Melamine (English name: Melamine) is a triazine nitrogen-containing heterocyclic organic compound and an important nitrogen-containing heterocyclic organic chemical raw material. Triamine for short, also known as 2,4,6-triamino-1,3,5-triazine, 1,3,5-triazine-2,4,6-triamine, 2,4,6-triamino Urea, melamine, melamine, cyanuric triamide, molecular formula C3N6H6, C3N3(NH2)3, molecular weight 126.12.

Melamine is a pure white monoclinic crystal, odorless, with a density of 1.573g/cm3 (16℃). Melting point under normal pressure is 354℃ (decomposition); rapid heating and sublimation, sublimation temperature is 300℃. Soluble in hot water, slightly soluble in cold water, very slightly soluble in hot ethanol, insoluble in ether, benzene and carbon tetrachloride, soluble in methanol, formaldehyde, acetic acid, hot ethylene glycol, glycerin, pyridine, etc. Low toxicity. It is relatively stable under normal circumstances, but may decompose and release cyanide at high temperatures.

It is weakly alkaline (pKb=8) and can form melamine salts with hydrochloric acid, sulfuric acid, nitric acid, acetic acid, oxalic acid, etc. In neutral or slightly alkaline conditions, it condenses with formaldehyde to form various hydroxymethyl melamines, but in slightly acidic conditions (pH value 5.5 to 6.5), it undergoes a polycondensation reaction with hydroxymethyl derivatives to form resin products. When hydrolyzed by strong acid or strong alkali aqueous solution, the amine group is gradually replaced by the hydroxyl group, first generating ammelide, further hydrolyzing to generate ammelide, and finally generating cyanuric acid.

Currently, melamine is considered mildly toxic, with the oral LD50 of rats greater than 3 g/kg body weight. According to an experimental report in 1945, no obvious poisoning was observed after feeding large doses of melamine to rats, rabbits and dogs. Long-term ingestion of melamine in animals can cause damage to the reproductive and urinary systems, bladder and kidney stones, and can further induce bladder cancer. The third volume of the "International Chemical Safety Manual" and the International Chemical Safety Card jointly compiled by the International Program on Chemical Safety and the European Commission in 1994 only state that long-term or repeated intake of large amounts of melamine may have effects on the kidneys and bladder. Lead to the formation of stones. However, the preliminary investigation results of the 2007 pet food contamination incident in the United States concluded that wheat protein powder adulterated with ≤6.6% melamine was the cause of pet food poisoning, which cast doubt on the conclusion that the above-mentioned toxicity was mild. However, for safety reasons, tableware generally made of melamine will be marked "not for use in microwave ovens."

On September 12, 2008, the Ministry of Health of the People's Republic of my country released the "Diagnosis and Treatment Plan for Urinary System Stones in Infants and Young Children Related to Consumption of Contaminated Sanlu Brand Infant Formula Milk Powder". Relevant parties can refer to it.

The plan points out that most stones involve the bilateral collecting system and bilateral ureters, which is different from the clinical manifestations of adult urinary system stones. Multiple stones have a higher probability of affecting renal function. Since many children do not have the ability to complain of symptoms, parents need to strengthen observation of the children involved. Relying on abdominal B-ultrasound and/or CT examination can help determine the diagnosis early. In terms of treatment, there is currently no specific antidote for the toxic effects of melamine. Clinical practice mainly relies on symptomatic and supportive treatment. If necessary, surgical intervention can be considered to relieve the risk of long-term renal damage in children. Early diagnosis and early treatment are the keys to a speedy recovery for children

Melamine is a low-toxic chemical raw material. Animal experiment results show that it is metabolized quickly in the animal body and does not persist, mainly affecting the urinary system.

There is an obvious dose-effect relationship between melamine dosage and clinical diseases. The maximum tolerated level of melamine in infants is 15 mg per kilogram of milk powder. A risk assessment conducted by experts on contaminated infant formula shows that, taking a 7-kg infant as an example, assuming a daily intake of 150 grams of milk powder, the safety predetermined value, that is, the maximum tolerated dose, is 15 mg/kg of milk powder.

