Investigating the effects of microplastic ingestion in Scyliorhinus canicula from the South of Sicily

Microplastic contamination and biological alterations in Atlantic wild fish populations, and human health risks associated to fillet consumption

This study tested the hypothesis that long-term exposure to microplastics (MPs) is causing biological alterations in North Atlantic wild populations of Trisopterus luscus (pouting) and Merluccius merluccius (hake). It also estimated the human risk of MP intake (HRI) through fillet consumption, and combined the HRI and polymer health hazard in the Risk of Intake and Polymer Hazard Index (RIPHI). Fish (103) were analysed for MPs (gastrointestinal tract, gills, liver, brain, muscle), biomarkers (physical condition, neurotoxicity, energy production, oxidative stress and damage) and general stress (Integrated Biomarker Response - IBR). After particle analysis (Fourier Transform Infrared spectroscopy, Raman spectroscopy) and data correction for contamination, MPs accounted for 77 % of 311 particles. From 103 fish, 79 % contained MPs. The overall mean concentration ±SD was 0.09 ± 0.09 MP g-1 (2.32 ± 2.35 MPs ind-1) with no significant interspecific differences (p > 0.05). Among body sites, brain had the highest MP concentration (pouting: 0.6 MP g-1; hake: 0.5 MP g-1). Most abundant polymers were polyethylene (40 %), polypropylene (21 %) and polymethyl methacrylate (12 %). Fragments (<150 μm) predominated. MP profiles pointed to prey-predator transfer. Fish with MPs had higher stress levels (IBR, pouting: 0.317; hake: 0.200) than specimens without MPs (pouting: 0.0; hake: 0.062). Oxidative stress was the effect most clearly linked to MPs. Hake fillet poses lower HRI (e.g., 0.2 to 1.5 MPs day-1) than pouting fillet (e.g., 0.4 to 3.0 MPs day-1). RIPHI values showed the opposite trend (e.g., hake: 138 to 1038; pouting: 113 to 845), indicating medium to high risk to human consumers. Findings related long-term MPs exposure in the natural habitat with biological alterations in wild fish populations, highlight the importance of food diversification for a healthy alimentation, and stress the urgent need of reducing MPs pollution to promote ecosystem sustainability and global health.

Microplastics/nanoplastics and neurological health: An overview of neurological defects and mechanisms

The widespread use of plastic products worldwide has brought about serious environmental issues. In natural environments, it's difficult for plastic products to degrade completely, and so they exist in the form of micro/nanoplastics (M/NPs), which have become a new type of pollutant. Prolonged exposure to M/NPs can lead to a series of health problems in humans, particularly toxicity to the nervous system, with consequences including neurodevelopmental abnormalities, neuronal death, neurological inflammation, and neurodegenerative diseases. Although direct evidence from humans is still limited, model organisms and organoids serve as powerful tools to provide important insights. This article summarizes the effects of M/NPs on the nervous system, focusing on cognitive function, neural development, and neuronal death. Mechanisms such as neurotransmitter synthesis and release, inflammatory responses, oxidative stress, the gut-brain axis, and the liver-brain axis are covered. The neurotoxicity induced by M/NPs may exacerbate or directly trigger neurodegenerative diseases and neurodevelopmental disorders. We particularly emphasize potential therapeutic agents that may counteract the neurotoxic effects induced by M/NPs, highlighting a novel future research direction. In summary, this paper cites evidence and provides mechanistic perspectives on the effects of M/NPs on neurological health, providing clues for eliminating M/NP hazards to human health in the future.

High microplastic and anthropogenic particle contamination in the gastrointestinal tracts of tiger sharks (Galeocerdo cuvier) caught in the western North Atlantic Ocean

Few studies have documented microplastics (<5 mm) in shark gastrointestinal (GI) tracts. Here, we report microplastic contamination in the tiger shark (Galeocerdo cuvier), an apex predator and generalist feeder, at several different life stages. We examined seven stomachs and one spiral valve from eight individuals captured off the United States Atlantic and Gulf of Mexico coasts (eastern US) and conducted a literature review of publications reporting anthropogenic debris ingestion in elasmobranchs. Specimens were chemically digested in potassium hydroxide (KOH) and density separated using calcium chloride (CaCl2) before quantifying and categorizing suspected anthropogenic particles (>45 μm) by size, morphology, and colour. Anthropogenic particles were found in the stomachs and spiral valve of all sharks. A total of 3151 anthropogenic particles were observed across all stomachs with 1603 anthropogenic particles observed in a single specimen. A subset of suspected anthropogenic particles (14%) were chemically identified using Raman spectroscopy and μ-Fourier Transform Infrared spectroscopy to confirm anthropogenic origin. Overall, ≥95% of particles analyzed via spectroscopy were confirmed anthropogenic, with 45% confirmed as microplastics. Of the microplastics, polypropylene (32%) was the most common polymer. Diverse microparticle morphologies were found, with fragments (57%) and fibers (41%) most frequently observed. The high occurrence and abundance of anthropogenic particle contamination in tiger sharks is likely due to their generalist feeding strategy and high trophic position compared to other marine species. The literature review resulted in 32 studies published through 2022. Several methodologies were employed, and varying amounts of contamination were reported, but none reported contamination as high as detected in our study. Anthropogenic particle ingestion studies should continue in the tiger shark, in addition to other elasmobranch species, to further understand the effects of anthropogenic activities and associated pollution on these predators.

Exploring the Impact of Contaminants of Emerging Concern on Fish and Invertebrates Physiology in the Mediterranean Sea

In this historical context, the Mediterranean Sea faces an increasing threat from emerging pollutants such as pharmaceuticals, personal care products, heavy metals, pesticides and microplastics, which pose a serious risk to the environment and human health. In this regard, aquatic invertebrates and fish are particularly vulnerable to the toxic effects of these pollutants, and several species have been identified as bio-indicators for their detection. Among these, bivalve molluscs and elasmobranchs are now widely used as bio-indicators to accurately assess the effects of contaminants. The study focuses on the catshark Scyliorhinus canicular and on the Mediterranean mussel Mytilus galloprovincialis. The first one is a useful indicator of localised contamination levels due to its exposure to pollutants that accumulate on the seabed. Moreover, it has a high trophic position and plays an important role in the Mediterranean Sea ecosystem. The bivalve mollusc Mytilus galloprovincialis, on the other hand, being a filter-feeding organism, can acquire and bioaccumulate foreign particles present in its environment. Additionally, because it is also a species of commercial interest, it has a direct impact on human health. In conclusion, the increasing presence of emerging pollutants in the Mediterranean Sea is a serious issue that requires immediate attention. Bivalve molluscs and elasmobranchs are two examples of bio-indicators that must be used to precisely determine the effects of these pollutants on the marine ecosystem and human health.

Is Wild Marine Biota Affected by Microplastics?

The present review provides detailed information on the adverse effects of MPs on wild marine organisms, including tissue damage, fish condition, oxidative stress, immune toxicity, and genotoxicity. A bibliometric analysis was carried out on CiteSpace (version 6.1.R3) (Drexel University, Philadelphia, PA, USA) to verify how many papers studied the effects on wild marine species. The results showed a total of 395 articles, but only 22 really presented data on the effects or impacts on marine biota, and of these, only 12 articles highlighted negative effects. This review shows that the observed effects in wild organisms were less severe and milder than those found in the experimental conditions. The knowledge of negative effects caused by direct ingestion of microplastics in wild animals is still limited; more efforts are necessary to fully understand the role of MPs and the adverse effects on wild marine organisms, the ecosystem, and human health.