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世界卫生组织(WHO)关于中国大陆婴儿奶粉人为污染三聚氰胺的全球通报
作者:USMedEdu
发表时间:2008-09-26
更新时间:2008-09-26
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Melamine-contamination event, China, September 2008

Melamine and Cyanuric acid: Toxicity, Preliminary Risk Assessment and Guidance on Levels in Food
Full information [pdf 70kb]
25 September 2008

http://www.who.int/foodsafety/fs_management/infosan_events/en/index.html


Description of the event
Nearly 40 000 cases of kidney stones in infants with three deaths (and one unconfirmed) related to the consumption of melamine-contaminated powdered infant formula have been reported from across China as of 21 September 2008. Almost 12 900 are currently hospitalized. Kidney stones in infants are very rare.

While the exact onset date of illness resulting from contamination and the beginning of the contamination itself remain unknown, a manufacturer (Sanlu) received a complaint of illness in March 2008.

Chinese media reported at the beginning of September that Sanlu brand infant formula produced by Hebei-based Sanlu Group was contaminated with melamine. Sanlu\'s powdered infant formula is widely consumed by infants across China because the product is relatively affordable compared to others.

Following inspections conducted by China’s national inspection agency, at least 22 dairy manufacturers across the country were found to have melamine in some of their products.

Two companies, Guangdong Yashili and Qingdao Suokang, exported their products to Bangladesh, Burundi, Myanmar, Gabon and Yemen. While contamination in those exported products remains unconfirmed, a recall has been ordered from China.

Other countries, however, have also reported finding melamine in dairy products manufactured in China.

So far, contamination has also been found in liquid milk, frozen yogurt dessert and in coffee drink. All these products were most probably manufactured using ingredients made from melamine contaminated milk.

In 2007, melamine was found in pet feed manufactured in China and exported to the United States of America, and caused the death of a large number of dogs and cats due to kidney failure.

Presentation of melamine
Melamine is a chemical compound that has a number of industrial uses, including the production of laminates, glues, dinnerware, adhesives, molding compounds, coatings and flame retardants. Melamine is a name used both for the chemical and for the plastic made from it. In this event, all references are to the chemical. There are no approved direct food uses for melamine, nor are there any recommendations in the Codex Alimentarius. Melamine is illegally added to inflate the apparent protein content of food products. Because it is high in nitrogen, the addition of melamine to a food artificially increases the apparent protein content as measured with standard tests.

Source of the contamination
In this event, contamination appears to have happened as fraudulent contamination in primary production. Chinese government officials have pinpointed milk collecting stations as the sites where the melamine was added. According to Sanlu, contaminated milk was used in the manufacture of powdered infant formula processed before 6 August 2008 and the tainted milk powder has also been used in the manufacture of a number of other products.

Contamination levels
There are a total of 175 infant formula manufacturers across China, of which 66 have halted production and the remaining 109 manufacturers have undergone inspection due to the current events of melamine contamination. The inspections\' results presented by the Administration of Quality Supervision, Inspection and Quarantine (AQSIQ) show evidence of the presence of melamine. Out of 491 batches tested, 69 of them, produced by 22 companies, tested positive for Melamine.

According to the State Council of China, the levels found in the batches ranged between 0.09 mg/kg and 619 mg/kg. Batches from the company Shijiangzhuang Sanlu Co. contained the highest levels, up to 2563 mg/kg.

Toxicology of melamine
In this section

Description of the event
Melamine contamination
Toxicology of melamine
Epidemiology and treatment
Actions taken by INFOSAN

Based on the previous incidents of melamine contaminated pet food and the development of kidney stones and subsequent acute kidney failure in cats and dogs, it appears that melamine and its structural analogues, such as cyanuric acid, may act together to form crystals. This crystal formation occurs at very high-dose levels and is a threshold and concentration dependent phenomenon, which would not be relevant at low levels of exposure (US FDA/CFSAN Interim Melamine and Analogues safety/risk assessment http://www.cfsan.fda.gov/~dms/melamra.html).

Exposure
Consumer exposure to melamine is considered to be low, but may occur through the extraction of melamine from compression moulds by acidic foods, such as lemon or orange juice or curdled milk, at high temperature. Taking into account these sources the estimated oral uptake of melamine is around 0.007 mg melamine/kg/day (OECD 1998).

