Obesogenic polystyrene microplastic exposures disrupt the gut-liver-adipose axis

Synergistic human health risks of microplastics and co-contaminants: A quantitative risk assessment in water

The pervasive presence of microplastics (MPs) in aquatic environments, coupled with their potential to act as vectors for toxic contaminants, raises significant concerns for human health. This study quantifies the health risks associated with the ingestion of microplastics and their co-contaminants in aquatic medium, considering both individual and interactive effects. The analysis encompasses four MP types (PP, PS, PET, PE) and prevalent contaminants including heavy metals (Cr, Cu, Ni, Pb), polycyclic aromatic hydrocarbons (PAHs, expressed as BaP equivalents), and plastic additives (DEHP, DBP, BPA)-to calculate individual Hazard Quotient (HQ), interaction-based Hazard Index (HIint), individual Incremental Lifetime Cancer Risk (ILCR), and interaction-based ILCR (ILCRint). The mean concentration of MPs in aqueous media was determined to be 2.19 mg/L (95 % CI), and Chronic Daily Intake (CDI) values were derived from particle counts converted to mass using polymer-specific densities. Reference Dose (RfD) values were calculated using the Weight of Evidence (WoE) approach, which integrates findings from rodent toxicity studies, identifying PP and PS as having low RfD values 25 × 10⁻⁴ mg/kg bw/day and 8 × 10⁻⁴ mg/kg bw/day, respectively. HQ-based toxicity rankings indicated the order of risk as PP > PS > PE > PET. Findings revealed a pronounced HIint of 18.646 × 10³ and 16.649 × 10⁶ at the 50th and 90th percentiles in children, underscoring significant synergistic effects from combined exposure to MPs and leached plastic additives. Co-contaminant scenarios further escalated health risks, with HI values reaching 52.236 in the presence of heavy metals and 53.141 with PAHs. The maximum allowable MP concentration, considering additive leaching, was estimated at 0.011 mg/L. This research highlights the need for firstly understanding the transformations of microplastic in the aquatic medium along with co-contaminants and framing regulatory measures and improved monitoring to protect human health from the growing threat of microplastic pollution. By integrating exposure modeling, dose-response assessment, and Monte Carlo simulations, the study delivers a robust framework for environmental health guidelines. It emphasizes the complex, multifaceted risks MPs pose and their associated contaminants, calling for innovative solutions to safeguard public health against this pervasive environmental challenge.

Microplastic pollution: a review of specific blood-tissue barrier breaches and health effects

Microplastic (1 μm - 5 mm) and nanoplastic (<1 μm) pollution is a heightening global challenge affecting the environment and the health of living creatures within. As primary precursors for plastic manufacturing, microplastics predominantly get into the environment through plastic product degradation and integrate into water, food chain and consumer products leading to potential health consequences. The mammalian system is equipped with several blood-tissue barriers with exclusive tight junctions that selectively regulate material transfer and protect vulnerable and functionally important organs. Nonetheless, emerging evidence indicates microplastics interact, traverse and compromise the integrity of these complex barriers. This review summarises the known and potential impact of microplastics on human health, focusing on specific organ barrier breaches. Evidence of microplastic traversal and deposition in distal mammalian organs are discussed. We further highlight current challenges facing both researchers and clinicians and provide an outlook for expanding our understanding of the impact of microplastic on health.

Exploring the micro- and nanoplastics-diabetes nexus: Shattered barriers, toxic links, and methodological horizons

Micro- and nanoplastics (MNPs) are emerging environmental contaminants with increasing evidence linking them to metabolic dysfunction, including diabetes-related outcomes. While experimental studies have demonstrated that MNPs disrupt glucose metabolism, insulin signaling, and lipid homeostasis through oxidative stress, systemic inflammation, and endocrine disruption, the implications for human health remain largely unexplored. Given the widespread presence of MNPs in food, water, and air, chronic low-dose exposure may contribute to metabolic disorders, yet epidemiological data are scarce. This review synthesizes current findings on MNP-induced metabolic disturbances, highlighting their impact on insulin resistance, hepatic fat accumulation, gut microbiota dysbiosis, and adipose tissue dysfunction. Additionally, we evaluate the analytical methodologies used to detect MNPs in biological systems and assess the relevance of exposure levels in real-world scenarios. By contextualizing these mechanisms within a broader public health framework, this review underscores the urgent need for large-scale human studies to establish causal links between MNP exposure and metabolic diseases. Addressing these knowledge gaps is critical for informing risk assessment, regulatory policies, and future research directions aimed at mitigating the metabolic risks associated with environmental plastic pollution.

Effects of micro- and nanoplastic exposure on macrophages: a review of molecular and cellular mechanisms

Micro- and nanoplastics (MNPs), pervasive environmental pollutants, contaminate water, soil, air, and the food chain and ultimately accumulate in living organisms. Macrophages are the main immune cells that gather around MNPs and engulf them through the process of phagocytosis. This internalization triggers M1 polarization and the secretion of inflammatory cytokines, including IL-1, IL-18, IL-12, TNF-α, and IFN-γ. Furthermore, MNPs damage mitochondria and lysosomes, causing overactivation of iNOS and excessive production of ROS. This results in cellular stress and induce apoptosis, necroptosis, and, in some cases, metosis in macrophages. The internalization of MNPs also increases the expression of receptors, involving CD36, SR-A, LOX-1, and the macrophage receptor with a collagenous structure (MARCO) while decreasing ABCA-1 and ABCG-1. MNPs in adipose tissue macrophages trigger proinflammatory cytokine secretion, causing adipogenesis, lipid accumulation, insulin resistance, and the secretion of inflammatory cytokines in adipocytes. Various factors influence the rate of MNP internalization by macrophages, including size, charge, and concentration, which affect internalization through passive diffusion. Receptor-mediated phagocytosis of MNPs occurs directly via receptors like T-cell immunoglobulin and mucin domain containing 4 (TIM-4) and MARCO. The attachment of biomolecules, including proteins, antibodies, opsonins, or microbes to MNPs (forming corona structures) promotes indirect receptor-mediated endocytosis, as macrophages possess receptors like TLRs and FcγRIII. MNPs also cause gut dysbiosis, a risk factor for proinflammatory microenvironment and M1 polarization. Here, we review the mechanisms and consequences of MNP macrophage exposure, which is linked to autoimmunity, inflammation, and cardiometabolic syndrome manifestations, including atherosclerosis and obesity, highlighting the immunotoxicity of MNPs.

Impacts of microplastics on gut health: Current status and future directions

BACKGROUND AND OBJECTIVES

Microplastics are pervasive environmental pollutants, attracting significant concern due to their potential adverse effects on ecosystems and human health. This study hypothesizes that microplastics may significantly impact gastrointestinal (GI) health through various mechanisms. The objective of this systematic review is to explore the effects of microplastics on GI health, focusing on animal models such as mice, fish and earthworms.

METHODS

A systematic review approach was employed, analyzing studies that investigate the impact of microplastics on the gut microbiota, gut barrier integrity and GI inflammation. The review includes a synthesis of findings from multiple animal models.

RESULTS

The review reveals consistent evidence that microplastics can disrupt the gut microbiota, impair the gut barrier, and induce inflammatory responses in the GI tract. Statistical analysis shows a significant correlation between microplastic exposure and GI health deterioration across various animal models.

CONCLUSIONS

The findings underscore the harmful effects of microplastics on GI health, emphasizing the urgent need for policy interventions to reduce plastic pollution. Implementing measures to limit the production and usage of disposable plastics is crucial for mitigating the risks posed by microplastic contamination to promote environmental sustainability and safeguard human well-being.

Environmental Pollutants, Occupational Exposures, and Liver Disease

Environmental pollutants significantly impact liver disease development, progression, and outcomes. This review examines the complex relationship between environmental exposures and liver pathology, from malignant conditions like hepatocellular carcinoma to steatotic and cholestatic liver diseases. Key environmental factors include air pollutants, volatile organic compounds, persistent organic pollutants, heavy metals, and per- and polyfluoroalkyl substances. These compounds can act through multiple mechanisms, including endocrine disruption, metabolic perturbation, oxidative stress, and direct hepatotoxicity. The impact of these exposures is often modified by factors such as sex, diet, and genetic predisposition. Recent research has revealed that even low-level exposures to certain chemicals can significantly affect liver health, particularly when combined with other risk factors. The emergence of exposomics as a research tool promises to enhance our understanding of how environmental factors influence liver disease. Importantly, exposure effects can vary by demographic and socioeconomic factors, highlighting environmental justice concerns. Implementation of this knowledge in clinical practice requires new diagnostic approaches, healthcare system adaptations, and increased awareness among medical professionals. In conclusion, this review provides a comprehensive examination of current evidence linking environmental exposures to liver disease and discusses implications for clinical practice and public health policy.

