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仅仅是“科学”—转基因作物的局限性、风险和替代物

【编者按】本文是英国伦敦国王学院医学与分子遗传学系迈克尔•安东尼博士,从《中国日报》上了解到中国百名学者上书反对转基因主粮商业化的消息后,怀着科学的良知和对人类前途的责任,从专业技术角度,援引了大量的科学研究的实证依据和权威性文件,论述了转基因作物的风险、局限性以及更佳的替代方案。希望能够为我们的政府和人民提供更多的事实和真相,以便做出正确的判断。翻译过程难免错漏之处,故而将英文原文附在后面,读者可自行甄别。下面楷体字附上迈克尔博士的信件正文部分。

亲爱的XXX教授,

我怀着极大的兴趣阅读了标题为《学者们激烈反对转基因证书》的文章,其出现在3月11日的《中国日报》上。

正如一些一直批评转基因遗传改造作物之价值、并强调它们现在已被证明是健康和环境之危险的人,我高兴地看到一批知名学者反对在中国推出转基因水稻。虽然我很理解中国政府关切于为了贵国庞大人口的粮食生产,但重要的是:他们意识到一种转基因作物方法将会引起的危害远远超过其可提供的任何好处,以及满足我们粮食生产需求的安全、可靠、天然的替代品已经存在。

……

若我可看到这份学者请愿书并且在你们的允许下把它传阅给志同道合的朋友,这将是非常令人振奋的。

如果你们在宣传活动中需要来自像我自己一样持续批评转基因作物的西方科学家的任何帮助,请随时联系我而不要犹豫。我附加了一份文件,我协助编制了这份文件,并希望它将对你们有所帮助。

谨以最良好的祝愿,祝你和你的家人在虎年健康、成功、幸福!

迈克尔

 

转基因作物——仅仅是“科学”

研究证明其局限性、风险和替代物

GM CROPS – JUST THE SCIENCE

research documenting the limitations, risks, and alternatives

 

作者:迈克尔·安东尼 博士

Dr. Michael Antoniou

伦敦国王学院医学院医学与分子遗传学系

King’s College London School of Medicine Department

of Medical and Molecular Genetics

翻译:義成 莎莎 mountriver nicename

支持者声称转基因(遗传改造)作物(具有如下优点):

·安全且更有营养;

·有利于环境;

·减少除草剂与杀虫剂的使用;

·提高作物产量,因此可帮助农民并可解决粮食危机;

·创造一个更加富裕、稳定的经济;

·只是一种自然育种的延伸,并且没有与自然育种作物不同的任何风险。

然而,不断壮大且越来越多的科学团体以及实地经验显示转基因生物未能符合这些声称。相反,转基因作物(具有以下弊端):

• 有毒性,可引起过敏症,或者比它们的自然相关物种更少营养;

• 能够破坏生态系统,伤害脆弱的植物和野生动物种群,并且损害生物多样性

• 从长期看,增加了(农药、除草剂)化学品的投放;

• 与传统作物相比,实现产量不是更好,而是往往更糟糕;

• 造成或加剧了社会和经济问题的范围;

• 是实验室制造的,一旦被释放,有害的转基因生物不能被从环境中召回。

被科学证明的风险与明确的实际利益缺乏,已经使得专家们视转基因技术为一种粗陋、过时的技术。鉴于有效供应、科学证明、能源效率以及满足当今和未来的全球粮食需求的安全方式,我们不必蒙受它们呈现的风险。

本文介绍了关键的科学证据——114项研究和其他权威性文件——证明转基因作物的局限性与风险,以及当前可用的许多更安全、更有效的替代品。

目录

转基因是一种自然的植物育种的延伸吗?...

吃转基因食品安全吗?...

关于转基因食品的动物研究引起关注...

家畜的饲养研究...

动物饲养研究突出了对人的潜在健康问题吗?...

转基因食品是否更有营养?...

转基因食品可以帮助缓解世界粮食危机?...

转基因作物是否有增产潜力?...

失败的收益率...

非洲的三种转基因作物...

转基因甘薯...

转基因木薯...

抗虫棉(Bt棉)...

气候变暖对农业的影响...

石油峰值和农业...

转基因作物和气候变暖...

特培作物的非转基因研究成效...

转基因作物是否环保?...

转基因作物和除草剂...

杀虫剂产生型的转基因作物...

