- In 2008, a number of infant urinary tract stone cases were reported in Gansu and other provinces in Mainland China . Investigations showed that most victims had consumed the Sanlu brand baby formula contaminated by melamine. Melamine was also associated with massive pet food recall in the USA in 2007.
- Melamine (also known as tripolycyanamide, or 2,4,6-triamino-1,3,5-triazine) is an industrial chemical used for the production of melamine resins which can be used in glues, paper, textiles, kitchen utensils, etc.
- However, some people have abused melamine to boost nitrogen levels during protein test for dairy products. Melamine is not allowed to be added to food in any quantity.
Safety and Public Health Significance
- Melamine appears to be metabolically inactive and it has low oral acute toxicity. Human data on oral exposure to melamine is not available until the recent infant urinary tract stone cases in the Mainland.
- Melamine may be present in the environment or in the food-chain due to their widespread uses in industry. Melamine in foods may come from melamine-formaldehyde tableware (melamine-ware), pesticide - cyromazine, and sanitiser - trichloromelamine. Nevertheless, according to the World Health Organization (WHO), the concentration of melamine in foods from the above sources is generally low, less than 1 mg/kg.
- Excessive exposure to melamine has been found to cause urinary tract stones, crystals in urine and proliferation of epithelial cells of urinary bladder in experimental animals.
- Studies showed that melamine did not damage genetic materials in cells or cause birth defects.
- The International Agency for Research on Cancer (IARC) of the World Health Organization (1999) considered that there was inadequate evidence in humans for the carcinogenicity of melamine and there was sufficient evidence in experimental animals for the carcinogenicity of melamine under conditions in which it produces bladder calculi (i.e. stones). IARC classified melamine as Group 3 agent, i.e. not classifiable as to its carcinogenicity to humans.
- In December 2008, WHO established a Tolerable Daily Intake (TDI) of 0.2 mg/kg body weight for melamine. The TDI is applicable to the whole population, including infants.
Regulation of Melamine in Food
- According to WHO, addition of melamine into food is not approved by the FAO/WHO Codex Alimentarius or by any national authorities.
- To protect public health, the administration amended the Harmful Substance in Food Regulation (Cap. 132 AF). Under the amendment regulation, milk, any food intended to be consumed principally by children under the age of 36 months and any food intended to be consumed principally by pregnant or lactating women shall not contain melamine exceeding 1 mg/kg. For other food, melamine level shall not exceed 2.5 mg/kg. The amendment regulation was published in the Gazette on 23 September 2008 and came into operation on the day of the gazettal.
Advice to the Public
- Purchase food from reliable retailers and caterers.
- Melamine-ware may release more melamine and formaldehyde during prolonged contact with highly acidic foods at high temperature. The public should use melamine-ware according to product specifications and instructions.
Advice to the Trade
- Be cautious about the origins from which food products are sourced, and should only do so from reliable sources.
- Trade members should ensure that their food products comply with local legislation and are fit for human consumption.
Risk Assessment Section
Centre for Food Safety