Quality assessment of the blue mussel (Mytilus edulis): comparison between commercial and wild types

Microplastics in intertidal water of South Australia and the mussel Mytilus spp.; the contrasting effect of population on concentration

Microplastics, plastic particles <5 mm in size, are of global concern as human-caused pollutants in marine and fresh waters, and yet little is known of their distribution, behaviour and ecological impact in the intertidal environment of South Australia. This study confirms for the first time, the presence of microplastic in the South Australian intertidal ecosystem by quantifying the abundance of particles in intertidal water and in the keystone species, the blue mussel, Mytilus spp., an important fisheries species, at ten and six locations respectively, along the South Australian coastline. For a remote region known for its pristine environment, microplastic concentration in intertidal water was found to be low to moderate (mean = 8.21 particles l^-1 ± 4.91) relative to global levels and microplastic abundance in mussels (mean = 3.58 ± 8.18 particles individual^-1) was within the range also reported globally. Microplastic particles were ubiquitous across sites and bioavailable by size in water (mean = 906.36 μm) and in mussel (mean = 983.29 μm) raising concerns for the health of South Australia's unique coastal ecosystems and for the human food chain. Furthermore, a positive correlation was found between human coastal population size and microplastic concentration in intertidal water, irrespective of influences from industry - tourism, fishing and shipping ports. FTIR analysis determined plastic type to include polyamide (PA), polyethylene (PE), polypropylene (PP), acrylic resin, polyethyleneterephthalate (PET) and cellulose, suggesting synthetic and semi-synthetic particles from single-use, short-life cycle products, fabrics, ropes and cordage. Our findings shed light on the urgent need to establish the local sources of microplastic pollution in order to assist the community, industry and government to reduce the impact of microplastic on the fragile marine systems within South Australian intertidal waters and on the organisms associated with the human food chain.

Microplastic pollution in fragile coastal ecosystems with special reference to the X-Press Pearl maritime disaster, southeast coast of India

Microplastics (MPs) are a global environmental concern and pose a serious threat to marine ecosystems. This study aimed to determine the abundance and distribution of MPs in beach sediments (12 beaches), marine biota (6 beaches) and the influence of microbes on MPs degradation in eco-sensitive Palk Bay and Gulf of Mannar coast. The mean MP abundance 65.4 ± 39.8 particles/m² in beach sediments; 0.19 ± 1.3 particles/individual fish and 0.22 ± 0.11 particles g^-1 wet weight in barnacles. Polyethylene fragments (33.4%) and fibres (48%) were the most abundant MPs identified in sediments and finfish, respectively. Histopathological examination of fish has revealed health consequences such as respiratory system damage, epithelial degradation and enterocyte vacuolization. In addition, eight bacterial and seventeen fungal strains were isolated from the beached MPs. The results also indicated weathering of MPs due to microbial interactions. Model simulations helped in tracking the fate and transboundary landfall of spilled MPs across the Indian Ocean coastline after the X-Press Pearl disaster. Due to regional circulations induced by the monsoonal wind fields, a potential dispersal of pellets has occurred along the coast of Sri Lanka, but no landfall and ecological damage are predicted along the coast of India.

Distribution and transport of microplastics in groundwater (Shiraz aquifer, southwest Iran)

Despite the significance of groundwater to the hydrological cycle and as a source of potable water, very little information exists on microplastics (MPs) in this environment. In the present study, MPs have been determined in ten well samples obtained from an alluvial aquifer in a semi-arid region (Shiraz, Iran) following filtration, digestion and inspection under a binocular microscope. A total of 96 MPs were identified, and concentrations ranged from 0.1 to 1.3 MP L^-1 (mean and median = 0.48 and 0.43 MP L^-1, respectively) and exhibited a complex distribution across the area that reflected differences in land use and local hydrology and geology. The majority of MPs (about 70%) were fibres of ≤ 500 μm in length, but fragments and films were present at some sites, and the dominant polymers were polystyrene, polyethylene and polyethylene terephthalate. Coupling meteorological and water table monitoring data from the regional water organization and published information on aquifer hydrology, we estimate a lag time from precipitation to water table intrusion of between one and five months and groundwater velocity flows of between 0.01 and 0.07 m d^-1. Although the extent of retardation of MPs within the pores of groundwater is unknown, by considering empirical data and theoretical predictions on particle flow through porous media in the literature we surmise that MP residence times in the aquifer are likely to range from years to decades, thereby impeding any clear means of source identification. Nevertheless, and more generally, the consumption of potable groundwater may make to a contribution to MP exposure through ingestion.

Micro(nano)plastics pollution and human health: How plastics can induce carcinogenesis to humans?

Microplastics (MPs) and nanoplastics (NPs) are key indicators of the plasticine era, widely spread across different ecosystems. MPs and NPs become global stressors due to their inherent physicochemical characteristics and potential impact on ecosystems and humans. MPs and NPs have been exposed to humans via various pathways, such as tap water, bottled water, seafood, beverages, milk, fish, salts, fruits, and vegetables. This paper highlights MPs and NPs pathways to the food chains and how these plastic particles can cause risks to human health. MPs have been evident in vivo and vitro and have been at health risks, such as respiratory, immune, reproductive, and digestive systems. The present work emphasizes how various MPs and NPs, and associated toxic chemicals, such as polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs), impact human health. Polystyrene (PS) and polyvinyl chloride (PVC) are common MPs and NPs, reported in human implants via ingestion, inhalation, and dermal exposure, which can cause carcinogenesis, according to Agency for Toxic Substances and Disease Registry (ATSDR) reports. Inhalation, ingestion, and dermal exposure-response cause genotoxicity, cell division and viability, cytotoxicity, oxidative stress induction, metabolism disruption, DNA damage, inflammation, and immunological responses in humans. Lastly, this review work concluded with current knowledge on potential risks to human health and knowledge gaps with recommendations for further investigation in this field.

Status and prospects of atmospheric microplastics: A review of methods, occurrence, composition, source and health risks

The global pollution of microplastics (MPs) has attracted widespread attention, and the atmosphere was an indispensable media for the global transmission of MPs. With the growing awareness of MPs, atmospheric microplastics (AMPs) have been proposed as a new topic in recent years. Compared with the extensive studies on MPs in Marine and terrestrial environments, the studies of AMPs remain limited. In this study, sampling and analysis methods, occurrence, source analysis and health risk of AMPs were summarized and discussed. According to the different sampling methods, AMPs can be divided into suspension microplastics (SAMPs) and deposition microplastics (DAMPs). Previous studies have shown that SAMPs and DAMPs differ in composition and abundance, with SAMPs generally having a higher fraction of fragments. The mechanism of the migration of AMPs between different media was not clear yet. We further collated global data on the composition characteristics of MPs in soil and fresh water, which showed that the fragment MPs in soil and fresh water was higher than that in the atmosphere. Polymers in soil and fresh water were mainly PP and PE, while AMPs in the atmosphere were mainly PET. The shape composition of the MPs in both atmospheric and freshwater systems suggests that there may be the same dominant factor. The transport of AMPs and source apportionment were the important issues of current research, but both of them were at the initial stage. Therefore, AMPs needs to be further studied, especially for the source and fate, which would be conducive to understand the global distribution of AMPs. Furthermore, a standardized manual on sampling and processing of AMPs was also necessary to facilitate the comparative analysis of data between different studies and the construction of global models.

