecosystems upon which all humanity depends for food, oxygen, livelihood, and well-being.

Human Health Findings

Coal miners, oil workers and gas field workers who extract fossil carbon feedstocks for plastic production suffer increased mortality from traumatic injury, coal workers' pneumoconiosis, silicosis, cardiovascular disease, chronic obstructive pulmonary disease, and lung cancer. Plastic production workers are at increased risk of leukemia, lymphoma, hepatic angiosarcoma, brain cancer, breast cancer, mesothelioma, neurotoxic injury, and decreased fertility. Workers producing plastic textiles die of bladder cancer, lung cancer, mesothelioma, and interstitial lung disease at increased rates. Plastic recycling workers have increased rates of cardiovascular disease, toxic metal poisoning, neuropathy, and lung cancer. Residents of "fenceline" communities adjacent to plastic production and waste disposal sites experience increased risks of premature birth, low birth weight, asthma, childhood leukemia, cardiovascular disease, chronic obstructive pulmonary disease, and lung cancer.During use and also in disposal, plastics release toxic chemicals including additives and residual monomers into the environment and into people. National biomonitoring surveys in the USA document population-wide exposures to these chemicals. Plastic additives disrupt endocrine function and increase risk for premature births, neurodevelopmental disorders, male reproductive birth defects, infertility, obesity, cardiovascular disease, renal disease, and cancers. Chemical-laden MNPs formed through the environmental degradation of plastic waste can enter living organisms, including humans. Emerging, albeit still incomplete evidence indicates that MNPs may cause toxicity due to their physical and toxicological effects as well as by acting as vectors that transport toxic chemicals and bacterial pathogens into tissues and cells.Infants in the womb and young children are two populations at particularly high risk of plastic-related health effects. Because of the exquisite sensitivity of early development to hazardous chemicals and children's unique patterns of exposure, plastic-associated exposures are linked to increased risks of prematurity, stillbirth, low birth weight, birth defects of the reproductive organs, neurodevelopmental impairment, impaired lung growth, and childhood cancer. Early-life exposures to plastic-associated chemicals also increase the risk of multiple non-communicable diseases later in life.

Economic Findings

Plastic's harms to human health result in significant economic costs. We estimate that in 2015 the health-related costs of plastic production exceeded $250 billion (2015 Int$) globally, and that in the USA alone the health costs of disease and disability caused by the plastic-associated chemicals PBDE, BPA and DEHP exceeded $920 billion (2015 Int$). Plastic production results in greenhouse gas (GHG) emissions equivalent to 1.96 gigatons of carbon dioxide (CO2e) annually. Using the US Environmental Protection Agency's (EPA) social cost of carbon metric, we estimate the annual costs of these GHG emissions to be $341 billion (2015 Int$).These costs, large as they are, almost certainly underestimate the full economic losses resulting from plastics' negative impacts on human health and the global environment. All of plastics' economic costs-and also its social costs-are externalized by the petrochemical and plastic manufacturing industry and are borne by citizens, taxpayers, and governments in countries around the world without compensation.

Social Justice Findings

The adverse effects of plastics and plastic pollution on human health, the economy and the environment are not evenly distributed. They disproportionately affect poor, disempowered, and marginalized populations such as workers, racial and ethnic minorities, "fenceline" communities, Indigenous groups, women, and children, all of whom had little to do with creating the current plastics crisis and lack the political influence or the resources to address it. Plastics' harmful impacts across its life cycle are most keenly felt in the Global South, in small island states, and in disenfranchised areas in the Global North. Social and environmental justice (SEJ) principles require reversal of these inequitable burdens to ensure that no group bears a disproportionate share of plastics' negative impacts and that those who benefit economically from plastic bear their fair share of its currently externalized costs.

Conclusions

It is now clear that current patterns of plastic production, use, and disposal are not sustainable and are responsible for significant harms to human health, the environment, and the economy as well as for deep societal injustices.The main driver of these worsening harms is an almost exponential and still accelerating increase in global plastic production. Plastics' harms are further magnified by low rates of recovery and recycling and by the long persistence of plastic waste in the environment.The thousands of chemicals in plastics-monomers, additives, processing agents, and non-intentionally added substances-include amongst their number known human carcinogens, endocrine disruptors, neurotoxicants, and persistent organic pollutants. These chemicals are responsible for many of plastics' known harms to human and planetary health. The chemicals leach out of plastics, enter the environment, cause pollution, and result in human exposure and disease. All efforts to reduce plastics' hazards must address the hazards of plastic-associated chemicals.

