Melamine In Foods

Melamine in Foods

What is melamine •

Melamine is a cyclic nitrogenous compound

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Formula : C3N6H6

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Solubility in water 3.1g/l of water @ 20 Celsius Toxicity LD50 (rats) – 3248 mg/kg. Not a proven carcinogen. Not genotoxic. Melamine was considered harmless compound before the current issue Melamine is not a Food Additive

Structural analogues of melamine Triazines

Uses of melamine •

Melamine resin – polymerized melamine for manufacturing of kitchen ware, table ware, table top laminates and packaging material.

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Manufacture of nitrogen fertilizers

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Melamine polysulfonate – concrete plasticizer

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Melamine cyanurate – Fire retardant material

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As a pharmaceutical to treat African Trypanosomaisis.

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Used as a non protein nitrogen source of cattle feed.

Recent Melamine scandal •

In 2007 many pet illnesses and deaths in USA was traced down to Melamine adulterated wheat gluten products in pet foods.

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Recent infant deaths and illnesses due to renal failures in China are related to melamine adulterated infant milk manufactured in China

Health effects due to melamine •

Melamine in pure state is non toxic at low levels. LD50 (oral,rats) is 3248 mg/ Kg. Compare this value with some of the chemicals in foods and common medicines. (LD50 – oral, rats) – Table Salt – 3000 mg/Kg – Caffeine – 192 mg/Kg – Nicotine – 55 mg/Kg – Aspirin – 200 mg/Kg – Paracetamol – 1944 mg/Kg

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Melamine when combined with cyanuric acid in the body, it can create Kidney Stones due to formation of water insoluble Melamine cyanurate. This can lead to kidney malfunctions, mainly in infants.

Sources of Melamine in foods • Will full adulteration – As in Some dairy manufacturing companies in China.

• Use of raw material contaminated with melamine – Most Chocolate and other consumer products affected due use of milk powder contaminated with melamine. – Melamine was not a routine quality control testing parameter of any food product / food ingredient, prior to the recent melamine issue.

• Naturally through food chain – Some pesticides used in agriculture get converted to melamine. (Cyromazine – An approved chemical in Sri Lanka as an insecticide)

Will full adulteration •

World over payments for cows milk is based on Fat & SNF (Solid Non Fat) content of the liquid milk.

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Suppliers try to get an advantage by diluting milk with water to increase volume

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If fat content is below 3.5% (country dependent) and SNF is lower than 8.0% (Country dependent), milk is rejected or payments are generally reduced by half or by a fraction due to adulteration.

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Therefore suppliers add various material such as Sugar, urea etc.. to increase SNF %. Melamine is a recent addition to the list, probably due to difficulty of identifying the material at the inspection / testing at the time of purchasing liquid milk.

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Melamine is not water soluble. Therefore it has to be dissolved in formaldehyde before adding to liquid milk.

Will full adulteration •

The most widely used protein analysis method of food is “Kjeldhal method”. In this method all organic nitrogen (mainly protein) is converted to Ammonium sulphate, to determine the total nitrogen content. The nitrogen content is them multiplied by a factor (Mostly 6.25) to estimate the protein content.

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This is fairly accurate and simple method. However if nitrogen rich material such as Melamine (Melamine has 66% of nitrogen), is added, it will increase the nitrogen content and thereby give false high content of protein.

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The Wheat gluten product used in pet food manufacturing and Milk Powder must have adulterated to increase false high percentage of protein.

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World milk powder prices are about 3500 - 4000 USD per MT, where as industrial grade melamine in China is about 700 USD a MT.

Use of contaminated Raw materials • Most blamed raw material for melamine contamination is some of the Milk products from China. The values ranged from 1 ppm to over 6000 ppm. • Most of the finished products manufactured using contaminated milk products were identified positive for Melamine. The reported values ranged from <1 ppm to few hundred ppm. • Recent study in Malaysia traced Melamine contamination of well known brand of biscuits to Ammonium bi carbonate, the most common raising agent in bakery industry. The values ranged from 33 ppm to 508 ppm.

Melamine through food chain •

Cyromyzine is a widely used pesticide in most of the countries. It is also used as an ecto-parasiticide in veterinary medicine.

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Cyromyzine is a systemic insecticide, which get absorbed in to plant tissues. In the plant the pesticide get convert to Melamine.

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WHO reported that metabolite of pesticide Cyromyzine was found in plants and animals. Therefore there may be some amount of melamine in food materials of plant and animal origins

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Information in this area is not yet extensively available.

Cyromyzine

Melamine

Identification of melamine •

There are no simple methods or quick methods to identify / determine melamine in foods.

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The methods recommended by FDA requires expensive equipments such as GC-MS, LC-MS, and HPLC. GC-MS is considered as the most sensitive and can detect levels low as 0.05 ppm.

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Currently the facility is not available in Sri Lanka. Testing cost in Singapore is 300 S$ per sample.

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An ELISA testing kit method is available, but the kit is validated only for milk and milk products. The consumables and the initial costs are fairly high. – ELISA Kit for 86 tests – 370 USD – Other equipments required - >7000 USD

Specifications & limits of melamine •

Since melamine in foods is a recent issue, food authorities world over are still evaluating the limits of melamine in foods and food raw materials.

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Lack of established limits resulted indiscriminate ban on foods. Foods containing 1 ppm and 100 ppm melamine are treated alike.

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Since melamine is not a food additive, ideally it should not be in foods and limit should be zero. But we are not living in an ideal world.

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It is necessary to establish limits to identify purposely adulated foods and foods that are not adulated, but unavoidable under normal safe manufacturing conditions.

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Limits are established for much more poisonous materials than melamine. –

E.g.; Aflatoxin, Heavy metals, Pesticide residues

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Therefore food authorities will compelled to come up with reasonable and safe limits to protect the consumers as well as food industry.

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It is also said that if everyone goes for melamine zero foods, there will be worldwide shortage of foods, particularly in developing world and available foods will be prohibitively expensive.

Specifications & limits of melamine •

WHO reported that due to widespread use of melamine, also in material in contact with foods, low levels may be detected in foods, not necessarily due to adulteration.

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FDA of USA suggested following limits are safe. – 1 mg/Kg for Infant foods – 2.5 mg / Kg for all other foods

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European Union, Canada, China and many other countries have adapted the FDA limits.

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However, it looks like that prohibiting of melamine positive foods are done by case by case evaluation.

Key References • • • • • •

http://en.wikipedia.org/wiki/Melamine http://www.fda.gov/oc/opacom/hottopics/melamine.html http://www.who.int/foodsafety/fs_management/Melamine.pdf http://www.wvu.edu/~Agexten/ipm/insects/ld50.htm http://msds.chem.ox.ac.uk/consumer.html http://www.hazard.com/msds/