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Melamine

Lead Authors


Professor Jack Vanden Heuvel and his Fall 2008 Veterinary Biology Seminar at Pennsylvania State University
Lead Editor:
Steven G. Gilbert

Chemical Description


Melamine (CAS No. 108-78-1) is an organic base and a trimer of cyanamide, with a 1,3,5-triazine skeleton. Like cyanamide, it contains 66% Nitrogen by mass and, if mixed with resins, has fire-retardant properties due to its release of nitrogen gas when burned or charred, and it also has several other industrial uses. Melamine was found as a metabolite of the pesticide cyromazine in plants, goats, hens, and rats. Cyanuric Acid (CAS No 108-80-5) is a structural analogue of melamine that may be found as an impurity of melamine. Cyanuric Acid is an Food and Drug Administration-accepted component of feed-grade biuret, a ruminant feed additive. It is also found in swimming pool water as the dissociation product of dichloroisocyanurates used for water disinfection. Consumers may be exposed to Cyanuric Acid by swallowing swimming pool water, by drinking water processed from surface water, and by eating fish in which the chemical has accumulated (OECD 1999). When used in drinking water for disinfection purposes, sodium dichloroisocyanurate is rapidly dechlorinated to cyanurate.

Melamine cyanurate, also known as melamine-Cyanuric Acid adduct or melamine-Cyanuric Acid complex, is a crystalline complex formed from a 1:1 mixture of melamine and Cyanuric Acid.

Uses


The primary use of melamine is in the production of plastics. These manufactured plastics include countertops, dry-erase boards, glues, fabrics, housewares, and fire retardants. Melamine is also included in Yellow 150, which is used in ink production and to dye plastics, and it is also used in cement to increase its workability when laying it down. The latest concern with melamine surrounds its use as a protein replacement: melamine allows for protein-free consumption of Nitrogen. Adding melamine to fertilizers as a cheaper Nitrogen source increases crop yields, and crops produced with melamine-fortified fertilizers can be used to feed livestock - most importantly, cattle. These cattle then appear to contain more protein than is actually present.

History


Melamine was developed by a German scientist in the 1830s and has been used in the manufacture of plastics and laminates, specifically dishwasher-safe plastic dishware, which was popular until ceramic and glass dishes became more favorable in the 1970s. Protein levels in foods are determined by nitrogen content, and melamine has also been used to increase the nitrogen content of foods, which gives the impression that the foods contain more protein. In the 1960s, South African veterinarians attempted to supplement sheep feed with the chemical, wrongly believing the bacteria in the guts of the animals would be able to convert the melamine to biological proteins. Even at low doses, the by-product of melamine, Cyanuric Acid, forms fatal kidney crystals. In the 1970s, Italian scientists developed a way to test for melamine in fish foods and found that almost 60% of tested samples contained melamine. More recently, manufacturers have added melamine, disguised as wheat gluten or rice protein, to everything from baby formula to pet foods in order to label their products as containing greater amounts of protein. 

Health Effects


Human Exposure and Health Effects


Human exposure to melamine has occurred mainly through ingestion of baby formula and some brands of biscuits and instant coffee. The Food and Drug Administration (FDA) has released a study stating that products containing less than 1 ppm of melamine are safe to consume, and it found that many common baby formulas contain 0.14 ppm. Chinese manufacturers have added melamine to their products to disguise protein content, and four infants in China have died from overexposure. Only trace amounts are found in food products in the U.S., but melamine levels in Chinese products have been found to be considerably higher (though the exact amounts are still unspecified). Reports of adult melamine exposure have been minimal because melamine is excreted from the body within three or four hours. Children are at greatest risk for melamine poisoning because of their undeveloped kidneys and their consumption of baby formula. Further tests by the FDA are ongoing.

