Grilling food at a high temperature and/or on a campfire, often, and eating a lot of it may damage one's health. Distance to the heat source, how early food is placed onto the grill, and the type of fuel used can affect the formation of harmful substances.

This is the main conclusion in VKM's health risk assessment of grilled food.

It is known that heat treatment such as grilling and frying can give rise to unwanted toxic compounds in the food, so-called process-induced contaminants.

Grilling is a common way of preparing food in Norway, and the grilling season has become longer. The food selection has become ever wider and sales of different types of grills are increasing. Many factors may thus have changed since VKM's previous assessment of health risks from the consumption of grilled food, which was published in 2007.

To be able to give current and relevant advice to consumers and others who sell or offer grilled food, the Norwegian Food Safety Authority has asked VKM for updated knowledge about the formation of process-induced contaminants in different food products by different grilling methods, and an assessment of what risk this may pose.

"We find that for most people, there will be a low health risk associated with consumption of grilled food, but there may be some who grill mainly fatty meat products, often.They should grill in in a way that reduces the formation of harmful substances," says the scientific leader of the project group, Espen Mariussen.

Main findings

• Harmful substances can be formed at high cooking temperatures. When grilling, the temperature is higher and less controllable than when frying in a pan.
• There is good evidence that two groups of genotoxic and carcinogenic substances, heterocyclic amines (HAA) and polycyclic aromatic hydrocarbons (PAH), are formed in higher concentrations in grilled food than in fried food.
• VKM has assessed PAH, for which there are good studies of occurrence in barbecued food.
• PAHs are formed when fat burns after dripping from the food onto the heat source. PAHs can also be released from coal, briquettes and wood. The smoke with PAH settles on the food.
• The occurrence of PAH in grilled food varies greatly and depends on how the food is grilled. The concentration of PAH is highest in very well-done meat with a high fat content, such as pork ribs and hamburgers.

The highest concentration of PAH was found in sausage grilled on a campfire. This is caused by unburnt fat or soot/smoke from the fire that stick to the sausage.

• By avoiding fat dripping directly onto the heat source, preventing smoke from coming into contact with the food, and not overcooking the food, the amount of PAH in grilled food can be reduced.
• When using charcoal, the PAH emission is higher immediately after lighting, and the amount of PAH in the food can be reduced by waiting sufficiently long before start grilling.
• It is not the number of times you grill that is a critical factor, but how.
• A "worst-case" scenario shows that the annual consumption of more than 15-25 meals that have been grilled in a way that produces a high PAH incidence may provide too low margin of exposure* for the risk to be low.
• If, on the other hand, you prefer lean barbecue food that is not overcooked, then you can eat it more than 100 times a year according to our calculations and still have a high enough margin of exposure.

* Margin of exposure is the ratio between the lowest dose (reference point) that causes increased cancer in experimental animals and the calculated intake. Exposure margin below 10,000 is considered a public health concern.

Uncertainties

The most important knowledge gaps found by VKM, related to the health risk assessment of grilled food:

• There is a lack of systematic reviews of health outcomes linked to the consumption of grilled food as compared to other preparation methods.
• There is a lack of data on the population's consumption of grilled food, which foods are grilled, frequencies of grilling and which grilling methods are used.
• There is a lack of comparable data on the occurrence of PAH and other heat-induced contaminants in food that has been grilled using different grilling methods in comparison to frying.
• There is a lack of toxicological data on individual HAAs to improve hazard characterisation.
• There is a lack of data on process-induced contaminants in grilled food other than meat and fish, such as vegetables and bread.

The risk assessment has been carried out on behalf of the Norwegian Food Safety Authority, and will be used as a basis for giving current, relevant advice to consumers and others who sell/offer grilled food.

The work has been carried out by VKM's Panel on Contaminants, led by Helle Katrine Knutsen.