原發表於「與媒體對抗」,http://www.socialforce.tw/blog/blog_614__122423.html


FDA News, FOR IMMEDIATE RELEASE
October 3, 2008
美國食品暨藥物管理局,有關三聚氰胺的新聞稿
2008年10月3日


說明:有鑑於國內的多數討論,並不習慣將基礎訊息漢字化,往往形成各說各話的局面。因此,修伯特‧魚特翻譯美國食品暨藥物管理局在10月3日,針對三聚氰胺發表的新聞稿。事出特殊,本文採用英漢對照的方式呈現,敬請參閱。

FDA Issues Interim Safety and Risk Assessment of Melamine and Melamine-related Compounds in Food
美國食品暨藥物管理局,發佈食品中三聚氰胺與相關化合物的暫時性安全暨風險評估

The U.S. Food and Drug Administration (FDA) today issued the results of its interim safety and risk assessment of melamine and melamine-related compounds in food, including infant formula.
美國食品暨藥物管理局(以下簡稱FDA),今日發佈包含嬰兒奶粉在內的,食品中三聚氰胺與相關化合物(以下簡稱三聚氰胺)的暫時性安全暨風險評估的結果。

A safety/risk assessment is a scientifically based methodology used to estimate the risk to human health from exposure to specified compounds. It is based on available data and certain scientific assumptions in the absence of data. The purpose of the FDA interim safety/risk assessment was to identify the level of melamine and melamine-related compounds in food which would not raise public health concerns. The interim safety/risk assessment evaluated the melamine exposure in infant formula and in other foods.
安全暨風險評估是植基於科學的方法論,用於估計人體暴露在特定化合物時的健康風險,基礎是有效的數據和缺乏數據時的可靠科學假設。FDA暫時性安全暨風險評估的目的,是確認食品中所含三聚氰胺的何種標準,將引起公共衛生疑慮。這份結果評估嬰兒奶粉與其它食品中的三聚氰胺暴露值。

The safety/risk assessment, prompted by reports of melamine contamination of milk-derived ingredients and finished food products containing milk manufactured in China, was conducted by scientists from FDA's Center for Food Safety and Applied Nutrition and the Center for Veterinary Medicine. The FDA reviewed scientific literature on melamine toxicity.
為何提出這份評估,是因為中國製造的奶類相關製品含有三聚氰胺。這份評估由FDA所屬的食品安全暨實用營養中心,以及獸醫中心的科學家所指導,而FDA則重新探討三聚氰胺毒性的科學文獻。


Infant Formula
嬰兒奶粉


FDA is currently unable to establish any level of melamine and melamine-related compounds in infant formula that does not raise public health concerns. In large part, this is because of gaps in our scientific knowledge about the toxicity of melamine and its analogues in infants, including:
FDA目前無法設立不引起公共衛生疑慮的三聚氰胺標準。大部分的原因是有關三聚氰胺對嬰兒毒性的科學知識有落差,包括:

a. the consequences of the continuous use of infant formulas as the sole source of nutrition;
第一、連續使用嬰兒奶粉,作為營養單一來源的結果;

b. the uncertainties associated with the possible presence and co-ingestion of more than one melamine analogue; and
第二、可能存在並同時攝取超過一種三聚氰胺類似物;以及

c. for premature infants with immature kidney function, the possibility that they may be fed these formulas as the sole source of nutrition and thus on a body weight basis experience greater levels of intake for a longer time than is experienced by term infants.
第三、因為早產兒腎臟功能不成熟,且有以嬰兒奶粉作為單一營養來源的可能性,如此一來,比起足月嬰兒將會在同等體重單位上攝取更多更久的量。

There is too much uncertainty to set a level in infant formula and rule out any public health concern. However, it is important to understand that this does not mean that any exposure to any detectable level of melamine and melamine–related compounds in formula will result in harm to infants.
設立嬰兒奶粉的標準,與消除公共衛生疑慮有太多的不確定性。然而,重要的一點是這不意味著任何嬰兒奶粉中,含有可測出值的三聚氰胺與相關化合物,將導致嬰兒受害。


