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Toxics
Special Issues
Quantification and Identification of Micro- and Nanoplastics in Environmental Matrices
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Quantification and Identification of Micro- and Nanoplastics in Environmental Matrices

A special issue of Toxics (ISSN 2305-6304). This special issue belongs to the section "Ecotoxicology".

Deadline for manuscript submissions: closed (15 February 2024) | Viewed by 22531

Special Issue Editors

Dr. Fabiana Corami

E-Mail Website
Guest Editor
Institute of Polar Sciences, CNR-ISP, Via Torino, 155, 30172 Venezia, Mestre, Italy
Interests: microplastics; trace elements in sediments; water and biota; bioaccumulation; geospeciation
Special Issues, Collections and Topics in MDPI journals
Dr. Lucio Litti

E-Mail Website
Guest Editor
Department of Chemical Sciences, University of Padova, 2-35122 Padova, Italy
Interests: plasmonics; surface enhanced effects; Raman spectroscopy; sensors; chemosensors
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Microplastics (MPs), especially those below 100 µm (small microplastics, SMPs) and nanoplastics (NPs), are emerging contaminants whose presence is ubiquitous. They represent a concern for seawater, freshwater, sediments, soil, and air, since they may adversely affect ecosystem functions, but they can be a hazard also for biota and human health. Microplastics and nanoplastics (MNPs) can be ingested by various organisms. Invertebrates ingest them according to the size of their mouthparts; hence, MNPs can enter the trophic web, and they may be bioaccumulated and biomagnified, also becoming a risk for human health. MNPs can interact with environmental components, attracting and accumulating other pollutants on their surfaces; they can also be a potential vector of pathogens and viruses, which can accumulate on their surfaces. Moreover, the chemical composition and size of MNPs can play a pivotal role in determining their ecotoxicological risk. Thus, they may become toxicity enhancers.

In the last decade, there has been a shift in the scientific paradigm and goals regarding the investigation of plastic pollution: from the assessment of the presence of MNPs to the quantification and the unambiguous identification of these pollutants in different environmental matrices. However, there are still several gaps to fill for a better understanding of the pathways and destiny of MNPs in the environment and their interactions with organisms.

This Special Issue intends to present the current research on MNPs in different environmental matrices and the possibility of using the results of these studies for a risk assessment. Authors are kindly invited to submit original research papers, reviews, and short communications.

Dr. Fabiana Corami
Dr. Lucio Litti
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Toxics is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • microplastics
  • nanoplastics
  • bioplastics
  • aquatic ecosystems
  • soil
  • air
  • biota
  • analytical methodologies
  • quality control
  • plastic pollution

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Published Papers (7 papers)

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Research

13 pages, 5565 KiB  
Article
The Influence of Textile Type, Textile Weight, and Detergent Dosage on Microfiber Emissions from Top-Loading Washing Machines
by Pongsiri Julapong, Palot Srichonphaisarn, Thidarat Meekoch, Carlito Baltazar Tabelin, Onchanok Juntarasakul and Theerayut Phengsaart
Toxics 2024, 12(3), 210; https://doi.org/10.3390/toxics12030210 - 12 Mar 2024
Cited by 9 | Viewed by 2792
Abstract
The use of washing machines to wash textiles gradually breaks down synthetic fibers like polyethylene terephthalate (PET) or polyester (PES) in diverse clothing materials, a process that is growing in notoriety because it generates microplastics (MPs). In this study, we investigated the emission [...] Read more.
The use of washing machines to wash textiles gradually breaks down synthetic fibers like polyethylene terephthalate (PET) or polyester (PES) in diverse clothing materials, a process that is growing in notoriety because it generates microplastics (MPs). In this study, we investigated the emission of microfibers, including both microplastic fibers (MPFs) and natural fibers (MFs), from top-loading washing machines. Our investigation focused on four popular textiles with prevalent weave structures (plain, satin, and twill): (i) PES, (ii) tetron cotton (TC), (iii) chief value cotton (CVC), and (iv) cotton (CO) fabrics. This study also examined the effects of textile weight and detergent dosage on MF emissions. After washing, MFs were collected through filtration, and their concentrations were determined using micro-Fourier Transform Interferometry (μFTIR). The results showed varying concentrations of MFs in the washing effluent depending on the type of textile. Specifically, CVC exhibited the highest emission at 4022 particles/L, followed by TC, PES, and CO at 2844 particles/L, 2382 particles/L, and 2279 particles/L, respectively. The hydrophobic nature of PES makes this type of textile prone to rapid degradation in detergent-rich environments, leading to high MF emissions. Additionally, the mechanical properties of textiles, such as tensile and bending strengths, may play a crucial role in the generation of MFs in washing machines. Textiles made of CO with twill weaves demonstrated superior strength and correlated with lower emissions of MFs. In comparison, textiles made of CVC and satin weave exhibited lower mechanical properties, which could explain their high emissions of MFs. Finally, the MF emissions of textiles composed of PES and TC, which are plain weaved, could be attributed to their intermediate mechanical properties compared with those of CVC and CO. Full article
(This article belongs to the Special Issue Quantification and Identification of Micro- and Nanoplastics in Environmental Matrices)
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Figure 1

