Common laboratory reagents: Are they a double-edged sword in microplastics research?

A critical review of sampling, extraction and analysis methods for tyre and road wear particles

Tyre and road wear particles (TRWPs) have become an increasing contamination concern because of their extensive distribution in the environment. A comprehensive overview of the methods for sampling, treatment and analysis of environmental samples for TRWPs (and their benefits and limitations) is lacking. We evaluate and critically assess the sampling, treatment and analysis methods previously reported for water, air, road dust and sediment/soil samples. We suggest research frameworks for studying TRWPs in these media. Microscopy and thermal analysis techniques such as scanning electron microscopy (with energy dispersive X-ray analysis), environmental scanning electron microscopy, 2-dimensional gas chromatography mass spectrometry and liquid chromatography with tandem mass spectrometry in the case of complex samples, are optimal methods for determination of the number and mass of TRWPs. Issues for further investigation and analysis recommendations are provided.

Colony complexity affects microplastic loads in Pocillopora corals

Microplastic (MP) pollution poses a significant threat to marine ecosystems. Coral reefs, often located near land-based sources of these pollutants, act as potential sinks due to their complex three-dimensional structures. While the interactions between reef-building corals and MPs have been increasingly investigated, the role of coral structural complexity in MP accumulation remains poorly understood. This study investigated the influence of coral structural complexity on MP trapping efficiency under natural conditions, specifically aiming to: I) quantify and characterize MPs trapped by Pocillopora corals, II) compare MP distribution across coral compartments (surface, tissue, and skeleton), and III) assess the relationship between seven metrics of coral complexity (i.e., S/V ratio, fractal dimension, compactness, convexity, sphericity, packing, and rugosity) and MP loads. Six Pocillopora sp. colonies, comprising 36 fragments, were sampled from a reef in Kāne'ohe Bay, Hawai'i. MPs were extracted from the coral surface, tissue, and skeleton for quantification and characterization using microscopy and FTIR spectroscopy. Coral complexity was assessed using photogrammetry and 3D scanning. MPs were found at an average of 0.029 ± 0.079 particles per g coral, mostly at the coral surface (61 %). Compact, thick-branched coral morphologies showed higher MP accumulation, likely due to increased formation of stagnant water regions and reduced turbulence. Our results demonstrate that coral complexity plays a significant role in MP deposition under natural conditions, with potential implications for coral health and the transfer of MPs to other reef sinks. This highlights the importance of considering coral morphological complexity when evaluating the risk of MP pollution.

Release of microplastics from polymeric ultrafiltration membrane system for drinking water treatment under different operating conditions

Drinking water has emerged as an important route for microplastics (MPs) to enter the human body, prompting concerns about their adverse health impacts. Membrane filtration technology is widely recognized as an effective treatment solution for combating MP pollution in water. However, recent research disputes that polymeric membrane systems may serve as additional sources of MPs in drinking water. The aim of this research is to investigate MP release from ultrafiltration membrane systems under different operating conditions by providing concrete evidence, identifying the operational factors contributing to the release, and elucidating the underlying possible mechanisms. Two key pieces of evidence were found to support the assertion that MPs were released from membrane systems, i.e., negative removal efficiency and an alteration in MP compositions observed between feed and permeate samples. Surprisingly, the MPs released from the membrane system originated not only from the membrane material and its additives but also from plastic-made equipment and even the other polymers used in the system. Overall results reveal that destructive activities such as shear stress, mechanical abrasion, and chemical oxidation processes, along with the carrying of MPs from external sources, are identified as potential mechanisms driving the concentration increase and polymer composition shift of MPs in permeate water. This study enhances an understanding of MP pollution in drinking water caused by membrane technology, potentially spurring the development of mitigation strategies for this issue.