Biological Effects of Micro-/Nano-Plastics in Macrophages

The environmental impact of plastics is worsened by their inadequate end-of-life disposal, leading to the ubiquitous presence of micro- (MPs) and nanosized (NPs) plastic particles. MPs and NPs are thus widely present in water and air and inevitably enter the food chain, with inhalation and ingestion as the main exposure routes for humans. Many recent studies have demonstrated that MPs and NPs gain access to several body compartments, where they are taken up by cells, increase the production of reactive oxygen species, and lead to inflammatory changes. In most tissues, resident macrophages engage in the first approach to foreign materials, and this interaction largely affects the subsequent fate of the material and the possible pathological outcomes. On the other hand, macrophages are the main organizers and controllers of both inflammatory responses and tissue repair. Here, we aim to summarize the available information on the interaction of macrophages with MPs and NPs. Particular attention will be devoted to the consequences of this interaction on macrophage viability and functions, as well as to possible implications in pathology.

First evidence of microplastics in human ovarian follicular fluid: An emerging threat to female fertility

Several studies have assessed the presence of microplastics (MPs) in human biological fluids and tissues highlighting potential health risks associated to oxidative stress, inflammation, immune dysfunction, neurotoxicity and reprotoxicity. However, only few studies have evaluated MP presence and effects in ovarian tissues of mammalians and, to date, no studies have detected MPs in human ovarian follicular fluids. Based on these premises, in this study, 18 women (undergoing assisted reproductive treatment at In Vitro Fertilisation center in Salerno, Southern Italy) were selected to assess the presence of MPs in follicular fluid. Plastic particles < 10 µm were measured using Scanning Electron Microscopy (SEM) coupled with an EDX (X Energy Dispersion) detector. MPs (size <10 µm) were detected in 14 out of 18 samples of follicular fluid, with an average concentration of 2191 particles/mL (0-7181particles/mL) and with a mean diameter of 4.48 µm (3.18-5.54 µm). Moreover, a significant correlation between MP concentration in follicular fluid samples and Follicle-Stimulating Hormone (FSH) (p-value <0.05), as well as a weak (non-significant) correlation with Body Mass Index (BMI), age and 17β-estradiol (E2), was found. On the contrary, no correlation with anti-Müllerian Hormone (AMH), fertilization outcomes, miscarriages, or live birth was observed. Since several studies on animal models have demonstrated the negative effects of MPs on ovarian function, the present study, that verified for the first time the presence of MPs in human follicular fluid, is of great significance for the scientific community in terms of raising awareness of the impact that these increasingly pervasive emerging contaminants have on reproductive function and human health.

The microplastic-crisis: Role of bacteria in fighting microplastic-effects in the digestive system

Plastic particles smaller than 5 mm, referred to as Microplastics, pose health risks, like metabolic, immunological, neurological, reproductive, and carcinogenic effects, after being ingested. Smaller plastic particles are more likely to be absorbed by human cells, with nanoplastics showing higher potential for cellular damage, including DNA fragmentation and altered protein functions. Micro- and nanoplastics (MNPs) affect the gastrointestinal tract by altering the microbial composition, they could influence digestive enzymes, and possibly disrupt mucus layers. In the stomach, they potentially interfere with digestion and barrier functions, while in the intestines, they could increase permeability via inflammation and tissue disruption. MNPs can lead to microbial dysbiosis, leading to gastrointestinal symptoms. By activating inflammatory pathways, altering T cell functions and affecting dendritic cells and macrophages, immune system homeostasis could possibly be disrupted. Probiotics offer potential strategies to alleviate plastic effects, by either degrading plastic particles or directly countering health effects. We compared genetic sequences of probiotics to the genome of known plastic degraders and concluded that no probiotic bacteria could serve the role of plastic degradation. However, probiotics could directly mitigate MNP-health effects. They can restore microbial diversity, enhance the gut barrier, regulate bile acid metabolism, reduce inflammation, regulate insulin balance, and counteract metabolic disruptions. Antioxidative properties protect against lipid peroxidation and MNP-related reproductive system damage. Probiotics can also bind and degrade toxins, like heavy metals and bisphenol A. Additionally, bacteria could be used to aggregate MNPs and reduce their impact. Therefore, probiotics offer a variety of strategies to counter MNP-induced health effects.

Emerging and Promising Keywords in Biomolecules and Therapeutics for 21st Century Diseases

Recent technological advancements and environmental changes are leading to an increase in various diseases such as obesity, fibrosis, metabolic disorders, and degenerative diseases associated with aging. Additionally, micro- and nanoplastics are emerging as as potential contributors to many of these conditions, posing a serious threat to human health. This special issue aims to explore new directions and opportunities for future drug development through recent review articles published in the issue, focusing on these key medical topics.