转基因作物和野生动物...

阿根廷的例子...

转基因作物和非目标性的昆虫以及有机生物体...

转基因和非转基因作物能共存吗...

对转基因的替代...

有机生物农业和低投入耕作在非洲改进了产量...

有机和低投入的办法在发展中国家增进农民的收入...

谁拥有高科技...

结论...

原文...

注释:References.

转基因是一种自然的植物育种的延伸吗?

自然繁殖或育种只能发生于密切相关的生命体之间(猫与猫,而不是猫与狗;小麦与小麦,而不是小麦与番茄或鱼)。就这样,子代从亲代继承的携带生命体各部分信息的基因(群),以一种有序的方式一代一代传下去。

转基因不像自然的植物育种。转基因用实验室技术以插入人工改造的基因单元,重新规划了植物DNA蓝图而使之带有全新的属性。这种过程在自然界从未发生过。通过加入来自多种生物包括病毒、细菌、植物和动物的DNA片段,人工改造的基因单元在实验室中被创造出来。例如,在最常见的可耐受除草剂的大豆中的遗传改造基因(转基因),是用来自一种植物病毒、一种土壤细菌和一种矮牵牛植物的基因拼装起来的。

植物的转基因转化过程是不成熟的、不精确的,并导致广泛的突变,导致植物DNA蓝图的重大变化[1]。这些突变以非预期的和潜在危害的方式,非自然地改变了基因(群)的功能[2],详情见下文;不利影响包括作物生长情况较差、毒性作用、过敏反应以及对环境的破坏。

吃转基因食品安全吗?

与该行业者的宣称相反,转基因食品在被释放销售之前,其对人类的安全性没有被适当地测试[3,4]。实际上,唯一发表的研究报告,其直接测试转基因食品对人类的安全性,发现了潜在的问题[5]。到目前为止,这项研究并没有跟进。

对于安全性质问的典型回答是,在美国和其他地区,人们已吃了转基因食品超过10年而无不良影响,这证明这些产品是安全的。但转基因食品在被广泛食用的美国和其他国家,并没有被标签;其对消费者健康的影响并没有被监测。

正因为如此,来自转基因食品对健康的任何影响,必须满足不同寻常的条件才会被注意到。对健康的影响还必须是:

• 立即出现于食用一种已知是转基因(尽管其不被标记)的食品之后,这种反应被称作急性毒性。

• 引起完全不同于常见疾病的症状;如果转基因食品造成了普通的或缓慢发作的象过敏或癌症之类疾病的上升,则没有人会知道是什么引起这样的上升。

• 是肉眼可见的强烈而明显;没有人用显微镜去检查个人身体组织的损害,在他们吃了转基因食品之后。但是,需要这样的检查类型以便对诸如癌前变化等问题发出预警。

为了检测对健康是重要却更微妙的影响、或者需要时间来显示的影响(慢性影响),对更大人口的长期、可控研究是必需的。

在目前情况下,转基因食品对健康的温和或缓慢发作的影响可能需要数十年才会广为人知,正如反式脂肪(另一种人工食品类型)的危害作用经过几十年才被认识。来自反式脂肪的“慢性毒药“的影响,造成了世界各地数以百万计人过早死亡[6]。

转基因食品的任何有害影响将是缓慢浮出表面且不太明显的另一个原因是因为,即使在转基因作物消费历史最悠久的美国,转基因食品只占美国饮食的一小部分(玉米少于15%,大豆产品不到5%)。

然而,有迹象表明美国食品供应并非很好。由美国疾病控制中心提供的报告显示,在1994年(就在转基因食品商业化之前)至1999年的几年中,与食物有关的疾病增加了2至10倍 [7]。是否与转基因食品有关联?没有人知道,因为其对人类(健康影响)的研究还没有完成。

关于转基因食品的动物研究引起关注

虽然对人类的研究还没有完成,但是科学家正在报导越来越多的检测转基因食品对实验动物影响的研究。这些研究,总结如下,提出了关于转基因食品对人以及动物的安全性的严重关切。

小动物饲养研究

• 被喂食转基因西红柿的大鼠产生了胃溃疡[8];

• 被喂食转基因大豆的小鼠,其肝脏、胰腺、睾丸功能受到扰乱[9,10,11];

• 转基因豌豆给小鼠造成过敏反应[12];