Acute Animal Toxicity

A basic conclusion about melamine's acute animal toxicity is that melamine alone is not hazardous to animals. However, melamine combined with Cyanuric Acid has an enhanced toxic effect. The Hazardous Substances Data Bank reported several experimental cases to evaluate the toxicity of melamine in animals, and very few, and minor, effects were observed under acute exposure (Bingham, 2001). Melamine, when applied to a rabbit at a dose as high as 1g/kg for 18 hours, did not cause primary skin irritation or signs of system toxicity (Bingham, 2001). In contrast, feeding of melamine and Cyanuric Acid to fish and pigs resulted in the presence of renal crystals (Reimschuessel, 2008). Those animals exposed to only melamine (400 mg/kg) showed few symptoms after three days, while the combination of the two chemicals (400 mg of each compound/kg) caused renal failure and the formation of renal crystals (Reimschuessel , 2008). Another study occurred with different species of fish, rats, rabbits, and algae, which were given very high doses of melamine, ranging from an average of 1000mg/l for a species of fish, 3296 mg/kg for mice, and 940 mg/l for algae. The test durations ranged from 48 to 96 hours, and LD50 values were obtained. The conclusion from these tests was that melamine has a low acute toxicity for the three trophic levels. The study stated, "The Bioaccumulation potential of melamine and the aquatic concentrations are low. No remarkable contribution of food from aquatic organisms to the uptake of melamine in humans is therefore expected" (UNEP, 1998). According to the Food and Drug Administration, the toxicity of the combination of melamine and Cyanuric Acid is a "concentration dependent phenomenon," in which only high doses will produce any effects such as the renal crystals (FDA, 2007).

Melamine can cause acute renal failure in dogs and cats (Thompson, 2008) when ingested at concentrations of 50 ppb and above, particularly in the presence of Cyanuric Acid (FDA, 2007). Melamine, in combination with Cyanuric Acid, causes the deposition of crystals in the kidneys which can lead to kidney failure (Yang and Batlle, 2008). Animals have experienced renal failure through ingestion of melamine-contaminated pet food, which may have contained melamine to artificially boost protein content determination (Thompson, 2008). 

Chronic Animal Toxicity

Chronic exposure to melamine in animals has been proven to cause urinary tract-related problems. Animals primarily obtain melamine by ingesting contaminated pet food, and an intake of 3% melamine over one year was linked to a variety of symptoms in dogs. These included a decrease in the number of urinary particles (urinary specific gravity), increased amounts of urine, and melamine crystallization. Additionally, chronic exposure may eventually result in kidney stones and damage to the reproductive tract and bladder (including bladder cancer).

Pharmacology and Metabolism


Melamine is not metabolized and is rapidly eliminated in the urine with a half-life in plasma of around three hours (OECD 1998).

Current Events

Title of Article

Date

Website Address

Summary

Tainted milk deaths rise in China

December 2, 2008

http://www.cnn.com/2008/WORLD/asiapcf/12/01/china.milk/index.html?eref=rss_health

NEW: 294,000 infants have suffered from urinary ailments, authorities say. Health authorities have investigated 11 infant death cases. Beijing had already confirmed three infant deaths linked to tainted milk.  Melamine, an industrial chemical, can make food appear to have high protein content.

FDA sets 'safe' levels for melamine in baby formula

November 29, 2008

http://www.cnn.com/2008/US/11/28/infant.formula.melamine/index.html?eref=rss_health

FDA has tested 74 samples of U.S.-made baby formula. Some samples tested positive but at safe levels, officials say. Levels are far below those associated with Chinese contamination.

FDA finds more traces of melamine in formula

November 28, 2008

http://www.cnn.com/2008/HEALTH/11/27/infant.formula.melamine/index.html?eref=rss_health

Tiny amounts of toxics have been found in several infant formula samples. FDA has not set a melamine safety threshold for infants. Contamination thought to come via manufacturing process, contact with can liners. Thousands of children sickened, several died in China from tainted formula.

Trace of melamine found in 1 formula sample

November 26, 2008

http://rss.cnn.com/~r/rss/cnn_health/~3/Aoob5QzI-h4/index.html

Sample was one of 77 tested, Food and Drug Administration says. FDA spokeswoman declines to name maker of formula. International Formula Council: level considered safe for infants by several nations. Test comes after contaminated formula in China linked to infant deaths.

