《农业转基因生物知识100问》争议点之三：Pusztai事件
蒋高明
99. 国外转基因“事件”有哪些？
答：（1）关于Pusztai事件 英国Rowett研究所Pusztai博士用转雪花莲凝集素基因的马铃薯喂大鼠，1998年秋在英国电视台发表讲话，声称大鼠食用后“体重和器官重量减轻，免疫系统受到破坏”。此事引起国际轰动，绿色和平组织、地球之友等组织称其为“杀手”马铃薯，策划了破坏试验地、焚烧转基因作物、阻止转基因产品进出口、游行示威等活动。英国政府对此非常重视，委托皇家学会组织了同行评审，评审结果指出Pusztai的实验结论不成立，存在六方面的错误，即不能确定转基因和非转基因马铃薯的化学成分有差异；对食用转基因马铃薯的大鼠未补充蛋白质以防止饥饿；供试动物数量少，饲喂几种不同的食物，且都不是大鼠的标准食物，缺少统计学意义；实验设计不合理，未作双盲测定；统计方法不当；实验结果无一致性等。 事情果然如此吗？真的存在六方面的错误吗？北京大学科学与社会研究中心科学技术哲学专业硕士生何玲撰文指出了这件事情的疑点： (1)访谈Pusztai的电视节目于1998年8月10日播出，3天后即被Rowett研究所劝退，并不是等到皇家学会于99年5月公布调查结果之后。
(2)1999年10月，权威医学期刊The Lancet发表了Pusztai与其合作者Stanley Ewen共同署名发表的就这一研究的论文，而皇家学会的调查评论发表于1999年5月，皇家学会为什么没有等到Pusztai的研究正式发表之后再来作结论呢？
(3)Pusztai在Rowett研究所工作了35年，已经发表了270篇论文和3本专著，何以这样一位老资格的科学家在自己熟悉的领域里的研究会有6方面如此之多的错误？ Pusztai发表的论文引起了欧洲对转基因食品安全性的怀疑，也触动了生物技术寡头的利益。英国首相办公室两个电话打到Pusztai工作过的研究所，并在三天内被解雇。《新科学家》(New Scientist)杂志以“转基因土豆的英雄传奇原来是一出闹剧”的标题撰文写道：“对转基因食品的可怕的警告被证明是错误的，引起恐慌的大鼠实验根本就没有做。”
但是，1999年2月21名科学家的一份联合声明使得Pusztai一下子从犯了错误的科学家变成了维护公众利益的悲剧英雄。1999年2月12日，分别来自9个国家的21名科学家发表声明支持Pusztai，要求Rowett研究所免除Pusztai的罪名，呼吁先行研究转基因生物体的未能预见的危害，在此之前暂停转基因作物的种植。科学家们谴责Rowett研究所主任Philip James剥夺了Pusztai的言论自由并且压制了科学数据，Pusztai从此成为维护公众利益而勇敢揭露生物公司内幕并因此被阴谋迫害的英雄。英国众议院的一些成员立刻要求暂停转基因作物的种植，并争论政府或者生物技术公司是否压制了对他们不利的科研数据。 后来，英国著名的柳叶刀杂志(The Lancet)正式发表Pusztai的论文就是证实了Pusztai的研究结果。柳叶刀主编Horton征求了六位评审人意见，六位中有五位同意发表，其中有一位评审人认为Pusztai的数据是“有错误的”，但是他说“我希望看到这篇文章公开发表，这样同行的科学家们可以作出自己的判断……如果不发表这篇文章的话，那就可能有压制不利数据的嫌疑”。 国内停转专家仅引用的是《新科学家》对Pusztai实验结果的单方面指责，完全没有引用后面《柳叶刀》对该事件的进一步事实澄清。这好比看一场悬念片，仅看到一半就匆忙下了结论。而国内学者得到的信息是从某些转基因推手断章取义得来的，是选择性失明。 《农业转基因生物知识100问》中的第99问依然以讹传讹，就是对国内读者的知情权不尊重了。
最近，笔者收到美国著名学者Jeffrey M. Smith 的电子邮件，他在《Biotech's Dirty Tricks Exposed in New Documentary Scientists Under Attack》一文中，重新回顾了Pusztai事件始末。因为时间关系，不能翻译成中文，这里特将一些关键的句子用黑体加横线标准出来，供有兴趣的读者参考。
The insect-killing, career-ending potato "As a scientist looking at it and actively working on the field, I find that it's very, very unfair to use our fellow citizens as guinea pigs." - Arpad Pusztai, UK's World in Action TV showWhen Dr. Pusztai voiced his concerns about the health risks of genetically modified (GM) foods during a nationally televised interview in August 1998, his was not simply just another voice in a contentious debate. Pusztai was the world leader in his field, and he had received major government funding to come up with the official method for testing the safety of GM foods. His protocols were supposed to become the required tests before any new GMO entered the European market. Pusztai was an insider, and an advocate of GM foods—that is until he actually ran those tests on supposedly