Figure 1
<p>A schematic diagram of the experimental procedures used in this study.</p> Full article ">Figure 2
<p>Parameters in the washing experiments of four types of textiles.</p> Full article ">Figure 3
<p>A schematic diagram illustrates how MFs were quantified using a microscope.</p> Full article ">Figure 4
<p>Microfiber emissions as a function of textile weight and detergent dosage: (<b>a-1</b>) MF emissions on textile weight in different detergent dosage, (<b>a-2</b>) arithmetic mean of all parameters that are equal in textile weight, (<b>b-1</b>) MF emissions on detergent dosage in different textile weight, and (<b>b-2</b>) arithmetic mean of all parameters that are equal in detergent dosage.</p> Full article ">Figure 5
<p>Microfiber emissions as a function of textile type during laundry cleaning in washing machines.</p> Full article ">Figure 6
<p>SEM photomicrographs taken at 15 kV (50× magnification) of the four textile types: (<b>a</b>) 100% CO; (<b>b</b>) CVC; (<b>c</b>) TC; (<b>d</b>) 100% PES.</p> Full article ">Figure 7
<p>Schematic illustrations of the three common woven structures: (<b>a</b>) plain weave, (<b>b</b>) twill weave, and (<b>c</b>) satin weave.</p> Full article ">
18 pages, 4028 KiB  
Article
Quantification and Chemical Characterization of Plastic Additives and Small Microplastics (<100 μm) in Highway Road Dust
by Beatrice Rosso, Barbara Bravo, Elena Gregoris, Carlo Barbante, Andrea Gambaro and Fabiana Corami
Toxics 2023, 11(11), 936; https://doi.org/10.3390/toxics11110936 - 17 Nov 2023
Cited by 4 | Viewed by 2754
Abstract
Road dust is one of the environment’s most important microplastic and plastic additive sources. Traffic vehicles and the wear of tires can release these emerging contaminants, which can be resuspended in the air and washed off by stormwater runoff. In this study, a [...] Read more.
Road dust is one of the environment’s most important microplastic and plastic additive sources. Traffic vehicles and the wear of tires can release these emerging contaminants, which can be resuspended in the air and washed off by stormwater runoff. In this study, a concurrent quantification and chemical characterization of additives, plasticizers, natural and non-plastic synthetic fibers (APFs), and small microplastics (SMPs, <100 µm) in samples of highway road dust (HWRD) was performed. The sampling procedure was optimized, as well as pretreatment (extraction, purification, and filtration) and analysis via micro-FTIR. The average length of the SMPs was 88 µm, while the average width was 50 µm. The highest abundance of SMPs was detected in HWRD 7 (802 ± 39 SMPs/g). Among the polymers characterized and quantified, vinyl ester and polytetrafluoroethylene were predominant. APFs’ average particle length was 80 µm and their width was 45 µm, confirming that both of these emerging pollutants are less than 100 µm in size. Their maximum concentration was in RD7, with 1044 ± 45 APFs/g. Lubricants and plasticizers are the two most abundant categories, followed by vulcanizing agents, accelerators, and pre-vulcanizing retarders derived mainly from tires. A potential relationship between APFs and SMPs in the different seasons was observed, as their concentration was lower in summer for both and higher in winter 2022. These results will be significant in investigating the load of these pollutants from highways, which is urgently necessary for more accurate inclusion in emission inventories, receptor modeling, and health protection programs by policymakers, especially in air and water pollution policies, to prevent risks to human health. Full article
(This article belongs to the Special Issue Quantification and Identification of Micro- and Nanoplastics in Environmental Matrices)
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Figure 1

