Reader Ang Tze Siang wrote in to ask if PET (polyethylene terephthalate) plastic bottles can be reused safely as drinking bottles. Food correspondent Eunice Quek finds the answer.

Dr Wong Kwok Onn, director of the regulatory programmes department, regulatory administration group under the Agri-Food & Veterinary Authority (AVA), says it is not advisable to repeatedly use the same single-use bottles over a prolonged period.

He said: "PET plastic bottles used for commercial bottling of drinking water and beverages are designed for one-time usage.

"Repeated washing and usage may age and damage these plastic bottles. This will affect the integrity of the plastic material and possibly cause the release of chemical compounds into the beverage."

His advice is to use properly designed reusable bottles for repeated use. These can be bought at the kitchenware section in retail stores.

In recent years, BPA-free (Bisphenol A-free) plastic containers have become more popular with Singapore consumers as they become more aware of food safety, and retailers now offer an array of BPA-free water bottles for sale.

According to the AVA, BPA is a chemical used globally in the production of polycarbonate food containers, protective coatings for food and beverage cans, and a wide range of other consumer items such as eyewear and cosmetics.

It says the current migration levels of BPA from plastic and canned food containers available in the local market are "within safe levels".

A Straits Times report last year said Singapore consumer watchdog Case bought 20 different brands of reusable plastic bottles from supermarkets and retail outlets to test for BPA.

Of the 20 water bottles tested, no BPA was found in 19 of them, and the last one - by Chinese manufacturer Zenxin - had BPA (0.08 micrograms per ml of water) within the acceptable limit.