Microplastic pollution in urban Lake Phewa, Nepal: the first report on abundance and composition in surface water of lake in different seasons

Microplastics are man-made pollutants which have been detected in surface water and groundwater. Research on microplastic concentration in aquatic environment is attracting scientists from developing countries, but in Nepal no information regarding microplastic in freshwater system is available. Therefore, this study investigates the presence and abundance of microplastic in lake surface water of Phewa Lake, the second largest lake in Nepal. The average concentration of microplastic for surface water was 2.96 ± 1.83 particles/L in winter (dry) season and 1.51 ± 0.62 particles/L in rainy (wet) season. Significant difference with t = 4.687 (p < 0.01) in microplastic concentration was observed in two different seasons. Fibers (93.04% for winter and 96.69% for rainy season) were the commonly found microplastic type in lake water and transparent as the dominant color for the two seasons. Almost all the detected microplastic were found to be < 1 mm in size. Due to the small size of microplastic and unavailability of micro-Fourier transform infrared spectroscopy (μ-FTIR) and Raman spectroscopy in Nepal, polymer identification was not done. The findings from this study can provide a valuable baseline data on microplastics for the first time in Nepal's freshwater lake environment.

In vivo oxidative stress responses of the freshwater basket clam Corbicula javanicus to microplastic fibres and particles

Microplastics have been detected in several aquatic organisms, especially bivalves such as clams, oysters, and mussels. To understand the ecotoxicological implication of microplastic accumulation in biota, it is crucial to investigate effects at the physiological level to identify knowledge gaps regarding the threat posed to the environment and assist decision-makers to set the necessary priorities. Typically, xenobiotics elicit an overproduction of reactive oxygen species in organisms, resulting in oxidative stress and cellular damage when not combated by the antioxidative system. Therefore, the present study aimed to establish the impacts of microplastic particles and fibres on the freshwater basket clam Corbicula javanicus. We measured the oxidative stress responses following microplastic exposure as the specific activities of the antioxidative enzymes glutathione S-transferase and catalase. When exposed to polyester fibres from the fleece jackets, the enzyme activities increased in the clams, while the enzyme activities decreased with high-density polyethylene microplastic fragments from bottle caps. All the exposures showed that the adverse effects on the antioxidative response system were elicited, indicating the negative ecotoxicological implications of microplastic pollution.

An assessment workflow to recover microplastics from complex biological matrices

A criteria-guided workflow was applied to assess the effectiveness of microplastic separation methods on complex marine biological matrices. Efficacy of four methods (nitric acid, HNO₃, and potassium hydroxide, KOH, digestions, and sodium chloride, NaCl, and potassium iodide, KI, density flotations) was evaluated on four taxa (hard coral, sponge, sea squirt, sea cucumber) using five microplastics (polyethylene, polystyrene, polyethylene terephthalate, PET, polyvinylchloride, rayon). Matrix clarification was only unacceptably low for KOH. PET discoloured regardless of reagent. Rayon threads unravelled into monofilaments after exposure to all reagents, with discolouration also occurring with HNO₃. Recovery rates were overall high, except for dense microplastics treated with NaCl and only KI yielded high rayon recovery efficiency. All polymers were accurately assigned, with subtle spectral changes observed. These results demonstrate specific limitations to separation methods applied to different biological matrices and microplastics and highlight the need to assess their suitability to provide estimates of microplastic contamination.

Microplastics in the tissues of commercial semi-intensive shrimp pond-farmed Litopenaeus vannamei from the Gulf of California ecoregion

The omnipresence of microplastics (MPs) in marine and coastal environments has attracted attention owing to their effects on various organisms, including humans. We present the first study of MPs in the gastrointestinal tract (GT), gills (GI), and exoskeleton (EX) of the farmed whiteleg shrimp Litopenaeus vannamei from commercial aquaculture facilities in northwestern Mexico that have operated semi-intensively for the last two decades. We found that the number of MP items per tissue was 7.6 ± 0.6 in the GT, 6.3 ± 0.9 in the GI, and 4.3 ± 0.9 in the EX, with an average of 18.5 ± 1.2 MP items per shrimp (1.06 items/g, wet weight [ww]). MP concentrations were 261.7 ± 84.5, 13.1 ± 1.8, and 2.6 ± 0.6 items/g (ww) in the GT, GI, and EX, respectively. Microplastics ranged from 30 to 2800 μm in size (360 ± 39 μm) with fibers (∼90.8%), filament-shape (∼93.4%), and transparent (∼47.7%) being the most common ones. Polyethylene (∼54.5%) and polyamide (∼24.2%) were the most commonly identified polymers, although polyesters (∼12.1%), polystyrene (∼6.1%), and nylon (∼3.0%) were also found. The abundance of MPs in farmed L. vannamei may be related to their feeding habits and the availability of MP sources in aquaculture facilities.

A review of atmospheric microplastics pollution: In-depth sighting of sources, analytical methods, physiognomies, transport and risks

Micro-sized plastics were first examined for atmospheric environment in 2016. From then on, they have been detected in both indoor and outdoor atmospheric samples, with indoor environments demonstrated as containing a big proportion of these particles. The sparse distribution of these particles, is attributed to their swift and long distance transportation that is mainly eased by their tiny size (1 μm to 5 mm) and low density. Due to ongoing limitation on detectable size, analysis methods together with a lack of standardized sampling and analytical procedures, few studies were conducted on airborne microplastics (MPs). Thus, the facts regarding the occurrence, global spatial distribution, fate, and threats to ecosystem and human health of airborne MPs, are still far from being fully clarified. This literature review is a broad depiction of a state of knowledge on atmospheric MPs. Within it, robust and concise information on the sources, inspection, transport, and threats pertaining to airborne MPs are presented. Particularly, the paper entails some information concerning traffic-generated MPs pollution, which has not been frequently discussed within previously published reports. In addition, this paper has widely unveiled sectors and aspects in need of further attention, with the gaps to be filled pinpointed.

Contamination and ecological risk of microplastics and phthalates in the surface water of the Tha Dee Sub-River basin, Nakhon Si Thammarat Province, Thailand

Plastic waste has become a significant source of water pollution worldwide, releasing microplastics (MPs) and hazardous chemicals into aquatic environments. The purpose of this study was to determine the occurrence and ecological risk of MPs and phthalates (PAEs) in the surface water of the Tha Dee Sub-River basin in Nakhon Si Thammarat Province, Thailand. MPs, PAEs, and water quality parameters, including turbidity, pH, conductivity, dissolved oxygen, and salinity, were investigated simultaneously at 26 sampling stations. The average number of MPs per liter was 0.5 ± 0.4. Filaments were the most common MPs (59%), and transparent/white was the most prevalent color (51%). Four PAEs were found, with an average total concentration of 25.78 ± 93.87 µg/L, and diethyl phthalate was observed in the highest concentrations. Although there was no association between PAEs and other parameters, there was a significant correlation among particular PAEs (P < 0.05), indicating that they came from the same source. The pollution load index of MPs indicated a minor risk, but PAEs posed a medium risk to fish in the study area. This study's findings suggest that further research into the sources of PAEs and their contamination of aquatic life is needed.

Impact of climatic and non-climatic stressors on ocean life and human health: A review

Ocean life forms are fundamentally well adapted to natural environmental variations, and they can even tolerate extreme conditions for a short time. However, several anthropogenic stressors are causing such drastic changes in the ocean ecosystem. First, the review attempts to outline the impact of climatic and non-climatic stressors on ocean life, and it also outlines the synergistic impact of both stressors. Then the impact on human health caused by the damage of the marine ecosystem has been discussed. Furthermore, the type of prior studies and current mitigation adaptation programs have been presented. Finally, some perspectives about future research and mitigation adaptation are offered.

A reliable method for the isolation and characterization of microplastics in fish gastrointestinal tracts using an infrared tunable quantum cascade laser system

Societal and environmental concern due to frequent reports of microplastics in fish stomachs raised as they may accumulate along the trophic chain. The request for analysing microplastics in fish stresses two major analytical issues: sample treatment and final characterization. The, so far, workhorse for chemical characterization is infrared spectroscopy which is time-consuming. Here, a quantum cascade laser-based device is used to accelerate the characterization stage. Its novelty poses new challenges for sample processing and particle handling because the unknown particles must be transferred to a reflective slide. In this study, three sample digestion protocols (alkaline-oxidative with H₂O₂, and alkaline-oxidative with NaClO and enzymatic-oxidative) and three different procedures to transfer the filter cake to reflective slides are compared. A simplified enzymatic-oxidative digestion (validated through an interlaboratory exercise) combined with a Syncore® automatic evaporation system and a Laser Direct Infrared Imaging (LDIR) device is proposed first time as a reliable and relatively fast method to treat gastrointestinal tracts of fish. Analytical recoveries were studied using samples of Scomber scombrus and they were ca. 100% for big -i.e., >500 μm- and ca. 90% for medium -i.e., 200-300 μm- particles and ca. 75% for 10 μm thick fibres.

Widespread microplastic pollution across the Caribbean Sea confirmed using queen conch

The Caribbean Sea is reported to have one of the highest levels of plastic pollution of any marine ecosystem. Much less is known about the levels of microplastics as an emerging pollutant in the marine environment, especially in the water column and benthic substrates where they can be easily ingested by marine organisms. This study was carried out to quantify marine microplastics in the Wider Caribbean using the mollusk, queen conch (Aliger gigas). We analyzed feces collected from queen conch, a non-lethal method of sampling, to investigate microplastic pollution in eleven sites across the Wider Caribbean. Microplastics were extracted by degradation of organic matter from feces with peroxide (30%) over 48 h. Microplastics were then analyzed by stereomicroscope and scanning electron microscope. Microplastics were found to be present in the feces of all 175 queen conch sampled, and in statistically different abundances among sites, but with no obvious geographical pattern. The highest and lowest levels were found in Central America; the highest being in Belize (270 ± 55 microplastics/queen conch) and Alacranes, Mexico (203 ± 29 microplastics/queen conch), whilst the lowest levels were found in Puerto Morelos, Mexico. Fibers, mostly between 1000 and 1500 μm in size, were the most frequent microplastic particle types at every site and represented between 60 and 98% of all microplastic particles found. Our results suggest that the use of queen conch feces is a suitable method for detecting benthic microplastic pollution, and have confirmed that microplastic pollution of marine benthos is widespread across the Wider Caribbean.

Deposition and Mobilization of Microplastics in a Low-Energy Fluvial Environment from a Geomorphological Perspective

Though microplastic (MP/MiP) pollution of the environment is a popular research topic, a relatively limited number of studies are investigating its geomorphological context. However, site-specific hydrological and morphological parameters fundamentally affect the MP transport, deposition and mobilization. Therefore, we aimed to evaluate the geomorphological influencing factors on MP deposition in the fluvial sediments of the Tisza River (Central Europe). Between the two surveys (in 2019 and 2020), small flood waves rearranged the MP pollution, as in the sediments of the Tisza it decreased by 30% and in the tributaries by 48%. The previously highly polluted upstream and downstream sections became moderately polluted, but the contamination increased in the Middle Tisza, and the hot-spots were rearranged. The increasing longitudinal trend in the MP content exists if the minimum values of the hydrologically uniform sections are considered. The tributaries are important MP sources, as 80% of them had a higher (by 20%) MP content in their sediments than the Tisza had near the confluence, and they increased the MP content of the Tisza by 52% on average. The point-bars were the most polluted in-channel forms, while the side-bars and sediment sheets had less MP content, by 18 and 23%, respectively. The spatial trend of the MP content of these forms was not the same. Therefore, during the planning of sampling campaigns, it is very important to consider the geomorphological setting of a sampling site: we suggest sampling side-bars. No clear connection between the particle size of the sediments and their MP content was found.

Floating microplastic debris in a rural river in Germany: Distribution, types and potential sources and sinks

Microplastic debris affects marine as well as freshwater ecosystems and an increasing number of studies have documented the contamination in aquatic environments worldwide. However, while the research focuses on oceans and larger rivers, little is known about the situation in smaller rivers within rural catchments. Since microplastics pose various risks to ecosystems, wildlife and human health, it is important to identify potential sources, sinks and transport patterns, which are probably different for small rivers. In this study, we investigate the contamination with microplastic debris of the river Ems, representing a smaller river in Northwest Germany with an agricultural catchment. We hypothesised that with increasing river length the plastic concentration increases, especially downstream of towns, waste water treatment plant (WWTP) effluents and major tributaries as they may be important point sources of microplastics. We collected 36 surface water samples at 18 sampling sites within the first 70 km using manual driftnets. We sampled every 7 km and upstream and downstream of three larger towns, four major tributaries and four WWTP effluents. Overall, we found 1.54 ± 1.54 items m^-3, which corresponds to the plastic concentrations in larger streams. However, the shape of the detected items differed as we did not find potential primary microplastic. Furthermore, the pattern contradicts our assumption, that the contamination increased with distance to the river's source. Downstream of towns, we found significantly less floating microplastic indicating possible sinks due to sedimentation at sites with slowing flow velocity caused by weirs in towns. Hence, the non-linear distribution pattern of microplastics indicates potential sinks of microplastics due to flow alterations on the river course. This should be considered in future studies modelling microplastic distribution and transport. Furthermore, studies especially in smaller rivers are urgently needed to identify and quantify sources and sinks and to find applicable solutions to reduce microplastic loads.

Indole decreases the virulence of the bivalve model pathogens Vibrio tasmaniensis LGP32 and Vibrio crassostreae J2-9

Indole signaling plays an important role in bacterial pathogenesis. In this study, the impact of indole on biofilm formation, swimming and swarming motility were explored in Vibrio tasmaniensis LGP32 and Vibrio crassostreae J2-9, two model pathogens of bivalves. The results showed that indole decreased swimming and swarming motility in both strains, and decreased biofilm formation in V. crassostreae J2-9. Furthermore, indole affected a large number of genes at RNA level, including genes related to metabolism, ABC transporters, flagellar assembly, chemotaxis, and response regulators. Finally, the bacterial virulence towards mussel larvae was decreased by pretreatment with indole in both V. tasmaniensis LGP32 and V. crassostreae J2-9. After 5 days, the survival rate of mussel larvae increased 2.4-fold and 2.8-fold in mussel larvae challenged with V. tasmaniensis LGP32 pretreated with 200 µM and 500 µM indole, respectively. The survival rate of mussel larvae increased 1.5-fold and 1.9-fold in mussel larvae challenged with V. crassostreae J2-9 pretreated with 200 µM and 500 µM indole, respectively. These data indicate that indole has a significant impact on the virulence of V. tasmaniensis LGP32 and V. crassostreae J2-9, and indole signaling could be a promising target for antivirulence therapy.

