Microplastics (MPs) in marine food chains: Is it a food safety issue?

Surface physicochemical properties and dibutyl phthalate adsorption of microplastics naturally aged in seawater

Microplastics (MPs) are prevalent in marine environments and can adsorb contaminants from surrounding seawater, potentially transferring harmful chemicals through the food chain and raising ecological concerns. While the adsorption of aquatic pollutants by MPs has been intensively studied, research on phthalate esters (PAEs, common plasticizers frequently found in seawater) remains limited, primarily focusing on pristine MPs in artificial media. This study characterized the surface physicochemical properties of polyethylene (PE) and polystyrene (PS) MPs before and after natural aging for one week to three months off the coast, and investigated the adsorption isotherms of dibutyl phthalate (DBP, one of the most abundant PAEs in seawater) on these MPs in both natural seawater and ultrapure water. Surface characterization revealed significant alterations in MP surface characteristics due to natural aging, with morphologies and nanomechanical features varied by MP type and oxidation occurring after one-month aging. The best-performing Langmuir-Freundlich model suggested that DBP adsorption onto MPs involved multilayer processes on heterogeneous surfaces with varying adsorption energies. Further analysis indicated that PS had a higher DBP adsorption capacity than PE, attributed to its porous glassy structure and π-π interactions with DBP. The trivial impact of natural aging could relate to competing effects of increased roughness and the formation of polar oxygen-containing groups on aged MPs. The "salting-out" effect in natural seawater was likely impeded by free ion competition and MP aggregation under higher ionic strength. This study provides valuable insights into the interactions between MPs and their coexisting contaminants in marine environments.

A comprehensive review of urban microplastic pollution sources, environment and human health impacts, and regulatory efforts

Microplastic (MP) pollution in urban environments is a pervasive and complex problem with significant environmental and human health implications. Although studies have been conducted on MP pollution in urban environments, there are still research gaps in understanding the exact sources, regulation, and impact of urban MP on the environment and public health. Therefore, the goal of this study is to provide a comprehensive overview of the complex pathways, harmful effects, and regulatory efforts of urban MP pollution. It discusses the research challenges and suggests future directions for addressing MPs related to environmental issues in urban settings. In this study, original research papers published from 2010 to 2024 across ten database categories, including PubMed, Google Scholar, Scopus, and Web of Science, were selected and reviewed to improve our understanding of urban MP pollution. The analysis revealed multifaceted sources of MPs, including surface runoff, wastewater discharge, atmospheric deposition, and biological interactions, which contribute to the contamination of aquatic and terrestrial ecosystems. MPs pose a threat to marine and terrestrial life, freshwater organisms, soil health, plant communities, and human health through ingestion, inhalation, and dermal exposure. Current regulatory measures for MP pollution include improved waste management, upgraded wastewater treatment, stormwater management, product innovation, public awareness campaigns, and community engagement. Despite these regulatory measures, several challenges such as; the absence of standardized MPs testing methods, MPs enter into the environment through a multitude of sources and pathways, countries struggle in balancing trade interests with environmental concerns have hindered effective policy implementation and enforcement. Addressing MP pollution in urban environments is essential for preserving ecosystems, safeguarding public health, and advancing sustainable development. Interdisciplinary collaboration, innovative research, stringent regulations, and public participation are vital for mitigating this critical issue and ensuring a cleaner and healthier future for urban environments and the planet.