Figure 1
<p>HWRD samples were collected from a highway 32.3 km long, namely, Passante di Mestre, on the mainland near Venice in Italy (Casale sul Sile, Treviso, Italy), as highlighted in the map (<b>a</b>). In picture (<b>b</b>), the red dots highlighted the sampling site.</p> Full article ">Figure 2
<p>Count fields obtained via micro-FTIR before (<b>a</b>) and after (<b>b</b>) the optimization of the oleo-extraction resulted in a change from suboptimal identification (some interferents, e.g., different aggregates of oil, bitumen, and other organic interferents still coated the particles under examination) to optimal identification for SMPs and APFs.</p> Full article ">Figure 3
<p>Abundance and polymer distribution of SMPs in HWRD samples analyzed (SMPs/g). The number of dry days before each sampling campaign is reported for each sample collected.</p> Full article ">Figure 4
<p>SMP size distribution in HWRD samples analyzed.</p> Full article ">Figure 5
<p>Abundance and distribution of APFs in the samples of road dust analyzed (APFs/g). APFs are grouped according to their function.</p> Full article ">
18 pages, 4588 KiB  
Article
Application of Pattern Recognition and Computer Vision Tools to Improve the Morphological Analysis of Microplastic Items in Biological Samples
by Aleksander Maria Astel and Paulina Piskuła
Toxics 2023, 11(9), 779; https://doi.org/10.3390/toxics11090779 - 13 Sep 2023
Cited by 3 | Viewed by 1681
Abstract
Since, in many routine analytical laboratories, a stereomicroscope coupled with a digital camera is not equipped with advanced software enabling automatic detection of features of observed objects, in the present study, a procedure of feature detection using open-source software was proposed and validated. [...] Read more.
Since, in many routine analytical laboratories, a stereomicroscope coupled with a digital camera is not equipped with advanced software enabling automatic detection of features of observed objects, in the present study, a procedure of feature detection using open-source software was proposed and validated. Within the framework of applying microscopic expertise coupled with image analysis, a set of digital images of microplastic (MP) items identified in organs of fish was used to determine shape descriptors (such as length, width, item area, etc.). The edge points required to compute shape characteristics were set manually in digital images acquired by the camera coupled with a binocular, and respective values were computed via the use of built-in MotiConnect software. As an alternative, a new approach consisting of digital image thresholding, binarization, the use of connected-component labeling, and the computation of shape descriptors on a pixel level via using the functions available in an OpenCV library or self-written in C++ was proposed. Overall, 74.4% of the images were suitable for thresholding without any additional pretreatment. A significant correlation was obtained between the shape descriptors computed by the software and computed using the proposed approach. The range of correlation coefficients at a very high level of significance, according to the pair of correlated measures, was higher than 0.69. The length of fibers can be satisfactorily approximated using a value of half the length of the outer perimeter (r higher than 0.75). Compactness and circularity significantly differ for particles and fibers. Full article
(This article belongs to the Special Issue Quantification and Identification of Micro- and Nanoplastics in Environmental Matrices)
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Figure 1

Figure 1
<p>Images of MPs, which were acquired using the Motic Zoom SMZ-161-BLED stereomicroscope coupled with a digital camera ((<b>A</b>–<b>C</b>)—particles; (<b>D</b>–<b>F</b>)—fibers).</p> Full article ">Figure 2
<p>Schematic diagram of microplastic extraction, identification protocol, and digital image pretreatment steps.</p> Full article ">Figure 3
<p>Greyscale images and thresholded images ((<b>A</b>–<b>C</b>,<b>E</b>)—fibers; (<b>D</b>,<b>F</b>)–particles). Th—threshold value.</p> Full article ">Figure 4
<p>RGB images of MPs that were characterized by the similarity between their color and that of the background ((<b>A</b>,<b>C</b>)—fibers; (<b>B</b>,<b>D</b>)—particles).</p> Full article ">Figure 5
<p>Schematic diagram of applying a label to pixel B according to the eight-connected mask used in the Union–Find algorithm: (<b>A</b>) row-wise scanning; (<b>B</b>) initiation of the region labeling triggered by the pixel that fulfills the starting criteria; (<b>C</b>) cases when a new label is applied; (<b>D</b>) cases when already used label is applied to the pixel; (<b>E</b>) cases when two separate labels belong to the same region.</p> Full article ">Figure 6
<p>Linear regressions with confidence intervals expressing a directly proportional relationship between the length and width of particles (determined in MotiConnect 1.5.9.10-build-171215 software) and length (<b>A</b>), <span class="html-italic">Ra</span> (<b>B</b>), maximal ferret (<b>B</b>), width (<b>C</b>), <span class="html-italic">Rb</span> (<b>D</b>), and minimal ferret (<b>D</b>) (all determined algorithmically), respectively.</p> Full article ">Figure 7
<p>Linear regressions with confidence intervals expressing a directly proportional relationship between the area of particles calculated using the length and width of the MP items determined in MotiConnect 1.5.9.10-build-171215 software and the area calculated based on pixels (<b>A</b>), smallest rectangle (<b>B</b>), and the ellipse axes (<b>B</b>), respectively.</p> Full article ">Figure 8
<p>Linear regression with confidence interval expressing a directly proportional relationship between the length of fibers determined using MotiConnect 1.5.9.10-build-171215 software and the length of fibers computed using the length of the outer perimeter.</p> Full article ">Figure 9
<p>The circularity of MP items (the numbering shown on the <span class="html-italic">X</span>-axis corresponds to the numbering of images taken using the digital camera (125); after thresholding, images possessed their original numeration).</p> Full article ">Figure 10
<p>The compactness of MP items (the numbering shown on the <span class="html-italic">X</span>-axis corresponds to the numbering of images taken by the digital camera (125); after thresholding, images possessed their original numeration).</p> Full article ">
16 pages, 1180 KiB  
Article
Effect of Aging on Physicochemical Properties and Size Distribution of PET Microplastic: Influence on Adsorption of Diclofenac and Toxicity Assessment
by Josipa Papac Zjačić, Stefani Tonković, Anamarija Pulitika, Zvonimir Katančić, Marin Kovačić, Hrvoje Kušić, Zlata Hrnjak Murgić and Ana Lončarić Božić
Toxics 2023, 11(7), 615; https://doi.org/10.3390/toxics11070615 - 14 Jul 2023
Cited by 7 | Viewed by 2336
Abstract
Microplastics (MPs) are detected in the water, sediments, as well as biota, mainly as a consequence of the degradation of plastic products/waste under environmental conditions. Due to their potentially harmful effects on ecosystems and organisms, MPs are regarded as emerging pollutants. The highly [...] Read more.
Microplastics (MPs) are detected in the water, sediments, as well as biota, mainly as a consequence of the degradation of plastic products/waste under environmental conditions. Due to their potentially harmful effects on ecosystems and organisms, MPs are regarded as emerging pollutants. The highly problematic aspect of MPs is their interaction with organic and inorganic pollutants; MPs can act as vectors for their further transport in the environment. The objective of this study was to investigate the effects of ageing on the changes in physicochemical properties and size distribution of polyethylene terephthalate (PET), as well as to investigate the adsorption capacity of pristine and aged PET MPs, using pharmaceutical diclofenac (DCF) as a model organic pollutant. An ecotoxicity assessment of such samples was performed. Characterization of the PET samples (bottles and films) was carried out to detect the thermooxidative aging effects. The influence of the temperature and MP dosage on the extent of adsorption of DCF was elucidated by employing an empirical modeling approach using the response surface methodology (RSM). Aquatic toxicity was investigated by examining the green microalgae Pseudokirchneriella subcapitata. It was found that the thermooxidative ageing process resulted in mild surface changes in PET MPs, which were reflected in changes in hydrophobicity, the amount of amorphous phase, and the particle size distribution. The fractions of the particle size distribution in the range 100–500 μm for aged PET are higher due to the increase in amorphous phase. The proposed mechanisms of interactions between DCF and PET MPs are hydrophobic and π–π interactions as well as hydrogen bonding. RSM revealed that the adsorption favors low temperatures and low dosages of MP. The combination of MPs and DCF exhibited higher toxicity than the individual components. Full article
(This article belongs to the Special Issue Quantification and Identification of Micro- and Nanoplastics in Environmental Matrices)
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Figure 1