harmless GM potatoes. The high-tech spuds were engineered to produce their own pesticide. "The point of the whole genetic modification experiment was to protect the potato against aphids, which are one of the major pests in Scotland," he said. His team inserted a gene from the snowdrop plant into the potatoes, which did in fact protect the GM crop from the insects. As part of his safety studies, he fed that insecticide producing GM potato to rats, along with a complete and balanced diet. Another group of rats ate natural potatoes. A third was fed not only the natural potatoes, but they also received a dose of the same insecticide that the GM potato produced. This way, if the insecticide was harmful, he would see the same health problems in both the group that ate the GM potatoes, and those that ate the diet spiked with theinsecticide. To his surprise, only those that ate the GM potato had severe problems—in every organ and every system he looked at. Massive health problems linked to GMOs "After the animals were killed and dissected," Pusztai recalled, "we found out that in comparison with the non-genetically modified potatoes, their internal organs developed differently." The intestines and stomach lining, for example, increased in size, the liver and kidneys were smaller, and the overall rate of growth was retarded. And the immune system suffered. Pusztai emphasized, "They found in those data 36 – 36! – very highly significant differences between the GM-fed animals and the non-GM fed animals." Since the rats that ate the natural potatoes plus the insecticide did not have these issues, there was one obvious conclusion—the process of genetically engineering the potatoes caused unpredicted side effects, turning a harmless food into a dangerous one. When Pusztai saw the extensive damage that his potatoes caused in the lab animals, he also realized that if biotech companies had done the safety studies, the dangerous potatoes would have easily made it to market. He knew this because a few months earlier, he had reviewed the confidential submissions from the biotech companies which allowed their GM soy and corn onto the market. "They were flimsy," he said. "They were not scientifically well founded." They would never detect the changes in GMO-fed animals. Reading the industry studies was a turning point in Pusztai's life. He realized what he was doing and what the industry scientists were doing was diametrically opposed. He was doing safety studies. Companies like Monsanto, on the other hand, were doing as little as possible to get their