Toxicity of melamine
Melamine is not metabolized and is rapidly eliminated in the urine. No human data could be found on the oral toxicity of melamine but there are data from animal studies. These show the compound to have a low acute toxicity, with an oral LD50 in the rat of 3161 mg/kg body weight. In animal feeding studies, high doses of melamine have an effect on the urinary bladder, in particular causing inflammation, the formation of bladder stones and crystals in the urine. Analysis of the bladder stones has shown that these are a mixture of melamine, protein, uric acid and phosphate. Animal studies have generally not shown any renal toxicity or the formation of kidney stones.

Carcinogenicity
The International Agency for Research on Cancer (IARC) has concluded that there is sufficient evidence in experimental animals for the carcinogenicity of melamine under conditions in which it produces bladder stones. There is inadequate evidence for carcinogenicity in humans.

Role of melamine in the formation of kidney stones
Animal data have not shown that melamine alone causes renal failure or the formation of kidney stones. Evidence from an earlier outbreak of acute renal failure in cats and dogs associated with contaminated pet food suggests that a combination of melamine and cyanuric acid does cause renal toxicity. Both of these compounds were found in the pet food together with other triazine compounds. Subsequent experimental studies in animals have shown that when they are fed a mixture of melamine and cyanuric acid this causes the formation of crystals in the tubules of the kidneys, eventually blocking them and causing renal damage and renal failure. The source of the cyanuric acid in the pet food was unknown but it may have been present as a contaminant of the melamine that had been illegally added to wheat gluten used in formulating the petfood. In the current event in China, the presence of cyanuric acid has not yet been confirmed.

Health-based Guidance Values
Following the petfood incident in 2007 described above, several authorities have preformed preliminary risk assessments.

The US FDA has published an interim safety/risk assessment on melamine and structural analogues and has established for melamine a tolerable daily intake TDI of 0.63 mg per kg of body weight per day.

The European Food Safety Authority has published a provisional statement and recommended to apply a TDI of 0.5 mg per kg of body weight per day as tolerable intake value for melamine.

Epidemiology and treatment
In this section

Description of the event
Melamine contamination
Toxicology of melamine
Epidemiology and treatment
Actions taken by INFOSAN

Suggested surveillance case definition
Identification of possible cases related to the consumption of melamine-contaminated products from China

Member States should be aware of the possible distribution of the contaminated products either through formal or informal channels, because of the large quantities involved and the seriousness of the public health consequences of this event. The period of production of contaminated product is uncertain and the incriminated raw material and products may have been exported as infant formula or other milk containing products to other Member States. Therefore WHO is suggesting this surveillance case definition to Member States to increase their awareness of signs that their population may be affected.

Clinical description
The following symptoms have been observed in infants affected by the melamine-contaminated infant formula in China:

Unexplained crying in infants, especially when urinating, possible vomiting
Macroscopic or microscopic haematuria
Acute obstructive renal failure: oliguria or anuria
Stones discharged while passing urine. For example, a baby boy with urethral obstruction with stones normally has dysuria
High blood pressure, edema, painful when knocked on kidney area
WHO experts believe an additional symptom may be unexplained fever arising from urinary tract infections/bacteraemia secondary to urine stasis resulting from obstruction.

Surveillance case definition
A case is defined as an infant with kidney stones or other kidney problems (e.g. anuria, renal failure) having consumed powdered infant formula produced in China before 6 August 2008, and where other potential causes of kidney stones have been excluded by differential diagnosis.

Treatment
The World Health Organization has agreed to circulate the information contained herein regarding the treatment plan that is being implemented in China by the Ministry of Health. The information below does not reflect the rules, regulations, policies and guidelines of the World Health Organization.

The following regimen has been issued by the Ministry of Health, China.

