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作者：Donella H. Meadows
日期：10.16.00
當我還是個化學系的學生的時候，我的教授用肯定的話語告訴我們：在水裡加氟化物是件好事，因為上百萬的孩童可以因此避免蛀牙；而那些反對的人實在是又可笑又無知。我們這些正處於學習初期的化學家從這裡學到了兩個事情：氟化物是好的東西、科學家最瞭解事情的真相。
你會如何保護他的牙齒呢？
就在那個時候，瑞秋卡森正針對另一個關於殺蟲劑的議題，挑戰著科學的智慧。我受的教育告訴我：她也是個極可笑的人。然而，當我的閱讀量越來越多，涉略的範圍從化學拓展到生態學時，我瞭解到她是對的。儘管我仍然十分尊敬科學，但我逐漸瞭解到有一些科學家會匆促地下判斷、對問題瞭解有限或過時，或是忠於自己的意識型態和收入來源更甚於真相。
但當時的我並未質疑氟化物，大家一致認為它是好東西。牙醫師們支持它，製造牙膏的人更大肆宣揚它的優點。這個國家有一半以上的城市在飲用水中添加氟化物，也沒有產生明顯的壞影響。於是我把反對添加氟化物的人和那些不明飛行物體的擁護者和相信占星術的人歸為同一類：瘋子。
我從來也沒察看相關證據，在這件事情上我是完全地不科學。
最後，我還是得為此受罪。即將要添加氟化物到水中的鎮上人們一直要求我寫一篇關於這個主題的文章。我拖著、找一些藉口搪塞。他們送了許多資料給我，我一直沒讀----直到有一天出於好奇。
是否該添加氟化物？
然後我上網去、詢問我的同事們。當我越深入瞭解這個問題，我越感困惑。添加氟化物就像是死刑或是槍枝管制這類的議題一樣，總是存在廣泛的兩極化意見、牽涉到既得利益。站在不同邊的人各自選取對他們有利的證據，而且總是有足夠的證據來滿足雙方人馬。我頭昏了。
在這個過程中我變得比較沒有偏見。我瞭解了並不是所有支持氟化物的人們都作了功課，也不是所有反氟化物的人都是瘋子----他們裡面有許多牙醫師與科學家，還有1500名美國環保署的人員。兩方人士都相當程度地誇大其詞。
經過我旋風式地深入對這個爭論性的議題之後，以下我是我認為值得提出的結論。
- 氟化物的確能夠避免蛀牙。早在1940年代，一個牙醫師就注意到有「德州齒症」（一種因用水中自然含有高含量氟所造成的褐色、斑駁的牙齒症狀）的人們同時也具有異常低的蛀牙率。在比較了許多不同社區用水的自然含氟量之後，才確定了飲水中添氟百萬分之一是既保護牙齒又能避免引發牙齒斑駁的症狀（稱作氟中毒）。
- 自來水並不是唯一的氟來源。百萬分之一的劑量是在當牙膏中還沒有添加氟化物時所做的計算。今天我們可以從無酒精飲料、污染的空氣、水果果汁和孩童的維他命補充片中得到氟。一些研究顯示由於暴露於氟化物的機會增加，使得在水中添加氟化物的作法不但沒有保護牙齒的功能，反而增加氟中毒的危險。
- 氟是有毒的是物質，不需要太多的量就可以殺死植物、魚、貝、蟹、蝦和牛。對人類來說，過量的氟不但造成牙齒斑駁，也減低骨頭的強度。有一些科學的研究甚至認為氟與癌症、腦的損傷有所關連。市自來水處在飲水中添加的氟是來自佛羅里達的磷肥植物，這種植物能夠從煙囪所排放出來的廢氣中吸收氟化物以降低空氣污染的程度。所以這些氟化物中不但含氟，還有重金屬和其他污染物。如果沒拿來放在飲水中，將會被當作危險廢棄物來處理。
- 即使在自我吹噓的「美國牙醫協會期刊」中，也可以看到關於氟化物到底如何作用的爭論。它可能是經由吸收的過程植入牙齒的琺瑯質而作用，也可能是由於它能清洗嘴巴、避免斑菌的生長。在牙膏中添加氟化物的效果很可能與在飲水中添加氟化物一樣好。
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流行病學的證據並不足以說服任何一方。如果你比較一個在飲水中添加氟的城市（如多倫多）和一個不添加的城市（如溫哥華），你可以經由刻意挑選城市而得到你想要的結果。大多數的歐洲城市不在飲水中添氟，美國城市則多有添加。那麼是不是在歐洲就有較高的蛀牙率而美國人的骨頭受到較多的傷害？專家們的會議結果並不同意這兩個說法。這表示在飲水中添加低劑量的氟化物不管是正面的還是反面的效應都不是很大。
- 從這些結論理我們看到了不確定性、看到各種其他氟的來源、瞭解過量的可能性和氟對於其他生物形式的毒性。如果我住在一個正在決定是否要在飲水中添加氟的城市，我要問：難道沒有更好的方式來保護孩童的牙齒嗎？如果我們只是為了孩子的牙齒健康，為什麼我們要在整個供水系統中添加氟化物呢？這裡面有百萬加侖的水不過是用來沖洗廁所、沖澡並為草坪灑水罷了。為什麼要因此讓所有的人暴露於一種化學物質，同時有著具爭議性的好處，和某種無法掌握的風險！？為什麼將這樣的化學物質丟入供水中，然後讓它隨著污水處理廠和下水道而去，但是卻幾乎不曉得在那之後會發生什麼事？
全文及圖示詳見: http://www.gristmagazine.com/grist/citizen/citizen101600.stm
版權歸屬 Grist Magazine 環境信託基金會(蕭惠中譯，黃媺雯 審校)
中英對照全文：http://news.ngo.org.tw/reviewer
/donella/re-donella20001030.htm
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by Donella Meadows 10.16.00
Back when I was a chemistry major, my professors told me in no uncertain terms that water fluoridation is a boon. It prevents millions of children from getting cavities. People who oppose it are hysterical know-nothings. We budding chemists absorbed both the specific lesson and the general lesson. Fluoride is good. Scientists know best.
