Toxicity induced via ingestion of naturally-aged polystyrene microplastics by a small-sized terrestrial bird and its potential role as vectors for the dispersion of these pollutants

Microplastic in an apex predator: evidence from Barn owl (Tyto alba) pellets in two sites with different levels of anthropization

Plastic pollution in terrestrial and freshwater environments and its accumulation along food chains has been poorly studied in birds. The Barn owl (Tyto alba) is an opportunistic and nocturnal apex predator feeding mostly on small mammals. In this note, we reported evidence of microplastics (MPs) contamination in Barn owl pellets collected, for the first time, in two sites with different levels of anthropization (low: natural landscape mosaic vs. high extensive croplands). The following polymers have been recorded: polyvinylchloride (PVC), polyethylene (PE), expanded polyester (EPS), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyester (PL), viscose, and starch-based biopolymer. We found significant higher MPs frequency in the most anthropized site. Our results suggest that pellet' analysis may represent a cost-effective method for monitoring MP contamination along food chains in terrestrial ecosystems.

Birds as bioindicators of plastic pollution in terrestrial and freshwater environments: A 30-year review

Plastic pollution is a global concern that has grown ever more acute in recent years. Most research has focused on the impact of plastic pollution in marine environments. However, plastic is increasingly being detected in terrestrial and freshwater environments with key inland sources including landfills, where it is accessible to a wide range of organisms. Birds are effective bioindicators of pollutants for many reasons, including their high mobility and high intra- and interspecific variation in trophic levels. Freshwater and terrestrial bird species are under-represented in plastic pollution research compared to marine species. We reviewed 106 studies (spanning from 1994 onwards) that have detected plastics in bird species dwelling in freshwater and/or terrestrial habitats, identifying knowledge gaps. Seventy-two studies focused solely on macroplastics (fragments >5 mm), compared to 22 microplastic (fragments <5 mm) studies. A further 12 studies identified plastics as both microplastics and macroplastics. No study investigated nanoplastic (particles <100 nm) exposure. Research to date has geographical and species' biases while ignoring nanoplastic sequestration in free-living freshwater, terrestrial and marine bird species. Building on the baseline search presented here, we urge researchers to develop and validate standardised field sampling techniques and laboratory analytical protocols such as Raman spectroscopy to allow for the quantification and identification of micro- and nanoplastics in terrestrial and freshwater environments and the species therein. Future studies should consistently report the internalised and background concentrations, types, sizes and forms of plastics. This will enable a better understanding of the sources of plastic pollution and their routes of exposure to birds of terrestrial and freshwater environments, providing a more comprehensive insight into the potential impacts on birds.

Dynamics and effects of plastic contaminants' assimilation in gulls

Polybrominated diphenyl ethers are persistent disrupters assimilated by organisms, yet little is known about their link to plastic ingestion and health effects. In an experiment, two groups of yellow-legged/lesser black-backed gulls (Larus michahellis/Larus fuscus) were fed plastics with BDE99 to assess leaching into brain, preen oil, liver and fat tissues and evaluate effects on health and stress parameters. Although most plastic was regurgitated, we observed a clear relation between plastic ingestion and chemical leaching. BDE99 exhibited higher levels in brain tissue of gulls from the plastic groups. Also, only values of cholinesterases measured in plasma were significantly reduced in the 'plastic' groups. Cholinesterase activity in the brain also tended to decrease, suggesting a negative effect in gulls' neurofunction. Results indicate that chemical leaching occurs, even when plastics stay in the stomach for a short period of time and showed that this can affect gulls' health.

White Stork Pellets: Non-Invasive Solution to Monitor Anthropogenic Particle Pollution

The present study applied a non-invasive method to analyse anthropogenic particles and prey items in white stork (Ciconia ciconia) pellets. Pellets (n = 20) were obtained from white stork nests during the 2020 breeding season from two sites in Croatia. In total, 7869 anthropogenic particles were isolated. The majority of particles were fragments, while previous studies on other birds often reported fibres. An ATR-FTIR polymer analysis detected glass and construction and building materials, as well as several compounds associated with plastic masses. Polymer investigation revealed the presence of dotriacontane and octacosane, which are by-products of polyethylene (PE) degradation and transformation. Additionally, the detection of vinylidene chloride (VDC) highlights the historical contribution of polyvinylidene chloride (PVDC) to plastic pollution. Significant variation in particle quantity and size between the sampling sites was detected, with larger particles found at sites associated with the metal mechanical engineering industry and agriculture. Prey assessment revealed chitin remains of large insects such as Orthoptera and Coleoptera. This research confirms the potential of pellet analysis as a valuable tool for assessing the presence of anthropogenic particles in the environment. However, further research is needed to fully understand the extent of particle ingestion, particle sources and potential impact.

