Prohibited Substances in Food


‘Prohibited Substances in Food’ refer to any non-food substance added to food during the food production and operation processes which endanger human health. The majority of significant food safety incidents that occurred on a global scale in recent years have been caused by the addition of such non-food substances or the use of prohibited drugs in animal husbandry and agriculture. As these substances pose significant hazards to health and threaten insidiously to human health and safety, the food safety incidents caused can induce serious impacts.


Why are these substances prohibited from the use in food?


1.     Malachite green

It is a type of synthetic organic compound used as an industrial dye and bactericide which has the function of treating fish diseases. When malachite green is used in fish cultivation, it penetrates into its body tissues and produces metabolites that remain in fish body for a long time. It is a potential carcinogenic chemical and may lead to developmental hazards.


2.     Nitrofurans

They are a group of chemical substances with wide antibacterial property which has the function of killing pathogens like fungi and protozoa. They were once commonly used in the livestock, poultry industry and aquaculture. So far, there is evidence suggesting that nitrofurans may cause cancer in animals, pathologic changes in the haematological system, and damages to the eyes, liver and kidneys.


3.     Diethylstilboestrol

It is a synthetic oestrogen that was used in poultry farming and added to feed for accelerating animals’ growth. The substance is usually residual in the organs or muscle tissues of food animals, and has already classified as carcinogenic to humans (Group 1) by the International Agency for Research on Cancer (IARC).


4.     Chloramphenicol

It is a broad-spectrum antibiotic that was widely used against infectious diseases of meat animals and aquatic products due to inexpensive. Studies have revealed that intake of chloramphenicol over extended periods of time can cause antibiotic resistance to certain bacteria and serious adverse effects on the hematopoietic system, inhibiting the hematopoietic function of bone marrow.


5.     Melamine

It is an industrial chemical that was adulterated to dairy products to cause a false increase in the protein content. Studies have indicated that excessive intake of melamine causes urinary stones in animals.


6.     Sudan dyes

Sudan dyes are a group of industrial dyes added to food for enhancing and maintaining its colour. It has been found that illegally adding to poultry feed makes the egg yolk in a bright red. Studies have revealed that consumption of Sudan dyes over extended periods of time may cause cancer and genetic hazards in animals.


7.     Borax or boric acid

They are boron-containing compounds added to food for extending its shelf life and giving a chewy and crunchy texture. It has been found in some Chinese food like glutinous rice dumplings and shrimp dumplings. Studies have indicated that short-term intake of excessive boric acid may cause vomiting and diarrhoea symptoms. In severe cases, it damages the stomach, bowels, liver and kidneys.


How can the laws, regulations and notification mechanism ensure the safety of food supply to Macao?

According to existing laws, regulations and import regimes, all fresh and live food products imported to Macao must be subject to mandatory inspection and quarantine before entering the local market. Chemical tests include the prohibited substances, like malachite green, chloramphenicol and nitrofurans. If any problem is detected in the products during the entry inspection, the Municipal Affairs Bureau (aka IAM) will immediately notify the relevant authorities of the places of origin via the cooperation and coordination mechanisms. It will also temporarily suspend the import of suspected products until the risk is removed.


Since China is the major source of food supply to Macao, the regulatory authorities on the entry-exit inspection and quarantine of Macao and China have developed a long-term and close cooperation plan to jointly ensure the safety of food products supply to Macao.


At the same time, in accordance with the ‘Food Safety Law’ and Administrative Regulation No. 6/2014 ‘List of Prohibited Substances in Food’ dated 3 March which was amended by Administrative Regulation No. 3/2016 dated 11 February, the malachite green, nitrofurans, diethylstilboestrol, chloramphenicol, melamine, Sudan dyes, borax or boric acid are substances forbidden to be used in food. Any food produced, supplied or sold in Macao must not be detected with these chemicals. Any offender in violation of regulations will be punished by law.