LAUSR

Abstract Growing popularity and public interest in bottled water necessitate a more in-depth investigation of microplastics in bottled water. Previous studies on microplastics in bottled water have focused on quantifying microplastics and reviewing their detection methods, but neglected the methodological aspects. Thus, this study was conducted to perform a quality assessment of methodological aspects from microplastics in bottled water studies directly adopting the Criteria for Reporting and Evaluating Ecotoxicity Data (CRED) evaluation criteria. A total of 12 bottled water microplastics studies published from 2015 until 2021 were selected and used in the quality assessment of methodological aspects via eight CRED criteria, namely sampling methods, sample size, sample processing and storage, laboratory preparation, clean air conditions, negative control, positive control and polymer identification. The quality assessment findings indicated no study scored a maximum of two in all criteria. Furthermore, the selected studies with scores between 0 and 2 for the eight criterias have provided an overview of adopted contamination control measures for microplastics analysis in bottled water. Current quality assessment score which is higher than previous microplastics bottled water studies, could be linked with improvements of proper quality assurance and contamination control measures in recent years. Understanding current methodological aspects via the quality assessment scores will help future studies to apply appropriate contamination control measures, improve comparability and allow for development of microplastics method harmonisation and standardisation.