All About Green

Tidbits About Plastic Drink Bottles

Originally published in Green Country, Issue 119 (Apr 2016)
Author: Green Power
Beverage bottles made of polyethylene terephthalate (PET)

As the weather warms, chilled bottled drinks in convenience stores catch our eyes. Enormous amounts of plastic bottles are wasted as we purchase cold drinks. You may think the waste can be minimised by reusing the bottles. The fact is quite the opposite; doing so may also pose risks to our health.

There are two main types of plastic bottles in the market: one is made from Polyethylene Terephthalate (PET) and is transparently brown, green or colourless. It is used for soda, fruit juices, tea and water. A recycling label of "1" can be found on the bottom of the bottle. PET is widely used for being acid-base tolerant and lightweight. However, it is not heat-tolerant, and a hot drink will twist the shape of the bottle. Also, the heavy metal antimony is added during the production of the plastic bottles. This carcinogen may be transferred to the drink. The Centre for Food Safety has carried out research and stated that the antimony level in PET plastic bottles in Hong Kong is too low to pose a health threat. The main risk of reusing the bottles is hygiene problems, as the bottle mouth is too small and cannot be easily cleaned, which lead to germs multiplying.

Another common type of plastic bottle is translucent and milky. It's made from Polypropylene (PP), with a recycling label of "5" printed in the bottom. It is used to carry milk and soy milk that are usually warmed before drinking. This kind of plastic bottle will not change shape even at a high temperature of 167℃. There is no data that shows PP will release harmful materials. However, as with the case of PET, the small bottle mouth makes it hard to clean thoroughly before reuse.

Although there is a low health risk in reusing a bottle if we wash it properly, the plastic material may still be denatured if it is reused too many times or heated repeatedly or put under sunlight for too long. We should stop reusing it when the plastic bottle changes colour. Apart from reuse, recycling also helps to reduce plastic waste. Nonetheless, the plummeting oil price in recent years lowered the viability of plastic recycling and some merchants even refuse to take in recycled plastic bottles. Reuse or recycling is not the best choice. We should opt for a durable bottle made from safe materials that can be easily washed, and bring our own drinks from now on.