• 被喂食转基因油菜的大鼠得了肝脏肿大,这往往是毒性标志[13];

• 用转基因马铃薯喂食大鼠造成其肠道内壁的过度增长,类似癌前状态[14,15];

• 被喂食可产生抗虫成分转基因玉米的大鼠生长很慢,遭受肝、肾功能问题折磨,并在其血液中显示某些脂肪的更高水平[16];

• 超过三代被喂食可产生抗虫成分转基因玉米的大鼠,遭受肝、肾伤害的折磨,并且出现了血液生化指标的变更[17];

• 被喂食可产生抗虫成分转基因玉米的年老与年幼的小鼠,在免疫系统细胞群和生化活力方面出现了显著的紊乱[18];

• 超过四代被喂食可产生抗虫成分转基因玉米的小鼠,显示出在各器官(肝、脾、胰腺)中异常结构变化的增加,重大变化在于其内脏中基因功能的模式,反映了这个器官系统的化学反应的紊乱(例如,在胆固醇制造,蛋白质制造和降解),以及最重要的,生育率下降[19];

• 终生(24个月)被喂食转基因大豆的小鼠在它们的肝脏中显示更严重的衰老迹象[20];

• 被喂食转基因大豆的兔子表现出肾和心脏中酶功能的紊乱[21]。

家畜的饲养研究

家畜已被转基因饲料喂养许多年。这是否意味着用于牲畜的转基因饲料是安全的?当然,这意味着影响不是急性的并且不会马上显示出来。然而,旨在评估转基因饲料缓慢发生、更微妙的对健康影响的长期研究,表明转基因饲料(对家畜)确有不利影响,证实了上述实验动物(呈现)的结果。

下面的问题已被发现:

• 超过三代被喂食可产生抗虫成分转基因Bt玉米的绵羊显示母羊的消化系统功能紊乱而其羔羊的肝脏和胰腺功能紊乱[22]。

• 在转基因饲料喂养的羊的消化道中,转基因DNA被发现存在处理情况并被检测到。这就提出了一个可能性,即抗生素耐药性与Bt杀虫基因可以进入肠道细菌[23],一种已知的水平基因转移。水平基因转移能够导致对抗生素有抗药性的致病细菌(“超级细菌”)以及可能导致带有潜在有害后果的Bt杀虫成分在肠道中产生。多年来管理者和生物技术行业声称水平基因转移不会发生于转基因DNA;但这一研究挑战了这种声称。

• 饲料中的转基因DNA被动物的器官吸纳。少量的转基因DNA出现在人们食用的牛奶和肉类中[24,25,26]。(转基因DNA)对动物与食用它们的人群的健康影响还没有被研究。

动物饲养研究突出了对人的潜在健康问题吗?

食品添加剂和新的药物在做人体试验之前,必须先在小鼠或大鼠身上测试。如果有害作用在这些初步的动物实验中被发现,然后这样的药物很可能会被取消人用资格。只有当动物研究显示没有不良影响,该药物才可以进一步对人类志愿者进行测试。

但在实验动物中引起不良影响的转基因作物已在许多国家被批准商业化。这表明,与新药相比,更不严格的标准被用来评价转基因作物的安全性。

事实上,至少在一个国家――美国――转基因生物的安全评价是自愿的,而不是由法律规定;不过,迄今为止,所有转基因生物已自愿接受审查。在几乎所有国家,安全评估并不科学严谨。例如,被转基因作物开发人员通常进行展示其产品安全性的动物饲养研究,就是持续时间太短且使用科目太少以至于无法可靠地检测到重要的有害影响[27]。

虽然该行业对其自己的转基因产品进行不严谨的研究[28],但与此并行,是系统且持续地妨碍着独立科学家对转基因生物进行更严格和深入的独立研究的能力。关于转基因生物的比较和基本农艺研究,安全和组成的评估,环境影响的评估,都受到生物技术工业的限制和压制[29,30]。

与合同相联系的专利授权被用于限制独立研究人员使用商业化转基因种子。对已被授予专利的转基因作物的研究许可或被隐瞒或难以获取,以至于研究被有效阻止。在(研究)许可被最终给予的情况下,生物技术公司持有权力阻止出版物,导致许多重大研究永远无法被发表[31,32]。

该业界和其同盟也使用广泛的公共关系战略,以抹黑和/或钳制那些发表对转基因持批评研究的科学家[33]。

转基因食品是否更有营养?