Other Food Products
其它食品


In food products other than infant formula, the FDA concludes that levels of melamine and melamine-related compounds below 2.5 parts per million (ppm) do not raise concerns. This conclusion assumes a worst case exposure scenario in which 50% of the diet is contaminated at this level, and applies a 10-fold safety factor to the Tolerable Daily Intake (TDI) to account for any uncertainties. The TDI is an estimate of the maximum amount of an agent to which an individual could be exposed on a daily basis over the course of a lifetime without an appreciable health risk.
嬰兒奶粉之外,FDA推定三聚氰胺含量低於2.5ppm(百萬分之一),不會產生疑慮。該推論是假定最糟糕的暴露想定,亦即50%的飲食含有2.5ppm的三聚氰胺,並對每日可容忍量適用10倍的安全因子,避免任何不確定性。每日可忍受量是某種劑量的最大值:個體一輩子的連續暴露,以每日為單位基礎,而不會有可察覺的健康風險的量值。

FDA continues to screen products, collaborate with foreign governments and their regulatory agencies, and monitor reports of contamination from international sources to help ensure that potentially contaminated products from foreign sources are examined if imported into the United States. If products are adulterated because they contain melamine and/or a melamine-related compound, the agency will take appropriate actions to prevent the products from entering commerce.
FDA將繼續過濾產品,與國外政府和主管機關共同合作,並監控國際產品的汙染報告,協助確保若進口到美國時,潛在的汙染產品將被驗出。若產品攙有三聚氰胺,FDA將採取適當行動,預防污染產品進入商業流通。

-----我是說明的分隔線-----

上面是FDA的新聞稿,在
同日發布的說明(Interim Safety and Risk Assessment of Melamine and its Analogues in Food for Humansa)有詳細的解釋。

FDA提到最近的研究報告(見註腳),無有害作用值的極限是「no-observed-adverse-effect-levels (NOAELs) are 63 mg/kg bw/d (13 weeks, oral with feed, in rats); 240 mg/kg bw/d (28 days, oral with feed, in rats); 417 mg/kg bw/d (14 days, oral with feed, in rats); and 1,600 mg/kg bw/d (13 weeks, oral with feed, in mice).

第一項是FDA現在採用的標準,亦即以每天每公斤體重直接餵食63mg(1/1000gram),不會產生有害的作用值。由動物實驗,換算到人類中長期慢性疾病的安全因子是100,也就是要將動物實驗值的數據除上安全因子(100),這樣得到人類的每公斤體重每日可容忍量是0.63mg。

計算如下:
63 mg melamine and its analogues/kg-bw/d (NOAEL) divided by 100-fold safety factor=0.63 mg melamine and its analogues/kg-bw/d (TDI).

然而,最近的研究又顯示三聚氰胺與三聚氰酸所結合的毒性更高,為避免這高度的不確定性,決定將安全因子再提高10倍到1000,人類每公斤體重的每日可忍受量就成為0.063mg。

計算如下:
0.63 mg melamine and its analogues/kg-bw/d divided by added 10-fold safety factor = 0.063 mg melamine and its analogues /kg-bw/d.

FDA又假設一個人的平均體重為60公斤,如此每日可忍受量就是3.78mg。

計算如下:
0.063 mg/kg-bw/d x 60 kg/person = 3.78 mg melamine and its analogues/person/day

但是每天的飲食不會通通都含有奶製品或污染物吧,所以用最糟糕的假設,每天飲食的50%含有三聚氰胺與類似物。在一天3公斤的飲食中,有1.5公斤受到汙染,那麼平均下來一公斤的食物就含有3.78/1.5 = 2.52(mg)

而2.52mg/ 1kg的換算,就是2.5ppm。美國FDA表示,這是他們認為不會造成有害作用值的上限。

-----我是進一步評論的分隔線-----

好吧,即使在研究證據不充分,我們還是得參酌美國FDA看法的情況下,就先假定長期攝取2.5ppm (2500ppb)的飲食是不會造成有害作用,而且政府用此為強而有力的後盾時,台灣消費者是否就能放心?

首先,要求更詳細的實驗數據,畢竟這是暫時性的評估。我相信各國會施壓中國,從廣大的人體試驗(不要笑,這是很悲哀的)結果,了解三聚氰胺與類似物對人體長期的影響。而各國也可能會有更具體的動物實驗,犧牲不少小鼠與大鼠,換取人類免於飲食恐懼的威脅。

其次,如同商品的營養成分必須標示反式脂肪的數據,雖然含量在2500ppb以下的產品可能得以販售,卻必須標示三聚氰胺與類似物的含量。在這個自由貿易的年代,公開資訊是非常重要的一環。

第三,檢討政府的危機處理能力。從預防而言,檢討管理與檢驗中國商品的政策;從反應而言,檢討施政反覆,與他國合作不利的癥結;從經驗而言,針對將來可能的類似事件,預先擬定不同想定,例如影響到20%的食品業、或影響到10%的食品業,與對社會不同層面的衝擊。

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