Raised levels of a chemical linked to cancer have been found in a range of foods from KFC meals to breakfast cereals.
Food watchdogs identified the increased quantities of acrylamide in 14 popular products.
The chemical is formed when foods are roasted, toasted or fried at very high temperatures.
Scientists say it is potentially carcinogenic if consumed regularly over a lifetime.
The Food Standards Agency tested 300 products to understand the scale of the problem.
The largest amount was found in crisps, including a number of expensive brands such as Burts Sea Salted crisps.
Exposure: The largest amount of the chemical was found in crisps, such as Seabrook’s Sea SaltedThere were also raised levels in Tesco ready salted crisps, Tayto cheese and onion crisps, Seabrook Sea Salted crisps, Pipers Anglesey sea salt crisps and the Co-op’s Sea Salt and Chardonnay crisps.
Manufacturers suggested the problem was caused by last year’s bad weather which changed sugar levels in potatoes, which in turn created more acrylamide.
In terms of take-out food, raised levels were found in a sample of KFC fries bought at a restaurant in Congleton, Cheshire, and a fish and chip shop in the town.
Breakfast cereals containing bran, which is cooked at a particularly high temperature, also contained more acrylamide.
Raised levels were found in Tesco bran flakes, Sainsbury’s wholegrain bran flakes, the Co-op’s wheat bran flakes and puffed wheat sold by the Good Grain Company.
Higher than expected levels were also found in Fox’s Ginger biscuits and TUC biscuits.
The FSA stresses it does not consider the levels of the chemical found to be dangerous, however it is keen that they are brought down as a precautionary measure.
A spokesman said: ‘We will work with the relevant local authority to encourage food manufacturers to review their acrylamide reduction strategies.’
The watchdog said there is no need for the public to give up the foods named in its survey, however it gave advice on how people can reduce exposure.
This includes cooking chips only to a light golden colour while advising that ‘bread should be toasted to the lightest colour acceptable’.
Danger: The chemical is formed when foods are roasted, toasted or fried at very high temperatures as in TUC Original biscuitsIt said manufacturers’ instructions for frying or oven-heating foods, such as chips, should be followed carefully.
The FSA also tested the products for the presence of a second type of cancer risk chemical called furan. No official safety limit exists for the chemical, however higher levels were found in roast coffee and popcorn.
KFC said it has contacted all of its outlets to ensure cooking methods are designed to guarantee low acrylamide levels.
It added: ‘We believe that this was a one–off anomalous result as the levels in every other test carried out on KFC fries were significantly lower.’
Burt’s said the wet weather had changed the character of potatoes to create higher levels of the unwanted chemical.
As a result, it is switching to new varieties that should reduce the level and is improving its sorting process to remove overcooked crisps.
Tesco said: ‘Food safety is incredibly important to us, and we are working closely with our suppliers to ensure all acrylamide levels are below the recommended indicative value.’