FDA blocks import of Chinese milk products

November 14, 2008

http://www.cnn.com/2008/HEALTH/11/13/china.melamine.milk.fda/index.html?eref=rss_health

FDA begins blocking China milk products to ensure contaminant-free products. Over 53,000 infants in China sickened by infant formula containing melamine.  Melamine has been added to Chinese milk formula to boost appearance of protein. Over 13 countries have reported finding contaminated milk products from China.

China:  More eggs found containing melamine

October 30, 2008

http://www.cnn.com/2008/HEALTH/10/29/melamine.china.eggs/index.html?eref=rss_health

Tainted eggs from Hanwei were discovered in Hong Kong late last week. U.N. concerned that melamine has been introduced to animal feed. Tainted milk powder scandal sickened 50,000 Chinese children; killed four. Chinese food exports to the United States have risen five-fold since 1990.

Melamine scandal spreads to Chinese eggs

October 29, 2008

http://www.cnn.com/2008/HEALTH/10/28/melamine.china.eggs/index.html?eref=rss_health

Tainted eggs from Hanwei were discovered in Hong Kong late last week. U.N. concerned that melamine has been introduced to animal feed. Tainted milk powder scandal sickened 50,000 Chinese children; killed four. Chinese food exports to the United States have risen fivefold since 1990.

More melamine found in chocolate bars

October 6, 2008

http://www.cnn.com/2008/WORLD/asiapcf/10/04/milk.melamine.china.ap/index.html?eref=rss_health

South Korea orders four more Chinese-made food products to be destroyed. Melamine found in Snickers Peanut Funsize and M&Ms chocolate milk. Tainted milk formula has killed four infants and sickened more than 50,000. Melamine-contaminated products have been pulled from shelves in many countries.

FDA: Tiny amount of melamine OK for adults

October 3, 2008

http://www.cnn.com/2008/HEALTH/10/03/fda.melamine.amount.ap/index.html?eref=rss_health

FDA says eating tiny amount of melamine - 2.5 parts per million - not harmful. Officials stress they won't tolerate any melamine deliberately added to food supply. No safe level of melamine for infants. Melamine-tainted formula has sickened 54,000, killed 4 children in China.

Melamine found in 31 new milk powder brands

October 1, 2008

http://www.cnn.com/2008/WORLD/asiapcf/10/01/hongkong.melanine.ap/index.html?eref=rss_health

Thirty-one new batches of Chinese milk powder found contaminated with melamine. Melamine found in at least 100 samples from 265 batches tested in China. Hong Kong: amount of melamine in Cadbury chocolates legally acceptable. Melamine contamination has killed 4 children and sickened 54,000 others.

Melamine-tainted tea recalled in Asia

September 30, 2008

http://www.cnn.com/2008/WORLD/asiapcf/09/30/china.tainted.milk/index.html?eref=rss_health

Unilever recalls four batches of Lipton Milk Tea sold in Hong Kong. Unilever Hong Kong describes it as a precautionary measure. Chinese milk products have been contaminated with melamine.

Cadbury recalls Chinese-made candy

September 29, 2008

http://www.cnn.com/2008/WORLD/asiapcf/09/29/cadbury.milk/index.html?eref=rss_health

All recalled products produced in Cadbury's Beijing plant.  Candy distributed in Taiwan, Hong Kong,Australia, 2 small islands. 22 more arrested in tainted-milk case, raising total to 40. Milk contaminated with melamine, an industrial chemical.

Melamine scandal hits candy makers

September 29, 2008

http://www.cnn.com/2008/WORLD/asiapcf/09/29/candy.milk.ap/index.html?eref=rss_health

It was not immediately clear if tests found melamine in Cadbury chocolates. Kraft, Mars recall products but stress they were cleared of melamine. China's food safety scandal started with discovery of melamine in baby milk powder. Authorities: Suppliers might have added melamine to deceive quality tests for protein.

Dairy-related illnesses rise in Hong Kong

September 25, 2008

http://www.cnn.com/2008/WORLD/asiapcf/09/24/china.milk/index.html?eref=rss_health

NEW: South Korea bans importation of all Chinese products containing milk. Confirmed cases of kidney stones from dairy products grow to four in Hong Kong.  Authorities in China have arrested 18 people in a nationwide investigation. HK's Centre for Food Safety finds melamine in White Rabbit Creamy Candy.

Melamine 'widespread' in China's food chain

September 23, 2008

http://www.newscientist.com/article/dn14791-melamine-widespread-in-chinas-food-chain.html?feedId=online-news_rss20

The chemical causing kidney damage in Chinese infants could be contaminating food other than dairy products, say experts.

Tainted milk sickens 12,892 Chinese children

September 22, 2008

http://www.cnn.com/2008/WORLD/asiapcf/09/21/china.tainted.milk/index.html?eref=rss_health

NEW: Four infants dead, 12,892 sick after drinking baby formula.  NEW: Hong Kong girl, 3, first case outside mainland China, released from hospital. Nestle says none of its products in China are made from milk with melamine. Hong Kong government says melamine found in Chinese-made Nestle milk powder.

FDA: Melamine-tainted poultry, fish safe for humans

May 18, 2007

http://www.cnn.com/2007/HEALTH/05/18/pet.food.poultry/index.html?eref=rss_health

About 80,000 suspect chickens declared safe for human consumption. Fish at two U.S. hatcheries also ruled safe after testing negative for melamine. Eight more pet foods added to recall list, including first ferret food.

Fish meant for humans fed tainted food

May 9, 2007

http://www.cnn.com/2007/HEALTH/05/08/fish.food/index.html?eref=rss_health

U.S. health officials said Tuesday that fish intended for human consumption were fed meal that was contaminated with melamine and related products.

Wash. Post: How two innocuous seeming chemicals killed all those cats and dogs lately

May 7, 2007

http://ksjtracker.mit.edu/?p=2903

(Please see the article.)

Melamine found in some Walgreen's holiday teddy Bears with chocolate bars

December 10, 2008

http://www.abc15.com/content/news/investigators/consumralerts story/melamine-found-in-some-walgreens-holiday-teddy/fjlapge&xui8sa3m5vnm2g.cspx

173 teddy bears were recalled. Anyone who purchased these teddy bears should return them to Walgreens for a full refund.

Melamine tainted cookies found on NY store shelves

December 10, 2008

http://www.newsinferno.com/archives/4346

NYSDAM discovered melamine in Koala's March Crème-Filled Strawberry Cookies. The recall was initiated by distributor Lotte, USA.

Regulation


The Food and Drug Administration (FDA) currently regulates the importing of international foods and dairy products that might contain melamine by sampling and testing milk-derived ingredients, particularly those imported from China. They have been taking aggressive measures against the importation of melamine-infused products by 1) necessitating state and local "checks" and/or inspections at Asian markets, particularly on Chinese-imported foods that contain high amounts of milk proteins, and 2) investigating, sampling, and testing milk-derived ingredients that might contain milk proteins from a Chinese source. The FDA has also issued a health information advisory, warned various Chinese communities about the risks of melamine poisoning, is in the process of conducting a nation-wide investigation of all Asian imported infant formulas, worked with U.S. manufacturers to emphasize the importance of banning infant formula or milk-based materials from China, and is advising consumers not to purchase infant formulas or milk-based products that have been manufactured in China.

While the Food and Drug Administration regulates the diets of livestock, pets, and humans, the United States Department of Agriculture (USDA) shares responsibility in inspecting and regulating meat, poultry, and egg products. In one case where chickens and swine were reported to have been given contaminated feed, both the FDA and the USDA were involved in the investigation. The presence of melamine in the animals' food did not appear to have an ill effect, due in part to what the FDA is calling the "dilution factor." Contaminated pet foods pose a serious risk for pets because these foods compose the majority of pets' diets, but contaminated animal feed compose only a small portion of farm animals' rations. With the known signs of kidney failure not present, the resulting farm animal meats were ruled a "very low risk." In fact, one USDA report states, "A 132-pound human would have to eat more than 800 pounds per day of pork or other food containing melamine and its compounds to risk health effects." Other measures are being taken in addition to testing the animals, including improving the screening process for melamine by creating protein tests that do not rely on the measurement of nitrogen levels.

