1. Drank Bottled Water Today, But Is There a Group 1 Carcinogen in It?
The weather is extremely hot. Terms like a blast furnace or steam room do not even sound like exaggerations. Amidst this scorching sunlight, if you look closely while walking down the streets, you will notice piles of bottled water stacked outside convenience stores and supermarkets.

[Convenience Store Employee : Bottled water naturally takes up space and can obstruct the walkway (inside the store), so usually putting it outside is just the basic thing to do.]

Is bottled water exposed to severe heat and intense sunlight like these days safe? Let us look into this issue—or more accurately, the issue of "bottled water PET bottles exposed to direct sunlight." Four years ago, the Board of Audit and Inspection conducted a direct investigation and experiment regarding this while performing an "inspection on the management status of drinking water quality." They brought in four bottled water products, including three domestic products and one imported product. They set up a chamber mimicking the harsh conditions of strong ultraviolet (UV) intensity and a temperature of 50 degrees Celsius (122 degrees Fahrenheit), typical of a summer afternoon around 2:00 PM to 3:00 PM. After exposing the water bottles inside to this chamber for 15 and 30 days respectively, they drew water from the bottles and tested the water quality. The Board of Audit and Inspection explained that a 15-day exposure corresponds to about 3.9 months in real natural conditions, while a 30-day exposure test corresponds to about 7.8 months in nature. As a result of this experiment, formaldehyde, a Group 1 carcinogen, along with another hazardous substance, acetaldehyde, and some heavy metal antimony, were detected in some products.

[Kang Sang-wook, Professor of Chemical and Energy Engineering at Sangmyung University : When PET molecules are continuously exposed to ultraviolet rays, the (molecular) chains break down, and the chemical substances generated in the process are aldehydes.]

Formaldehyde is classified as a Group 1 carcinogen by the International Agency for Research on Cancer and is known as a causative agent of sick house syndrome and atopic dermatitis. Antimony is a toxic heavy metal used in plating or pigment work, and if poisoned, it causes gastrointestinal diseases and is also a substance suspected of carcinogenicity.

2. How Harmful Is It?
The most important thing would likely be whether this leaching amount is actually harmful to the human body. Looking at formaldehyde first, it was detected below the permissible level for formaldehyde under South Korea's drinking water quality standards. The current water quality standard for formaldehyde is 0.5 milligrams per liter, and in the 15-day exposure test, 0.18 milligrams was found to have leached from an imported product. In the 30-day exposure test, one imported product recorded 0.31 milligrams, and the highest among the three domestic products was 0.17 milligrams. While they met domestic standards, the situation changes according to the standards of countries with stricter drinking water quality standards. For instance, in Japan, the permissible limit is 0.08 milligrams, meaning three out of the aforementioned four products exceeded Japan's standard. What about the leaching amount of the heavy metal antimony? The 15-day exposure yielded about 0.003 to 0.004 milligrams, and the 30-day exposure test yielded about 0.001 to 0.003 milligrams. However, in the case of antimony and acetaldehyde, there are no domestic water quality standards. On the other hand, quite a few countries have established permissible standards for antimony: Australia sets it at 0.003, the United States at 0.006, and Japan at 0.015. This means Australia has particularly stringent regulations. Comparing against these countries' standards, no products exceeded the U.S. or Japanese limits. However, quite a few products exceeded the Australian standard. Out of a total of 8 cases from the 15-day and 30-day tests, 4 cases exceeded Australia's permissible limit. What these figures signify is not that you should immediately stop drinking bottled water exposed to sunlight, but rather that the tendency for hazardous substances inside PET bottles to actually leach out when exposed to high temperatures and strong UV rays for long periods—as seen these days—has been proven to be true. It was also revealed as a fact that formaldehyde and acetaldehyde, which were non-detectable—meaning not detected at all—before the exposure experiment, leached out after the experiment. In the case of antimony, trace amounts were present even before the experiment, but the amounts increased significantly after undergoing the 15-day and 30-day UV exposure experiments.

3. Enforcement Starting July 31, But a Two-Year Grace Period?
Consequently, based on these experimental results, the Board of Audit and Inspection requested corrective measures from the Ministry of Environment—now referred to as the Ministry of Climate, Energy and Environment. They urged the ministry to conduct precise reviews, such as conducting hazardous substance leaching tests under various conditions in the manufacturing and distribution processes of bottled water in PET bottles, to establish management standards, and to devise ways to distribute bottled water while minimizing exposure to direct sunlight. Accordingly, it took four years for the ministry to revise and enforce the regulations. The revised notice on labeling standards for bottled drinking water took effect last week on July 31. Previously, there was only a principle to hygienically store water in a cool, dark, and shaded place. Moving forward, it is mandatory to keep bottled water away from windows where direct sunlight enters indoor spaces, and if there are windows, devices to block light must be installed. Furthermore, if water must inevitably be stored outdoors, covers must be placed over it. However, the problem is that while the aforementioned regulations began applying from July 31, a two-year grace period has been granted. What does a grace period mean here? It means that while the system itself goes into effect, crackdowns will not be enforced, so businesses should manage it properly on their own. Of course, considering the circumstances of convenience stores and supermarkets, it is not easy to secure additional space given the lack of indoor space. However, the Board of Audit and Inspection also investigated the distribution status of bottled water. When they randomly checked 270 retail stores and convenience stores in Seoul, over 100 stores—meaning 37 percent—were storing bottled water in PET bottles exposed directly to outdoor sunlight environments. Even if securing indoor space immediately is difficult, the obligation to use covers during outdoor storage is a measure that could be implemented right away. Considering that ultraviolet rays from direct sunlight play a major role alongside high temperatures, simply covering them with a shield can yield significant effects, making this a truly regrettable decision. I mentioned that the experiment at the Board of Audit and Inspection was conducted four years ago, in 2022, but in fact, that was not the first time. Experts have already raised this as a suspicious issue well over a decade ago. Thus, the National Institute of Environmental Research already conducted an experiment back in 2013. It was confirmed that acetaldehyde leached out above the threshold value—meaning at a level where humans can smell it with their noses—leading to the conclusion that high-temperature exposure in summer should be avoided. Counting from back then, it took 13 years from raising the issue and conducting scientific experiments to the revision of the notice, and to grant another two-year grace period on top of that—one cannot help but feel that this is an overly passive response. Hopefully, voluntary measures will be taken by the industry instead.

(Reported by Jang Se-man | Produced by Shin Hee-sook | Video by Seo Byung-wook | Graphics by Yook Do-hyun | Produced by SBS Digital News)