Majority of potable water microplastics are smaller than the 20 μm EU methodology limit for consumable water quality

Abstract

Microplastic (MP) content in nutrition including potable water is unregulated, although MP concentrations in individual brands of bottled water diverge by several orders of magnitude. The EU Directive 2020/2184 on consumable water quality recently proposed methodological approaches to the detection of MPs in potable water in the size range of 20–5000 μm. However, fine MPs in the 1–20 μm range are far more likely to pass the human intestine into blood and organs. To evaluate the impact of this omission on the total number of detected MPs, we determined MP concentrations down to 1 μm in ten different brands of polyethylene terephthalate (PET) bottled water and one tap water sample using automated Raman microspectroscopy. We found that MP concentrations ranged from 19 to 1,154 (n/L) [0.001 to 0.250 μg/L], and although all the investigated samples of bottled water were stored in PET containers, PET accounted only for a small percentage of identified MPs in most samples. Importantly, 98 and 94% of MPs measured less than 20 and 10 μm in diameter, respectively, demonstrating the importance of small MP inclusion in potable water analyses and regulation. The current study presents a protocol to identify MPs down to 1 μm in any type of potable water regardless of hardness, and demonstrates the importance of implementing both negative and positive procedural, quality control measures.