The micro-, submicron-, and nanoplastic hunt: A review of detection methods for plastic particles

Plastic particle pollution has been shown to be almost completely ubiquitous within our surrounding environment. This ubiquity in combination with a variety of unique properties (e.g. density, hydrophobicity, surface functionalization, particle shape and size, transition temperatures, and mechanical properties) and the ever-increasing levels of plastic production and use has begun to garner heightened levels of interest within the scientific community. However, as a result of these properties, plastic particles are often reported to be challenging to study in complex (i.e. real) environments. Therefore, this review aims to summarize research generated on multiple facets of the micro- and nanoplastics field; ranging from size and shape definitions to detection and characterization techniques to generating reference particles; in order to provide a more complete understanding of the current strategies for the analysis of plastic particles. This information is then used to provide generalized recommendations for researchers to consider as they attempt to study plastics in analytically complex environments; including method validation using reference particles obtained via the presented creation methods, encouraging efforts towards method standardization through the reporting of all technical details utilized in a study, and providing analytical pathway recommendations depending upon the exact knowledge desired and samples being studied.

Are We Underestimating Anthropogenic Microfiber Pollution? A Critical Review of Occurrence, Methods, and Reporting

Anthropogenic microfibers, a ubiquitous environmental contaminant, can be categorized as synthetic, semisynthetic, or natural according to material of origin and production process. Although natural fibers, such as cotton and wool, originated from natural sources, they often contain chemical additives, including colorants (e.g., dyes, pigments) and finishes (e.g., flame retardants, antimicrobial agents, ultraviolet light stabilizers). These additives are applied to textiles during production to give textiles desired properties like enhanced durability. Anthropogenically modified "natural" and semisynthetic fibers are sufficiently persistent to undergo long-range transport and accumulate in the environment, where they are ingested by biota. Although most research and communication on microfibers have focused on the sources, pathways, and effects of synthetic fibers in the environment, natural and semisynthetic fibers warrant further investigation because of their abundance. Because of the challenges in enumerating and identifying natural and semisynthetic fibers in environmental samples and the focus on microplastic or synthetic fibers, reports of anthropogenic microfibers in the environment may be underestimated. In this critical review, we 1) report that natural and semisynthetic microfibers are abundant, 2) highlight that some environmental compartments are relatively understudied in the microfiber literature, and 3) report which methods are suitable to enumerate and characterize the full suite of anthropogenic microfibers. We then use these findings to 4) recommend best practices to assess the abundance of anthropogenic microfibers in the environment, including natural and semisynthetic fibers. By focusing exclusively on synthetic fibers in the environment, we are neglecting a major component of anthropogenic microfiber pollution. Environ Toxicol Chem 2022;41:822-837. © 2021 SETAC.

A first assessment of microplastic abundance in sandy beach sediments of the Paranaguá Estuarine Complex, South Brazil (RAMSAR site)

Here we present the first assessment of microplastic (1-5 mm) abundance in drift line sediments from nineteen sandy beaches at the Paranaguá Estuarine Complex, a subtropical estuarine system from South Brazil. This estuarine system harbors Brazil's second-largest grain port, the Guaraqueçaba Environmental Protection Area, and a RAMSAR site. Sediment samples were washed through a 5 and 1 mm mesh sieve and then visually inspected. We found a total of 398 microplastic particles, of which the majority were foams (63.7%), hard plastic fragments (13.8%), paint fragments (12.8%), and pellets (7.2%). Almost all sampled beaches, including those located within the Guaraqueçaba Environmental Protection Area, were contaminated by microplastics. The most likely microplastic sources for the Paranaguá Estuarine Complex beaches are urban and port activities. However, small communities and marine sources may also contribute to microplastic presence.

Microplastic in the coral reef environments of the Gulf of Mannar, India - Characteristics, distributions, sources and ecological risks

Microplastics (MPs; particles <5 mm) are widely distributed in various habitats from the land to the oceans. They have even reached the remotest of places, including the deep seas and Polar Regions. Although research on MPs pollution in the marine environment has received widespread attention in recent years, the distribution, sources and ecological risks of MPs in coastal areas remain unclear. This study assessed the abundance, characteristics, sources and ecological risk of MPs in surface waters and sediment of the mainland coast and four island groups comprising the coral reef environment of the Gulf of Mannar (GoM), southeast India. Mean MPs abundance across all 95 sampling sites ranged from 28.4 to 126.6 items L^-1 in water and from 31.4 to 137.6 items kg^-1 in sediment. MP fibers <2 mm dominated the water, while fragments >3 mm were predominant in sediments. Polyethylene (PE) and polypropylene (PP) were the most common polymers in both matrices. The major proportion of MPs in the GoM derived from land-based sources, with distance to the mainland, coastal population density and improper handling of solid waste being the main factors influencing the abundance of MPs. Polymer Hazard Index (PHI), Pollution Load Index (PLI) and Potential Ecological Risk Index (PERI) were used to assess current levels of MPs. While the GoM has high PHI values (>1000) resulting from MPs with high hazard scores (e.g. polyamide, polystyrene, polyvinyl chloride), the PLI values (1.46 and 1.51) indicate low MPs pollution levels in GoM waters and sediments, and the PERI values (31.7 and 24.4) indicate that this represents a minor ecological risk. The results from the current study enhance our understanding of the characteristics, sources, and associated environmental risks of MPs to marine ecosystems. This data may provide a baseline for future monitoring and the formulation of environmental policy.

To Waste or Not to Waste: Questioning Potential Health Risks of Micro- and Nanoplastics with a Focus on Their Ingestion and Potential Carcinogenicity

Micro- and nanoplastics (MNPs) are recognized as emerging contaminants, especially in food, with unknown health significance. MNPs passing through the gastrointestinal tract have been brought in context with disruption of the gut microbiome. Several molecular mechanisms have been described to facilitate tissue uptake of MNPs, which then are involved in local inflammatory and immune responses. Furthermore, MNPs can act as potential transporters ("vectors") of contaminants and as chemosensitizers for toxic substances ("Trojan Horse effect"). In this review, we summarize current multidisciplinary knowledge of ingested MNPs and their potential adverse health effects. We discuss new insights into analytical and molecular modeling tools to help us better understand the local deposition and uptake of MNPs that might drive carcinogenic signaling. We present bioethical insights to basically re-consider the "culture of consumerism." Finally, we map out prominent research questions in accordance with the Sustainable Development Goals of the United Nations.

The Occurrence of Microplastics in Sediment Cores from Two Mangrove Areas in Southern Thailand

Mangroves are areas that connect the land and sea, and are important to the ecosystem. They are important places for food sources and the habitat of aquatic fauna in the tidal areas. However, the existence of plastic debris poses a risk to the aquatic environment. This study aimed to investigate the accumulation of microplastics (MPs) in sediment cores from two mangrove areas. The first mangrove area is in the outer section of the Songkhla lagoon (SK), while the second is in the coastal area of Pattani province (PN). Sediment core sampling was performed from SK = 8 stations and PN = 5 stations. Surface enrichment of MP was observed, especially in sediments of 0–4 cm. MPs were found throughout the depth in both areas, while fewer MPs were found in deeper sediment core layers (p < 0.05) at some stations inside the mangrove zone. Simple linear regression of the observed MPs and distance in the horizontal were found to be significant at SK within the mangrove zone with r2 = 0.79 (p < 0.05). MP fibers were the most commonly found MP type in both areas and were less than 1 mm. Blue and black MPs were the most abundant colors found in both areas. The six polymer types reported in this study comprised polyethylene, rayon, rubber, styrene, Poly (vinyl acetate), and paint. The findings of the present study suggest that long-term monitoring of marine debris along coastlines is necessary to help improve national policies and measures related to marine plastic debris.

Plastic cutting boards as a source of microplastics in meat

Plastic cutting boards were found to be the source of polythene microplastic contamination in cut meat commercially available at butchers and a supermarket chain in the Middle East, making them also a direct source of microplastic in wastewater. The mean size of the microplastic in the raw meat was 1279.2 ± 835.0 µm, but decreased when the meat was cooked or fried. The microplastic melted during both cooking and frying processes and recrystallised partially upon cooling. Washing the meat for a short time (10 seconds) before preparing it reduced the microplastic contamination insignificantly, and only extensive washing of the meat over longer periods of time (3 min) helped decrease the microplastic count to 0.07 MP/g meat. The composition of the cutting boards was analysed by FT-IR spectroscopy, differential scanning calorimetry and subjected to wear, tensile and hardness tests. From a 3D photo of a spent cutting board, it was calculatedthat 875 g polythene was lost from the cutting board at the end of its lifetime.

The occurrence and abundance of microplastics in surface water of the midstream and downstream of the Cisadane River, Indonesia

This study investigates microplastic contamination in the midstream to downstream of the Cisadane River and its confluence with the Java Sea. The abundance ranged between 13.33 and 113.33 particles m^-3 in surface water samples. Microplastic abundance in the downstream area was higher than midstream. We discovered 11 microplastic polymer types, with polyethylene, polystyrene, and polypropylene dominating (>70%) the chemical composition study result, which we hypothesized was owing to their ubiquitous use in daily household and industrial activities. Microplastic fragments with a diameter of 500-1000 m predominated in surface water samples. This study identifies possible microplastics pollution hotspots throughout the Cisadane rivers and selects sites that require additional sampling. Runoff from cities and landfills has the potential to have a significant impact on the accumulation and movement of microplastics from the inland to the Cisadane estuarine area. Additional research is necessary to determine how and where these microplastics particles enter rivers.

Feeding Habits and the Occurrence of Anthropogenic Debris in the Stomach Content of Marine Fish from Pattani Bay, Gulf of Thailand

Simple Summary

In this work, the feeding behaviour of fish from a natural bay environment and the ingested anthropogenic fragments in a fish community in relation to their feeding habits and habitats were investigated. The identification of 34 fish species and analysis of their stomach content by visual inspection were carried out. The ingestion of anthropogenic debris by fish differed between season and their feeding features. The planktivorous fish having higher ingestion of anthropogenic debris than other species were found. The study results enhance the understanding of the spatiotemporal variation of feeding habits of fish communities and support future alerts relating to the risk of anthropogenic pollution in marine food webs.

Abstract

This study assessed the feeding habits and ingestion of anthropogenic debris in 34 marine fish species from the southern Gulf of Thailand. A total of 5478 fish samples of 12 families were categorised into seven groups: planktivore, Lucifer feeder, fish feeder, Acetes feeder, shrimp feeder, piscivore, and zoobenthivore fish. A total of 2477 anthropogenic debris items were extracted from 12 fish species by visual inspection. Their ingestion of anthropogenic debris was influenced by season (p < 0.0001), with the highest ingestion during the northeast monsoon season. Furthermore, planktivorous fish displayed more ingested anthropogenic debris than the other investigated species (p = 0.022). Blue-coloured anthropogenic debris was commonly detected in the stomachs of fish and significantly differed between species (p > 0.001). Water depth and season significantly influenced the availability of food types (AF) for fish (p < 0.001). These findings provide evidence of the ingestion of anthropogenic debris by fish inhabiting a natural bay and signal the future anthropogenic pollution of marine fish.

Finding Biomarkers in Antioxidant Molecular Mechanisms for Ensuring Food Safety of Bivalves Threatened by Marine Pollution

Aquaculture production as an important source of protein for our diet is sure to continue in the coming years. However, marine pollution will also likely give rise to serious problems for the food safety of molluscs. Seafood is widely recognized for its high nutritional value in our diet, leading to major health benefits. However, the threat of marine pollution including heavy metals, persistent organic pollutants and other emerging pollutants is of ever-growing importance and seafood safety may not be guaranteed. New approaches for the search of biomarkers would help us to monitor pollutants and move towards a more global point of view; protocols for the aquaculture industry would also be improved. Rapid and accurate detection of food safety problems in bivalves could be carried out easily by protein biomarkers. Hence, proteomic technologies could be considered as a useful tool for the discovery of protein biomarkers as a first step to improve the protocols of seafood safety. It has been demonstrated that marine pollutants are altering the bivalve proteome, affecting many biological processes and molecular functions. The main response mechanism of bivalves in a polluted marine environment is based on the antioxidant defense system against oxidative stress. All these proteomic data provided from the literature suggest that alterations in oxidative stress due to marine pollution are closely linked to robust and confident biomarkers for seafood safety.

Detection of microplastics in Litopenaeus vannamei (Penaeidae) and Macrobrachium rosenbergii (Palaemonidae) in cultured pond

BACKGROUND

The presence of plastic particles in freshwater species is becoming a global concern owing to the potential impact on food security and human health. In this study, we investigated the presence microplastics (MPs) in two economically important freshwater species: the giant freshwater prawn (Macrobrachium rosenbergii) and the white leg shrimp (Litopenaeus vannamei) cultured in a polyculture pond in the central part of Thailand.

METHODS

The gastrointestinal tract (GT) of 300 giant freshwater prawn (160 female and 140 male) and 150 white leg shrimp specimens were investigated for the presence of MPs.

RESULTS

From the pooled samples, a total of 1,166 MP items were identified. Specifically, the GTs of female and male freshwater prawns and white leg shrimps contained an average of 33.31 ± 19.42, 33.43 ± 19.07, and 11.00 ± 4.60 MP items per individual, respectively. Further, their mean MP contents per g of gut material were 32.66 ± 5.10, 32.14 ± 4.85, and 10.28 ± 1.19 MP items, respectively. In the GT of these species, MPs with sizes in the range 500-1000 µm, were predominant, and white/transparent MPs were most prevalent (63.67%). Furthermore, regarding the morphotypes of the MPs, fibers, fragments, films, and spheres were frequently observed, with fibers shows predominance. Specifically, the proportions of fibers in the GTs of female Macrobrachium rosenbergii, male Macrobrachium rosenbergii, and Litopenaeus vannamei were 83.3, 79.91, and 46.06%, respectively. Four MP polymer types, polyethylene, polycaprolactone, polyvinyl alcohol, and acrylonitrile butadiene styrene, were also identified via FTIR spectroscopy, which further confirmed the presence of MPs in the GT of the freshwater-cultured species.

DISCUSSION

Our findings indicated that consuming shrimps and prawns without first removing the MPs from their GTs is one of the mean by which humans get exposed to MPs. Thus, MPs in freshwater species can be passed down the food chain to humans.

