Microplastics, Volume 3, Issue 2 (June 2024) – 10 articles

The study of microplastics (MPs) in soils is impeded by similarities between plastic and non-plastic particles and the misidentification of MP by current analytical methods such as visual microscopic examination. Soil MPs pose serious ecological and public health risks because of their abundance, persistence, and ubiquity. Thus, reliable identification methods are badly needed for scientific study. One possible solution is UV–Vis–NIR spectroscopy, which has the ability to rapidly identify and quantify concentrations of soil microplastics. In this study, a full-range, field portable spectrometer (350–2500 nm) with ultra-high spectral resolution (1.5 nm, 3.0 nm, and 3.8 nm) identified three types of common plastics: low-density polyethylene (LDPE), polyvinyl chloride (PVC), and polypropylene (PP). Three sets of artificially MP-treated vermiculite soil samples were prepared for model prediction testing and validation: 150 samples for model calibration and 50 samples for model validation. A partial least square regression model using the spectral signatures for quantification of soil and MP mixtures was built with all three plastic polymers. Prediction R² values of all three polymers showed promising results: polypropylene R² = 0.943, polyvinyl chloride R² = 0.983, and polyethylene R² = 0.957. Our study supports previous work showing that combining ultra-high-resolution UV–Vis–NIR spectrometry with quantitative modeling can improve the accuracy and speed of MP identification and quantification in soil. Full article

The availability of compostable plastic bags has increased greatly in the past few years, as it is perceived that this type of bags will be degraded after disposal. However, there are some knowledge gaps regarding the potential effects on the soil ecosystems. We assessed the rate of degradation of samples of four different types of commercial compostable bags in vermicomposting systems with the earthworm species Eisenia andrei. We also evaluated the biological response of E. andrei (survival and reproduction) to microplastics (MPs) from fragments of the plastic bags (<2000 µm) and assessed seedling emergence in common garden cress (Lepidium sativum L.) exposed to micronized plastic (<250 µm) and the respective leachate, following OECD and ISO guidelines, respectively. The rate of degradation differed significantly depending on the type of plastic rather than the substrate in the vermicomposting system. This finding suggests that the degradation process is more dependent on the microbial community colonizing the different plastic types than on earthworm activity. Regarding the biological response of the soil system, L. sativum seedling emergence was not significantly affected; however, earthworm reproduction was affected, suggesting that although compostable, some of the formulations may potentially be toxic to soil fauna. Full article

The environmental impact of tire wear emissions has become increasingly apparent, and efforts to reduce their impact on the environment are on the rise. To minimise the generation of tire wear, it is essential to consider the influencing factors. However, as it cannot be entirely prevented, measures to reduce immissions are also necessary. This paper summarises possible measures derived from the literature, stakeholder workshops, and the authors’ own conclusions, taking into account the different perspectives: tire, vehicle, road, sustainable mobility and emissions treatment. The presentation of the entry paths of tire wear into the environment and the hotspots of generation can be used to prioritise reduction measures. Measures should be implemented at a political level, technical solutions applied, and awareness raised among the general public. It is evident that reducing tire wear is a complex task that requires a transdisciplinary approach. Full article

In the last few years, microplastics research has exploded, with the field exploring new procedures and techniques that focus on a variety of scientific and policy issues. As there are not standardized definitions for many terms in the field, including the term microplastic itself, researchers utilize the same labels to describe different aspects of microplastic pollution. Here we provide a visual tool, called a Hub for Interactive Literature (HIL), to assist researchers in identifying and targeting specific literature. Currently, there are four Hubs for Interactive Learning (HILs) corresponding to previously published reviews, including a scoping review of microplastics literature as well as three reviews examining the human exposure and health effects of microplastics, the unique liver carcinogenicity of polyvinyl chloride (PVC) microplastics, and micro and nanoplastics found in the air. The HILs incorporate all of the literature used to produce the corresponding reviews. A couple of advantages that HILs provide in their capacity as a supportive instrument are the filtering options and easily accessed original references. This tool can be leveraged by researchers to rapidly review microplastics research and isolate specific subtopics of interest to develop new conclusions and quickly identify data gaps. We give an in-depth look at the HIL corresponding to a scoping review of microplastics literature to exhibit the novel functionality and advantages of this exciting tool. We demonstrate a novel world map of the literature to show that microplastics are a global scientific and public health issue. The map offers the additional functionality of filtering the references by country. We also provide a brief description of the current HILs to show the flexibility and personalization available when using this method. Full article

Microplastic (MP) has emerged as a significant environmental challenge due to increased plastic production and its widespread presence in the environment. This study aimed to assess MP concentrations throughout the treatment process at nine wastewater treatment plants (WWTPs) in Germany, from influent to effluent. A customized sampling technique was employed, followed by field and laboratory preparation and the quantification of polymers (PE, PP, PS, PMMA, and PET) using TED-GCMS. MP concentrations decreased progressively in the WWTPs, with influent concentrations ranging from 2.5 to 13.6 mg/L. Effluent concentrations in the conventional WWTPs ranged from 0.001 to 0.051 mg/L, while advanced treatment via filtration yielded concentrations below the limit of quantification at 0.005 mg/L. All tested of the WWTPs demonstrated an over 99% removal efficiency for microplastics. Despite effective retention by the WWTPs, a critical evaluation of the results is necessary. There is a need to optimize existing technologies and enhance the standardization of sampling, processing, and measurement methods, as well as intensify efforts towards creating preventive measures to reduce plastic emissions. Full article