Tracking the micro- and nanoplastics in the terrestrial-freshwater food webs. Bivalves as sentinel species

Micro- (MPs) and nanoplastics (NPs) are currently ubiquitous in the ecosystems, and freshwater biota is still insufficiently studied to understand the global fate, transport paths, and consequences of their presence. Thus, in this study, we investigated the role of bivalves and a trophic transfer of MPs and NPs in an experimental food chain. The food chain consisted of terrestrial non-selective detritivore Dendrobaena (Eisenia) sp., freshwater benthic filter feeder Unio tumidus, and freshwater benthic detritivore-collectors Asellus aquaticus or Gammarus sp. Animals were exposed to different fluorescently labeled micro- and nanoplastics (PMMA 20 μm, nanoPS 15-18 nm, and 100 nm, PS 1 μm and 20 μm, PE from cosmetics) as well as to the faeces of animals exposed to plastics to assess their influence on the environmental transportation, availability to biota, and bioaccumulation of supplied particles. Damaged and intact fluorescent particles were observed in the faeces of terrestrial detritivores and in the droppings of aquatic filter feeders, respectively. They were also present in the guts of bivalves and of crustaceans which were fed with bivalve droppings. Bivalves (Unio tumidus, and additionally Unio pictorum, and Sphaerium corneum) produced droppings containing micro- and nanoparticles filtered from suspension and deposited them onto the tank bottom, making them available for broader feeding guilds of animals (e.g. collectors, like crustaceans). Finally, the natural ageing of PS and its morphological changes, leakage of the fluorescent labelling, and agglomeration of particles were demonstrated. That supports our hypothesis of the crucial role of the characterization of physical and chemical materials in adequately understanding the mechanisms of their interaction with biota. Microscopical methods (confocal, fluorescent, scanning electron) and Raman and FT-IR spectroscopy were used to track the particles' passage in a food web and monitor structural changes of the MPs' and NPs' surface.

Accumulation of microplastics in predatory birds near a densely populated urban area

The pollution due to plastic and other anthropogenic particles has steadily increased over the last few decades, presenting a significant threat to the environment and organisms, including avian species. This research aimed to investigate the occurrence of anthropogenic pollutants in the digestive and respiratory systems of four birds of prey: Common Buzzard (Buteo buteo), Black Kite (Milvus migrans), Eurasian Sparrowhawk (Accipiter nisus), and Northern Goshawk (Accipiter gentilis). The results revealed widespread contamination in all species with microplastics (MPs) and cellulosic anthropogenic fibers (AFs), with an average of 7.9 MPs and 9.2 AFs per specimen. Every digestive system contained at least one MP, while 65 % of specimens exhibited MPs in their respiratory systems. This is the work reporting a high incidence of MPs in the respiratory system of birds, clearly indicating inhalation as a pathway for exposure to plastic pollution. The content of MPs and AFs varied significantly when comparing specimens collected from central Madrid with those recovered from other parts of the region, including rural environments, suburban areas, or less populated cities. This result aligns with the assumption that anthropogenic particles disperse from urban centers to surrounding areas. Additionally, the dominant particle shape consisted of small-sized fibers (> 98 %), primarily composed of polyester, polyethylene, acrylic materials, and cellulose fibers exhibiting indicators of industrial treatment. These findings emphasize the necessity for further research on the impact of plastic and other anthropogenic material contamination in avian species, calling for effective strategies to mitigate plastic pollution.