Microplastics in German paper mills' wastewater and process water treatment plants: Investigation of sources, removal rates, and emissions

Although the paper industry processes polymeric materials and discharges large amounts of wastewater, no research on microplastics in the wastewater from paper mills has been published to date. This study is the first to investigate this issue. The wastewater treatment plants of twelve representatively selected German paper mills were investigated using an analysis protocol based on µ-Raman spectroscopy. The results show that treated process water from surface waters is negligible as a source of microplastics (MPs) ≥ 20 µm. The microplastics concentrations in untreated wastewater range from 106 to 108 (MPs ≥ 20 µm)/m3. Sources of microplastics in wastewater include recovered paper, functional polymers, and coating colors, among others. The most frequently detected polymers are polyethylene and polystyrene. In four cases, moving bed biofilm reactors were identified as a source of microplastics. The microplastics concentration in treated wastewater ranges from 102 to 104 (MPs ≥ 20 µm)/m3. Hence, the removal rate of the wastewater treatment plants exceeds 99 %. Mechanical treatment and the activated sludge process have the highest removal rates of all treatment stages. The loads emitted into surface waters range from 106 to 108 (MPs ≥ 20 µm)/h, comparable to municipal wastewater treatment plants with a population equivalent of over 10,000 inhabitants. Compared with other wastewater-related emissions (the total emissions of municipal wastewater treatment plants, or combined sewer overflow), the contribution of paper mills to microplastics in the aquatic environment is low. The results of the removal efficiency can be transferred to other branches of industry and municipal wastewater treatment plants.

Forensic determination of adhesive vinyl microplastics in urban soils

Plastic production and consumption hubs are mainly concentrated in urban centers, causing the soil in these places to become sinks of plastic fragments. Adhesive vinyl polymers are widely used in various commercial sectors and, to the best of our knowledge, this is the first study to investigate the potential for this type of material to form microplastics in urban soils. This proof-of-concept work started by studying the soil around a sign made of adhesive vinyl that had been exposed to the weather for eight years and showed evident signs of degradation, like cracking and color fading. We separated the microplastics with a two-step density separation protocol and selected only the microplastics targeted by this research, finding up to 5,570 fragments produced from 1 cm2 of adhesive vinyl film. In the soil below the sign, we registered 5.6 × 104 fragments kg-1 of dry soil on its topsoil layer (0-10 cm), 1.2 × 104 fragments kg-1 in the 10-20 cm layer, and 1 × 104 fragments kg-1 in the 20-30 layer. At a distance of 1 and 2 m from the sign, the highest concentration of fragments was also in the topsoil, respectively 9.3 × 103 and 5.3 × 102 fragments kg-1. We also observed that vertical and horizontal transport was not favored, causing the formation of hotspots near the source and that the area of the fragments did not influence vertical transport. Another important finding regarding the characterization technique is that degraded polyvinyl chloride is unlikely to be identified through FTIR without comparison to the source. Here, we presented a low-cost forensic assessment of the association between the presence of MPs and its source that can be used both for the development of public policies and for setting up quality controls for polluting companies.The results here presented reveal the need to rethink the use and types of materials used for visual identities and signage in urban environments.

Microplastic contamination in three environmental compartments of a coastal lagoon in the southern Gulf of Mexico

The Sontecomapan lagoon (Mexico) is a Ramsar site within the Los Tuxtlas Biosphere Reserve, facing the Gulf of Mexico. Although the site has a protected area status, it is vulnerable to microplastic contamination, whose long-term effects are uncertain. This study gives the first approach to the degree of contamination by microplastics in surface waters, zooplankton, and sediments in the lagoon. The samples in these three environmental compartments were collected in June 2018 and analyzed in the laboratory to extract and quantify the microplastics. The microplastics sampled were classified into fibers, fragments, and foams and identified as polyester, acrylic, and rayon, among others. In the surface waters, the mean concentration of microplastics was 7.5 ± 5.3 items/L, which is higher than the values registered in other protected coastal systems, perhaps because of differences in the methods used. Zooplankton, represented by copepods, luciferids, and chaetognaths, showed concentrations of 0.002 ± 0.005, 0.011 ± 0.011, and 0.019 ± 0.016 items/individual, respectively. These values were low compared to systems with high anthropic influence, and the differences between the three kinds of organisms were attributed to their feeding habits. In the sediments, the mean concentration was 8.5 ± 12.5 items/kg, lower than the values registered in sites of high human impact; the maximum value here found (43 items/kg) was recorded in the internal part of a lagoon arm of almost stagnant water. In general, the degree of contamination by microplastics in the lagoon was low; however, their presence indicates a potential risk to the biota.