We introduce a novel microscopic image dataset augmented with segmentation and detection labels specifically designed for microplastic analysis in sewage environments. Recognizing the increasing concern over microplastics—particles of synthetic polymers smaller than 5 mm—and their detrimental effects on marine ecosystems and human health, our research focuses on enhancing detection and analytical methodologies through advanced computer vision and deep learning techniques. The dataset comprises high-resolution microscopic images of microplastics collected from sewage, meticulously labeled for both segmentation and detection tasks, aiming to facilitate accurate and efficient identification and quantification of microplastic pollution. In addition to dataset development, we present example deep learning models optimized for segmentation and detection of microplastics within complex sewage samples. The models demonstrate significant potential in automating the analysis of microplastic contamination, offering a scalable solution to environmental monitoring challenges. Furthermore, we ensure the accessibility and reproducibility 12 of our research by making the dataset and model codes publicly available, accompanied by detailed 13 documentation on GitHub and LabelBox. Full article

Microplastics are tangible particles of less than 0.2 inches in diameter that are ubiquitously distributed in the biosphere and accumulate in water bodies. During the east-coast hot summers (23–29 °C) of 2021 and 2022, June through September, we captured copious amounts of the jellyfish Chrysaora chesapeakei, a predominant species found in the Patuxent River of the Chesapeake Bay in Maryland on the United States East Coast. We determined that their gelatinous bodies trapped many microplastics through fluorescent microscopy studies using Rhodamine B staining and Raman Spectroscopy. The chemical nature of the microplastics was detected using gas chromatography–mass spectroscopy headspace (SPME-GC-MS) and solvent extraction (GC-MS) methods through a professional commercial materials evaluation laboratory. Numerous plastic-affiliated volatile organic compounds (VOCs) from diverse chemical origins and their functional groups (alkanes, alkenes, acids, aldehydes, ketones, ethers, esters, and alcohols) along with other non-microplastic volatile organic compounds were observed. Our findings corroborate data in the available scientific literature, distinguishing our finding’s suitability. Full article

Primary consumers of microplastics are often zooplankton species such as the mysid shrimp, Americamysis bahia. Ingesting and interacting with these plastics can cause stress and lead to death. In the presence of some environmental stressors, gene expression may be altered without changing DNA sequences via the epigenetic methylation of the DNA. Mysid shrimp were exposed to 5-micrometer fluorescent polystyrene microbeads at different concentrations and different lengths of time. No significant effects were observed on mortality within 72 h, but mortality increased significantly thereafter. Microplastics were consumed by mysids and adhered to the mysid carapace and appendages. An ELISA-like (Enzyme-Linked Imuunosorbent Assay) colorimetric assay was employed to assess mysid DNA for differences in global percent methylation. No significant difference in the average percent methylated DNA nor difference in the number of methylation detections between treatments was found. This is one of few studies that has investigated DNA methylation effects due to microplastics-induced stress and the first study to detect DNA methylation in any member of the order Mysida. Full article

The tremendous plastic production and poor post-use management are current and future sources of environmental and human contamination due to their degradation products: microplastics and nanoplastics (MNPLs). Methodological developments have allowed MNPLs to be detected in an increasing variety of human foods, as well as in stool and colonic mucosa. It was suggested early that the direct contact between MNPLs and intestinal tissues could represent a potential risk for human health. In order to assess this, over the last 3 years, numerous studies have evaluated the impact of MNPL ingestion on intestinal homeostasis in rodents. This comprehensive review reports the preclinical studies published between January 2021 and January 2024, and analyzes their contributions as well as their shortcomings. It shows that evidence is accumulating of the intestinal toxicity of spherical MNPLs, which lead to pro-inflammatory, pro-oxidative, barrier-disruptive and dysbiotic effects. However, the available literature has addressed only a minor part of the potential health issues of MNPLs. Many parameters contributing to MNPL toxicity need to be better taken into account in future studies. Particular attention should be paid to improve the representativeness of MNPLs, as well as to better consider the susceptibility factors of MNPL toxicity, generated especially by an underlying pathology or pathological imprinting. Full article

The usage of plastic and its decomposition products leads to their ubiquitous distribution, resulting in their uptake by all living beings, including humans. Polymethylmethacrylate (PMMA) is known as a biocompatible polymer and is used widely in medicine and dentistry, although recent findings have shown its induction of oxidative stress within cells. Worryingly, hardly any data exist investigating the uptake of PMMA particles by cells, the potential effects of these particles on cells and cell signaling pathways and their contributing factors. We assessed the uptake of PMMA beads via confocal microscopy after their incubation with HEK293, A549 and MRC5 cells. Through cell staining, we localized multiple PMMA beads within the cytosol of cells. No alterations regarding cell growth, cell morphology or cell division were found, implying no short-term toxicity towards human cells. Using a cAMP response element binding protein (CREB)-mediated reporter assay, we assessed whether internalized PMMA nanobeads alter cell signaling pathways after stimulation of the cells. CREB was chosen as a well-described transcription factor involved in various cellular processes. Our data led to the assumption that PMMA nano- and microbeads are internalized via endocytosis and end up in lysosomes within the cell cytosol. We concluded that differences regarding the surface composition of the PMMA nanobeads affect their potential to alter cell signaling. These findings emphasize the key role the surface composition plays regarding microplastics and their risks for human health, whereas the usage of medical-grade PMMA remains safe. Full article