Eating crisps could cause cause cancer, a study by government-backed scientists has found, as they contain high levels of acrylamide, a known carcinogen.
Tests conducted by Fera Science on behalf of campaign group Changing Markets, found t he highest levels of the chemical were found in Tyrells "Sweet Potato Lightly Salted" crisps, which contained more than three times the recommended amount, according to European food standards.
According to EU benchmarks crisps should not contain more than 750 milligrams per kilogram of acrylamide. Despite this Tyrells "Sweet Potato Lightly Salted" crisps contain 2486 milligrams per kilogram.
The research also found Morrisons' "Cheese and Onion Popped Potato Snacks" and Aldi's premium brand "Passions Barbeque Flavour Popped Potato Chips" contained twice as much acrylamide than the recommended level.
In total nearly one in five potato crisp varieties sampled from major retail food outlets in the UK contained high levels of acrylamide, it said.
It comes after food safety watchdogs launched a major public awareness campaign earlier this year to help people reduce acrylamide in food, in which members of the public were advised not to overcook roast potatoes or burn toast.
Acrylamide is a chemical which forms naturally in both manufactured and home cooked food as a result of burning and cooking at high temperatures such as baking, frying, grilling and roasting.
The Food Standards Agency is also planning to extend the warning to every food-serving business in Britain. Under a new European Union food hygiene directive, due to be adopted in the UK by the the end of 2017, pubs and restaurants will be told to take reasonable steps to reduce acrylamide in food or face enforcement measures.
At present there are no restrictions on acrylamide in shop bought food, however tougher rules including a legally binding maximum limit for acrylamide in food is being discussed by European Commission and Member States, and will be voted on in June.
Nusa Urbancic, an acrylamide expert at Changing Markets, said: "Eating crisps with high levels of acrylamide increases the risk of cancer for all consumers and it represents a specific concern for children.
"The FSA concluded that children are 2 to 3 times more at risk for cancer due to dietary exposure to acrylamide. We are convinced that all companies should be doing whatever is in their power to reduce the levels of this carcinogen in our food.
"This is perfectly feasible and the industry has developed measures to do this already 10 years ago. We do not understand why companies, like Tyrells do not put this into practice consistently."
A spokesman for Tyrells crisps said: "Sweet potato crisps are made from wholly natural vegetables which incur varying changes in their carbohydrate composition in the course of harvesting at different times of the year. The FSA stated that studies on human subjects have provided limited and inconsistent evidence of increased risk of developing cancer through raised levels of acrylamide."
An FSA spokesperson said: "We are committed to reducing acrylamide in food, working with partners and European Commission to find workable solutions. The FSA has been actively supporting the food industry in its development of codes of practice on acrylamide reduction for use throughout the food chain. The approach will require manufacturers to act on acrylamide or face enforcement action."
Aldi and Morrisons were contacted for comment.