Four cooking oil samples were found to contain a cancer-causing substance at levels higher than the European Union's limit, the Centre for Food Safety said yesterday.
The centre took 39 cooking oil samples from an oil plant in Kwai Chung's Wing Kin Industrial Building, the plant's supplier in Tuen Mun, and 13 restaurants in various districts that allegedly bought oil from the establishment.
Tests revealed two samples that came from the Tuen Mun supplier contained the carcinogen Benzopyrene at 16 and 17 micrograms per kilogram of oil, exceeding the mainland's legal limit of 10 micrograms per kg and the EU's limit of two micrograms per kg. The substance was found in two samples from the Kwai Chung plant at levels of 5.8 and 6.2 micrograms per kg respectively, lower than the mainland's limit but exceeding the EU's.
The announcement came after media reports last week alleging the Kwai Chung plant had supplied substandard oil to various eateries. The plant reportedly mixed unknown substances into the oil it received from the Tuen Mun supplier.
Hong Kong does not set a limit on Benzopyrene in foodstuffs. The health risk in consuming the cooking oils concerned was not high, the centre's spokesman said. "However, for the sake of prudence, the Centre for Food Safety has requested the cooking oil supplier to stop selling and recall the affected product."
The department has sent a notice to the suppliers requiring improvement of hygiene conditions. However, it did not say whether they would be prosecuted, and investigations were continuing.
The centre's findings did not indicate whether the problematic oils were tied to "gutter oil", or oil illegally produced by collecting discarded oil from restaurant waste, a practice that has sparked controversy on the mainland.
"The oils [named by the centre] are substandard, but we cannot call them 'gutter oil' before identifying their sources," William Chui Chun-ming, president of the Society of Hospital Pharmacists, said.
Gutter oil can be a source of carcinogens if producers fail to remove harmful substances during the process of recycling discarded oil. Still, other types of contamination during the production process could also be the reason behind the presence of cancer-causing substances, he said. "Benzopyrene can be found in smoke and burned wood, and it could appear in oil if the burnt matter accidentally falls into it," he added.
Given that Benzopyrene is a carcinogen, people should avoid ingesting it, he said.