A Preliminary Assessment of Size-Fractionated Microplastics in Indoor Aerosol—Kuwait’s Baseline

The omnipresence of microplastic (MP) in various environmental samples, including aerosols, has raised public health concerns; however, there is presently very limited information on MPs in indoor aerosol. This paper presents a unique dataset where smaller MPs have been sampled using a six-stage cascade impactor from indoor environments in Kuwait. The MP concentration in the indoor air varied between 3.2 and 27.1 particles m⁻³, and the relative MP concentration decreased linearly from the lowest to the highest size fraction. A significant effect of location was observed for the total number of MPs (F_2,14 = 5.80, p = 0.02) and the inhalable fraction (F_2,14 = 8.38, p = 0.005), while location had no effect on the respirable fraction (F_2,14 = 0.54, p = 0.60). A significant effect of the type of air conditioning used was also observed for the total number of MPs (F_2,19 = 5.58, p = 0.01) and the inhalable fraction (F_2,19 = 6.45, p = 0.008), while location had no effect on the respirable fraction (F_2,19 = 1.30, p = 0.30). For the total number of MPs and the inhalable fraction, the concentration was significantly higher for the split unit air-conditioning as compared to the central air-conditioning plants. The presence/absence of carpets had no significant effect on the MP concentrations (total: F_1,19 = 4.08, p = 0.06; inhalable: F_1,19 = 3.03, p = 0.10; respirable: F_1,19 = 4.27, p = 0.05). The shape was dominantly fibers, with few fragments in lower size fractions. These datasets represent the first baseline information for Kuwait, and the smaller MPs in all the samples further underscore the need to develop standardized protocols of MP collection in the ≤2.5 µm fraction that can have more conspicuous health implications.

Occurrence, human exposure, and risk of microplastics in the indoor environment

Microplastics (MPs) are a group of emerging contaminants that have attracted increasing scientific and societal attention over the past decade due to their ubiquitous detection in all environmental compartments. So far, most studies on MPs focus on characterizing their occurrence, fate, and impact in the aquatic environment. Therefore, very little is known about the magnitude, patterns, and associated risks of human exposure to MPs, particularly indoors. This is a significant research gap given that people spend most of their time (up to 90%) indoors, which is exacerbated over the past year by COVID-19 lockdown measures. Critical evaluation of the existing literature revealed the presence of MPs at higher concentrations in indoor air and dust (from homes and offices) compared to outdoors. This was attributed to several factors including: indoor MPs sources (e.g. furniture, textiles), increased deposition of atmospheric MPs indoors, and less atmospheric mixing and dilution compared to outdoor air. Current understanding is that indoor human exposure to MPs occurs via a combination of inhalation, ingestion, and dermal contact. Dietary intake was considered the major pathway of human exposure to MPs until recent studies revealed potential high exposure via inhalation. Moreover, exposure via inadvertent dust ingestion and dermal contact cannot be neglected, particularly for young children. This is alarming due to the potential toxic implications of MPs exposure. Early toxicological evidence indicates that small MPs (<20 µm) can cause oxidative stress and inflammation, while particles <5 µm can be engulfed by cells and translocated to accumulate in different organs. Also, there is increasing concern over potential leaching of toxic chemicals used as plastic additives (e.g. plasticizers and flame retardants) upon exposure to MPs due to their large surface area. However, MPs exposure and risk assessment in humans is still in its infancy and more research is necessary to provide the knowledge base required for regulations to protect human health and environment against MPs.

Microplastics impact shell and pearl biomineralization of the pearl oyster Pinctada fucata

Microplastics are extremely widespread aquatic pollutants that severely detriment marine life. In this study, the influence of microplastics on biomineralization was investigated. For the first time, multiple forms and types of microplastics were detected and isolated from the shells and pearls of Pinctada fucata. According to the present study, the abundance of microplastics in shells and pearls was estimated at 1.95 ± 1.43 items/g and 0.53 ± 0.37 items/g respectively. Interestingly, microplastics were less abundant in high-quality round pearls. Microplastics may hinder the growth of calcite and aragonite crystals, which are crucial components required for shell formation. During the process of biomineralization microplastics became embedded in shells, suggesting the existence of a novel pathway by which microplastics accumulate in bivalves. After a 96-h exposure to microplastics, the expression level of typical biomineralization-related genes increased, including amorphous calcium carbonate binding protein (ACCBP) gene which experienced a significant increase. ACCBP promotes the formation of amorphous calcium carbonate (ACC), which is the pivotal precursor of shell formation-related biominerals. ACCBP is highly expressed during the developmental stage of juvenile oysters and the shell-damage repair process. The increased expression of ACCBP suggests biomineralization is enhanced as a result of microplastics exposure. These results provide important evidence that microplastics exposure may impact the appearance of biominerals and the expression of biomineralization-related genes, posing a new potential threat to aquatic organisms.

Potential microplastic release from the maritime industry: Abrasion of rope

While land-based sources of plastic pollution have gained increasing attention in recent years, ocean-based sources have been less well studied. The aim of this study was to compare a variety of ropes (differing in age, wear surface and material) to quantify and characterise the production of microplastic during use. This was achieved by simulating, in laboratory and field experiments, rope hauling activity which is typically performed on board maritime vessels, such as fishing boats. Microplastic generation was quantified by collecting fragments that were released as a consequence of abrasion. Notably, we show that microplastic fragments generated from rope wear during use were characteristically irregular in shape, rather than fibrous such as those assigned to synthetic rope by previous studies. Therefore, we suggest that some of the plastic fragments found in the marine environment may have been falsely attributed to land-based sources but have in fact arisen form the abrasion of rope. Our research found that new and one-year old polypropylene rope released significantly fewer microplastic fragments (14 ± 3 and 22 ± 5) and less microplastic mass (11 ± 2 and 12 ± 3 μg) per metre hauled compared to ropes of two (720 ± 51, 247 ± 18 μg) or ten (767 ± 55, 1052 ± 75 μg) years of age. We show that a substantial amount of microplastic contamination is likely to directly enter the marine environment due to in situ rope abrasion and that rope age is an important factor influencing microplastic release. Our research suggests the need for standards on rope maintenance, replacement, and recycling along with innovation in synthetic rope design with the aim to reduce microplastic emission.

Prevalence of Microplastics in the Eastern Oyster Crassostrea virginica in the Chesapeake Bay: The Impact of Different Digestion Methods on Microplastic Properties

This study aimed to determine the microplastic prevalence in eastern oysters (C. virginica) in three sites in the Chesapeake Bay in Virginia and optimize the digestion methods. The digestion results illustrate that the lowest recovery rate and digestion recovery were related to enzymatic, enzymatic + hydrogen peroxide (H₂O₂), and HCl 5% treatments, while the highest digestion recovery and recovery rate were observed in H₂O₂ and basic (KOH) treatments. Nitric acid digestion resulted in satisfying digestion recovery (100%), while no blue polyethylene microplastics were observed due to the poor recovery rate. In addition, nitric acid altered the color, changed the Raman spectrum intensity, and melted polypropylene (PP) and polyethylene terephthalate (PET). In order to determine the number of microplastics, 144 oysters with an approximately similar size and weight from three sites, including the James River, York River, and Eastern Shore, were evaluated. Fragments were the most abundant microplastics among the different microplastics, followed by fibers and beads, in the three sites. A significantly higher number of fragments were found in the James River, probably due to the greater amount of human activities. The number of microplastics per gram of oyster tissue was higher in the James River, with 7 MPs/g tissue, than in the York River and Eastern Shore, with 6.7 and 5.6 MPs/g tissue.

Influence of Particle Size on Ecotoxicity of Low-Density Polyethylene Microplastics, with and without Adsorbed Benzo-a-Pyrene, in Clam Scrobicularia plana

This study investigated the ecotoxicological effects of differently sized (4–6 µm and 20–25 µm) low-density polyethylene (LDPE) microplastics (MPs), with and without adsorbed benzo-a-pyrene (BaP), in clam Scrobicularia plana. Biomarkers of oxidative stress (superoxide dismutase—SOD; catalase—CAT), biotransformation (glutathione-S-transferases—GST), oxidative damage (lipid peroxidation—LPO) and neurotoxicity (acetylcholinesterase—AChE) were analysed in gills and digestive glands at different time intervals for a total of 14 days of exposure. In order to have a better impact perspective of these contaminants, an integrated biomarker response index (IBR) and Health Index were applied. Biomarker alterations are apparently more related to smaller sized (4–6 µm) MPs in gills and to virgin LDPE MPs in the digestive gland according to IBR results, while the digestive gland was more affected by these MPs according to the health index.