Identification and analysis of microplastics in para-tumor and tumor of human prostate

BACKGROUND

While microplastics are widely found in various human organs and tissues, the relationship between microplastics and human health, especially prostate health, remains unclear. This study aims to identify and quantify the properties, types, and abundance of microplastics in paired para-tumor and tumor tissues of human prostate. Additionally, the potential correlation between microplastics abundance and prostate cancer are investigated.

METHODS

Paired para-tumor and tumor samples of the prostate were collected from 22 patients who underwent robot-assisted radical prostatectomy. A combination of laser direct infrared spectroscopy, scanning electron microscopy and pyrolysis-gas chromatography-mass spectrometry was utilized to analyse the properties, type and abundance of microplastics. Correlations between microplastics abundance, demographic characteristics and clinical features of patients were also examined.

FINDINGS

Laser direct infrared analysis revealed the presence of microplastics, including polyamide, polyethylene terephthalate, and polyvinyl chloride, in both para-tumor and tumor tissues of human prostate. However, polystyrene was exclusively detected in tumor tissues. The particle size distribution in the prostate tissue mainly ranged from 20 to 100 μm. Approximately 31.58% of para-tumor samples exhibited sizes between 20 and 30 μm, while 35.21% of tumor samples displayed sizes between 50 and 100 μm. The shapes of these microplastics varied considerably with irregular forms being predominant. Additionally, microplastics were detected by pyrolysis-gas chromatography-mass spectrometry in 20 paired prostate tissues. The mean abundance of microplastics was found to be 181.0 μg/g and 290.3 μg/g in para-tumor and tumor of human prostate samples, respectively. Among the 11 target types microplastics polymers, only polystyrene, polypropylene, polyethylene, and polyvinyl chloride were detected. Notably, polystyrene, polyethylene, and polyvinyl chloride, except for polypropylene, demonstrated significantly higher abundance in tumor tissues compared to their respective paired para-tumor. Furthermore, a positive correlation was observed between polystyrene abundance in the tumor samples of human prostate and frequency of take-out food consumption.

INTERPRETATION

This research provides both qualitative and quantitative evidence of the microplastics presence as well as their properties, types, and abundance in paired para-tumor and tumor samples of human prostate. Correlations between microplastics abundance, demographics, and clinical characteristics of patients need to be further validated in future studies with a larger sample size.

FUNDING

This work was supported by the National Key Research and Development Program of China (2022YFC2702600) and the National Natural Science Foundation of China (Grant No. 82071698, No. 82101676, and No. 82271630).

Take-out food enhances the risk of MPs ingestion and obesity, altering the gut microbiome in young adults

Young people are consuming large amounts of microplastics (MPs) due to the booming development of the take-out industry. To investigate the association between MPs exposure and obesity, 121 volunteers were divided into high MPs exposure (HME) and low MPs exposure (LME) according to the frequency of take-out food consumption. Fecal samples were collected for MPs detection using Raman spectra analysis, and identification of the gut microbiota was based on 16 S rDNA/ITS, while metabolite analysis was performed by LC-MS/MS. High levels of MPs and body mass index (BMI) were observed in the HME group (P < 0.05). Both the multiple linear regression (MLR) model and the binary logistic regression (BLR) (OR: 1.264, 95 % CI: 1.108-1.441, P < 0.001) analysis showed a positive correlation between MPs content and BMI. Microbial community analysis revealed that Veillonella, Alistipes and Dothideomycotes (pathogenic fungi) increased in HME participants, whereas Faecalibacterium and Coprococcus decreased. Meanwhile, analysis of stool metabolites showed that vancomycin resistance, selenocompound metabolism and drug metabolism pathways were enhanced in HME participants. These findings indicate that frequent consumption of take-out food may elevate the intake of microplastics, consequently modifying the gut microbiota and metabolites of young adults, and could represent a potential risk factor for obesity.