Clinical manifestations
Unexplained crying, especially when urinating, possible vomiting
Macroscopic or microscopic haematuria
Acute obstructive renal failure: oliguria or anuria
Stones discharged while passing urine. For example, a baby boy with urethral obstruction with stones normally has dysuria
High blood pressure, edema, painful when knocked on kidney area
Key diagnostic criteria
Been fed with melamine-contaminated infant milk formula
Having one or more of the above clinical manifestations
Laboratory test results: routine urine tests with macroscopic or microscopic haematuria; blood biochemistry; liver and kidney function tests; urine calcium/creatinine ratio (usually normal); urinary red blood cell morphology shows normal morphology of red blood cells (not glomerular haematuria); parathyroid hormone test (usually normal).
Imaging examination: preferably ultrasound B exam of urinary system. If necessary, abdominal CT scan and intravenous urography (not to be used in case of anuria or renal failure). Kidney radionuclide scans can be used where available to evaluate renal function.
Ultrasound examination features:
General features: bilateral renal enlargement; increased echo on solid tissue; normal parenchyma thickness; slight pyelectasia and calicectasis; blunt renal calyx. If the obstruction locates in the ureter, then the ureter above the obstruction point dilates. Some cases have edema with perinephric fat and soft tissue around the ureter. As the disease develops, the renal pelvis and ureter wall may have secondary edema. A few cases have ascites.
Stone features: most stones affect the collecting system and ureters on both sides. Ureteral stones are mostly at pelviureteral junction, the part where the ureter passes across iliac artery, and ureter-bladder junction. Stones stay collectively, covering massive areas. Lighter echo in the background. Most stones are different from the calcium oxalate stones. Urinary tract is mostly completely obstructed by the stones.
Differential diagnosis
Haematuria differentiation: need to rule out glomerular haematuria.
Stone differentiation: the stones are normally radiolucent and have a negative image on urinary tract x-ray. This feature differentiates the stones from those of radiopaque stones of calcium oxalate and calcium phosphate.
Differentiation of acute renal failure: need to rule out pre-renal and renal failure.
Clinical treatment
Immediately stop using melamine-contaminated infant formula milk powder.
Medical treatment: use infusion and urine alkalinization to dispel the stones. Correct the water, electrolyte and acid-base imbalance. Closely monitor routine urine tests, blood biochemistry, renal functions, ultrasound findings (with particular attention to the renal pelvis, ureter expansion, and the change of the stones in shape and location). If the stones are loose and sand-like, they are very likely to be passed out with urine.
Treatment of complicated acute renal failure: priority should be given to the treatment of life-threatening complications such as hyperkalemia. Measures include the administration of sodium bicarbonate and insulin. If possible, blood dialysis and peritoneal dialysis can be used early. Surgical measures can be taken to remove the obstruction if necessary.
Surgical treatment: if medical treatment is not effective, and hydrocele and kidney damage present, or blood dialysis and peritoneal dialysis are not available in case of renal failure, surgical methods can be considered to remove the obstruction. Stones can be removed by different methods including cystoscope retrograde intubation into the ureter, percutaneous kidney drainage, surgical removal and percutaneous kidney stone removal. Extracorporeal shock wave lithotripter (ESWL) is greatly limited in its application, because the stones are loose and mainly composed of urate, and the patients are infants.
Follow-up
Once the urinary obstruction is relieved, and the general condition and renal function and urination are back to normal, the children can be discharged.

Key issues to follow-up
Urine routine tests; ultrasound of urinary system; renal function tests; IVP (intravenous pyelogram) if necessary.

Actions taken by INFOSAN
In this section

Description of the event
Melamine contamination
Toxicology of melamine
Epidemiology and treatment
Actions taken by INFOSAN

INFOSAN is working directly with Ministry of Health (MoH), China in collaboration with the WHO Country Office in China. Through the INFOSAN Emergency surveillance system, WHO has learned of the contamination of infant formula with melamine and requested further information about the event on the 11 September 2008. MoH confirmed on 12 September 2008 that incriminated products from the Sanlu Company had not been exported and provided WHO with a description of the development of the event. Through further interaction between INFOSAN and MoH the issue of potential other use of the contaminated milk powder as well as parallel (illegal) distribution of contaminated milk powder was raised. An INFOSAN alert was subsequently distributed to the entire network on the 16 September 2008 alerting members of the event and of the possibility of contaminated products finding their way to other markets.

INFOSAN has several times during the past week, kept the entire network informed of developments in relation to this event as well as additional information on other products being found contaminated, information about the toxicity of the melamine and other information to help Member States better understand and assess the potential risks associated with melamine contaminated products.

