Water bottles, typically made of PET (Polyethylene terephthalate), can generate chemicals harmful to human health during the manufacturing process. These chemicals include antimony, acetaldehyde, and formaldehyde, which are classified as carcinogens by the International Agency for Research on Cancer (IARC). Although these substances are managed within safe limits during water production, their levels can increase depending on factors such as temperature, UV exposure, and storage duration.
The concentration of harmful substances rises with increasing temperature. A study conducted by the National Institute of Environmental Science in South Korea found that the average concentration of antimony increased fivefold in water stored at 45°C compared to water stored at 25°C over a 180-day period. Similarly, formaldehyde levels were more than four times higher in PET bottles stored at 50°C compared to those stored at 25°C.
The impact of high temperature is further amplified when combined with UV exposure. Researchers from Seoul National University conducted a study comparing brown PET bottles (which reduce UV exposure) with transparent PET bottles stored at 25°C and 50°C for up to 182 days. The results showed that as the temperature increased, the average concentration of acetaldehyde was up to 1.6 times higher in the transparent bottles. Higher acetaldehyde levels can cause an odd odor in the water inside the bottles.
It is advisable to check the storage conditions and location of water bottles when purchasing them. In fact, an audit conducted in Seoul found that out of 272 retail stores, 101 stores stored water bottles outdoors exposed to direct sunlight. Samples collected during the audit were subjected to UV and 50°C exposure for 15 and 30 days, revealing the presence of antimony, formaldehyde, and acetaldehyde. Antimony levels exceeded the Australian standard (3.0 μg/L) with concentrations ranging from 3.1 to 4.3 μg/L, while formaldehyde levels surpassed the Japanese standard (80 μg/L) with concentrations ranging from 120 to 310 μg/L. The Ministry of Environment is currently developing detailed management standards for water bottles.