Understanding Human Health Impacts Following Microplastic Exposure Necessitates Standardized Protocols

Microplastics (MPs; 1 µm to 5 mm) are a persistent and pervasive environmental pollutant of emergent and increasing concern. Human exposure to MPs through food, water, and air has been documented and thus motivates the need for a better understanding of the biological implications of MP exposure. These impacts are dependent on the properties of MPs, including size, morphology, and chemistry, as well as the dose and route of exposure. This overview offers a perspective on the current methods used to assess the bioactivity of MPs. First, we discuss methods associated with MP bioactivity research with an emphasis on the variety of assays, exposure conditions, and reference MP particles that have been used. Next, we review the challenges presented by common instrumentation and laboratory materials, the lack of standardized reference materials, and the limited understanding of MP dosimetry. Finally, we propose solutions that can help increase the applicability and impact of future studies while reducing redundancy in the field. The excellent protocols published in this issue are intended to contribute toward standardizing the field so that the MP knowledge base grows from a reliable foundation. © 2024 Wiley Periodicals LLC.

Pollution characteristics and prospective risk of microplastics in the Zhengzhou section of Yellow River, China

The ubiquitous occurrence of microplastics (MPs) in the freshwater has attracted widespread attention. The Zhengzhou section of the Yellow River was the most prosperous region in ancient China, and the rapid urbanization, industrialization, and agricultural practices contributed to MPs pollution in aquatic systems recently, whereas the contamination status of MPs in the area is still not available. In this study, a total of fourteen sampling cross-sections were selected in the region to collect water samples systematically for the analysis of MPs pollution characteristics and potential risks. Results showed that abundance of MPs in the water were ranged from 2.33 to 15.50 n/L, with an average value of 6.40 ± 3.40 n/L, which was higher than it in other inland rivers from China. Moreover, the MPs of 0.5-2 mm were the dominant sizes in Yellow River of Zhengzhou region, and most of them were black fibres. The top three polymers were Polyethylene terephthalate (PET), Polyamide (PA) and Polypropylene (PP). High diversity indices of MPs observed at S3, S4, S5, S6, S7, and S8 for size, colour, polymer and shape indicated diverse and complex sources of MPs in those cross-sections. The MPs in water from Zhengzhou area of Yellow River probably degraded from textiles, fishing net, plastic bags, mulching film, packaging bags, and tire wear. The chemical risk assessment revealed a level III risk for study area, while S8 and S11 in which PVA or PAN with higher hazard score detected were categorised as class V risk. Coincidentally, probabilistic risk assessment showed a considerable ecological risk of MPs from Yellow River in Zhengzhou City, with possibility of 99.48 and 98.01 % adverse effect for food dilution and translocation-mediated mechanism, respectively. The results are expected to assistance for development of policies and ultimately combating MPs pollution.

Environmental health science research: opportunities and challenges for some developing countries in Africa

Due to ongoing developmental projects, there is a need for regular monitoring of the impact of pollutants on the environment. This review documented the challenges and opportunities in the field of environmental health sciences in some African countries. A systematic review was used to investigate opportunities and challenges in the field of environmental health science in Africa by examining published work with a specific focus on Africa. The reports showed that funding and infrastructure as the major problems. The study also highlighted recruiting study participants, retention, and compensation as a bane in the field in Africa. The absence of modern equipment also hinders research. The review, however, noted research collaboration from the region including studies on emerging pollutants such as pharmaceuticals, per and polyfluoroalkyl substances (PFAS), and microplastic (MPs) as great opportunities. The study concluded that collaboration with other continents, exchange programs and improved governmental interventions may help.

Multimodal detection and analysis of microplastics in human thrombi from multiple anatomically distinct sites

BACKGROUND

Microplastic (MP) pollution has emerged as a significant environmental concern worldwide. While extensive research has focused on their presence in marine organisms and ecosystems, their potential impact on human health, particularly on the circulatory system, remains understudied. This project aimed to identify and quantify the mass concentrations, polymer types, and physical properties of MPs in human thrombi surgically retrieved from both arterial and venous systems at three anatomically distinct sites, namely, cerebral arteries in the brain, coronary arteries in the heart, and deep veins in the lower extremities. Furthermore, this study aimed to investigate the potential association between the levels of MPs and disease severity.