Unraveling the micro- and nanoplastic predicament: A human-centric insight

Micro- and nanoplastics are vast anthropogenic pollutants in our direct surroundings with a robust environmental stability and a potential for a long-lasting and increasing global circulation. This has raised concerns among the public and policy makers for human health upon exposure to these particles. The micro- and nanoplastic burden on humans is currently under debate, along with criticism on the experimental approaches used in hazard assessment. The present review presents an overview of the human-relevant aspects associated with the current micro-and nanoplastic burden. We focus on environmental circulation and the estimation of exposure quantities to humans, along with a state-of-the-art overview of particle accumulation in over 15 human organs and other specimen. Additionally, data regarding particle characteristics used in toxicity testing was extracted from 91 studies and discussed considering their environmental and human relevance.

Evidence of internalized microplastics in mussel tissues detected by volumetric Raman imaging

Microplastics are a global ecological concern due to their potential risk to wildlife and human health. Animals ingest microplastics, which can enter the trophic chain and ultimately impact human well-being. The ingestion of microplastics can cause physical and chemical damage to the animals' digestive systems, affecting their health. To estimate the risk to ecosystems and human health, it is crucial to understand the accumulation and localization of ingested microplastics within the cells and tissues of living organisms. However, analyzing this issue is challenging due to the risk of sample contamination, given the ubiquity of microplastics. Here, an analytical approach is employed to confirm the internalization of microplastics in cryogenic cross-sections of mussel tissue. Using 3D Raman confocal microscopy in combination with chemometrics, microplastics measuring 1 μm in size were detected. The results were further validated using optical and fluorescence microscopy. The findings revealed evidence of microplastics being internalized in the digestive epithelial tissues of exposed mussels (Mytilus galloprovincialis), specifically within the digestive cells forming digestive alveoli. This study highlights the need to investigate the internalization of microplastics in organisms like mussels, as it helps us understand the potential risks they pose to aquatic biota and ultimately to human health. By employing advanced imaging techniques, challenges associated with sample contamination can be overcome and valuable insights into the impact of microplastics on marine ecosystems and human consumers are provided.

Exposure to microplastics affects fatty acid composition in the Japanese quail depending on sex and particle size

Plastic ingestion in birds is a widespread phenomenon of increasing concern. However, little is known about how exposure to microplastics (MP) affects the health of birds. In other organisms, MP exposure alters lipid metabolism and composition. If also true in birds, this could affect their fitness, especially since birds heavily rely on lipids during migration and egg production. Therefore, the aim of this study was to determine if ingestion of MP (polypropylene and polyethylene collected in nature) in two size ranges, large (3 mm) and small (<125 μm), affects lipid metabolism in the Japanese quail (Coturnix japonica). We orally exposed 55 one-week-old quail during 5 weeks to a total of 600 mg of MP in sizes of either large, small, or a mixture of both. After the exposure period, females fed small MP had higher liver masses compared to control females (on average ± SD, 8.95 ± 2.3 g vs. 6.34 ± 1.0 g), while liver lipid content did not differ in either males or females. The levels of monounsaturated fatty acids were lower in females exposed to large MP and the mixture of both MP sizes compared to controls. Females exposed to MP also had different levels of oleic- (18:1) and palmitoleic (16:1) acid compared to controls dependent on MP size. Exposure to small MP increased levels of palmitic- (16:0) and palmitoleic (16:1) acid in both males and females suggesting a possible increase in de novo fatty acid synthesis. Taken together, our results point towards a sex-specific sensitivity to MP as well as size-dependent MP effects on lipid metabolism in birds. Disruption of fatty acid composition could affect important life stages in female birds, such as migration and egg-laying. We stress the importance of further research focused on determining the mechanisms of action of MP on lipid metabolism.

Microplastics induced inflammation in the spleen of developmental Japanese quail (Coturnix japonica) via ROS-mediated p38 MAPK and TNF signaling pathway activation1