Recommendations

To protect human and planetary health, especially the health of vulnerable and at-risk populations, and put the world on track to end plastic pollution by 2040, this Commission supports urgent adoption by the world's nations of a strong and comprehensive Global Plastics Treaty in accord with the mandate set forth in the March 2022 resolution of the United Nations Environment Assembly (UNEA).International measures such as a Global Plastics Treaty are needed to curb plastic production and pollution, because the harms to human health and the environment caused by plastics, plastic-associated chemicals and plastic waste transcend national boundaries, are planetary in their scale, and have disproportionate impacts on the health and well-being of people in the world's poorest nations. Effective implementation of the Global Plastics Treaty will require that international action be coordinated and complemented by interventions at the national, regional, and local levels.This Commission urges that a cap on global plastic production with targets, timetables, and national contributions be a central provision of the Global Plastics Treaty. We recommend inclusion of the following additional provisions:The Treaty needs to extend beyond microplastics and marine litter to include all of the many thousands of chemicals incorporated into plastics.The Treaty needs to include a provision banning or severely restricting manufacture and use of unnecessary, avoidable, and problematic plastic items, especially single-use items such as manufactured plastic microbeads.The Treaty needs to include requirements on extended producer responsibility (EPR) that make fossil carbon producers, plastic producers, and the manufacturers of plastic products legally and financially responsible for the safety and end-of-life management of all the materials they produce and sell.The Treaty needs to mandate reductions in the chemical complexity of plastic products; health-protective standards for plastics and plastic additives; a requirement for use of sustainable non-toxic materials; full disclosure of all components; and traceability of components. International cooperation will be essential to implementing and enforcing these standards.The Treaty needs to include SEJ remedies at each stage of the plastic life cycle designed to fill gaps in community knowledge and advance both distributional and procedural equity.This Commission encourages inclusion in the Global Plastic Treaty of a provision calling for exploration of listing at least some plastic polymers as persistent organic pollutants (POPs) under the Stockholm Convention.This Commission encourages a strong interface between the Global Plastics Treaty and the Basel and London Conventions to enhance management of hazardous plastic waste and slow current massive exports of plastic waste into the world's least-developed countries.This Commission recommends the creation of a Permanent Science Policy Advisory Body to guide the Treaty's implementation. The main priorities of this Body would be to guide Member States and other stakeholders in evaluating which solutions are most effective in reducing plastic consumption, enhancing plastic waste recovery and recycling, and curbing the generation of plastic waste. This Body could also assess trade-offs among these solutions and evaluate safer alternatives to current plastics. It could monitor the transnational export of plastic waste. It could coordinate robust oceanic-, land-, and air-based MNP monitoring programs.This Commission recommends urgent investment by national governments in research into solutions to the global plastic crisis. This research will need to determine which solutions are most effective and cost-effective in the context of particular countries and assess the risks and benefits of proposed solutions. Oceanographic and environmental research is needed to better measure concentrations and impacts of plastics <10 µm and understand their distribution and fate in the global environment. Biomedical research is needed to elucidate the human health impacts of plastics, especially MNPs.

Summary

This Commission finds that plastics are both a boon to humanity and a stealth threat to human and planetary health. Plastics convey enormous benefits, but current linear patterns of plastic production, use, and disposal that pay little attention to sustainable design or safe materials and a near absence of recovery, reuse, and recycling are responsible for grave harms to health, widespread environmental damage, great economic costs, and deep societal injustices. These harms are rapidly worsening.While there remain gaps in knowledge about plastics' harms and uncertainties about their full magnitude, the evidence available today demonstrates unequivocally that these impacts are great and that they will increase in severity in the absence of urgent and effective intervention at global scale. Manufacture and use of essential plastics may continue. However, reckless increases in plastic production, and especially increases in the manufacture of an ever-increasing array of unnecessary single-use plastic products, need to be curbed.Global intervention against the plastic crisis is needed now because the costs of failure to act will be immense.

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

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

Dietary nano-selenium alleviates heat stress-induced intestinal damage through affecting intestinal antioxidant capacity and microbiota in rainbow trout (Oncorhynchus mykiss)

Heat stress-induced intestinal damage is a key event in fish pathology. Nano-selenium (nano-Se) shows remarkably high biological activity and low toxicity, making it an ideal and ecological Se formulation; however, to date, the protective effects of nano-Se against heat stress-induced intestinal injury and pertinent molecular mechanisms remain unknown. Herein, rainbow trout (Oncorhynchus mykiss) were fed either a basal diet or basal diet + 5 mg/kg nano-Se. Samples were collected before (18 °C for 9 days; CG18 and Se18 groups) and after (24 °C for 8 h; CG24 and Se24 groups) heat stress treatment. On heat stress exposure, intestinal villus height, muscularis thickness, and goblet cell number decreased, and expression of tight junction proteins (ZO-1, occludin, and claudin-8d) was downregulated; dietary supplementation with nano-Se alleviated these effects. Furthermore, in the presence of nano-Se, catalase activity was elevated, and expression of diverse heat shock proteins (Hsp70b, Hsp90α, and Hsp30), selenoproteins (Gpx1a, Gpx1b1, and Trx), and anti-inflammatory cytokine (TGF-β) was upregulated. In contrast, nano-Se supplementation significantly alleviated the increase of the expression of pro-inflammatory cytokines (IL-1β and TNF-α) and the malondialdehyde content. We also observed that heat stress markedly increased the relative abundance of Actinobacteria, Firmicutes, Methylobacterium, Akkermansia, and Deinococcus and decreased that of Proteobacteria; nano-Se supplementation restored these changes, making their distribution similar to that in the control group. Overall, our findings suggest that nano-Se plays a protective role against heat stress-induced intestinal damage in rainbow trout by promoting the recovery of antioxidant enzyme activity, enhancing protein repair, alleviating inflammatory responses, and restoring intestinal microbiota composition.