The Chinese authorities, in their on-going investigation, discovered that 2 producers found to have products contaminated with melamine had exports going to five countries, INFOSAN informed these five countries of the situation.

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共有4条评论
1   [USMedEdu 于 2008-09-30 14:48:54 提到] [FROM: 10.]
Melamine-contaminated powdered infant formula in China - update 2

29 September 2008 -- More than 54,000 infants and young children have sought medical treatment in relation to the melamine-contaminated dairy products in China, causing kidney stone. Three deaths among infants have been confirmed, more than 13,000 infants are in hospital. Kidney stones in infants are normally very rare.

The World Health Organization has published “Melamine and Cyanuric acid: Toxicity, Preliminary Risk Assessment and Guidance on Levels in Food”. This preliminary guidance was developed to assist national authorities in the decision-making process on deciding possible health concern of melamine levels in food.

This preliminary guidance is proposed as a first pragmatic approach until more data become available which would allow a more detailed assessment.

 
2   [USMedEdu 于 2008-09-30 14:47:21 提到] [FROM: 10.]
Questions and Answers on melamine

http://www.who.int/csr/media/faq/QAmelamine/en/index.html



What is melamine?
Melamine is an organic base chemical most commonly found in the form of white crystals rich in nitrogen

What is melamine generally used for?
Melamine is widely used in plastics, adhesives, countertops, dishware, whiteboards.

Why was melamine added into milk and powdered infant formula
In China, where adulteration has occurred, water has been added to raw milk to increase its volume. As a result of this dilution the milk has a lower protein concentration. Companies using the milk for further production (e.g. of powdered infant formula) normally check the protein level through a test measuring nitrogen content. The addition of melamine increases the nitrogen content of the milk and therefore its apparent protein content.

Addition of melamine into food is not approved by the FAO/WHO Codex Alimentarius (food standard commission), or by any national authorities.

Has melamine been found in other food products?
In 2007, melamine was found in wheat gluten and rice protein concentrate exported from China and used in the manufacture of pet food in the United States. This caused the death of a large number of dogs and cats due to kidney failure.

In the present event, melamine contamination has been found in a number of different brands of powdered infant formula, in one brand of a frozen yogurt dessert and in one brand of canned coffee drink. All these products were most probably manufactured using ingredients made from melamine-contaminated milk.

What are the health effects of melamine consumptions in humans?
While there are no direct human studies on the effect of melamine data from animal studies can be used to predict adverse health effects. Melamine alone causes bladder stones in animal tests. When combined with cyanuric acid, which may also be present in melamine powder, melamine can form crystals that can give rise to kidney stones.

These small crystals can also block the small tubes in the kidney potentially stopping the production of urine, causing kidney failure and, in some cases, death. Melamine has also been shown to have carcinogenic effects in animals in certain circumstances, but there is insufficient evidence to make a judgment on carcinogenic risk in humans.

What are the symptoms and signs of melamine poisoning?
Irritability, blood in urine, little or no urine, signs of kidney infection, high blood pressure

What is the treatment for kidney stones and kidney failure?
Patients may receive various types of treatment, depending on the severity of the kidney effects. Treatment may include infusion of fluids and urine alkalinisation, correction of electrolyte and acid-base disturbance, haemodialysis or peritoneal dialysis, or surgical removal of kidney stones.
 
3   [dokknife 于 2008-09-29 12:58:05 提到] [FROM: 10.]
世界卫生组织提醒人们:中国不是万恶之源

--------------------------------------------------------------------------------

德国之声 2008-09-27 17:25:13

中国爆出奶制品内发现三聚氰胺的丑闻之后,引起了全世界的关注。由于受到污染的产品不仅仅在中国本土销售,有可能还出口到了国外,因此在很多国家和地区都引发了针对中国奶制品的调查。欧盟已经对中国进口奶制品做出了严格规定。此外,毒奶粉丑闻在台湾地区也引起了重大动荡,甚至导致内阁人事变动。

鸡肉和猪肉里发现药物成分,蔬菜里有杀虫剂,现在牛奶里又出现了三聚氰胺。骇人听闻的中国食品质量丑闻可谓层出不穷。世界卫生组织驻中国代表,瑞典人特罗德森对此非常清楚,"官方表示迄今为止有三名婴儿死亡,媒体则报道说有四个。此外还有1200多名婴儿还在医院接受治疗,其中大约100人病情严重。我们认为,死亡婴儿人数还会大幅升高。"

