The State Food and Drug Administration, China’s food safety watchdog, has ordered a nationwide inspection of all cooking oil as reports released by The China Dailyindicated that almost one-tenth of Chinese supplies contained cancer-causing agents and were made illegally.

According to the Administration’s website, “If food service providers are found to be using cooking oil from an unclear source, or if they have bought ‘drainage oil,’ their operations will be immediately halted and they will be dealt with in accordance with the law.”

The Administration also ordered increased inspections of all food service providers and promised to punish manufacturers found to be producing cooking oil refined from discarded kitchen waste or “drainage oil.”

The Taipei Times reported that one-tenth of drainage oil is most likely made from highly toxic, recycled kitchen or restaurant waste containing aflatoxin.  Chronic exposure to aflatoxin can cause cancer.

He Dongping, a food science expert at the Wuhan Polytechnic University told the China Youth Daily that, “People in China consume about 2 to 3 million tons of illegal cooking oil every year.” Dongping cited statistics indicating that the Chinese population consumes about 22.5 million tons of cooking oil per year.

This discovery comes on the heels of ongoing melamine-tainted milk trials and other violations putting China in the food safety spotlight.