Microplastic accumulation in commercial fish from the Adriatic Sea

We assessed the presence and concentration of microplastics in fishes from the Northern Adriatic Sea on sale for human consumption. Microplastics were extracted from the digestive tract of 180 specimens, belonging to 6 different species (2 pelagic, and 4 demersal). Microplastics were identified through Nile red staining, and selected particles were analyzed by μ-Raman spectroscopy. The 47.8% of examined fish were found to contain microplastics (233 fragments). The mean concentration of microplastics in the 6 species ranged between 4.11 ± 2.85 items/individual in Adriatic soles, and 1.75 ± 0.71 items/individual in pilchards. Microplastics ranged in size between 0.054 mm and 0.765 mm. Polyethylene and polypropylene were the polymer types identified through μ-Raman spectroscopy. Despite our estimates are underestimations, these results are of particular concern, as the fish analyzed are consumed without being eviscerated, and the microplastics they contain are transferred directly to humans.

Accumulation of chemical elements and occurrence of microplastics in small pelagic fish from a neritic environment

The assessment of contaminant exposure in marine organisms often focuses on the most toxic chemical elements from upper trophic level species. Information on mid-trophic level species and particularly on potentially less harmful elements is lacking. Additionally, microplastics have been considered emergent contaminants in aquatic environments which have not been extensively studied in species from mid-trophic levels in food chains. This study aims to contribute to an overall assessment of environmental impacts of such chemicals in a community of small pelagic fish in the North Atlantic. The concentrations of 16 chemical elements, rarely simultaneously quantified (including minerals, trace elements and heavy metals), and the presence of microplastics were analysed in sardines (Sardina pilchardus) and mackerels (Scomber spp. and Trachurus trachurus) sampled along the Portuguese coast. Biochemical stress assessments and stable isotope analyses were also performed. The chemical element concentrations in S. pilchardus, T. trachurus, and Scomber spp. were relatively low and lower than the levels reported for the same species in the North Atlantic and adjacent areas. No clear relationships were found between chemical elements and oxidative damage in fish. However, the concentration of several chemical elements showed differences among species, being related with the species' habitat use, trophic niches, and specific feeding strategies. The presence of plastic pieces in the stomachs of 29% of the sampled fishes is particularly concerning, as these small pelagic fish from mid-trophic levels compose a significant part of the diet of humans and other top predators. This study highlights the importance of multidisciplinary approaches focusing on the individual, including position data, stable isotopes, and oxidative stress biomarkers as complementary tools in contamination assessment of the marine mid-trophic levels in food chains.

Quantifying spatial variation in the uptake of microplastic by mussels using biodeposit traps: A field-based study

Spatial uptake patterns of microplastics (MP) by marine species are largely unexplored under field conditions. A novel "biodeposit trap" that measure uptake and egestion of MP by suspension-feeders through the analysis of their biodeposits, was designed and used to estimate the spatial variation of these processes by mussels in field conditions. Traps containing wild or farmed mussels or control empty shells were deployed at three sites characterised by different MP concentrations and water flow conditions. A different MP dimensional composition was observed between MP pools present in biodeposit and control traps, with the latter shifted towards higher dimensional range (0.05-5 mm). Conversely, mussels accumulated small MP (0.02-0.05 mm) into their biodeposits without any significant difference between wild and farmed specimens. MP uptake rates were on average 4-5 times higher at the site where MP contamination was expected to be highest and where water flow conditions were considered moderate.

ABUNDANCE AND CHARACTERISTICS OF MICROPLASTICS IN MARKET BIVALVE Aulacomya Atra (MYTILIDAE: BIVALVIA)

Seafood contamination with microplastics is one major route for human intake. Shellfish are among the most important since most shellfish species are eaten fresh and entirely. The aim of the present study was to report the abundance and characteristics of microplastics in commercial bivalve Aulacomya atra sold in fisheries from three Peruvian provinces. Market surveys were carried out and standard microplastic extraction, observation, and analysis methods were conducted. The mean microplastic abundance in the three provinces was 0.56 ± 0.08 MP g-1. Lima, the most populated province in Peru, presented the highest concentration (1.04 ± 0.17 MP g-1). The majority of the microplastics were fiber/lines (58.8 %) and blue (40.5 %). The polymer identity of most fiber/lines was polyester, suggesting microfibers that shed from clothes during laundry may be one major source of contamination. Other identified polymers were polyethylene (PE), polypropylene (PP), and polystyrene (PS). The annual dietary microplastic intake by the Peruvian population was estimated to be ~48.18 MP person-1 year-1 via A. atra consumption only, although values could vary depending on the region. The need for a better supply chain, handling conditions, and further research are discussed.

Microplastic contamination assessment in water and economic fishes in different trophic guilds from an urban water supply reservoir after flooding

Rain and floods events are responsible for the transport of microplastics in freshwater ecosystems, yet to date, rare study has examined microplastics pollution in urban water supply reservoirs during such events. In this study, we investigated the concentrations and characteristics of microplastic in water and economic fish species with different feeding guilds in the Dafangying Reservoir, an important source of drinking water for Hefei city. Microplastic concentrations in water were relatively higher than that in natural lakes, indicating abundant microplastic contaminants input through overland runoff triggered by flooding. Our results detected five types (fiber, debris, film, microbead and particle) and six colors (black, transparent, blue, yellow, red and green) of microplastics in water samples. Fiber accounted for the dominant shape, which may result from the household sewage from washing clothes and desquamated fiber transported by wind and overland runoff. Meanwhile, transparent was the predominant microplastic color, which can be ascribe to the widely use of intentionally manufactured transparent disposable plastic commodities in cities. Then in fish samples, the microplastic concentrations ranged from 8.75 to 51.3 items/individual in fish guts, and 9.5-52.6 items/individual in fish gills. Our results demonstrated significant higher microplastic concentrations in planktivorous and herbivorous species. The filter feeding capture mode, i.e., engulfing floating prey through frequently drawing in large volume of water confused with microplastics, may result in the higher microplastic concentrations of planktivorous fishes. Due to the dense microplastics adhering on plant surface, herbivorous fishes can concentrate higher microplastics abundance through the ingestion of macrophytes. According to the biological concentration factor (BCF), all the determined microplastics gave BCF far below 1, suggesting the low bioaccumulation capacity of microplastics in fish species.

Co-production of future scenarios of policy action plans in a science-policy-industry interface - The case of microfibre pollution from waste water treatment plants in Norway

One of the ambitions of the UN Decade of Ocean Science is stakeholder interaction to co-produce new ideas and solutions for policy action plans to ensure that environmental challenges are mitigated in a timely manner. Regulations around the release of microfibres are largely lacking, and we are at an excellent point of departure to test integrative methods of such co-production. We co-designed conceptual maps and Bayesian Belief Networks with probabilistic future scenarios within both inter- and intra-sectoral workshops with industry and scientific stakeholders to gain comparable results of policy action scenarios for curbing the challenge of microfibre pollution within this context. We found that when scientists worked on this alone, their focus was different than when working together with industry directly. Scientists focused on methods for avoiding release into the environment from a technical vantage point, whereas industry emphasized regulatory requirements needed to avoid ambiguity within the sector.