foods on the market as quickly as possible. Pusztai also realized that the GM soy and corn already on the market had been produced using the same process that had created his dangerous potato. Thus, the GM crops being consumed in the UK and the US might lead to similar damage in the gut, brain and organs of the entire population. Thus, during his TV interview, Pusztai flatly stated: "If I had the choice, I would certainly not eat [GM foods] until I see at least comparable experimental evidence which we are producing for genetically modified potatoes." Ambushed After the TV show aired, Pusztai was a hero at his prestigious Rowett Institute, where the director praised his work to the press, calling it world-class research. After two days of high-profile media coverage throughout Europe, however, the director received two phone calls from the UK Prime Minister's Office. "It's only when we think there was political pressure coming from the top that the situation changed," said Pusztai. "And then the director, to save his own skin, decided that the best way to deal with the situation [was] A) to destroy me, B) to make me shut up." Pusztai was told the next morning that his contract would not be renewed, he was silenced with threats of a lawsuit, his team was disbanded, and the protocols were not to be implemented in GMO safety assessments. And then came the attacks. Coordinated between the Institute, biotech academics, and even the pro-GMO UK government, a campaign to destroy Pusztai's reputation was launched. They were determined to counter the negative media coverage and protect the reputation of GMOs—even if it meant promoting blatant lies and sacrificing a top scientist's career. Because Pusztai was gagged, he said, "whatever they did say on TV, radio and wrote in the newspapers, I could not deny it, I could not correct it, I could not say what was the real situation." "The most hurtful thing of all," remembers Pusztai's wife Susan, "was that he wasn't allowed to talk to his colleagues and his colleagues were not allowed to talk to him. So whenever he entered a ro
《农业转基因生物知识100问》争议点之三：Pusztai事件蒋高明
[本博注] 今天早上发了针对《农业转基因生物知识100问》之99问Pusztai实验的科学性问题，上篇文章分析指出，完全是国外利益集团包括英国首相府一手制造了Pusztai冤案。那么，这样的信息是如何变成了中国挺转派作为支持转基因主粮商业化的工具呢？是谁在传播这一错误信息中又制造了冤案，是谁在信息传播中造谣呢？刚才收到国外朋友的来信，正好替我们做了很好的回答。现特转发到这里，供大家参考。 Pusztai的土豆和方舟子的造谣 发布: FooBar日期: January 07, 2011 04:55PM
送交者 ： babyfat
近日坛中有人提及“Pusztai事件”，babyfat孤陋寡闻，居然连转基因争论史上赫赫有名的公案都没有听说过！此事之所以有名，盖因Pusztai是第一个在文章中谈论转基因作物危害的科学家。此案的过程跌宕起伏，牵扯各方利益，旁观者众说纷纭，真相委实难以判断，简直是一个罗生门。(事件原委详见：[en.wikipedia.org] 和 [www.wyzxsx.com] )。这等热闹的事情，“科唬作家”方舟子怎会错过？于是就有了这一篇【科学大争论——转基因作物安全吗？】[blog.sina.com.cn]， 里面有一部分专门讲述此事（中），于是我就去了解了一下，不看不知道，一看吓一跳：靠！这种事你也要造谣？难道真的欺负中国人不懂英文？我说的是小方对Pusztai论文的造谣，详情如下：
