Overview: Melamine contamination of dairy products in China
Since this issue first came to the attention of international organizations on 11 September 2008, the Joint FAO/WHO International Food Safety Authorities Network (INFOSAN) has been in close contact with the Chinese authorities to obtain the most up-to-date information on the situation and relay the same to national food safety authorities on this food safety crisis, one of the largest in recent years. During this period, the Chinese Authorities have been very active in addressing the problem and providing regular communications on the evolving situation.
According to the Ministry of Health China 39965 infants have received treatment after consuming infant formula and are in various stages of recovery. In total, 12 892 infants have been hospitalized, among them 104 are still in critical condition. Three (3) confirmed and one (1) unconfirmed deaths have been reported. Over 80% of patients are below 2 years of age.
The information available to date indicates that this crisis occurred as a result of the intentional adulteration of milk with melamine. Melamine is a high nitrogen compound which appears to have been added to diluted milk to give the appearance of normal protein levels when subjected to a test for protein levels that is based on nitrogen content. Earlier, this week the Chinese authorities indicated that this intentional adulteration of milk may have been happening for many months.
The level of melamine found in the contaminated infant formula was as high as 2,560 mg/kg in powdered infant formula produced by the company Sanlu, one of the biggest dairy manufacturers in China. Products from 22 other companies have also tested positive for melamine albeit at lower levels. Several of these companies export their products. Recalls have been issued within China and outside. Official reports from China indicate that other dairy based products, including liquid milk, ice cream and canned coffee drinks, have also been found to contain melamine. There are further reports from importing countries of dairy-based candies and confectionary products testing positive for melamine. Recalls and bans of potentially contaminated products have been issued by many countries.
Melamine is a by-product of the coal industry. It is a chemical compound with numerous industrial uses, including the production of plastics, dishware, kitchenware, commercial filters, laminates, adhesives, molding compounds, coatings and flame retardants.
Melamine ((1,3,5-triazine-2,4,6-triamine) is high in nitrogen (C3N6H6)
It is this characteristic that has led to its illegal addition to food and feed for the purpose of increasing the apparent protein content of food and feed products.
How does melamine give an apparent increase in protein content?
One of the standard tests for measuring the protein content in food actually measures the level of nitrogen and based on this estimated the level of protein in the food. As melamine is high in nitrogen such tests will interpret this nitrogen content as protein. Therefore, if milk has been diluted with water and melamine has been added, measuring the nitrogen level to determine protein content will disguise the fact that water has been added to the milk. However, there are a number of other methods now available to test the protein content in food which do not focus on the measurement of nitrogen content. When such tests are used the increased nitrogen content due to the presence of melamine will not be measured. In cases of diluted milk these tests will detect a reduced protein content.
Toxicity of melamine
Data on the toxicity of melamine are limited but animal studies to date indicate a low toxicity. There are no human studies on melamine toxicity. Several reviews of the available information have been undertaken by WHO, USFDA/USDA and EFSA. The reports of these assessments are available through the following links.
Following the incident in 2007 where petfood was found to be contaminated with melamine the USA and the EU have established provisional tolerable daily intakes (TDI) for melamine. Based on an interim safety/risk assessment on melamine and structural analogues the USFDA has established a TDI of 0.63 mg per kg of body weight per day. The European Food Safety Authority has recommended to apply a TDI of 0.5 mg per kg of body weight per day.
The range of foods which have been contaminated as a result of the adulteration of milk in China with melamine is still unfolding. From the information to date powdered infant formula appears to be contaminated to the greatest extent. However other dairy based products are also affected. The Chinese Authorities have indicated that liquid milk, yogurt ice cream and canned coffee drinks also tested positive for melamine. As many other countries test imported dairy products sweets and confectionary have also been reported as among the types of foods contaminated. To date, illness has occurred among infants and young children who have consumed contaminated powdered infant formula. There are no reports of illnesses due to consumption of other contaminated products.
Melamine and animal feed
In 2007, the adulteration of pet-food with melamine lead to the death of hundreds of cats and dogs in the USA. This also triggered the testing of other animal feed for melamine and low levels of melamine were found in feed for fish, poultry and pigs. Regulation regarding its use in animal feed do not always exist as it is only recent events which indicated the need to regulate for this substance. However, some countries have established regulations .and do not permit the use of melamine in animal feed.
Preventing the spread of melamine contaminated products
Melamine contaminated products can enter the market via either formal or informal trade. Information on those products found to be contaminated has been shared with the national authorities via INFOSAN, the FAO/WHO International Food Safety Authorities Network. Products entering countries via formal routes will be documented and in this way the authorities can check the import records to determine whether any affected product has entered the country. Import inspection plays a critical role in ensuring the safety of all imported foods and incidents such as this highlight the importance of a functioning and efficient import inspection service.
Informally traded products may be more difficult to trace and countries may need to take action against illegally imported product matching that found to be contaminated in China. National authorities need to be aware of potential markets for informally traded product in their country so that they can inspect such markets for the potential sale of contaminated products. Countries need to alert food inspectors regarding these contaminated product andprovide them with the information that is necessary to identify such products such as country of origin information and details of recalled products.
Action in case contaminated products are found
Countries should carefully monitor their markets for contaminated product and take appropriate action based on an assessment of the risk posed by the product to the consumer. Such action may vary according to the product and the extent of contamination and might include product recall and safe disposal of the product. While national authorities together with industry have the primary responsibility of ensuring that all products that reach the market are safe for consumption, consumers can also play a role. Consumers should try to be aware of the origin of products they are purchasing and seek that information from retailers if they are in doubt. They should follow the advice of national authorities regarding potentially contaminated products on the market. In particular they should be vigilant when purchasing foods for infants and young children as these are our most vulnerable population group.
Responsibility for food safety
The role of national authorities is critical to protect the consumer from unsafe food. Increased vigilance is necessary when there is a food safety incidence and in the short term additional food inspection activities, strengthened communication with the food industry and consumers and clear information on the actions being taken as well as clear guidance to stakeholders is critical.
However, food safety is not the sole responsibility of the national authorities. It is a shared responsibility between national authorities, the food industry and consumers. In general national authorities are the regulators and are responsible for providing guidance and ensuring the application of good hygienic and manufacturing practices within a country. Such guidance can be based on international standards such as the recommended standards guidelines and codes of practice which have been developed by the Codex Alimentarius Commission. Food industry is reminded of their essential role in food safety by ensuring the implementation of good practices from the point of primary production through to the finished product. There are numerous opportunities along the food chain where accidental or intentional contamination of the food chain can occur. The development of a strong food safety culture in all parts of the food industry is encouraged to prevent such contamination events from occurring. In turn consumers have a responsibility to also follow good practices in the purchase, transport, storage and preparation of food and to follow the guidance provided by national authorities and industry on best practices. By being informed consumers can contribute to minimizing their risk of being exposed to a foodborne hazard.
Presence of melamine in pesticides and fertilizers
As melamine is high in nitrogen it is reported to be a component in some fertilizers. Melamine itself is not used as a pesticide although it is recognized as one of the breakdown products of the pesticide cyromazin
Cyromazin has been evaluated by the Joint FAO/WHO Meeting on Pesticide Residues (JMPR) in 1990, 1992 and most recently in 2006 and 2007. The 40th Session of the Codex Committee on Pesticide Residues in 2008 adopted a number of Maximum Residue Levels for this pesticide based on the evaluations of JMPR.