References


Chemical Description and Uses

  1. OECD (1998) [Screening Information Data Set for Melamine|http://www.chem.unep.ch/irptc/sids/OECDSIDS/108781.pdf], CAS No. #108-78-1, 17 Sept 08.
  2. OECD (1999)Screening Information Data Set for Isocyanuric acid, CAS No 108-80-5, 17 Sept 08.
  3. World Health Organization (2008). Melamine and Cyanuric acid: Toxicity, Preliminary Risk Assessment and Guidance on Levels in Food (PDF) 25 September 2008 - Updated 30 October 2008.History
    Nestle, Marion. "Melamine taint - old problem has new urgency." San Francisco Chronicle 22 Oct. 2008: F1.
  4. Pickert, Kate. "Melamine." TIME 17 Sept. 2008.

Health Effects

  1. http://www.fda.gov/oc/opacom/hottopics/melamine.html
  2. http://www.fda.gov/oc/opacom/hottopics/melamine.html#warnings
  3. http://www.cfsan.fda.gov/~dms/melamra3.html
  4. http://www.cfsan.fda.gov/~dms/melamra4.html
  5. http://www.who.int/mediacentre/news/releases/2008/pr48/en/index.html
  6. http://www.fda.gov/bbs/topics/NEWS/2008/NEW01891.html
  7. http://www.fda.gov/consumer/updates/formula091508.html
  8. http://www.nytimes.com/2008/11/26/us/26formula.html?partner=rss&emc=rss
  9. http://www.cnn.com/2008/US/11/28/infant.formula.melamine/
  10. http://children.webmd.com/news/20081126/melamine-in-us-baby-formula
  11. http://emergency.cdc.gov/agent/melamine/chinafood.asp
  12. Reimschuessel R, Gieseker CM, Miller RA, Ward J, Boehmer J, Rummel N, Heller DN, Nochetto C, de Alwis GK, Bataller N, Andersen WC, Turnipseed SB, Karbiwnyk CM, Satzger RD, Crowe JB, Wilber NR, Reinhard MK, Roberts JF, Witkowski MR. Evaluation of the renal effects of experimental feeding of melamine and cyanuric acid to fish and pigs.Am J Vet Res. 2008 Sep;69(9):1217-28.
  13. Melamine. 18 August 1998. UNEP Publications (PDF). 10 December 2008. 
  14. Interim Melamine and Analogues Safety/Risk Assessment. 25 May 2007. U.S. Food and Drug Administration.
  15. Yang, V.L. and Batlle, D. (2008) Acute renal failure from adulteration of milk with melamine. The Scientific World Journal 8, 974-975. DOI 10.1100/tsw.2008.137. 
  16. Thompson et al. Characterization of Melamine-containing and Calcium Oxalate Crystals in Three Dogs with Suspected Pet Food-induced Nephrotoxicosis. Vet Pathol.2008; 45: 417-426 
  17. http://wordpress.pocosin.com/?p=558
  18. http://msds.chem.ox.ac.uk/ME/melamine.html  
  19. http://www.cdc.gov/niosh/ipcsneng/neng1154.html
  20. http://www.osha.gov/dts/chemicalsampling/data/CH_250440.html 

Pharmacology and Metabolism

  1. OECD (1998) Screening Information Data Set for Melamine, CAS No. #108-78-1 read athttp://www.chem.unep.ch/irptc/sids/OECDSIDS/108781.pdf, 17 Sept 08 Regulation
  2. Hostetler, Mark. Regulations: Melamine Risk Assessment. 16 December 2007. 10 December 2008 <http://www.preparedfoods.com/CDA/Archives/BNP_GUID_9-5-2006_A_10000000000000169745>.
  3. Questions and Answers About Melamine as a Contaminant in Food. December 2008. 10 December 2008 <http://www.ific.org/publications/qa/melamineqa.cfm>.
  4. US FDA/CFSAN Interim Melamine and Analogues Safety/Risk Assessment. 25 May 2007. 10 December 2008 <http://www.cfsan.fda.gov/~dms/melamra.html>.
  5. FDA/USDA: Melamine Poses Low Risk to Humans.  07 May 2007. 11 December 2008. <http://www.newsinferno.com/archives/1564>
  6. Johnson, Tom. USDA Clears Hogs for Processing. 16 May 2007. 11 December 2008. <http://www.meatingplace.com/>
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