Q1 What is gutter oil ?
A1 There is no agreed definition of "gutter oil". Generally, it refers to discarded oil recovered from gutters and ditches.

Q2 What is Benzo[a]pyrene ?
A2 Benzo[a]pyrene (B[a]P) is a kind of polycyclic aromatic hydrocarbons (PAHs). PAHs are ubiquitous in the environment as contaminants, being present in air, soil, water and food.

Q3 Why is food contaminated with PAHs ?
A3 PAHs may be formed during incomplete combustion or burning of organic matters. Almost all food contains PAHs to a certain extent. The two major sources of B[a]P (a type of PAH) in food are deposition and uptake of B[a]P from polluted air on food crops and formation and deposition of B[a]P during heat processing using methods such as roasting, smoking, and grilling. Levels of B[a]P may vary depending on the processing conditions and are often higher in barbecued/smoked meat or fish. Furthermore for fats and oils, drying of cereals and plants used for production of crude vegetable oils using direct application of combustion gases can result in contamination of the products with B[a]P as combustion products may come into contact with the grain, oil seeds and thus increasing B[a]P level in the oil product. The level of B[a]P in oil would be much reduced after oil refining processes and the ultimate level of BaP would depend on the conditions under which refining takes place and quality control.

Q4 What is the major dietary source of PAHs ?
A4 Major dietary contributors of PAHs depend on the consumption pattern (amount and types of food consumed) and the levels of PAHs in foods. According to the Joint Food and Agriculture Organization/World Health Organization Expert Committee on Food Additives (JECFA), cereals and cereal products, vegetables fats and oils are major contributors to dietary exposure to PAHs.

Q5 Will the B[a]P level in oil increase after repeated deep-frying ?
A5 There are reports which suggest that the level of B[a]P in oil will increase after repeated use. Since many factors can lead to high levels of B[a]P in oil, one cannot judge if oil had undergone repeated use just by the level of B[a]P in it.

Q6 Does the existence of B[a]P in oil mean that the oil had undergone high heat treatment, which in turn means that the oil had been used for frying food previously?  Does that equal to "gutter oil"?
A6 No. The presence of B[a]P in oil can be due to many different factors. Plant materials for oil production can be contaminated through deposits from air. The level of B[a]P in these materials can also increase through drying process using direct application of combustion gases. Furthermore, B[a]P level in oil may increase upon repeated use.

Q7 What amount of B[a]P consumed will be harmful to health ?
A7 B[a]P is toxic to genes and can cause cancer in human. B[a]P is classified as "carcinogenic to human" (i.e. Group 1 agent) by the International Agency for Research on Cancer (IARC) of the World Health Organization in 2009. Therefore, a safety reference value cannot be determined for B[a]P. To reduce the health risk associated with B[a]P, efforts should be made to minimise exposure to B[a]P as far as practicable.

Q8 Is there any international, regional or national regulation on B[a]P in edible oils ?
A8 The Codex Alimentarius Commission has not established standard of B[a]P in edible oils. The standards of B[a]P in edible oils in European Union and Mainland China were 2 μg /kg and 10 μg /kg respectively.

Q9 Is there any advice on reducing exposure to B[a]P ?
A9 Public should maintain a balanced and varied diet, which includes a wide variety of fruits and vegetables; Do not use reused cooking oil; avoid overindulgence in barbecued meat, particularly charcoal grilled meat and smoked meat/fish; and remove charred parts of food. Public may reduce consumption of fats and oils to reduce B[a]P exposure.