Occurrence, sampling, identification and characterization of microplastics in tap water: A systematic review and meta-analysis
Masoumeh Malekzadeh, Reza Dehghanzadeh, Seyedeh Masoumeh Ebrahimi, Parvin Sarbakhsh, Zahra Fathifar, Hassan Aslani
Abstract
Identifying microplastics (MPs) in tap water has recently attracted considerable attention. The present study aimed to systematically review MPs contamination and characteristics in tap water. All techniques used for sampling, processing, and analyzing MPs in tap water were also assessed. Furthermore, the characteristics of MPs, including abundance, type, color, and shape, were summarized. Various databases, including Web of Science, PubMed, ScienceDirect, Scopus, Springer, and MDPI, were searched to find published articles up to January 2025. The occurrence of MPs in tap water was meta-analyzed using a random-effects model. A total of 6100 articles were found, of which 43 were included in the systematic review. The results indicated that the pooled mean concentration of MPs in tap water was 56.98 particles per liter (P/L). Manual sampling with a sample volume of less than 1 liter was most commonly used, and microscopic, Raman, and Fourier-transform infrared spectroscopy (FTIR) methods were frequently applied for extracting and identifying MPs. The most abundant polymer identified was polyethylene (PE), followed by polyethylene terephthalate (PET) and polypropylene (PP). Fibers and fragments were the dominant forms of MPs found in water. The lack of a harmonized protocol and the difficulty in validating MP analysis methods in tap water have led to inconsistent and sometimes contradictory results, making comparisons unreliable. The findings of this systematic review can support the development of a comprehensive protocol and promote standardized, harmonized methods for MP analysis in tap water.