A review on the occurrence, analytical methods, and impact of microplastics in the environment

Mass concentration of plastic particles from two-dimensional images

Imaging techniques play a crucial role in characterizing environmental plastics. However, most reported findings rely on two-dimensional projections of particles resting on flat surfaces. This limitation makes it challenging to accurately determine mass concentration, which is essential for deriving toxicologically relevant exposure data. The primary issue arises from the loss of information regarding particle height or thickness. This study aims to evaluate the assumptions necessary to compensate this loss of information. To achieve this, we used a set of environmental plastic particles, mesoplastics and microplastics, from marine campaigns, and precisely measured their three spatial dimensions and mass. Our study demonstrated the feasibility of estimating the mass of plastic particles through two-dimensional images. However, for enhanced accuracy, additional information derived from the dataset of particles under examination is necessary. Specifically, estimating the mass of platelike particles requires information about their height. Similarly, calculating the volume for elongated shapes as cylinders, should be limited to particles with the same width and height and for which their length can be precisely determined, even if the image depicts twisted forms. In conclusion, while obtaining mass concentration from single two-dimensional images enables reasonable estimations, achieving the precision needed for exposure data requires acquiring additional information from the sample and carefully considering the shape of each individual particle.

What are the global patterns of microplastic ingestion by fish? A scientometric review

The billions of tons of plastic released into the environment mostly fragment into smaller particles that reach rivers and oceans, posing toxicity risks to aquatic organisms. As fish serve as excellent environmental indicator organisms, this study aims to comprehensively review and quantify published data regarding the abundance of microplastics (MPs) ingested by fish through scientometric analysis. Systematic analysis reveals that global aquatic ecosystems are contaminated by MPs, with the characteristics of these contaminants stemming from inadequate disposal management practices. The abundance of MPs was recorded in several fish species, notably Cyprinus carpio in natural environments and Danio rerio in controlled environments. According to the surveyed studies, laboratory experiments do not accurately represent the conditions found in natural environments. The results suggest that, in natural environments, the predominant colors of MPs are blue, black, and red. Fibers emerged as the most prevalent type, with polyethylene (PE) and polypropylene (PP) being the most frequently identified chemical compositions. On the other hand, laboratory studies showed that the spheres and fragments ingested were predominantly polystyrene (PS) green, followed by the colors blue and red. This discrepancy complicates drawing accurate conclusions regarding the actual effects of plastic particles on aquatic biota. Given the enduring presence of plastic in the environment, it is imperative to consider and implement environmental monitoring for effective, long-term management.

Microplastics in water: Occurrence, fate and removal

A global study on tap water samples has found that up to 83% of these contained microplastic fibres. These findings raise concerns about their potential health risks. Ingested microplastic particles have already been associated with harmful effects in animals, which raise concerns about similar outcomes in humans. Microplastics are ubiquitous in the environment, commonly found disposed in landfills and waste sites. Within indoor environments, the common sources are synthetic textiles, plastic bottles, and packaging. From the various point sources, they are globally distributed through air and water and can enter humans through various pathways. The finding of microplastics in fresh snow in the Antarctic highlights just how widely they are dispersed. The behaviour and health risks from microplastic particles are strongly influenced by their physicochemical properties, which is why their surfaces are important. Surface interactions are also important in pollutant transport via adsorption onto the microplastic particles. Our review covers the latest findings in microplastics research including the latest statistics in their abundance, their occurrence and fate in the environment, the methods of reducing microplastics exposure and their removal. We conclude by proposing future research directions into more effective remediation methods including new technologies and sustainable green remediation methods that need to be explored to achieve success in microplastics removal from waters at large scale.

Evaluation of particle generation due to deterioration of flooring in schools

Particulate matter is harmful to humans. An important indoor source of such particles is the deterioration of floor materials brought about by occupants walking. Accordingly, an experiment was conducted to simulate the deterioration of floor material spacing. Considering a school schedule with repeated semesters and vacations, the experiment was conducted by repeating heat-and-rest cycles. Similar results were obtained for particle emission rates under each condition during the first and second deterioration periods. The PVC tiles generated more particles under aged conditions than under non-aged conditions, whereas the wood generated fewer particles under aged conditions. In addition to the quantitative results, a study was conducted on the characteristics of the generated particles, and the particulate matter found in plastic was confirmed in the PVC tiles. Schools where children are present for more than 6 h a day may be exposed to more particulate matter. Therefore, replacing plastic-based materials with eco-friendly building materials is expected to have long-term health benefits for children.

Effects of polyethylene terephthalate microplastics on cell growth, intracellular products and oxidative stress of Scenedesmus sp

Polyethylene terephthalate (PET) has been widely utilized in the synthesis of textile materials and packaging of foods and beverages. In recent years, it has been commonly detected in the form of microplastics (MPs) in wastewater. However, the effects of PET MPs on microalgal intracellular products and their interrelationships have been poorly investigated. In this study, the microalgae Scenedesmus sp. Strain H-1 was exposed to PET MPs to explore their effects on the growth, intracellular products (such as lipids, carbohydrates, and proteins), and antioxidative defense systems of Scenedesmus sp. The results demonstrated that PET MPs significantly reduced Scenedesmus sp. cell growth, with a maximum inhibition rate of 38.25% in the 500 mg L-1 treatment group. PET MPs had negative effects on glucose and nitrate utilization rates and reduced intracellular carbohydrates, intracellular proteins, and photosynthetic pigments. Surprisingly, PET MPs reduced acetyl-CoA carboxylase activity but induced lipid accumulation in microalgae. In addition, PET MPs significantly decreased the essential linoleic acid concentration and increased the palmitic acid content, resulting in reduced biodiesel quality. PET MPs induced the production of reactive oxygen species and malondialdehyde as well as the activities of superoxide dismutase and catalase. The results of the PCA indicated that the response mechanism of Scenedesmus sp. to PET MPs exposure was synergistic. This study provides fundamental data on the impact of MPs on the intracellular products of microalgae.