According to the standards of the US Food and Drug Administration, the tolerable daily intake of melamine is 0.63 mg/kg body weight per day.

Batch list of melamine detected in liquid milk

Company serial number, manufacturer, product name, specification, model, trademark, production date/batch, melamine (mg/kg)

Mengniu 1 Mengniu (Wuhan) Youzhiyou Dairy Co., Ltd. Walnut milk 200ml/bag Youzhiyou 20080910 0.765

Mengniu 2 Inner Mongolia Mengniu Dairy (Group) Co., Ltd. Mengniu high calcium low-fat milk 250ml/box Mengniu 2008.08.07 0.8

Mengniu 3 Inner Mongolia Mengniu Dairy (Group) Co., Ltd. Full-fat sterilized pure milk 250ml/box Mengniu 2008.09.01 1.0

Mengniu 4 Inner Mongolia Mengniu Dairy (Group) ) Co., Ltd. high-calcium low-fat milk 250ml/box Mengniu 2008.08.01 1.5

Mengniu 5 Inner Mongolia Mengniu Dairy (Group) Co., Ltd. breakfast milk (wheat flavor) 250ml/pack Mengniu 20080814 1.9

Mengniu 6 Inner Mongolia Mengniu Dairy (Group) Co., Ltd. Mengniu Breakfast Milk 250ml/box Mengniu 2008.07.26/x 2.57

Mengniu 7 Inner Mongolia Mengniu Dairy (Group) Co., Ltd. Wonderful Points 250ml/ Box Mengniu 20080728/W206 3.17

Mengniu 8 Mengniu Dairy (Beijing) Co., Ltd. The company's high calcium low-fat milk 243ml (250g)/bag Mengniu 20080908/C206/GAfb 4.2

Mengniu 10 Mengniu Dairy (Ma'anshan) Co., Ltd. Mengniu large fruit yogurt 160g/box Mengniu M20080903 6.8 (A sample)

Mengniu 11 Mengniu Dairy (Maanshan) Co., Ltd. Mengniu large fruit yogurt 160g/box Mengniu M20080903 7 (B sample)

Yili 1 Jinan Yili Dairy Co., Ltd. Yili Mango + Yellow Peach yogurt 125g/box Yili 2008.09.07 0.69

Yili 2 Inner Mongolia Yili Industrial Group Co., Ltd. yogurt (papaya + sweet orange) 125g/bottle Yili 20080903 1.02

Yili 3 Inner Mongolia Yili Industrial Group Co., Ltd. pure milk 220ml/bag Yili 2008.09.13 2.2

Yili 4 Inner Mongolia Yili Industrial Group Co., Ltd. skimmed milk 250ml/box Yili 20080820 2.9

Yili 5 Inner Mongolia Yili Industrial Group Co., Ltd. pure milk 220ml/bag Yili 20080905MIAC6 5.5

Yili 6 Inner Mongolia Yili Industrial Group Co., Ltd. pure milk 242ml/bag Yili 20080906/LIA09 8

Yili 7 Inner Mongolia Yili Industrial Group Co., Ltd. high-calcium low-fat milk 250ml/box Yili 20080819 8.4

Guangming 1 Beijing Guangming Jianneng Dairy Co., Ltd. Guangming yogurt (original) 180g/bag Guangming 2008.09.12 0.6

Guangming 3 Beijing Guangming Jianneng Dairy Co., Ltd. Original Yogurt 100g/cup Guangming 20080910A 3.5

Guangming 4 Beijing Guangming Jianneng Dairy Co., Ltd. Large Fruit Strawberry Yogurt 450g/box Guangming 20080902BC 4.8

Guangming 5 Guangming Dairy Co., Ltd. Probiotic·Excellent Yoghurt (formerly

Flavor) 190g/can Guangming B20080908C 5.65

Guangming 6 Beijing Guangming Jianneng Dairy Co., Ltd. Yogurt Yogurt (original flavor) 580g/bottle Guangming B20080909A 8.6