商业化的转基因改良食品没有营养价值。目前,现有的转基因食品并没有更好的营养价值,在某些情况下还低于天然食品的营养。有些转基因食品在测试中被证明有毒性或过敏反应。

这些例子包括:

·转基因大豆的抗癌异黄酮含量比非转基因大豆低12-14%[34]

·经过基因改造含有维生素A的油菜大大减少了维生素E在油脂中的含量,并且改变了油脂成分[35]

·人类志愿者试吃转基因大豆豆粕表明,转基因的DNA在加工过程中能够生存,并在消化道中可以检测到。有证据表明基因横向转移到了肠道细菌中。[36 37]抗生素耐药性的基因横向转移和通过转基因食品进入肠道细菌的Bt杀虫基因是一个极其严重的问题。这是因为经过基因改造后的肠道细菌能对抗生素产生抗药性,或成为Bt杀虫剂工厂。虽然Bt的自然形态已被安全地作为农业杀虫剂使用多年,转基因的Bt毒素已进入农作物,在实验室动物试验中被发现对健康有潜在的不良影响[38 39 40]

·在80年代后期,使用转基因细菌生产的补充食品含有毒素41,最初造成37个美国人死亡,然后使超过5000名美国人患了重病。

·几种试验性转基因食品(非商业化的)被发现有害:

·对巴西坚果过敏的人对由巴西坚果基因改造过的大豆也有过敏反应42

·基因改造过程本身可能导致有害的影响。转基因马铃薯引起多个器官系统的毒性反应。[43 44]转基因豌豆引起了2倍的过敏反应 - 转基因蛋白有过敏性,刺激对其它食品成分的过敏反应。[45]这就提出了一个问题,转基因食品是否会导致增加对其它物质的过敏。

转基因食品可以帮助缓解世界粮食危机?

饥饿的根源不是缺乏食物,而是缺少获得食物的途径。穷人没有钱购买食物,并且越来越没有土地种植食物。饥饿基本上是社会、政治和经济的问题,这是转基因技术不能处理的。

由世界银行和联合国粮食和农业组织最近的报告发现,生物燃料热潮是当前粮食危机的主要原因。[46 47 ]但转基因作物生产商和经销商继续推动生物燃料的扩张。这表明,他们的首要工作是赚钱,而不是养活世界。

转基因公司专注于生产经济作物,用作动物饲料和在富裕国家用作生物燃料,而不是为人们生产粮食。

转基因作物促进工业农业在世界各地扩张并削弱了小农经济。这是一个问题严重的发展,有大量证据显示,小农场比大农场更有效率,每公顷土地能生产更多的作物。[48 49 50 51 52]

“气候灾害被用来推动生物机动车能源,但却造就了粮食灾难,现在粮食灾难被用来启动转基因工业的财运”。丹尼•侯顿,英国独立日报非洲记者,2008年。[53]

转基因作物是否有增产潜力?

充其量,转基因作物的表现并不比其非转基因的同类作物更好,近十年来转基因大豆产量一直在下降。[54]受到控制的转基因/非转基因大豆实地比较试验表明,50%的收益率下降是由转基因改造过程对基因的破坏性影响造成的。同样,实地测试Bt杀虫剂生产杂交玉米表明,它们需要较长的时间达到成熟阶段,并且产量比非转基因的同类作物的下降程度达12%。[56]

一份美国农业部报告证实了转基因作物的产量表现不佳,报告称,“用于商业用途的转基因作物不增加作物品种的产量潜力。事实上,产量甚至可能下降....或许,这些结果所提出的最大问题是:在农业金融上看来似乎有混合的甚至是负面的影响时,如何解释转基因作物的迅速普及”。[57]

联合国农业知识、科学和技术促进发展国际评估(IAASTD)报告[58]在2008年强调,基因改造不增加产量的潜力。这份关于农业未来的报告,由400名科学家撰写,并得到58个政府的支持,该报告指出,转基因农作物的产量“充满变数”,并在某些情况下 “产量下降”。报告同时指出,“该技术的评估滞后于其发展,信息传闻矛盾,以及可能带来的利益和损害的不确定性是不可避免的。”

