Disposable water and beverage bottles are generally made of a plastic known as PET or PETE (polyethylene terephthalate). Usually a triangular arrow symbol around the number 1 would be printed on these bottles (see diagram below).
Many people reuse disposable PET bottles. Improper cleaning and handling of these bottles might pose potential health risk. It is important for consumers to know the following information before reusing PET bottles.
Things to be considered when resuing PET bottles
Growth of bacteria
- Refilling water bottles can result in contamination of the water with bacteria and fungi that can grow in damp or partially full bottles once they have been opened.
- These organisms generally come from the air, your hands and mouth, or anything that comes in contact with the mouth of the bottle. With time and warm conditions, bacteria can multiply to harmful levels. But safe handling and proper cleaning can help prevent this from happening.
Migration of chemicals
- Chemicals such as chemical monomers and additives that are used in the manufacture of plastic may migrate into water or beverages no matter they were being used only once or repeatedly.
- The amount of chemical migration from plastic will depend on the nature of the substance it comes into contact, the contact temperature and the contact time. However, proper usage of the plastics will have insignificant chemical migration, which does not pose any health risk to consumers.
- For PET bottles, trace amount of antimony, a heavy metal which is used in the production of PET, can migrate into water upon storage. A previous study conducted by Centre for Food Safety, however, showed that concentrations of antimony in PET bottled beverages were very low (well below the WHO's guideline value for drinking-water quality) and would not pose any health risk.
- Manufacturers have to ensure that plastic bottles are safe to use for its immediate intended purpose (e.g. water bottle should be suitable for containing water and will not transfer its chemical constituents into water in an unacceptable amount). Yet, they may not be able to ensure the safety of their bottles for uses beyond which they are designed for (e.g. the use of a water bottle for storing vinegar or oil).
- It is important that consumers do not misuse plastic bottles as this may result in greater amount of chemical migration than would otherwise be expected.
- With all plastic types, migration increases with temperature and time of contact. Although increased migration of chemicals from plastic bottles does not necessarily pose health risk, it could change the organoleptic properties such as taste, colour and odour of water they contain. Therefore, it is better not to expose PET-bottled water to sunlight directly.
Bottle distortion during hot filling
- Disposable plastic bottles made of PET are not suitable for hot beverages because when contact temperature reaches 70 oC, the bottles may deform physically.
Unfounded health concerns regarding PET bottles
"PET bottles will leach out cancer-causing substances known as DEHP and/or DEHA."
- Some reports have specifically suggested that common plasticisers, DEHP and/or DEHA, can leach from PET bottles into the liquids they hold, particularly with reuse.
- Plasticisers are additives that increase the flexibility and elasticity of plastics. However, DEHP and DEHA are not needed for PET production. Therefore, the allegation is unfounded. The International Agency for Research on Cancer (IARC) classified DEHA as not classifiable as to its carcinogenicity to humans (Group 3) in 2000 and DEHP as possibly carcinogenic to humans (Group 2B) in 2011.
"PET bottles will release dioxins during freezing."
- Dioxins are a group of persistent environmental pollutants resulting from various industrial processes and combustion activities. Dioxins are toxic and can cause cancer.
- There is no reasonable scientific basis for expecting dioxins to be present in PET bottles in the first place. Moreover, dioxins cannot be formed in freezing temperatures.
Advice to the public
- Examine the bottle to ensure that it is not damaged.
- Clean bottle thoroughly and make sure the inside of the bottle air dries completely before use.
- Before filling bottles, wash and dry your hands thoroughly.
- Reuse bottles on a like-for-like basis. For example if a bottle was used for water when you bought it, don't put other liquids or beverages in it when you reuse it.
- Always cool water or drinks before putting them in plastic bottles.
- If it is labelled "avoid exposure to sunlight" in the original product, follow the instruction when reusing the bottle.
- Bottles should be used by one individual only. Don't share bottles – saliva can transfer germs that can lead to illnesses.
To assist in the identification of waste PET, the following symbol is used.
Risk Assessment Section
Centre for Food Safety