The allegation that acrolein formed during heating of used cooking oil can cause cancer has yet to be proved, according to the Health Ministry.

Director-General of Health Datuk Dr Noor Hisham Abdullah said based on the study carried out by the International Agency for Research on Cancer (IARC), acrolein could not be classified as carcinogen (cancer-causing substance or agent) as there was no solid evidence that it was carcinogenic.

He said this in response to the local news report that advised the public not to reuse cooking oil more than three times for fear that it would turn into toxic acrolien that could cause cancer.

"The ministry is seriously concerned about the safety of food that can threaten public health," he said in a statement here Monday.

Acrolein is a colourless liquid with a piercing, disagreeable, acrid smell. It is produced industrially from propylene and mainly used as a biocide to control weeds, algae and bacteria, as well as a building block to other chemical compounds. Small amount of acrolein can also be formed during heating of cooking oil to its smoke point.

Mohd Hisham said exposure to acrolein mostly occurred by breathing, such as of cigarette smoke and car exhaust fumes.

"Acrolein can cause irritation in the skin, eye, nasal passages, throat and can also damage the lungs," he said.

As such, he said used cooking oil should be disposed of if it had changed to dark brown in colour, become sticky or thick, produce rancid smell and a lot of smoke when heated.

Further information and guidelines to determine the quality of cooking oil can be obtained at the ministry's Food Safety and Quality Division's website at http://fsq.moh.gov.my or at MyHealth portal at http://www.myhealth.gov.my