失败的收益率

最终的研究确定,转基因作物和产量是“失败的收益率:转基因作物性能评估”。研究结果在2009年发表,作者是前美国环保署和食品安全中心的科学家,道格里安·谢尔曼医生。研究是根据公开的信息,由学术科学家进行同行评审,并采用充分的实验控制进行的。

在这项研究中,格里安-谢尔曼医生区分了内在收益率(也称为潜在的收益率)与业务收益率,内在收益率定义为理想的条件下可达到的最高产量,业务收益率是农民由于虫害,干旱,或其它环境压力因素下,减少种植,在正常现场条件下实现的收益率。

这项研究还区分传统育种方法所造成的产量影响和的基因性状造成的产量影响。生物科技公司利用常规育种和分子标记辅助育种,生产更高产的作物,最后以基因工程改造为耐除草剂或抗虫基因已成为常见的现象。在这种情况下,更高的产量不是由于基因工程而是由传统的育种方法获得的。 “失败的收益率” 梳理出这些区别并分析了基因工程和常规育种对增产作出的不同贡献。

根据对玉米和大豆,这两个最普遍种植的美国转基因农作物的研究得出结论认为,基因工程抗除草剂大豆和抗除草剂玉米并没有增加产量。同时,抗虫玉米产量的提高很小。对过去13年两种作物产量的增加,报告认为,主要是由于传统的农业育种或改善措施取得的。

作者得出结论:“在提高作物的内在或潜在的收益率方面,商业基因作物至今没有任何进展。相比之下,传统的育种在这方面十分成功;它可以完全归功于在美国和世界其它地区的内在增产,这是20世纪农业的特点。”[59]

这项研究的批评人士持反对意见,认为它不使用来自发展中国家的数据。忧思科学家联盟回应说,评价在发展中国家转基因作物对产量的贡献,同行评审的论文很少– 这不足以得出明确和可靠的结论。然而,发展中国家最广泛种植的食品/饲料作物,耐除草剂大豆,提供了一些线索。来自阿根廷的数据表明,阿根廷转基因大豆的种植增长超过了任何其它发展中国家,这意味着转基因品种的产量与传统的非转基因大豆相同,或比传统的非转基因大豆低。[60]

 “如果我们要战胜由于人口过剩和气候变化导致的饥饿,我们将需要增加作物产量,”古里安-谢尔曼博士说, “传统的育种优于基因工程。” [61]

如果转基因工程在富裕的美国无法提高内在的(潜在)收益率,在那里高投入的、灌溉的、得到大量补贴的农业是一种传统,那么,假定它将在发展中世界提高产量似乎不负责任的,在这些地区最需要的是增加粮食生产。

促进发展中世界的转基因作物计划是试验性的,而且似乎存在着与西方获得的数据不一致的期望。

在西方,粮食歉收,往往由政府包销,这种做法对农民给予补偿。这种支持系统在发展中世界是罕见的。在那些地区,农民可能确确实实在农场上下注,他们的整个生活依赖于作物,歉收会产生严重的后果。

非洲的三种转基因作物

转基因甘薯

该抗病毒甘薯一直是非洲的基本转基因展示项目,引发了大量的全球媒体报道。负责该项目的弗洛伦斯·万布古,孟山都训练有素的科学家,已被媒体报道为非洲女英雄和数以百万计人的救世主,根据她的宣称,转基因马铃薯在肯尼亚的产量翻了一番。福布斯杂志甚至宣称,她是全球各地将“彻底改观”未来的极少数人中的一个。[62]然而,最后发现,这项关于转基因甘薯的宣称是不真实的,田间试验结果显示,转基因农作物是失败的。[63 64]

在与未经证实的转基因甘薯品种相反,在乌干达一个成功的常规育种项目产生了新的高产抗病毒品种,并“提高了约100%的收益率”。在短短的几年间,乌干达项目以低成本取得成功。相反,转基因甘薯在超过12年的时间里,消耗了孟山都、世界银行和美国国际开发署6百万美元的资金。[65]

转基因木薯

木薯是非洲最重要的食物来源,从20世纪90年代中期开始,非洲开始大力宣传基因工程的前景,通过对抗木薯中的某种致命性病毒而实现大规模增产。甚至有种说法认为利用转基因技术使木薯产量提高10倍就能解决非洲的温饱问题。[66]  但这项技术成果寥寥。即使转基因木薯已经明显遇到技术障碍时[67],当地媒体仍继续报道这项技术会如何解决非洲人民的吃饭问题。[68 69]  同时,非转基因木薯中已经悄然出现抗病毒植株,即使在干旱条件下这种木薯仍显著增产。[70]