METHODS

Thrombus samples were collected from 30 patients who underwent thrombectomy procedures due to ischaemic stroke (IS), myocardial infarction (MI), or deep vein thrombosis (DVT). Pyrolysis-gas chromatography mass spectrometry (Py-GC/MS) was employed to identify and quantify the mass concentrations of the MPs. Laser direct infrared (LDIR) spectroscopy and scanning electron microscopy (SEM) were used to analyse the physical properties of the MPs. Demographic and clinical information were also examined. A rigorous quality control system was used to eliminate potential environmental contamination.

FINDINGS

MPs were detected by Py-GC/MS in 80% (24/30) of the thrombi obtained from patients with IS, MI, or DVT, with median concentrations of 61.75 μg/g, 141.80 μg/g, and 69.62 μg/g, respectively. Among the 10 target types of MP polymers, polyamide 66 (PA66), polyvinyl chloride (PVC), and polyethylene (PE) were identified. Further analyses suggested that higher concentrations of MPs may be associated with greater disease severity (adjusted β = 7.72, 95% CI: 2.01-13.43, p < 0.05). The level of D-dimer in the MP-detected group was significantly higher than that in the MP-undetected group (8.3 ± 1.5 μg/L vs 6.6 ± 0.5 μg/L, p < 0.001). Additionally, LDIR analysis showed that PE was dominant among the 15 types of identified MPs, accounting for 53.6% of all MPs, with a mean diameter of 35.6 μm. The shapes of the polymers detected using LDIR and SEM were found to be heterogeneous.

INTERPRETATION

This study presents both qualitative and quantitative evidence of the presence of MPs, and their mass concentrations, polymer types, and physical properties in thrombotic diseases through the use of multimodal detection methods. Higher concentrations of MPs may be associated with increased disease severity. Future research with a larger sample size is urgently needed to identify the sources of exposure and validate the observed trends in the study.

FUNDING

This study was funded by the SUMC Scientific Research Initiation Grant (SRIG, No. 009-510858038), Postdoctoral Research Initiation Grant (No. 202205230031-3), and the 2020 Li Ka Shing Foundation Cross-Disciplinary Research Grant (No. 2020LKSFG02C).

Revealing new insights: Two-center evidence of microplastics in human vitreous humor and their implications for ocular health

Microplastics (MPs), an emerging environmental contaminant, have raised growing health apprehension due to their detection in various human biospecimens. Despite extensive research into their prevalence in the environment and the human body, the ramifications of their existence within the enclosed confines of the human eye remain largely unexplored. Herein, we assembled a cohort of 49 patients with four ocular diseases (macular hole, macular epiretinal membrane, retinopathy and rhegmatogenous retinal detachment) from two medical centers. After processing the samples with an optimized method, we utilized Laser Direct Infrared (LD-IR) spectroscopy and Pyrolysis Gas Chromatography/Mass Spectrometry (Py-GC/MS) to analyze 49 vitreous samples, evaluating the characteristics of MPs within the internal environment of the human eye. Our results showed that LD-IR scanned a total of 8543 particles in the composite sample from 49 individual vitreous humor samples, identifying 1745 as plastic particles, predominantly below 50 μm. Concurrently, Py-GC/MS analysis of the 49 individual samples corroborated these findings, with nylon 66 exhibiting the highest content, followed by polyvinyl chloride, and detection of polystyrene. Notably, correlations were observed between MP levels and key ocular health parameters, particularly intraocular pressure and the presence of aqueous humor opacities. Intriguingly, individuals afflicted with retinopathy demonstrated heightened ocular health risks associated with MPs. In summary, this research provides significant insights into infiltration of MP pollutants within the human eye, shedding light on their potential implications for ocular health and advocating for further exploration of this emerging health risk.

