BEIJING - Nearly 20 percent of supermarkets in several big cities are still using plastic packaging that has been banned to wrap meat and cooked food, according to an investigation carried out by a non-governmental organization.

The International Food Packaging Association visited 46 supermarkets in the past six months in Beijing, Shanghai and Shenzhen, and found nearly one in five of them were still using plastic wrapping made of polyvinyl chloride (PVC) for fresh meat and cooked food.

"The situation might be even worse in small cities and rural areas," said Dong Jinshi, executive vice-president of the association.

The country's top quality watchdog banned the use of PVC to wrap meat, cooked food and fatty foods in 2005, because DEHP, which experts believe is harmful to humans, is used as the plasticizer to make it soft.

"DEHP is not soluble in water but soluble in oil. Therefore, PVC plastic wrap can't be used to package fatty foods," said Dong.

Doctors warn that DEHP can cause male fertility problems and induce female precocious puberty, and that experiments on animals have demonstrated a carcinogenic effect.

Sun Lusi, a professor at the Institute of Food Science and Technology of National Taiwan University, said DEHP is 20 times more toxic than melamine, the culprit in the 2008 baby formula tragedy in which six children died and 300,000 were seriously injured.

China Daily interviewed a dozen consumers of various age groups and from different places, but none knew about the potentially harmful effects of PVC film when used to wrap meat and cooked food.

China Daily visited three supermarkets in Beijing's Chaoyang district on Dec 25, and found PVC film was being used to pack fresh meat in one of them.

"We use what is provided," said Li Xiaocui, a worker at the Anjoy fresh meat counter in an outlet of Wumart.

It was a different story at a branch of Ito Yokado.

"We stopped using PVC packaging a year ago and all the wrapping that now enters the supermarket is inspected," said Shan Yanyan, a worker at the food department.

Some retailers still use PVC wrapping because it is stickier and cheaper, he said.

On Taobao.com, China's leading online retail platform, 20 meters of PE plastic wrap costs nearly 10 yuan ($1.6), but for 10 yuan buyers can get 100 meters of PVC wrapping.

Experts suggest an effective way to distinguish PE wrapping from PVC wrapping is to set a flame to it. PE wrapping drips oil and smells like a burning candle, while PVC wrapping gives off black smoke and a strong pungent odor.

However, this test is not very practical for most shoppers.

Dong said it is important that supermarket staff are given adequate training about the different plastic wraps and what they can be used for, especially as consumers are given little information about what the plastic film their food is wrapped in.

"Most PVC wrapping doesn't come with a warning stating it shouldn't be used for meat and fatty food. Most of it doesn't even have basic information, such as the production date and material," he said.

The market watchdogs should assume responsibility for consumers' health and carry out checks, he added.