Microplastic concentrations in cultured oysters in two seasons from two bays of Baja California, Mexico

As filter feeders, bivalve mollusks have a high potential risk of contamination by microplastics (MPs), which can be considered a transfer vector for humans through their consumption. Spatial-temporal differences in the MP concentration were evaluated in the cultured oyster Magallana gigas in Todos Santos Bay (TSB) and San Quintin Bay (SQB) during winter and summer (2019). MPs were found in all samples in both seasons, where microfibers were the most abundant particles observed. Only in winter, statistically significant differences were observed in the average concentration of ingested MPs between oysters from TSB and SQB. In each bay, the highest concentrations were observed during winter. Seasonal differences between MP concentrations were only found in TSB. During summer, the content of MPs was compared between the digestive system and the rest of the soft tissue in organisms from each site, and statistically significant differences were not observed, except by one site in SQB. Polymers were identified via μ-FTIR-ATR spectrometry. Polyester, polyacrylonitrile, and rayon were the most common plastics detected. However, due to the low concentration of MPs found in oysters, its consumption does not represent a risk to human health. Moreover, MP concentrations in organisms appear to respond to variables, such as temporality and the water circulation dynamics within the bays.

Concentration of microplastics in bivalves of the environment: a systematic review

The aim of this review was to identify the current knowledge regarding the concentration of microplastics in bivalves in the marine, estuarine, and freshwater environments. For this purpose, researches were conducted from September 2020 to February 2021 in the Scopus, Web of Science, and Google scholar databases, following a meticulous selection of articles. To comprehensively understand the selected articles, an extensive review was carried out in order to identify the methodologies employed, sampling sites, species evaluated, characteristics of the microplastics (concentrations, shapes, sizes, and polymers) and their relationship with the concentration of this particles in the environment. A total of 93 articles were selected, with an exponential growth in the number of articles from April 2014 to February 2021. Worldwide, 80 articles were realized in the Northern Hemisphere and thirteen in the Southern Hemisphere. The samplings of organisms were carried out in 36 countries, besides one in Antarctica. The concentration of microplastics were studied in 70 species, with mussels Mytilus spp. and the oysters Crassostrea spp. being the main genus studied. Due to the different methodologies used to digest the tissues of organisms and identify microplastics and species, it is difficult to make comparisons between the results of different studies. In addition, data on the concentrations of microplastics in the environment, as well as their composition and characteristics, are needed, enabling the verification of relationships with the concentrations identified in organisms, which does not occur in most studies. Thus, we suggest an increase in the number of studies to be realized in the southern hemisphere, future studies use the same methodology of digestion, the polymer identification of microplastics and samplings of the surrounding environment, enabling a greater comparison between studies.

Can the presence of additives result in false positive errors for microplastics in infant feeding bottles?

In recent years, it has been shown that food contact materials can be a potential source of microplastics (MP). Recently, it was reported that more than 16 million polypropylene (PP) particles L^-1 may be released from infant feeding bottles (IFBs) made of PP. In the present study seven different IFBs were investigated by the same method used in the aforementioned publication. In our tests, however, only one IFB showed a level of MP above the limit of detection. More importantly, the MP detected were not of the same material as the bottle and are more likely the result of contamination. In addition, there was a notable difference in released MP particles when the water simulant was filtered for µ-Raman spectroscopy at hot temperature (70°C) instead of filtering it after cooling down to room temperature. Thermal desorption gas chromatography mass spectrometry showed that these differences may be the result of migration and precipitation of additives such as fatty acid esters, often used as release agents in bottle production. These observations, that migrating additives could result in false positive errors for MP, indicate the need for critical consideration when polymers have been subjected to heat.

Ingestion of microplastics and its potential for causing structural alterations and oxidative stress in Indian green mussel Perna viridis- A multiple biomarker approach

The present study has investigated the distribution of microplastics in sediment and its impact on histological, ultrastructural, and oxidative stress mechanisms in Perna viridis (P. viridis) from Kasimedu, Chennai, India. The results confirmed that fibers were the predominant type of microplastics observed, followed by spheres, flakes, sheets, and fragments. The observed microplastics were confirmed as polyester, polypropylene, polyethylene, cellophane, and rayon using μ-FT-IR. Microplastic particles entangled in gills caused abrasion of ciliated structure and hemocyte infiltration in the hemolymph vessels. The digestive gland showed a shrunken nucleus, dark inclusions, and damage in the nucleoid core structure. Enlarged vacuoles and the presence of clusters of vesicles presumably represented the transformed golgi cisternae. Further, the results confirmed that oxidative stress markers were significantly high in gills and digestive diverticula of P. viridis. Overall, the results indicated that microplastics induced different toxic physiological and structural alterations in gills and digestive diverticula of P. viridis. These findings highlighted the necessity to focus on exposure studies to understand the absolute magnitude of the problem due to microplastic pollution in the urban estuarine ecosystems of Chennai, Tamil Nadu, India.

The distribution and ecological effects of microplastics in an estuarine ecosystem

Coastal sediments, where microplastics (MPs) accumulate, support benthic microalgae (BMA) that contribute to ecosystem functions such as primary production, nutrient recycling and sediment biostabilization. The potential interactions between MPs, BMA and associated properties and functions remain poorly understood. To examine these interactions, a survey of 22 intertidal sites was conducted. MP abundance, size and a suite of MP diversity indices (based on color and shape) were determined from surface sediments alongside biochemical and physical properties. MPs were detected at all sites and dominated by polypropylene (34%), polyester (18%) and polyethylene (11%). Fragment and fiber dominance (16-92% and 6-81% respectively) and color-shape category diversity varied significantly by site. Distance-based linear models demonstrated that estuary-wide, mean grain size and mud were the best predictors of MP abundance-diversity matrices, but variance explained was low (9%). Relationships were improved when the data was split into sandy and muddy habitats. In sandy habitats (<8% mud), physical properties of the bed (mean grain size, mud content and distance from the estuary mouth) were still selected as predictors of MP abundance-diversity (14% variance explained); but a number of bivariate relationships were detected with biochemical properties such as BMA associated pigments and organic matter. In muddy habitats (>8% mud), porewater ammonium was lower when fiber abundance and overall MP diversity were higher. The inclusion of porewater ammonium, organic matter content and pheophytins alongside physical properties explained a greater percentage of the variance in MP abundance-diversity for muddy habitats (21%). The results highlight the importance of examining plastic shapes and MP categories in addition to abundance and emphasize that functionally different habitats should be examined separately to increase our understanding of MP-biota-function relationships.

Legislation to limit the environmental plastic and microplastic pollution and their influence on human exposure

Plastic pollution is an emerging problem and is a consequence of the post-consumer plastic waste accumulation in the environment coupled to mismanaged waste programmes. Countries are counteracting the continuous growth of plastic litter with different strategies: introducing bans and limits on both plastic items and materials, promoting plastic recycling and recovery strategies and encouraging voluntary clean up actions, as well as raising public awareness. However, the toxicity of plastics to the environment and organisms is not only related to their polymer chains, but also to the fact that plastic materials contain hazardous additives and can adsorb environmental pollutants (i.e. heavy metals and persistent organic contaminants, respectively). The plastic/additives/pollutants combination may be ingested by marine organisms and then enter in the food chain. Therefore, legislation for additives and contaminants is crucial both to reduce environmental pollution and their toxic effects on organisms, which of course includes humans. In this review, the current policies on plastics and related contaminants are described focusing on current laws. Moreover, recommendations for seafood consumption are suggested, since each fish or mollusc eaten may potentially result in plastic particles, additives or contaminants ingestion.