Malachite Green and Nitrofurans Residues Found
in Turbot Imported from the Mainland


On 17 November 2006, the Shanghai Food and Drug Administration of the Mainland reported that malachite green and various veterinary drug residues were found in turbot.

Analysis Results and Actions Taken by the CFS

The CFS immediately contacted the Mainland authorities to understand the situation and stepped up surveillance. Five samples of turbot were collected from the local market for analysis of malachite green and several veterinary drugs residues. All results were available on 23 November 2006. Two samples were tested positive for malachite green at 340 and 480 parts per billion (ppb) respectively. For five out of five samples of turbot were found to contain low levels of nitrofurans, ranging from 4 ppb to 240 ppb. The results for the other veterinary drug residues were negative. The CFS has requested the Mainland authority to stop exporting turbot to Hong Kong. Besides, the CFS has liaised with the trade to stop the import and sale of turbot in Hong Kong. During the follow up investigation, no turbot was found in the market.

What is Malachite Green?

Malachite green is a chemical dye which has been used worldwide in aquaculture for a long period as an antifungal agent. The main concern in food is its cancer causing potential.

In Hong Kong, the maximum level of malachite green should be 0 μg/kg in any food (including live fish) under the Harmful Substances in Food Regulations, Cap.132AF.

What is Nitrofurans?

Nitrofurans is a family of antimicrobial agents which can be used as veterinary drugs. The main concern of nitrofurans in food is that a type of nitrofurans may cause cancer in experimental animals. However, for the types of nitrofurans detected in this survey, there is inadequate evidence that it can cause cancer in humans.

Based on the levels of nitrofurans residues found in the affected turbot samples, risk assessment suggested that the risk to health is low upon usual consumption of the fish.

Advice to Trade and Consumers

Further information

Further information about malachite green can be obtained from the following webpages: