[Reading Science] ② How Are Nanoplastics Measured Around the World?

The Gaps in Standards and Data South Korea Must Address

The discussion on microplastics and nanoplastics in tap water began with a multinational comparative study conducted in 2017 by the U.S.-based nonprofit investigative journalism organization Orb Media, in collaboration with researchers from the University of Minnesota.

The results were released through the British daily newspaper The Guardian, revealing that traces of microplastics were found in approximately 83% of 159 tap water samples collected from 14 countries across the United States, Europe, and Asia. Some samples from cities in the United States showed a relatively high frequency, while lower levels were observed in the United Kingdom and certain European regions.

However, the researchers emphasized that these figures should not be interpreted as a ranking of tap water quality by country. Differences in sampling methods, particle size criteria, pre-treatment processes, and the sensitivity of analytical equipment are all reflected in the results. In other words, the key issue is not the absolute amount detected, but rather "how much could actually be observed."

Since then, studies analyzing the presence of microplastics and nanoplastics in both tap water and bottled water have continued to be published internationally. These studies have consistently concluded that the amount detected can vary depending on the water source, purification processes, packaging, and pipeline conditions. Some research has even suggested that, when including particles at the nano level, there could be millions of particles per liter in bottled water.

A boy drinking tap water. Photo by Pixabay

However, such findings have been interpreted as "conditional results" stemming from differences in analytical instrument performance and processing criteria. The common conclusion emphasized by these studies is clear: what determines the results is not "how much was detected," but "how much could be detected." The more sensitive the equipment, the smaller the particles it can capture, resulting in higher reported figures.

In South Korea, a 2017 survey by the Ministry of Environment set the particle size threshold at "20 micrometers (μm) or larger" and found 0.2 to 0.6 microplastics per liter of tap water. However, this only reflects what can be measured within that range; for smaller, ultra-fine or nano-sized particles, the lack of an analytical system and standardized methods means the actual levels remain unknown. Ultimately, the relatively low figures in South Korea and the higher figures in the United States and Europe are not "absolute values" but are instead relative indicators resulting from differences in measurement conditions.

"Figures Are Only Reference Values... Standards Must Come First"

Park Saerom, Principal Researcher at the Korea Institute of Civil Engineering and Building Technology, stated, "The domestic figure of 0.2 to 0.6 per liter is the result for particles '20 μm or larger,' and there is currently no analytical method for smaller particles." She added, "Given the differences in removal efficiency by plastic type, shape, and size, as well as the variables in measurement conditions by country, direct comparisons are risky."

Choi Incheol, Researcher at the Water Utilization Research Division of the National Institute of Environmental Research, also commented, "Although the domestic tap water figures are relatively low, the absence of internationally standardized analytical methods means that absolute judgments should be withheld." He further noted, "The World Health Organization has also stated that the risks to human health are not yet clear. Establishing standardized analytical methods and a foundation for comprehensive surveys must come first."

In the end, the debate over microplastics and nanoplastics in tap water, sparked by the 2017 Orb Media report, continues to reach the same conclusion in the latest research. While the possibility of their presence has been confirmed, it is impossible to directly compare national data due to differences in measurement methods and technology. What is needed now is neither fear nor unconditional reassurance. The priority is to establish standardized analytical methods and build a data infrastructure tailored to South Korea's circumstances.

Only with such a foundation in place can judgments about the actual safety and management direction of South Korea's tap water be made based on scientific evidence. Experts unanimously agree: "The core of the controversy is not the figures, but the standards. In the absence of standards, figures are merely possibilities."