The amount of a cancer-causing chemical found in potato chips has fallen in the past three years, tests have shown. The tests by the Consumer Council and Centre for Food Safety found the products contained 33 to 1,000 milligrams of acrylamide per kilogram. This compared to a range of 1,300 to 1,700 milligrams in tests by the Food and Environmental Hygiene Department in 2003. Acrylamide is a contaminant formed during cooking, particularly at high temperatures. Samuel Yeung Tze-kiu, principal medical officer at the Centre for Food Safety, said the results showed the potato chip makers might have 'done something right'. But manufacturers said they were always modifying their procedures and had not done anything special in response to earlier tests. Dr Yeung said while acrylamide was still present in the foods, people should not to be too worried as they consumed a relatively low amount. But he said the World Health Organisation had yet to set a standard for consumption of the substance, so it was impossible to say what level of intake posed a risk. Tests on animals have found acrylamide increases the incidence of tumours in various organs. Calbee Four Seas Company, one of the biggest makers of potato chips in Hong Kong, said it had been modifying its manufacturing process over the years to minimise the production of carcinogens. He said this had nothing to do with the government's 2003 test and Calbee would continue to follow government regulations and standards. Calbee's BBQ flavoured potato chips were found to have 1,000 milligrams of acrylamide per kilogram. The tests found a relatively high incidence of acrylamide in other snacks, including Ginibis Party Animals Potato Snacks, with 2,600 milligrams a kilogram, and McDonald's French fries with 520. A spokeswoman for McDonald's said the fast food chain had stringent quality control procedures and would strive to serve safe, top-quality food of the highest standards.