Microplastics (plastics less than 5 mm) are the breakdown of larger plastic items. They are now widespread in freshwater environments, including rivers, lakes, streams and livestock, and domestic supply dams and reservoirs. These particles primarily come from sources like household waste, industrial activities, personal care products, atmospheric fallout, recreational activities, and fishing activities. The scientific concern around microplastics in freshwater ecosystems is multifaceted. Aquatic organisms, such as fish and invertebrates (prawns, mussels), can mistakenly ingest these particles, which may lead to physical harm like digestive blockages, reduced feeding efficiency, starvation, and reproductive issues. Furthermore, microplastics can adsorb harmful chemicals (e.g., DDT, heavy metals, and oil compounds) from the surrounding water environment, which may then enter the food chain when consumed by fish and other aquatic organisms. In addition, microplastics contaminated freshwater or irrigation water used can contaminate crops, fruit, and vegetables via the root systems. The presence of microplastics also disrupts the natural balance of aquatic ecosystems. While the long-term ecological consequences are still being studied, research suggests that microplastics may alter habitat conditions, affect nutrient cycling, and impact biodiversity. Additionally, they may serve as carriers for harmful pathogens, further compromising ecosystem health.

Understanding the pathways, impacts, and long-term consequences of microplastics in freshwater environments is crucial for developing effective mitigation strategies and policies to address this growing environmental challenge. The proposed Collection will publish articles on different aspects of microplastic contamination and their risk assessment in freshwater ecosystems, highlight the urgent need for better waste management strategies, and encourage more research about the toxicological impacts of microplastics on freshwater ecosystems.

The major aspects of this collection will cover:

• Toxicological effects of microplastics on freshwater fish

• Toxicological effects of microplastics on crops or vegetables via contaminated freshwater

• Toxicological effects of microplastics in freshwater drinking sources

• Contamination of water and food with freshwater microplastics and risks to humans

• Harmful chemicals adsorbed by microplastics from the surrounding water environment and their possible toxic effects on freshwater ecosystems

Keywords: Microplastics; Aquatic pollution; River pollution; Lake contamination; Microplastic degradation; Microplastic ingestion; Microplastic toxicity; Environmental monitoring

According to the latest data from The United Nations Office on Drugs and Crime (UNODC), drug use remains high worldwide. In 2021, 1 in every 17 people aged 15-64 globally had used a drug in the past 12 months (United Nations Office on Drugs and Crime, 2023). This consumption is a public health issue that affects the entire world. Increasingly, it is common to find substances of higher purity on the market or alternative substances to those classic drugs of abuse. The illicit drug market has seen significant changes due to the surge in the production of designer drugs that have been produced covertly since the late 1990s and early 2000s. Drug abuse was once limited to a specific set of compounds, but in recent years, many new designer drugs are constantly being made available for abuse. While mass spectra libraries are being updated, they soon become obsolete in what concerns new compounds, down to the delay in their addition to those libraries. The development of laboratory methods to evaluate the purity of these substances or their identification and quantification in case of intoxication is a continuous challenge for laboratories. Therefore, bioanalysis must be constantly updated to keep up with the growing illicit market of substances, so new analytical methods and sample preparation techniques are constantly subjected to developments and improvements. In this Topical Collection, we aim to explore the latest advancements in the field of drug abuse detection. We welcome reviews, original research articles, and case reports related to this topic. This collection serves as a valuable resource for academia and researchers, especially those working in toxicology.

Reference: United Nations Office on Drugs and Crime. (2023). World Drug Report 2023. United Nations publication. https://www.unodc.org/res/WDR-2023/WDR23_Exsum_fin_SP.pdf

Keywords: Drug of abuse; biomarkers; bioanalysis; toxicology