Eight food samples - including three of fresh meat, three frozen aquatic products, candied lotus seed and rice - failed Centre for Food Safety tests last month.
Of the 8,800 food samples tested, the overall satisfactory rate was 99.9%, in line with the pass rate for the whole of 2013.
Three samples of fresh meat were found to contain sulphur dioxide. Two samples of frozen fish fillet were found to contain mercury, while the other fish sample contained the veterinary drug chloramphenicol.
A candied lotus seed sample was found to contain sulphur dioxide, and a rice sample was found to contain cadmium.
The centre said these items would not likely cause any adverse health effects with normal consumption, but has traced their sources, asked vendors to stop selling them, and has taken follow-up food samples and issued warning letters.
