Hong Kong's consumer watchdog has asked bakeries to change the ingredients used to make cookies and biscuits, after at least 50 types sold in the city were found to contain carcinogenic substances.
On Tuesday, the Consumer Council said it had found traces of glycidol and acrylamide - chemical by-products of the manufacturing process that increase the risk of cancer - in almost 90 per cent of the 58 samples tested between August and October last year.
Meanwhile, 35 types of cookie were found to contain 3-MCPD, another chemical by-product that can harm the kidneys and male fertility.
"Those elements were generated because of the heating of the oil at certain temperatures," said Clement Chan Kam-wing, chairman of the council's publicity and community relations committee.
"We recommend manufacturers study the production process and try to replace the cooking oil."
The watchdog has given the test results to the Centre for Food Safety for further action.
Shortening, margarine and refined vegetable oil were the main types of oil used in making cookies, the council's CEO, Gilly Wong Fung-han, said.
A study by the watchdog last year found glycidol and 3-MCPD in almost 20 types of margarine sold in Hong Kong.
Wong also said the government should source healthy ingredients at a lower cost so consumers can continue to enjoy their favourite snacks, particularly over the upcoming Lunar New Year festivities.
The World Health Organisation does not set a limit for the consumption of glycidol and acrylamide, but the council said members of the public should eat "as little as possible".
Based on standards set by the European Food Safety Authority, an adult weighing 60kg should only consume 120 micrograms of 3-MCPD per day, the council said.
Egg rolls made by Hong Kong company Yuen Long Wing Wah were found to have the highest traces of glycidol at 1,900 mcg/kg, followed by butter egg rolls by Yu Pin King at 1,700mcg/kg.
Of the 48 types found to contain acrylamide, the Quadruple Belgian Chocolate Cookie by British supermarket chain Sainsbury's contained the highest traces at 340mcg/kg. The egg rolls made by Yuen Long Wing Wah were also found to contain 580mcg/kg of 3-MCPD.
In response, the distributor for Yu Pin King, and Sainsbury's, said it had discontinued the egg rolls, but the Sainsbury's product met the standards set by the Hong Kong government.
Yuen Long Wing Wah told the council it would improve its manufacturing process to decrease the production of the carcinogens and 3-MCPD.
Meanwhile, 46 types of cookie and biscuit were found to have mislabelled, or be missing, information on the product's nutritional content.
Twenty-nine of the samples that had nutrition labels were found to have mislabelled the sugar, sodium or fat content.
Chan called the failure to list ingredients by some manufacturers an "unsatisfactory practice".
One product from Conte de Cookie was found to have a 210 per cent difference between the indicated and actual sugar content. It said its cookies contained 7.3 grams of sugar for every 100 grams, but tests found it actually contained 22.6 grams.
All 58 samples tested were either high in fat or sugar, with 46 types of cookie found to be high in both.
The council said foods were considered high in sugar when the content exceeds 15 grams per 100 grams, and high in fat when 100 grams of solid food contains more than 20 grams of fat.
The watchdog reminded members of the public not to underestimate sugar, sodium or fat content in their favourite snacks, and to check the recommended serving sizes.
This article was first published in South China Morning Post.