Figure 1
<p>SEM micrographs of (<b>A</b>) PET bottle and (<b>B</b>) PET foil samples; magnification was 5000×.</p> Full article ">Figure 2
<p>Fractions of particle size distribution of pristine and aging (<b>A</b>) PET bottle and (<b>B</b>) PET foil samples after grinding and sieving.</p> Full article ">Figure 3
<p>Inhibition of samples PET_B (<b>left</b>) and PET_F (<b>right</b>) was determined after 72 h of exposure to <span class="html-italic">Pseudokirchneriella s.</span>; inhibition refers to the undiluted samples.</p> Full article ">Figure 4
<p>Effective concentrations of pristine and aged PET_B (<b>left</b>) and PET_F (<b>right</b>) were determined after 72 h of exposure to <span class="html-italic">Pseudokirchneriella s</span>.</p> Full article ">
15 pages, 2660 KiB  
Article
Influence of Gut Microbiota on Metabolism of Bisphenol A, a Major Component of Polycarbonate Plastics
by Weili Mao, Lingling Mao, Feifei Zhou, Jiafeng Shen, Nan Zhao, Hangbiao Jin, Jun Hu and Zefu Hu
Toxics 2023, 11(4), 340; https://doi.org/10.3390/toxics11040340 - 31 Mar 2023
Cited by 10 | Viewed by 2216
Abstract
Bisphenol A (BPA) is a major component of polycarbonate plastics and epoxy resins. While many studies have investigated the effect BPA exposure has upon changes in gut microbial communities, the influence of gut microbiota on an organism’s ability to metabolize BPA remains comparatively [...] Read more.
Bisphenol A (BPA) is a major component of polycarbonate plastics and epoxy resins. While many studies have investigated the effect BPA exposure has upon changes in gut microbial communities, the influence of gut microbiota on an organism’s ability to metabolize BPA remains comparatively unexplored. To remedy this, in this study, Sprague Dawley rats were intermittently (i.e., at a 7-day interval) or continuously dosed with 500 μg BPA/kg bw/day for 28 days, via oral gavage. In the rats which underwent the 7-day interval BPA exposure, neither their metabolism of BPA nor their gut microbiota structure changed greatly with dosing time. In contrast, following continuous BPA exposure, the relative level of Firmicutes and Proteobacteria in the rats’ guts significantly increased, and the alpha diversity of the rats’ gut bacteria was greatly reduced. Meanwhile, the mean proportion of BPA sulfate to total BPA in rat blood was gradually decreased from 30 (on day 1) to 7.4% (by day 28). After 28 days of continuous exposure, the mean proportion of BPA glucuronide to total BPA in the rats’ urine elevated from 70 to 81%, and in the rats’ feces the mean proportion of BPA gradually decreased from 83 to 65%. Under continuous BPA exposure, the abundances of 27, 25, and 24 gut microbial genera were significantly correlated with the proportion of BPA or its metabolites in the rats’ blood, urine, and feces, respectively. Overall, this study principally aimed to demonstrate that continuous BPA exposure disrupted the rats’ gut microbiota communities, which in turn altered the rats’ metabolism of BPA. These findings contribute to the better understanding of the metabolism of BPA in humans. Full article
(This article belongs to the Special Issue Quantification and Identification of Micro- and Nanoplastics in Environmental Matrices)
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Figure 1

