[Anchor]

On scorching days like today, leaving bottled water unattended for a long time can cause harmful substances from the plastic bottles to seep into the water. Starting tomorrow, the 31st, bottled water must be stored indoors away from direct sunlight, and covers must be used when keeping them outdoors. However, enforcement of these rules has been postponed for two years.

Reporter Jang Se-man has more.

[Reporter]

Amid temperatures soaring past 30°C (86°F), bottled water is piled up in front of a convenience store.

Touching it with a hand, the water is warmed up to the touch.

It is the same at another nearby convenience store, where bottled water placed on outdoor display shelves is exposed directly to sunlight.

Measuring the temperature with a thermal imaging camera, the surface temperature reached up to 46°C (115°F).

This happens because stores lack enough space to keep goods inside.

[Convenience Store Employee: Bottled water takes up space anyway and can cause inconvenience to movement (inside the store), so usually leaving them all outside is basically standard...]&br;
The problem is that long-term exposure to high-temperature direct sunlight in midsummer like this can cause harmful substances to leach from the PET bottles into the water.

According to an experiment conducted by the Board of Audit and Inspection four years ago, when bottled water was exposed to ultraviolet rays at 50°C (122°F) for 15 days, Group 1 carcinogens such as formaldehyde and the heavy metal antimony were leached.

This corresponds to being kept outside naturally for 3.9 months, but actual bottled water is distributed for up to a year or so.

In the case of formaldehyde, there was no problem under domestic standards, but it exceeded the allowable limit under Japanese standards. Antimony, which lacks domestic standards altogether, exceeded the allowable limit according to Australian standards.

During the process of applying high temperature and high pressure to plastic raw materials when making PET bottles, substances like formaldehyde are generated, and these flow into the bottled water when exposed to ultraviolet rays at high temperatures for a long time.

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

The Ministry of Climate and Environment has revised the distribution and storage regulations for bottled water so that starting tomorrow, indoor storage is mandatory to prevent exposure to sunlight, and covers must be placed if they are inevitably left outdoors.

However, considering circumstances such as a lack of storage space, enforcement has been decided to be deferred for two years. Controversy is expected as even the "mandatory use of covers," which could be applied immediately, has been delayed.

(Video Editing: Yu Mi-ra, VJ: Shin So-young)