What would you do to protect his teeth?
At just that time Rachel Carson was questioning scientific wisdom with regard to another issue: pesticides. I was taught that she was hysterical too. However, as I read more widely and went beyond chemistry to ecology, I decided she was right. While I continued to respect science greatly, I came to see that some scientists can be hasty in judgment, narrow in understanding, out of date, or more loyal to their ideology or source of income than to the truth.
But I didn't question fluoride. The consensus was strong. The dentists were behind it. Toothpaste makers hyped it. Half the nation's cities fluoridate their water with no obvious ill effect. I classed fluoride opponents with UFO spotters and horoscope believers. Loonies.
I never looked at the evidence. I was thoroughly unscientific.
So my sins finally caught up with me. People in towns on the verge of fluoridation kept asking me to write a column on the subject. I delayed. I made excuses. They sent me piles of information, which I didn't read -- until, out of curiosity, one day I did.
To fluoridate or not to fluoridate?
Then I went to web. Then I started asking my scientific colleagues. The deeper I got into the topic, the more confused I got. Fluoridation is like capital punishment or gun control. Wildly polarized. Vested interests. Each side hoarding up selective evidence to prove itself right. Enough conflicting evidence to keep both sides happy. My head spun.
I did come out of the process more open-minded. Not all pro-fluoridation folks have done their homework. Not all anti-fluoridation folks are loonies -- they include dentists and scientists and 1,500 employees of the U.S. EPA. Both sides exaggerate a lot.
Here, for what they're worth, are some conclusions I drew after my whirlwind immersion in this contentious topic
- Fluoride does protect against cavities. Back in the 1940s, a dentist noted that people with "Texas teeth" -- brown, mottled teeth that came from naturally high fluoride levels in their water -- also had unusually low cavity rates. Comparisons of communities with varying natural fluoride levels led to the conclusion that about one part per million in drinking water was ideal to reduce tooth decay without triggering the mottling (which is called fluorosis).
- Tap water isn't the only source of fluoride. That dosage of one part per million was calculated at a time when there was no fluoride in toothpaste. Nowadays we also get fluoride in soft drinks, in air pollution, in fruit juice, in children's vitamin supplements. Studies over time seem to show that rising exposure to fluoride from other sources makes water fluoridation less protective of teeth and more likely to cause fluorosis.
- Fluoride is toxic. It doesn't take much of it to kill vegetation, fish, mussels, crabs, shrimp, cattle. In human beings overexposure not only mottles teeth, it weakens bone. There are scientific papers linking fluoride to cancer and brain damage. The fluoride used by municipal water districts comes from phosphate fertilizer plants in Florida, where it is stripped from smokestacks to reduce air pollution. It contains not only fluoride, but heavy metals and other contaminants. If it were not put in drinking water, it would have to be treated as hazardous waste.
- There are arguments, even in the vaunted Journal of the American Dental Association, about how fluoride actually works. It may be by ingestion, getting itself implanted into tooth enamel. It may be by washing the mouth, inhibiting the growth of plaque bacteria. Fluoride in toothpaste may be just as effective as fluoride in drinking water.
- The epidemiological evidence doesn't seem to be compelling either way. If you compare one fluoridated city (say, Toronto) with one unfluoridated one (Vancouver), you can pick your cities to get any result you want. Most of Europe does not use fluoride, much of America does. Is there more tooth decay there and more bone damage here? Expert panels have come down either way. That suggests that neither the positive nor the negative effects of fluoride (at low concentrations) can be very big.
Given the uncertainties, given the variation in intake from other sources, given the possibility of overdose, given known toxicity to other forms of life, if I lived in a city deciding about fluoridation, I would ask, isn't there a better way to protect children's teeth? Why fluoridate the whole water supply, the millions of gallons with which we flush toilets and take showers and water lawns, if our only target is children's teeth? Why expose all people to a chemical of arguable benefit and some risk in a way they can't control? Why dump that chemical into water supplies and then sewage plants and then waterways with almost no understanding of what happens to it after that?
http://www.gristmagazine.com/grist/citizen/citizen101600.stm
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