Figure 1
<p>Representative chromatograms of BPA and its conjugated metabolites in (<b>a</b>) the 50% methanol/water solution and (<b>b</b>) rat blood.</p> Full article ">Figure 2
<p>Change in the relative abundances of gut microbiota at (<b>a</b>) phylum and (<b>b</b>) genus levels in SD rats over time, following intermittent oral administration of BPA. Change in the relative abundances of gut microbiota at (<b>c</b>) phylum and (<b>d</b>) genus levels in SD rats over time, following continuous oral administration of BPA.</p> Full article ">Figure 3
<p>Mean concentrations of BPA and its conjugated metabolites in SD rat feces, urine, and blood, following (<b>a</b>) intervallic and (<b>b</b>) continuous oral BPA administration. The vertical bars represent standard deviation.</p> Full article ">Figure 4
<p>Change in the molar concentration profile of BPA and its conjugated metabolites in feces, urine, and blood of SD rats over time, following (<b>a</b>) intervallic and (<b>b</b>) continuous oral BPA exposure.</p> Full article ">Figure 5
<p>Correlations between the abundances of rat gut bacteria at the genus level and proportion of BPA and its metabolites in feces, urine, and blood of rats following (<b>a</b>) intervallic and (<b>b</b>) continuous BPA exposure. The red and green squares indicate a significantly positive and negative correlation, respectively.</p> Full article ">Figure 5 Cont.
<p>Correlations between the abundances of rat gut bacteria at the genus level and proportion of BPA and its metabolites in feces, urine, and blood of rats following (<b>a</b>) intervallic and (<b>b</b>) continuous BPA exposure. The red and green squares indicate a significantly positive and negative correlation, respectively.</p> Full article ">
12 pages, 1451 KiB  
Communication
Chronic Exposure to Polystyrene Microplastic Fragments Has No Effect on Honey Bee Survival, but Reduces Feeding Rate and Body Weight
by Yahya Al Naggar, Christie M. Sayes, Clancy Collom, Taiwo Ayorinde, Suzhen Qi, Hesham R. El-Seedi, Robert J. Paxton and Kai Wang
Toxics 2023, 11(2), 100; https://doi.org/10.3390/toxics11020100 - 21 Jan 2023
Cited by 19 | Viewed by 5291
Abstract
Microplastics (MPs), in the form of fragments and fibers, were recently found in honey samples collected in Ecuador as well as in honey bees collected from Denmark and China. However, little is known about how MPs impact bee health. To fill this knowledge [...] Read more.
Microplastics (MPs), in the form of fragments and fibers, were recently found in honey samples collected in Ecuador as well as in honey bees collected from Denmark and China. However, little is known about how MPs impact bee health. To fill this knowledge gap, we investigated the potential toxicity of irregularly shaped polystyrene (PS)-MP fragments on honey bee health. In the first experiment of its kind with honey bees, we chronically exposed bees with a well-established gut microbiome to small (27 ± 17 µm) or large (93 ± 25 µm) PS-MP fragments at varying concentrations (1, 10, 100 µg mL−1) for 14 days. Bee mortality, food consumption, and body weight were all studied. We found that chronic exposure to PS-MP fragments has no effect on honey bee survival, but reduced the feeding rate and body weight, particularly at 10 µg PS-MP fragments per mL, which may have long-term consequences for honey bee health. The findings of this study could assist in the risk assessment of MPs on pollinator health. Full article
(This article belongs to the Special Issue Quantification and Identification of Micro- and Nanoplastics in Environmental Matrices)
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Figure 1

