In recent years, the omnipresence of microplastics has emerged as one of the most pressing environmental and public health concerns. These microscopic fragments, often less than five millimeters in size, have infiltrated diverse ecosystems, including the very water we depend on for survival. Drinking water, the foundation of human health, is now under scrutiny as researchers strive to quantify and understand the extent of microplastic contamination. A groundbreaking study by D’Ascanio and colleagues published in 2025 directly addresses a critical aspect of this issue: the reliability and efficacy of sampling methods used for detecting microplastics in drinking water. This research, appearing in Microplastics & Nanoplastics, offers a meticulous comparison between ASTM standardized techniques and innovative in-line sampling approaches, providing fresh insights that could reshape monitoring practices and regulatory frameworks worldwide.
The study emerges against a backdrop of rising alarm over the invisible pollutants embedded in everyday consumables. Microplastics have been detected in oceans, soils, and increasingly in potable water sources globally. While evidence of their presence is now well-established, comprehensive analysis has been hindered by methodological inconsistencies. Various institutions rely on differing sampling protocols, leading to data variability and challenging cross-comparisons between studies. D’Ascanio et al.’s research seeks to address this issue by rigorously evaluating two primary sampling paradigms—ASTM’s established standard method and emerging in-line continuous collection techniques.
The ASTM (American Society for Testing and Materials) method involves discrete sampling points where water is collected manually or semi-automatically, then transported to laboratories for microplastic extraction and analysis. This approach, although widely recognized, has limitations including potential contamination risks, temporal sampling restrictions, and labor intensity. Conversely, in-line sampling systems are designed to continuously collect water samples directly from drinking water streams, facilitating real-time or near-real-time monitoring. By integrating filtration and particle capture mechanisms within the water conveyance path, in-line methods promise enhanced temporal resolution and a reduction in external contamination.
Diving into the core of the paper, the authors conducted parallel sampling campaigns across various drinking water utilities, comparing both techniques over multiple temporal and spatial scales. Their methodology accounted for factors such as polymer type differentiation, particle size range identification, and concentration quantification. Sophisticated spectroscopic tools, including Fourier-transform infrared (FTIR) spectroscopy and Raman microspectroscopy, were employed to characterize the collected microplastics, ensuring accuracy in polymer classification.
One striking finding was the increased sensitivity of in-line sampling methods in detecting smaller-sized microplastics, which are often missed or underestimated in ASTM discrete sampling. These smaller fractions are particularly concerning due to their potential for deeper tissue penetration upon ingestion. The continuous nature of in-line collection also revealed short-term fluctuations in microplastic concentrations that traditional methods failed to capture, highlighting dynamic variations linked to operational cycles or transient contamination events in the water supply chain.
However, the research did not deem one method universally superior; each harbors distinct advantages and constraints. ASTM sampling’s standardized protocol remains essential for data consistency, particularly in regulatory contexts where uniformity is paramount. On the other hand, the flexibility and detailed temporal resolution offered by in-line systems open promising avenues for real-time risk assessment and rapid mitigation strategies, especially in densely populated urban areas reliant on complex water infrastructures.
The implications of these findings extend beyond academic circles. Regulatory agencies worldwide face increasing pressure to set enforceable guidelines on microplastic levels in drinking water. This study’s detailed comparison provides the empirical foundation necessary to harmonize testing protocols, ensuring reliability and comparability. Enhanced detection could also catalyze public awareness and pressure on industries to reduce plastic pollution at source.
Furthermore, the study underscores the critical role of technological advances in environmental monitoring. The use of miniaturized sensors, automated filters, and integrated data transmission embedded within in-line sampling devices demonstrates an infusion of engineering innovation into environmental science. This convergence promises not only improved detection but also cost-effectiveness and scalability essential for widespread deployment.
A notable contribution of the paper is its attention to contamination control throughout sampling and analysis. Microplastic contamination can originate from airborne fibers, laboratory equipment, or personnel clothing, confounding results. D’Ascanio and colleagues implemented rigorous blank controls, sample rinsing protocols, and procedural blanks to differentiate authentic environmental microplastics from artefacts, an essential step to ensure data integrity.
The researchers also evaluated polymer-specific recovery rates within each sampling method. Given the diverse chemical composition and physical properties of plastics—from polyethylene terephthalate (PET) to polypropylene (PP) and polyvinyl chloride (PVC)—capture efficiency can vary widely. The in-line method demonstrated consistent recovery across multiple polymer types, an encouraging indication of its versatility.
In addition to polymer types, particle morphology was carefully analyzed. Fragment shapes, fibers, beads, and films each have different environmental sources and biological interactions. The study found the in-line technique better retained fibrous microplastics, which are often shed from synthetic textiles and pose specific health risks due to their elongated shapes and potential to lodge in tissues.
Temporal variability in microplastic contamination emerged as another critical consideration, with the in-line system’s high-frequency sampling revealing episodic spikes potentially linked to infrastructural disturbances or water treatment fluctuations. Such data offer opportunities for utility managers to implement preventative or remedial measures in near-real time, a breakthrough in water safety management.
Another dimension explored was the economic and logistical feasibility of large-scale monitoring. While the ASTM method requires trained personnel and dedicated laboratory infrastructure, in-line sampling can be automated and remotely controlled, reducing manpower and operational downtime. These aspects position in-line systems as attractive candidates for integration into smart city infrastructures aimed at real-time environmental health surveillance.
The study also provocatively discusses future perspectives, calling for standardized hybrid approaches that blend ASTM and in-line methods to leverage strengths of both. It envisions networks of in-line sensors feeding data into centralized platforms while periodic discrete sampling provides quality assurance, creating a multi-tiered surveillance system.
Moreover, the authors touch upon the broader context of microplastic research—its interdisciplinary challenges encompassing material science, toxicology, epidemiology, and policy. Their methodology offers a template adaptable to other water matrices, such as recreational water bodies and wastewater treatment monitoring, extending impact beyond potable water contexts.
This research not only advances methodological rigor but also enriches the conceptual framework for tackling microplastic pollution. By demonstrating the practical advantages of continuous in-line sampling alongside recognized standards, it invites regulatory bodies, academia, and industry stakeholders to collaboratively redefine microplastic surveillance. The resulting synergy may accelerate scientific understanding, regulatory adaptation, and ultimately, public health protection.
In conclusion, D’Ascanio et al.’s 2025 study presents a pivotal analysis that may prove transformational for how microplastics in drinking water are detected and managed. Through their comprehensive comparison of ASTM and in-line sampling methods, the authors provide a new paradigm that balances accuracy, resolution, and operational practicality in addressing one of the 21st century’s silent contaminants. This work will undoubtedly inspire further research, policy evolution, and technology development, marking a significant stride toward safer, cleaner water for all.
Subject of Research: Microplastic sampling methods for drinking water
Article Title: Comparison of ASTM and in-line microplastic sampling methods for drinking water
Article References:
D’Ascanio, N.A., Glienke, J., Almuhtaram, H. et al. Comparison of ASTM and in-line microplastic sampling methods for drinking water. Micropl.& Nanopl. 5, 17 (2025). https://doi.org/10.1186/s43591-025-00124-x
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