Microplastics (MPs) have been found in virtually every environment on earth and become a source of pollution around the world. The toxicology of microplastics on immunity is an emerging area of research, and more studies are needed to fully understand the effects of microplastics exposure on animal health. Therefore, we tried to determine the immunotoxic effects of microplastics on avian spleen by using an animal model- Japanese quail (Coturnix japonica). One-week chicks were exposed to environmentally relevant concentrations of 0.02 mg/kg, 0.4 mg/kg and 8 mg/kg polystyrene microplastics in the feed for 5 weeks. The results demonstrated that microplastics induced microstructural injuries featured by cell disarrangement and vacuolation indicating splenic inflammation. Ultrastructural damages including membrane lysis and mitochondrial vacuolation also suggested inflammatory responses in the spleen by microplastics exposure. Meanwhile, increasing reactive oxygen species (ROS) and Malondialdehyde (MDA) while the inactivation of superoxide dismutase (SOD), catalase (CAT) and glutathione S-transferase (GST) indicated oxidative stress in the spleen. Moreover, the increasing level of proinflammatory cytokines including Tumor necrosis factor alpha (TNF-α), interferon gamma (IFN-γ), interleukin-1β (IL-1β), interleukin-6 (IL-6) and decreasing level of anti-inflammatory cytokine interleukin-10 (IL-10) implied splenic inflammation. Furthermore, transcriptomic analysis showed that microplastics induced inflammatory responses in the spleen through p38 mitogen-activated protein kinases (p38 MAPK) pathway activation and tumor necrosis factor (TNF) signaling stimulation. The signaling stimulation also aggravated cell apoptosis in the spleen. The present study may benefit to understand potential mechanisms of developmental immunotoxicology of microplastics.

The iron matters: Aged microplastics disrupted the iron homeostasis in the liver organoids

Plastic products undergo artificial and unintentional aging during daily use, causing the presence of aged microplastics (aMP). Humans are inevitably exposed to aMP. Liver is one of the critical target organs of MP through oral intake, however, limited research has focused on the hepatic toxicity of aMP compared to pristine MP (pMP). We utilized the human pluripotent stem cells-derived liver organoids (LOs) to compare the cytotoxicity of pristine polystyrene microplastics (pPS) (1 μm, carbonyl index 0.08) and aged polystyrene microplastics (aPS) (1 μm, carbonyl index 0.20) ranged from 20 to 200 ng/mL. Our findings indicate that aPS was more cytotoxic than pPS. We explored the disrupted iron homeostasis in terms of the [Fe2+] and [Fe3+] levels, iron storage and transport. A "vector-like effect" induced by aPS has been preliminarily suggested by the correlated change in total iron level and co-localization of PS and ferritin light chain (FTL) in the LOs following exposure to aPS and ferric ammonium citrate (FAC) individually and combinedly. In addition, we observed abnormal mitochondrial morphology, elevated lipid peroxidation, and declined GSH peroxidase activity, together with the declined expression of transferrin receptor (TFRC) and elevated expressions of SLC7A11, FTL. The gene handled iron transport and iron use were disrupted by aPS. Moreover, we employed FAC to introduce iron overload and Nacetylcysteine (NAC) to protect the lipid peroxidation. In aPS + FAC group, aggravated effects could be observed in aspects of [Fe2+] level, lipid peroxidation, and compromised expression levels of iron homeostasis-related markers, in contrast, in aPS + NAC group, most of changes recovered but the hepatocytoxicity remained. Specifically, a dimorphic change in elevated FTL and decreased ferritin heavy chain (FTH1) caused by 50 ng/mL aMP (57.33 ± 3.57 items/mL, equivalent to human intake level), indicated a specific response to low-dose aMP.

Raman Microspectroscopy evidence of microplastics in human semen

The presence of microplastics (MPs) in human fluids and organs is a great concern, since, as highlighted by recent studies on animal models, they could cause alterations of several physiological functions, including reproduction. In this study, semen samples collected from men living in a polluted area of the Campania Region (Southern Italy), were analyzed to assess the presence of MPs. N. 16 pigmented microplastic fragments (ranging from 2 to 6 μm in size) with spheric or irregular shapes were found in six out of ten samples. All the detected MPs were characterized in terms of morphology (size, colour, and shape) and chemical composition by Raman Microspectroscopy. Chemical composition showed the presence of polypropylene (PP), polyethylene (PE), polyethylene terephthalate (PET), polystyrene (PS), polyvinylchloride (PVC), polycarbonate (PC), polyoxymethylene (POM) and acrylic, suggesting ingestion and/or inhalation as a route of exposure to environmental MPs. In this work, we propose for the first time a mechanism by which MPs pass into the semen most likely through the epididymis and seminal vesicles, which are the most susceptible to inflammation.