Pusztai报告了一个实验结果：给大鼠喂食转基因土豆，结果导致大鼠的发育和多器官系统受损。小方是这样引述和评论这个实验的：
【普兹太（Pusztai）的实验存在的问题包括：试验的动物太少，不足以得出有统计意义的结果；缺乏合适的空白对照，以及用于喂养老鼠的膳食营养结构不平衡，后者也可能导致观察到的病变。{我们做实验应该有一个对照，一模一样的两组老鼠，一组喂转基因土豆，一组喂同一品种的非转基因土豆，结果再来比较，看看有什么差异才能说明问题。而他并没有用同一品种的土豆做对照，用的是另一品种的土豆。两种土豆的成分本来不一样，那么，吃这两种不同土豆的老鼠的身体有不同的变化，我们就不知道是不是由于转基因引起的，还是别的成分差异引起的。}】
前面的内容大概是小方引用其他科学家的，这些质疑多少有些 “道理”（后面我会一一回驳），但紧接着的话（加{}的）让我大跌眼镜，这部分大概就是小方同学的“私货”：他指责Pusztai用的转基因土豆和作为对照的非转基因土豆不是同一品种。饿的个神啊，这种低级错误也能犯，那Pusztai还能当教授？带着这个疑问，babyfat找来了Pusztai的原文，并不难找，就发表在lancet上。[www.sciencedirect.com]
在文章的方法部分， Pusztai明确阐述了实验的分组：
【ELISA analysis confirmed that the expression level of GNA in raw GM potatoes was 25?4 ug/g dry matter; the concentration was decreased to 4?9 ug/g after boiling for 1 h. Six rats were randomly allocated to each group, and were fed diets containing either raw or boiled GNA-GM potatoes, parent potatoes (Desiree), or parent-line potatoes supplemented with 25?4 ug/g GNA for 10 days. All potato diets were isocaloric and contained an average of 6% protein.】
实验开始之前先检测了转基因土豆中表达产物（GNA，雪花莲凝集素）的含量，结果表明：生土豆中的含量比熟土豆高。
然后开始进行实验分组：将大鼠分为六组（每组六只），分别给它们喂食
1. 生的转基因土豆
2. 生的非转基因土豆（是转基因土豆的父本）
3. 生的非转基因土豆并在食物中添加GNA
4. 煮熟的转基因土豆
5. 煮熟的非转基因土豆（是转基因土豆的父本）
6. 煮熟的非转基因土豆并在食物中添加GNA
由此可以看出：用作对照的非转基因土豆是转基因土豆的父本（转基因土豆是在父本土豆里转了一个基因）。根本不是所谓的“另一品种的土豆”！这样还不够，小方就继续造谣说“值得指出的是，普兹太是用生土豆喂老鼠，而人们一般只食用煮熟的土豆，食物中的有毒成分在加热后往往就不再具有毒性。”然后评论说生土豆里含有大量毒素，如何如何不好……My goodness, 人家明明既有喂食生土豆的实验组（3组），也有喂食熟土豆的实验组（3组），这不是睁着眼睛说瞎话吗？【babyfat注：设置生土豆的实验组的原因可能有二，一者为了观察生土豆是否比熟土豆更有害（转基因的和非转基因的）；二者，老鼠爱偷吃食物，这吃的土豆当然是生的，如果吃了生的转基因土豆比吃了非转基因土豆更有害，那么转基因对生态的影响可想而之】
对文章内容造谣完毕，小方同学意犹未尽，紧接者说“普兹太把论文提交著名的医学刊物《柳叶刀》发表。多数审稿人都对之提出批评，认为该论文的质量没有达到发表要求。”而事实是, 《柳叶刀》收到论文后十分慎重，请了6个同行予以评议（通常情况下只有3个），其中有5个同意发表，反对的一个还是与转基因有利益关系的科学家。（详见[en.wikipedia.org]）
综上所述，小方同学对这一事件的描述从论文内容到论文发表都是在彻头彻尾的造谣，其造谣手法与其在“打假”
中玩弄的手段惊人的一致：把无中生有的“事实”强加到对方身上，然后批驳这些并不存在的谬误。这实在是令人震惊！
“是否种植和使用转基因食品”是关系到国计民生的大问题，涉及到科学、政治和经济的方方面面，国家应该将各方面的专家召集起来，认真地讨论究竟是“利大于弊”还是“弊大于利”。争论的双方都应该提供事实和数据，而不是进行造谣传谣，这样才能作出真正有利于人民的决定。
附：“专家”对实验的评论也不太靠谱：
引用（【】后为babyfat的解释）
【试验的动物太少，不足以得出有统计意义的结果】；
每组六只，虽是小样本，但足够进行统计分析，这只是一个初步实验结果，但随后Pusztai被解雇，提供转基因土豆的公司被迫关门，实验无法再进行下去。
【缺乏合适的空白对照，】
有非转基因的空白对照；有人指出需要两组对照转空载体的对照和转其他凝集素基因的对照，有当然更好，但说明的问题不一样。
【以及用于喂养老鼠的膳食营养结构不平衡，后者也可能导致观察到的病变。】
转基因土豆和非转基因土豆里的营养成分的确有差别，但这也正说明了转基因对土豆的营养成分的影响。
Pusztai对实验结果的解释十分谨慎，他说“我从未谈论转基因食品，我只是在谈论我所用的转基因土豆，在科学中，你不能从一个问题跳到另一个问题”。[www.mindfully.org]
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