This article is about the chemical substance called melamine. The term "melamine" may also be used to refer to the plastic melamine resin.

Not to be confused with the pigment melanin, the hormone melatonin, or the melanotan peptides.

Template:Chembox new Melamine (Template:Pron-en melamine^ⓘ) 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 has several other industrial uses. Melamine is also a metabolite of cyromazine, a pesticide. It is formed in the body of mammals who have ingested cyromazine.^[1] It has been reported that cyromazine can also be converted to melamine in plants.^[2][3]

Melamine combines with cyanuric acid to form melamine cyanurate, which has been implicated in the Chinese protein export contaminations.

The German word melamin was coined by combining the names of 2 other chemical products: Melam (a distillation derivative of ammonium thiocyanate) and Amine. ^{[4] [5]}

Melamine is combined with formaldehyde to produce melamine resin, a very durable thermosetting plastic, and melamine foam, a polymeric cleaning product. The end products include countertops, dry erase boards, fabrics, glues, housewares and flame retardants. Melamine is one of the major components in Pigment Yellow 150, a colorant in inks and plastics.

Melamine also enters the fabrication of melamine poly-sulfonate used as superplasticizer for making high-resistance concrete. Sulfonated melamine formaldehyde (SMF) is a polymer used as cement admixture to reduce the water content in concrete while increasing the fluidity and the workability of the mix during its handling and pouring. It results in concrete with a lower porosity and a higher mechanical strength exhibiting an improved resistance to aggressive environments and a longer life-time.

The use of melamine as fertilizer for crops had been envisaged during the '50s and '60s because of its high nitrogen content (2/3)^[6]. However, the hydrolysis reactions of melamine leading to the nitrogen mineralisation in soils are very slow, precluding a broad use of melamine as fertilizing agent.

Melamine derivatives of arsenical drugs are potentially important in the treatment of African trypanosomiasis^[7]

Melamine use as non-protein nitrogen (NPN) for cattle was described in a 1958 patent.^[8] In 1978, however, a study concluded that melamine "may not be an acceptable non-protein N source for ruminants" because its hydrolysis in cattle is slower and less complete than other nitrogen sources such as cottonseed meal and urea.^[9]

Melamine is sometimes illegally added to food products in order to increase the apparent protein content. Standard tests such as the Kjeldahl and Dumas tests estimate protein levels by measuring the nitrogen content, so they can be misled by adding nitrogen-rich compounds such as melamine. ^[10]

Melamine by itself is nontoxic in low doses, but when combined with cyanuric acid it can cause fatal kidney stones due to the formation of an insoluble melamine cyanurate.^[11] Melamine is described as being "Harmful if swallowed, inhaled or absorbed through the skin. Chronic exposure may cause cancer or reproductive damage. Eye, skin and respiratory irritant.” However, the toxic dose is on a par with common table salt with an LD₅₀ of more than 3 grams per kilogram of bodyweight.^[12] FDA scientists explained that when melamine and cyanuric acid are absorbed into the bloodstream, they concentrate and interact in the urine-filled renal microtubules, then crystallize and form large numbers of round, yellow crystals, which in turn block and damage the renal cells that line the tubes, causing the kidneys to malfunction.^[13]

Melamine is reported to have an oral LD₅₀ of 3248 mg/kg based on rat data. It is also an irritant when inhaled or in contact with the skin or eyes. The reported dermal LD₅₀ is >1000 mg/kg for rabbits.^[14] In a 1945 study, large doses of melamine were given orally to rats, rabbits and dogs with "no significant toxic effects" observed.^[15]

A study by USSR researchers in the 1980s suggested that melamine cyanurate, commonly used as a fire retardant^[16], could be more toxic than either melamine or cyanuric acid alone.^[17] For rats and mice, the reported LD₅₀ for melamine cyanurate was 4.1 g/kg (given inside the stomach) and 3.5 g/kg (via inhalation), compared to 6.0 and 4.3 g/kg for melamine and 7.7 and 3.4 g/kg for cyanuric acid, respectively.

A toxicology study conducted after recalls of contaminated pet food concluded that the combination of melamine and cyanuric acid in diet does lead to acute renal failure in cats.^[18]

Ingestion of melamine may lead to reproductive damage, or bladder or kidney stones, which can lead to bladder cancer.^{[14][19][20][21]}<ref>{{cite journal | author = HD Heck and RW Tyl | title =The induction of bladder stones by terephthalic acid, dimethyl terephthalate, and melamine (2,4,6-triamino-s-triazine) and its relevance to risk assessment | A study in 1953 reported that dogs fed 3% melamine for a year had the following changes in their urine: (1) reduced specific gravity, (2) increased output, (3) melamine crystalluria, and (4) protein and occult blood.