Biomarkers of oxidative stress, inflammation, and genotoxicity to assess exposure to micro- and nanoplastics. A literature review

The increased awareness about possible health effects arising from micro- and nanoplastics (MNPs) pollution is driving a huge amount of studies. Many international efforts are in place to better understand and characterize the hazard of MNPs present in the environment. The literature search was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) methodology in two different databases (PubMed and Embase). The selection of articles was carried out blind, screening titles and abstracts according to inclusion and exclusion criteria. In general, these studies rely on the methodology already in use for assessing hazard from nanomaterials and particles of concern. However, only a limited number of studies have so far directly measured human exposure to MNPs and examined the relationship between such exposure and its impact on human health. This review aims to provide an overview of the current state of research on biomarkers of oxidative stress, inflammation, and genotoxicity that have been explored in relation to MNPs exposure, using human, cellular, animal, and plant models. Both in-vitro and in-vivo models suggest an increased level of oxidative stress and inflammation as the main mechanism of action (MOA) leading to adverse effects such as chronic inflammation, immunotoxicity and genotoxicity. With the identification of such biological endpoints, representing critical key initiating events (KIEs) towards adaptive or adverse outcomes, it is possible to identify a panel of surrogate biomarkers to be applied and validated especially in occupational settings, where higher levels of exposure may occur.

The Microplastics Iceberg: Filling Gaps in Our Understanding

Plastic is an indispensable material in modern society; however, high production rates combined with inadequate waste management and disposal have resulted in enormous stress on ecosystems. In addition, plastics can become smaller particles known as microplastics (MPs) due to physical, chemical, and biological drivers. MP pollution has become a significant environmental problem affecting terrestrial and aquatic ecosystems worldwide. Although the topic is not entirely new, it is of great importance to the field of polymers, drawing attention to specific gaps in the existing literature, identifying future areas of research, and improving the understanding of MP pollution and its environmental impacts. Despite progress in this field, problems remain. The lack of standardized methods for MP sampling, separation, extraction, and detection makes it difficult to collect information and establish links between studies. In addition, the distribution and pathways of MPs in ecosystems remain unknown because of their heterogeneous nature and the complex matrices in which they occur. Second, toxicological tests showed that MPs can be ingested by a wide range of organisms, such as Danio rerio and Eisenia fetida, resulting in gut obstruction, physical damage, histological changes, and oxidative stress. The uptake of MP and their toxicological effects depend on their shape, size, concentration, and polymer composition. Furthermore, MPs can enter the food chain, raising concerns regarding potential contaminations for human and environmental health. This review paper sheds light on the pressing issue of MP pollution and highlights the need for interdisciplinary collaboration between scientists, policymakers, and industry leaders.

First Report on Microplastics Quantification in Poultry Chicken and Potential Human Health Risks in Pakistan

Microplastics (MPs) are an emerging environmental health concern due to their widespread occurrence in food sources such as fish, meat, chicken, honey, sugar, salt, tea and drinking water, thereby posing possible risks to human health. This study aimed to observe the existence of MPs in the crop and gizzard of the farm chicken, a significant food source in Pakistan. Twenty-four chicken samples were taken from eight poultry farms across Punjab, Pakistan. A total of 1227 MP particles were found from 24 samples (crop and gizzards) originating from the 8 poultry farms. In all, 429 MP particles were found in 24 chicken crops, with a mean of 17.8 ± 12.1 MPs/crop. In contrast, 798 MP particles were found in 24 chicken gizzards, with a mean of 33.25 ± 17.8 MPs/gizzard. Comparatively larger particles, ranging between 300-500 µm, were more abundant (63%) than other considered sizes (300-150 µm [21%] and 150-50 µm [16%]). Additionally, fragments were the dominant type of shape in both sample types (crop [64%] and gizzard [53%]). The predominant colours of particles extracted from gizzards and crops were yellow (32%) and red (32%), respectively. Chemical characterisation of these particles detected four types of polymers: polyvinyl chloride (PVC) at 51.2%, followed by low-density polyethylene (LDPE) at 30.7%, polystyrene (PS) at 13.6% and polypropylene homopolymer (PPH) at 4.5%. In conclusion, we provide evidence for MPs in the gizzards and crops of farmed chickens which may originate from contaminated poultry feed. Only a few studies have been reported globally to assess MPs ingestion in chickens. The current study is the first report from Pakistan. It could be a valuable addition to support MPs literature to establish a relationship between MPs contamination and intake through the food chain.