Figure 1
<p>Physicochemical characterization of the microplastic particles used in this study. (<b>A</b>) Photograph of the white plastic cutlery prior to grinding. (<b>B</b>) Photograph of the plastic after grinding. (<b>C</b>) Photograph of size-separated microplastic particles. The mean (±SD) size of the first particle size population is 93 ± 23 μm. The mean (±SD) size of the second particle size population is 27 ± 17 μm. (<b>D</b>,<b>E</b>) Scanning electron micrographs of the microplastic particle size population with scale bars of 300 μm and 30 µm, respectively. (<b>F</b>) Raman spectroscopy of particles indicating polystyrene polymeric structure. (<b>G</b>) Elemental composition, as measured by energy-dispersive X-ray (EDX) spectroscopy, indicates the presence of carbon and calcium. Both particle size populations exhibited the same Raman and EDX spectral patterns.</p> Full article ">Figure 2
<p>Experimental design. Upper row: treatments (four cages per treatment); lower row: timing of microbiome establishment (D-5), PS-MPs treatment (D0).</p> Full article ">Figure 3
<p>Kaplan–Meier survival curves of honey bees fed sugar syrup containing PS-MP fragments at various concentrations for 14 days. Bees (<span class="html-italic">n</span> = 35 bees per cage, <span class="html-italic">n</span> = four cages per treatment) were fed ad libitum with various concentrations (1, 10, 100 µg mL<sup>−1</sup>) of either (<b>a</b>) small sized (27 ± 17 μm) or (<b>b</b>) large sized (93 ± 25 μm) PS-MP fragments. Controls received the same treatments devoid of PS-MP fragments. There were no significant differences between treatments (log-rank (Mantel–Cox), <span class="html-italic">p</span> &gt; 0.05).</p> Full article ">Figure 4
<p>Average sugar syrup consumption (mean ± SEM) of honey bees that were chronically exposed to PS-MP fragments at various concentrations for 14 days. Bees (<span class="html-italic">n</span> = 35 bees per cage, <span class="html-italic">n</span> = four cages per treatment) were fed ad libitum with various concentrations (1, 10, 100 µg mL<sup>−1</sup>) of either (<b>a</b>) small sized (27 ± 17 μm) or (<b>b</b>) large sized (93 ± 25 μm) PS-MP fragments. Controls received the same treatments devoid of PS-MP fragments. Different lowercase letters indicate statistically significant differences between treatments (one-way ANOVA with Tukey’s post hoc test, <span class="html-italic">p</span> &lt; 0.05).</p> Full article ">Figure 5
<p>Average dry body weight (±SEM, <span class="html-italic">n</span> = 24) of honey bees that were chronically exposed for 14 days to various concentrations (1, 10, 100 µg mL<sup>−1</sup>) of either (<b>a</b>) small sized (27 ± 17 μm) or (<b>b</b>) large sized (93 ± 25 μm) PS-MP fragments. Controls received the same treatments devoid of PS-MP fragments. Different lowercase letters indicate statistically significant differences between treatments (one-way ANOVA with Tukey’s post hoc test, <span class="html-italic">p</span> &lt; 0.05).</p> Full article ">
11 pages, 1955 KiB  
Article
Microplastics in Widely Used Polypropylene-Made Food Containers
by Jun Hu, Xin Xu, Ying Song, Wenqi Liu, Jianqiang Zhu, Hangbiao Jin and Zhu Meng
Toxics 2022, 10(12), 762; https://doi.org/10.3390/toxics10120762 - 7 Dec 2022
Cited by 12 | Viewed by 4221
Abstract
As a potential threat to human health, ingestion of microplastics (MPs) has become of concern. Limited studies have carefully characterized the occurrence of MPs in polypropylene-made takeout food containers (TOFCs), which have been widely used in China. In this study, TOFC samples ( [...] Read more.
As a potential threat to human health, ingestion of microplastics (MPs) has become of concern. Limited studies have carefully characterized the occurrence of MPs in polypropylene-made takeout food containers (TOFCs), which have been widely used in China. In this study, TOFC samples (n = 210) were collected from seven Chinese cities (Hangzhou, Guangzhou, Shanghai, Xining, Chengdu, Qingdao, and Dalian) and analyzed for MPs. All the TOFC samples contained MPs, with an abundance of 3–43 items/TOFC. The TOFCs from Chengdu (25 items/TOFC) contained the highest mean abundance of MPs, which is significantly (p < 0.01) higher than that from Shanghai (8.7 items/TOFC). Fiber accounted for 66–87% of the total for the shape of the MPs in the TOFCs from the different Chinese cities. Most of the MPs in the TOFCs from the different cities had a size of 201–500 μm and accounted for a mean 34–42% of the total MPs in the TOFCs. The major color type of the MPs in the TOFCs was transparent, accounting for a mean 39 (Qingdao)–73% (Hangzhou) of the total MPs. Polymer compositions of the MPs in the TOFCs were consistently dominated by polypropylene, which represented a mean 56–73% of the total MPs. The estimated daily intake of MPs for the general Chinese population through using TOFCs was in the range of 0.042–0.14 items/kg bw/day. To our knowledge, this is the most comprehensive study investigating the occurrence of MPs in TOFCs from China, which contributes to a better understanding of the sources of human oral exposure to MPs. Full article
(This article belongs to the Special Issue Quantification and Identification of Micro- and Nanoplastics in Environmental Matrices)
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<p>SEM images of fiber MPs on the inner surface of TOFCs.</p> Full article ">Figure 2
<p>Percentage (%) of different (<b>A</b>) shapes and (<b>B</b>) sizes of MPs in takeout food containers collected from different Chinese cities.</p> Full article ">Figure 3
<p>Percentage (%) of different colors of MPs in takeout food containers collected from different Chinese cities.</p> Full article ">Figure 4
<p>Polymer composition of MPs in takeout food containers collected from different cities in China. “Others” means other polymer compositions of MPs, mainly including polyethylene chlorinated, polyamide, polycarbonate, and polyethylene terephthalate. PP and PE indicate polypropylene and polyethylene, respectively.</p> Full article ">
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