Introduction

  1. 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.
  2. 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.
  3. 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

  1. Melamine appears to be metabolically inactive and it has low oral acute toxicity.
  2. 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.
  3. 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.
  4. Studies showed that melamine did not damage genetic materials in cells or cause birth defects.
  5. 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.
  6. The International Agency for Research on Cancer (IARC) of the WHO (2019) considered that there was inadequate evidence in humans for the carcinogenicity of melamine but there was sufficient evidence in experimental animals for the carcinogenicity of melamine. IARC classified melamine as Group 2B agent, i.e. possibly carcinogenic to humans.

Regulation of Melamine in Food

  1. According to WHO, addition of melamine into food is not approved by the Codex Alimentarius Commission or by any national authorities.
  2. To protect public health, the administration amended the Harmful Substance in Food Regulation (Cap. 132 AF). Under the amended Harmful Substances in Food Regulation (Cap. 132 AF), the maximum concentrations of melamine are listed below.
Description of food Maximum concentration
Liquid infant formula and liquid follow-up formula intended to be consumed principally by persons under the age of 12 months 0.15 milligram per kilogram of the food
Milk other than liquid infant formula and liquid follow-up formula intended to be consumed principally by persons under the age of 12 months 1 milligram per kilogram of the food
Any other food intended to be consumed principally by persons under the age of 36 months 1 milligram per kilogram of the food
Any food intended to be consumed principally by pregnant or lactating women 1 milligram per kilogram of the food
Any other food 2.5 milligrams per kilogram of the food

Advice to the Public

  1. Purchase food from reliable retailers and caterers.
  2. 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

  1. Be cautious about the origins from which food products are sourced, and should only do so from reliable sources.
  2. 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
May 2020