N6-methyladenosine methylation mediates non-coding RNAs modification in microplastic-induced cardiac injury

Owing to their potential adverse health effects, global contamination by microplastics (MPs) has attracted increased scientific and societal concerns. However, in vivo studies on MP toxicity, along with its effects and underlying mechanisms, remain limited. We recently found that non-coding RNA (ncRNAs) contribute to MP-mediated vascular toxicity. Moreover, previous studies have identified N6-methyladenosine (m6A) modifications in ncRNAs as influencing factors in cardiovascular disease. However, whether and how m6A modifications in ncRNAs are affected by MP-induced cardiotoxicity remain unknown. Herein, we profiled differentially expressed ncRNAs and their related m6A modification profiles in MP-exposed myocardial tissue using RNA sequencing (RNA-seq) and methylated RNA immunoprecipitation sequencing (MeRIP-seq). First, we observed that MPs accumulated in different organs and upregulated apoptosis in the heart, liver, spleen, and kidney cells. Furthermore, total m6A and METTL3 levels increased in the myocardium after exposure to MPs. RNA-seq results revealed that 392 lncRNAs and 302 circRNAs were differentially expressed in MP-treated mouse myocardium compared to the control group. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analyses showed that these altered lncRNAs and circRNAs were closely associated with endocytosis, cellular senescence, and cell cycle signaling pathways, which may cause cardiotoxicity. Furthermore, MeRIP-seq data showed different distributions and abundances of m6A modifications in lncRNAs and circRNAs. Additionally, we identified differentially m6A methylated lncRNAs and circRNAs through conjoint analysis of the two high-throughput sequencing datasets and found that both m6A modifications and the expression of circ-Arfgef2 and lncG3bp2 were upregulated after exposure to MPs. This suggests that MP-induced m6A modifications in ncRNAs are involved in cardiotoxicity. Our findings contribute to a better understanding of MP-induced cardiotoxicity and new molecular targets for treating cardiac injury.

Desorption behavior of antibiotics by microplastics (tire wear particles) in simulated gastrointestinal fluids

Microplastics (MPs) are widely distributed throughout the environment. Upon ingesting MPs, the pollutants that they carry are then desorbed into organisms. This results in the accumulation of various chemicals within the organism. This study systematically examined the mechanism of antibiotic desorption using tire wear particles (TWP) as a carrier of antibiotics in simulated human gastrointestinal fluid and fish intestinal fluid. The findings of this study revealed the formation of cracks, pores, and depressions on the surface of photoaged TWP in an aquatic environment, as well as additional adsorption sites that are more favorable for the attachment of pollutants. Furthermore, the simulated human gastric fluid had a higher desorption rate than that of the fish intestinal fluid. The competition for TWP adsorption sites in the gastrointestinal fluid and the potential dissolution of antibiotics were the primary drivers of the increase in the desorption rate. The desorption rate in the simulated human gastrointestinal fluid was greater than that in the simulated fish intestinal fluid due to the composition of the gastrointestinal fluid. However, the carrying of pollutants by MPs poses a potential threat to human health. This study improves our understanding of TWP toxicity and has significant implications for the development of risk assessments.

Polylactic acid microplastics induce higher biotoxicity of decabromodiphenyl ethane on earthworms (Eisenia fetida) compared to polyethylene and polypropylene microplastics

Decabromodiphenyl ethane (DBDPE) and microplastics (MPs), such as fossil-based polymers polyethylene (PE), polypropylene (PP), and bio-based plastics polylactic acid (PLA) are abundant in e-waste dismantling areas. However, the information on the effects of DBDPE combined with MPs (DBDPE-MPs) on earthworms is still limited. In this study, we explored the impacts of DBDPE-MPs on neurotoxic biomarkers, tissue damage, and transcriptomics of Eisenia fetida by simulating different exposure patterns of 10 mg kg^-1 DBDPE and 10 mg kg^-1 DBDPE-MPs (PLA, PP, and PE). Results showed that the activities of acetylcholinesterase, Na⁺/K⁺-ATPase, Ca²⁺/Mg²⁺-ATPase, carboxylate enzyme, and the contents of calcium and glutamate were significantly stimulated. DBDPE-MP co-exposure caused more severe damage to the epidermis, muscles, and tissues. Transcriptomic analysis revealed that differentially expressed genes (DEGs) of DBDPE-MPs were mainly related to inflammation, the immune system, digestive system, endocrine system, and metabolism. DBDPE and PP-MPs had similar influences on immunity and metabolism. However, DBDPE-PLA and DBDPE-PE further affected the endocrine system and signaling pathways. Specific DEGs showed that detoxification systems in the case of MPs were significantly upregulated. The study indicated that MPs exacerbated DBDPE toxicity in the nervous system, epidermis, and gene regulation of E. fetida, helping to assess the ecological risks of e-wastes and microplastics in soil.

The one-two punch of plastic exposure: Macro- and micro-plastics induce multi-organ damage in seabirds

Plastic pollution in the world's oceans is ubiquitous and increasing. The environment is inundated with microplastics (< 1 mm), and the health effects of these less conspicuous pollutants is poorly known. In addition, there is now evidence that macroplastics can release microplastics in the form of shedding or digestive fragmentation, meaning there is potential for macroplastic exposure to induce direct and indirect pathology through microplastics. Therefore, there is an urgent need for data from wild populations on the relationship between macro- and microplastic exposure and the potential compounding pathological effects of these forms of plastics. We investigated the presence and impact of microplastics in multiple tissues from Flesh-footed Shearwaters Ardenna carneipes, a species that ingests considerable quantities of plastics, and used histopathological techniques to measure physiological responses and inflammation from the plastics. All organs examined (kidney, spleen, proventriculus) had embedded microplastic particles and this correlated with macroplastic exposure. Considerable tissue damage was recorded, including a significant reduction in tubular glands and rugae in the proventriculus, and evidence of inflammation, fibrosis, and loss of organ structures in the kidney and spleen. This indicates macroplastics can induce damage directly at the site of exposure, while microplastics can be mobilised throughout the body causing widespread pathology. Collectively, these results indicate the scope and severity of the health impacts of plastic pollution may be grossly underestimated.

Adverse effects of pristine and aged polystyrene microplastics in mice and their Nrf2-mediated defense mechanisms with tissue specificity

Health hazards associated with microplastics (MPs) remain largely unknown, and the effects of aged MPs, one of their persistent forms, are poorly characterized. Male ICR mice were intratracheally instilled with 0.01 and 1 mg/day pristine and ultraviolet (UV)-aged polystyrene microplastics (PS and APS) with an average diameter of 4 - 5 μm daily for 1 week. UV irradiation caused the PS to have a rough surface, become fragmented, and increase their carbonyl groups. Both PS and APS caused structural damage to the mouse gut, liver, spleen, and testis. Inflammatory infiltration in liver, swollen and congested gut, and loose spleen globules, as well as the loose interstitium of the seminiferous tubules in testis were found in 1 mg/day APS group. Increases in serum alanine aminotransferase and immunoglobulin A levels in 1 mg/day APS group (p < 0.05) demonstrated that APS exposure could induce greater liver and spleen functional damage than PS. Meanwhile, triglyceride and total cholesterol levels in liver were enhanced in 1 mg/day APS group (p < 0.05). Superoxide dismutase and glutathione contents in 0.01 and 1 mg/day APS groups significantly decreased (p < 0.05), which suggesting that PS and APS could interfere with the antioxidant capacity in mice. Nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1) levels in the PS and APS groups showed significant increases in the liver and testis (p < 0.05), and a significant decrease in the spleen (p < 0.05), which were analyzed to get a first survey for Nrf2/HO-1-mediated tissue-specific defense mechanisms. In conclusion, acute exposure to PS and APS induced potential metabolic disorders, and APS could produce more serious immune damage and reproductive toxicity. These findings provide new insights in health risk assessment of aged MPs.