这三到四名婴儿因为就医过晚,而死于感染。世界卫生组织表示,目前仍在受肾结石之苦的那些患病婴儿能够得到很好的医治。世卫组织食品安全主管,丹麦人舒隆特对于中国有毒奶制品的出口也发表了意见:"从国际层面而言,了解是否有污染产品出口事关重要。中国官方已经对所有厂家进行了检查。其中两家的产品有问题。我们已经通知了五个相关国家,尽管这并不意味着他们肯定进口了有毒奶粉。但这些国家还是应该对他们从中国进口的产品进行检测。"

这些国家是加蓬,布隆迪,也门,孟加拉和缅甸。有关中国有毒奶粉出口的消息震惊世界,人们到处搜寻三聚氰胺的踪迹。但是世卫组织食品安全主管舒隆特表示,人们不必过度制造恐慌气氛,"很多包装材料中也含有三聚氰胺,因此食品中也会带上浓度很低的少量三聚氰胺。但这绝对是无害的。如果浓度高的话,就是说超过十万倍浓度的话,那就有危险,必须采取措施。因为这样人相对而言很快就会得上肾结石。"

世卫组织也在向前看,就中国今后如何避免类似丑闻进行研究。专家的建议是:中国不但需要明确的法律和法规,这些法律法规也必须得到切实的执行。但这恰恰是没有权力制衡和独立检测的一党制国家的弱点所在。"目前很多国家都存在的一个问题是,没有明确的责任归属。这也是中国的一个问题。人们发现了问题,并首先向卫生部食品监控部门报告。但是还有多达16个部门也对此负有责任。这不是一个完善的结构。我们已经对中国表达了这个意思,对其他国家也是这么说的。"

尽管如此,世卫组织依然告诫人们,不要把中国描绘成"万恶之源"。在规模庞大的食品生产领域中建立有效的监控系统并不简单,没有人能够做到完美。舒隆特表示,"我们可以把这里的情况与其他国家进行一番比较。1995年,欧洲发现疯牛病,并传播到全世界。稍候不久比利时又爆发了二恶英丑闻。但我们当时也并没有说,欧洲的所有有产品都很糟糕。这些问题会出现在发达国家,同样也会出现在新兴工业国家。现在我们帮助中国对相关机制进行改善。但是宣称所有食品安全问题都源于中国,则是完全错误的。"

有鉴于中国毒奶粉事件的影响,欧盟本周四做出决定,彻底停止从中国进口任何含有牛奶成分的婴儿食品,此外,牛奶含量超过15%的食品都要进行检测,由于欧盟并不从中国直接进口牛奶和奶粉,因此这一措施主要针对的是巧克力或者饼干等产品。此外,毒奶粉时间在台湾也掀起轩然大波,岛内媒体甚至认为这是马英九政府上台以来面对的最大政治危机。台湾卫生署制订标准,规定食品内三氯氰胺的检测浓度不能高于2.55个百万分之一浓度。但这一标准遭到各界强烈质疑,认为过于宽松,反对党民进党更是对马英九政府严厉抨击。本周四,台湾卫生署长林芳郁在压力之下请辞获准,政治分析家认为,这甚至可能会引起马英九政府的大规模人事动荡。

 
4   [USMedEdu 于 2008-09-26 10:09:44 提到] [FROM: 10.]
Melamine-contaminated powdered infant formula in China - update
22 September 2008

http://www.who.int/csr/don/2008_09_22/en/index.html


-- China’s Ministry of Health reported over the weekend that nearly 40,000 children have sought medical treatment related to the consumption of melamine-contaminated powdered infant formula. Almost 12,900 are currently hospitalized.

Three deaths have been confirmed as being related to contamination of infant formula. One is under further investigation.

Authorities of Singapore and Hong Kong SAR reported finding melamine in dairy products manufactured in China. A three-year old girl received treatment in Hong Kong due to consumption of the contaminated milk.

WHO will continue to share information through its International Food Safety Authorities Network (INFOSAN) to help national authorities to be better informed and enable them to better target their monitoring.
 
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