Nine of 52 fish samples taken under the routine food-surveillance programme were found to contain malachite green, Food & Environmental Hygiene Department Assistant Director Dr Thomas Chung says.

In the latest round of food surveillance, about 15,300 food samples were taken for microbiological and chemical tests. The overall failure rate was about 0.3%.

For the 9,800 chemical test results, 39 unsatisfactory samples were detected, including nine fish or fish products.

Testing of malachite green in food has been included in the routine food surveillance programme since September 8. Among the 52 samples taken, including 14 freshwater fish, nine were found to contain the chemical, Dr Chung said.

They included a sample of goldfish carp - the only live freshwater fish sample detected with malachite green,  two samples of green grouper, two samples of mud carp meat, three samples of canned mud carp and one eel-product sample.

15 failed preservatives tests

A total of 15 samples failed the testing of preservatives. Some were found to contain sorbic acid which is not permitted in those foods, including beef balls and sweetened vinegar. In some samples, such as beef and fish maw, non-permitted sulphur dioxide was detected.

Six samples, including curry powder and a sponge cake, were found to contain non-permitted colouring substances Sudan IV and Orange II. Four samples failed tests on veterinary drug residue and pesticide. 

Noting the results, Dr Chung called on the food trade to be more cautious.

"They should make sure that only permitted food additives are used and that their food supply does not contain excessive pesticides or chemical residues," he said.

Another three samples failed the chemical tests because they were found to contain cadmium, an environmental contaminant, that exceeded the permitted level. A clam-meat sample was found to contain dioxin slightly exceeding the action level, while a geoduck clam sample had paralytic shellfish poison, a natural toxin sometimes found in shellfish.

Adverse health effects unlikely

Dr Chung said taking into consideration the amount of chemicals detected, the unsatisfactory samples were unlikely to cause adverse health effects.

When unsatisfactory samples are detected, the department will follow up with the retailers and wholesale suppliers concerned to stop the sale of the same batch of food products in question, Dr Chung said.

The department will also inspect retail outlets and collect  food products concerned for tests to ensure food safety and safeguard public health, he added.

Among the 5,500 food samples for microbiological tests, which target pathogenic bacteria and viruses, eight were found to contain pathogens such as Norovirus, Bacillus cereus, Listeria monocytogenes and Staphylococcus aureus.

Dr Chung said the presence of pathogens is most likely related to improper food handling. He urged food handlers to stay alert and maintain good hygiene.