Microplastic Ingestion Induces Size-Specific Effects in Japanese Quail

Plastic pollution can pose a threat to birds. Yet, little is known about the sublethal effects of ingested microplastics (MP), and the effects of MP < 1 mm in birds remain unknown. This study therefore aimed at evaluating the toxicity of environmentally relevant polypropylene and polyethylene particles collected in the Norwegian coast in growing Japanese quail (Coturnix japonica). Birds were orally exposed to 600 mg MP over 5 weeks, covering small (<125 μm) and large (3 mm) MP, both separately and in a mixture. We evaluated multiple sublethal endpoints in quail, including oxidative stress, cytokine levels, blood-biochemical parameters, and reproductive hormones in blood, as well as body mass. Exposure to small MP significantly induced the activities of the antioxidant enzymes catalase, glutathione-S-transferase, and glutathione peroxidase. Exposure to large MP increased the levels of aspartate aminotransferase (liver parameter) and decreased 17β-estradiol levels in females. Body mass was not directly affected by MP ingestion; however, quail exposed to small MP and a mixture of large and small MP had a different growth rate compared to control quail. Our study used similar levels of MP as ingested by wild birds and demonstrated size-dependent effects of MP that can result in sublethal effects in avifauna.

Endoplasmic reticulum stress-controlled autophagic pathway promotes polystyrene microplastics-induced myocardial dysplasia in birds

In complex ecosystems, birds are generally long-lived and occupy high trophic positions, making them good bioindicators for monitoring environmental contaminants. The effects of microplastics (MPs) on myocardial development in bird is currently unknown. Chicks, as a high trophic level terrestrial bird, may be more affected by MPs exposure and. Therefore, we established an in vivo model of chicks exposed to different concentrations of polystyrene microplastics (PS-MPs) and selected 12-day-old chicken embryos in vitro to extract primary cardiomyocytes to further investigate the potential molecular mechanisms of the effect of PS-MPs on myocardial development in birds. Histopathological observations revealed that the PS-MPs treated exhibited loose and irregular myocardial arrangement, large cell gaps and broken myocardial fiber bundles. More mechanistically, TnnT2, Nkx2-5, Gata4, TBX5 and ACTN2 were down-regulated, endoplasmic reticulum (ER) stress markers GRP78, PERK, eIF2α, IRE1, ATF4, ATF6 and CHOP were overexpressed, autophagy-related genes LC3, ATG5, Beclin1 and P62 were down-expressed after PS-MPs exposure, and the addition of 4PBA effectively deregulated the above aberrant expression. Hence, our report indicated that PS-MPs induced myocardial dysplasia in birds is mainly attributed to the ER stress-mediated autophagic pathway. This provided data supporting the protection of birds from the health risks of MPs pollution. More critically, the study of cardiac developmental toxicity in birds may help to better explain or solve the problem of MPs pollution in complex ecosystems.

Plastics in the environment as potential threat to life: an overview

Plastics have become inevitable for human beings in their daily life. Million tons of plastic waste is entering in oceans, soil, freshwater, and sediments. Invasion of plastics in different ecosystems is causing severe problems to inhabitants. Wild animals such as seabirds, fishes, crustaceans, and other invertebrates are mostly effected by plastic entanglements and organic pollutants absorbed and carried by plastics/microplastics. Plastics can also be potentially harmful to human beings and other mammals. Keeping in view the possible harms of plastics, some mitigation strategies must be adopted which may include the use of bioplastics and some natural polymers such as squid-ring teeth protein. This review focuses on the possible sources of intrusion and fate of plastics in different ecosystems, their potential deleterious effects on wildlife, and the measures that can be taken to minimize and avoid the plastic use.

Microplastics in the Gulf of Mexico: A Bird’s Eye View

Microplastic debris is a persistent, ubiquitous global pollutant in oceans, estuaries, and freshwater systems. Some of the highest reported concentrations of microplastics, globally, are in the Gulf of Mexico (GoM), which is home to the majority of plastic manufacturers in the United States. A comprehensive understanding of the risk microplastics pose to wildlife is critical to the development of scientifically sound mitigation and policy initiatives. In this review, we synthesize existing knowledge of microplastic debris in the Gulf of Mexico and its effects on birds and make recommendations for further research. The current state of knowledge suggests that microplastics are widespread in the marine environment, come from known sources, and have the potential to be a major ecotoxicological concern for wild birds, especially in areas of high concentration such as the GoM. However, data for GoM birds are currently lacking regarding typical microplastic ingestion rates uptake of chemicals associated with plastics by avian tissues; and physiological, behavioral, and fitness consequences of microplastic ingestion. Filling these knowledge gaps is essential to understand the hazard microplastics pose to wild birds, and to the creation of effective policy actions and widespread mitigation measures to curb this emerging threat to wildlife.