Suspected sources of microplastics and nanoplastics: Contamination from experimental reagents and solvents

There is an increasing concern about the potential effects of microplastics (MPs) and nanoplastics on human health and other organisms. For the separation and detection of MPs, there are various approaches, and the distinct procedures led to different results. However, the presence of MPs in the reagents was not addressed, which could cause false and/or inaccurate results during MPs detection. In this study, the chemical reagents commonly used for the separation and detection of MPs were selected to ascertain whether these reagents introduce MPs. It was shown that a large number of MPs were detected in the reagent and solvent samples. The largest number of MPs (>1 μm) was detected in the KOH reagent, with the abundance of 3070 items/g. The order of MPs abundance in the selected reagents was: KOH > NaCl > CaCl2 > SDS > NaI > H2O2. The types of MPs were the same as the body and stopper of the reagent packaging bottles. MPs size detected in reagent bottles was primarily smaller than 10 μm. The abundance of MPs in the reagents were independent of their purity, however, there was a certain difference in MPs abundance in reagents from different manufacturers. Furthermore, the presence of nanoplastics (< 1 μm) was verified in the reagents through Py-GCMS, with the abundance (39.47-43.01 mg/kg) higher than that of MPs. The obtained results in this study raised specific requirements and cautions for MPs and nanoplastics related research in terms of quality control. Also, this work can facilitate a more accurate assessment of MPs concentrations in the environment.

Analysis of micro- and nanoplastics in wastewater treatment plants: key steps and environmental risk considerations

The analysis of micro- and nanoplastics (MNPs) in the environment is a critical objective due to their ubiquitous presence in natural habitats, as well as their occurrence in various food, beverage, and organism matrices. MNPs pose significant concerns due to their direct toxicological effects and their potential to serve as carriers for hazardous organic/inorganic contaminants and pathogens, thereby posing risks to both human health and ecosystem integrity. Understanding the fate of MNPs within wastewater treatment plants (WWTPs) holds paramount importance, as these facilities can be significant sources of MNP emissions. Additionally, during wastewater purification processes, MNPs can accumulate contaminants and pathogens, potentially transferring them into receiving water bodies. Hence, establishing a robust analytical framework encompassing sampling, extraction, and instrumental analysis is indispensable for monitoring MNP pollution and assessing associated risks. This comprehensive review critically evaluates the strengths and limitations of commonly employed methods for studying MNPs in wastewater, sludge, and analogous environmental samples. Furthermore, this paper proposes potential solutions to address identified methodological shortcomings. Lastly, a dedicated section investigates the association of plastic particles with chemicals and pathogens, alongside the analytical techniques employed to study such interactions. The insights generated from this work can be valuable reference material for both the scientific research community and environmental monitoring and management authorities.

Microplastics are overestimated due to poor quality control of reagents

Microplastics are widely distributed in the environment and pose potential ecological risks, increasing to be one of the most important environmental pollutants. However, when assessing the characteristics of microplastic contamination in environmental samples, inadequate quality control measures for the working solutions may introduce additional microplastic contamination and lead to an overestimation of microplastic abundance in the samples. In this study, we evaluated the microplastic contamination characteristics in commonly used flotation and digestion reagents to assess errors caused by microplastics in the reagents. The results showed that the abundance of microplastics in the reagents ranged from 0.8 to 43.4 items/g, with the abundance of microplastics in flotation reagents being lower than that in digestion reagents. The shapes of the detected microplastics included particles, fibers, and fragments, and their size and outline were generally small, with most being below 100 µm. The most common types of polymers detected were polyethylene and polypropylene. In order to improve the universality and readability of the results, the detected microplastic abundances were converted into the actual application concentration of the working fluid. It was found that the potential contamination of microplastics in untreated flotation solutions ranged from 1.5 to 30.8 items/mL, while in digestion solutions ranged from 0.1 to 2.3 items/mL. Our study emphasizes the need for quality control measures, such as suction filtration, when evaluating microplastics in environmental samples or conducting chemical and biological tests related to microplastics.