50ppb FDA 文章出處與討論

相信大家看過這個新聞報導,

==================================================
【聯合報╱記者劉惠敏╱台北報導】 2008.09.25 03:09 am
.............恕刪

劉培柏說，目前國際學術界至少還有幾十篇文章在討論標準、原則，尚無定論，且根據美國食品藥物管理局（FDA）去年五月廿四日一文，在討論【家禽、魚類內含三聚氰胺，其中就認為最低檢測標準應該訂為五十ppb】，超量對健康不利。
================================================

現在都認為美國FDA三聚氰胺的標準含量就是訂在50ppb. 在這裡給大家看看原文的出處 (文章日期與上面文章相差一日, 因該是相同的文章)

http://www.cfsan.fda.gov/~dms/melamra.html#execsum

看來看去, 那個50ppb 的討論到底在哪哩?
=============================================
Melamine and Analogues Intake Scenarios

..........The 50 ppb level represents a conservative estimate of the Limit of Detection (LOD) for the methods employed; a value that will ensure that the exposure scenarios are in turn conservative. (The LOD is the level below which a contaminant cannot be measured with current analytical methods.) "
===============================================
大家可以用翻譯軟體翻譯一下.

大家看清楚, 文章提到的50ppb 是用目前檢測手法可以量測到的最小單位 (Limited of Detection) 這哪是建議標準?!! 台灣官員的腦袋在裝啥東西哩?

文章都不看清楚就要亂開砲

好了, 罵完腦殘的政府官員, 回到重點, 這個FDA的文章到底在講啥

其中一個重點
=============================================
Toxicological Profile

..................恕刪

The NOAEL for stone formation of melamine toxicity is 63 mg/kg bw/day in a 13-week rat study
==============================================
上面文章的意思是, 用老鼠做了13周的實驗, 結論是NOAEL (no-observed-adverse-effect-levels) 是在每天63mg的量沒有產生任何不良反應.

結論
================================================
Margins of Safety and Levels of Concern for Melamine Compounds

The point of departure (POD) is the NOAEL of 63 mg/kg/day from the rodent subchronic bioassay. This POD was then divided by two 10-fold safety/uncertainty factors (SF/UF) to account for inter- and intra-species sensitivity, for a total SF/UF of 100. The resulting Tolerable Daily Intake (TDI) is 0.63 mg/kg bw/day. The TDI is defined as the estimated maximum amount of an agent to which individuals in a population may be exposed daily over their lifetimes without an appreciable health risk with respect to the endpoint from which the NOAEL is calculated.
===============================================

在根據老鼠實驗的結論, 63mg/day 在加上100倍(10 fold)的安全跟不確定值估算, 每天的可接受安全量TDI (Tolerable Daily Intake) [因該是在0.63mg/kg/day ]

所以答案在這裡, 每天每公斤0.63mg

附註: FDA 文章是討論一個60kg 的人在吃下用含有三聚氰胺飼料餵食的農產品(豬肉, 雞肉) 會不會有害健康.

=================================================
Margins of Safety and Levels of Concern for Melamine Compounds
...................恕刪the consumption of pork, poultry, eggs and domestic fish is very unlikely to pose a human health risk.
================================================

這是[Margins of Safety and Levels of Concern for Melamine Compounds]這一段, 最後一句話講的很清楚, 吃下農產品含有100ppb三聚氰胺是不會造成人體健康的, 因為食用量不會達到0.63mg 的每天容許量

那怎樣才算是安全? 0.63mg = 0.00063g
如果依照衛生署的2.5ppm 計算, 1kg 的奶粉三聚氰胺含量會在2.5mg. 以一個60kg 的人來說, 0.63mg/kg/day * 60kg = 37.8mg/day

所以, 每天吃一公斤含有2.5ppm 的奶粉, 會獲得 2.5mg 的三聚氰胺是不會超過FDA 安全標準的