Immediately after a leading food expert revealed that one in every 10 meals in the country may be cooked with dirty oil, the State Food and Drug Administration (SFDA) on Thursday issued an emergency notice to restaurants nationwide warning them against recycling oil.

Food service providers will be punished if they use illegal cooking oil or oil of an unknown origin. In severe cases, their licenses could be revoked, the notice said.

He Dongping, a food science professor at the Wuhan Polytechnic University (WHPU), told the China Youth Daily on Thursday that people in China consume "about 2 to 3 million tons" of illegal cooking oil every year.

"And the Chinese people's annual oil consumption is about 22.5 million tons, which means a ratio of 1:10," he told the newspaper.

The "illegal cooking oil" is usually made from discarded kitchen waste that has been refined, the report said, adding that the oil, which contains a highly toxic and carcinogenic substance called "aflatoxin", can cause cancer.

He's revelation was a result of a research project he is conducting, along with nine of his students, with the aim of finding an effective way to detect and identify illegal oil used in food production.

So far, no such method has been found, the report said.

According to He's research, the illegal cooking oil business is extremely profitable.

"One ton of cooking oil made from kitchen waste costs only 300 yuan (US$44). A barrel of oil makes a profit of 70 to 80 yuan. On average, one person collects four barrels. Even if the oil is sold at half the price of ordinary oil, you could make over 10,000 yuan a month. Even a chore man in the business gets a monthly wage of 2,500 yuan," He told the newspaper.

All efforts to contact He for a comment on Thursday failed.

Wang Chunsheng, who also teaches at WHPU, said "pressure from higher authorities and personal threats" were reasons for the researchers to refuse further interviews.

"He also works with the National Grain and Oil Standardization Committee. Without permits from superiors, releasing related data is not authorized," Wang said.

"The project has been going on for several years, during which time his students have received threats from illegal dealers. Now that his name is out in public, he is worried that his students might get in trouble," he said.

Most of the illegal cooking oil in Wuhan is sold to the under-developed areas of the city, an insider surnamed Liu told China Daily.

Having lived in central Wuhan for over 30 years, Liu said he had talked with some of his friends in the dining business about illegal cooking oil.

"I would say about 80 percent of the oil is sold to the less-developed areas, where regulations aren't too strict and public consciousness on food safety is weak," Liu said.

He said that illegal cooking oil had become widespread in the city for years, but with regulations getting stricter, the business is moving to the suburbs.

"Regulating illegal cooking oil involves several governmental departments, and the SFDA is only concerned with the restaurants," an official with the SFDA said.

"The production process belongs to the quality inspection departments and the Ministry of Health. Once the illegal cooking oil gets into the market, the State Administration of Industry and Commerce (SAIC) will step in," said Chen Hongrang, director of the publicity office with the SAIC.

(China Daily March 19, 2010)