抗虫棉(Bt棉)

南非的马卡哈西尼平原地区被称为抗虫棉小规模种植的示范基地,1998年种植了10万亩抗虫棉。2002年,这10万亩棉田只剩下22500亩,四年中减少了80%。2004年,85%种植抗虫棉的农户放弃了这种转基因棉花,因为棉田出现了虫害问题,而产量并未增加。继续种植抗虫棉的农户蒙受着经济损失,仅靠南非政府的经济补贴和政府扶植的市场勉强维持。[71]

刊登在《作物保护》上的一项研究表明:“马卡哈西尼平原地区种植的抗虫棉并未像预期那样带来实实在在的可持续的社会经济效益,原因在于作物的管理方法有问题。只有在高度集中的土壤系统中种植抗虫棉才能带来收益。”[72]

气候变暖对农业的影响

工业化农业是全球变暖的一大成因,它所排放的温室气体高达总量的20%,而某些增产方式更会加剧农业对环境的负面影响。例如,实现本质上增产往往需要施加更多用化石燃料制成的氮肥,一些氮肥由土壤微生物转化成一氧化二氮,这种温室气体的产生的温室效应约是二氧化碳的300倍。要想最大限度地减少全球农业对气候的影响,必须投资建设对工业肥料依赖性小的农业体系,按照农业生态学的原则提高土壤的保墒能力和恢复力。

转基因种子是由农用化学制品公司提供的,很大程度上依赖高昂的额外投入实现产值,如化肥,除草剂,杀虫剂。在气候变暖条件下推行转基因作物是一种危害生态的危险行为。

石油峰值和农业

一些分析员认为,目前石油峰值(即全球石油开采比率的最大值)已经出现。这将会对农业的发展模式造成巨大的影响。种植转基因作物必须辅以人工除草剂和化肥。合成杀虫剂的原料是石油,合成肥料制造使用天然气,而目前石油和天然气这两种化石燃料储量锐减。同样,化肥中的另一大原料,磷酸盐,也日益稀缺。

因此,基于美国转基因和化学性作物(依赖于化石燃料投入)的农业,其代价将日益高昂,前景堪忧。这在以下数据中可见一斑:

美国的食物系统中,每生产一千卡路里食物需要消耗一万卡路里的化石能源。[73]

·美国每年种植业和畜牧业需要消耗约7.2夸特(能源单位,1夸特相当于18000万桶石油的热能)化石能源。 [74 75]

·每公顷玉米和同类作物的生产平均需要消耗大约80亿卡路里(能源)。[76]

·种植业所消耗的能源的三分之二是用于化肥和农械。[77]

为了减少农业中的化石能源消耗,当前可用的手段包括减少化肥用量,选用合适的农械,土壤保持管理,节约灌溉,以及推行有机农业技术。[78]

在罗戴尔公司的耕作系统试验(FST)中,康奈尔大学的大卫·皮门特尔教授做了一项能源投入的比较分析,结果表明:有机耕作系统的能耗仅为传统耕作系统能耗的63%,主要原因在于传统耕作系统中使用的氮肥和除草剂需要消耗大量的能源。[79]

研究表明,低投入的有机耕作试点在非洲国家中成效显著。埃塞俄比亚的提格雷州在联合国粮农组织(FAO)的部分资助下推行了有机耕作试点工程,对使用堆肥和使用化肥的农田在六年中的产量进行了对比。对比结果显示,堆肥完全可以取代化肥,并且使用堆肥的农田平均可以增产30%以上。此外,农户发现,堆肥供给的作物更易抵抗病虫害和抑制顽固性杂草生长。[80]

转基因作物和气候变暖

气候变暖会引发突然的、极端的、不可预测的天气变化。为了人类的生存,必须尽可能保证农田的灵活性、恢复能力以及多样性。而转基因技术恰恰相反,它与作物多样性的原则背道而驰,而在灵活性方面更是需要数年的时间和几百万美元的投入来开发新品种。

每一种转基因作物都是针对特定的小环境“量身定制”。随着气候变暖,无法估计会出现怎样的土壤条件,而特殊的土壤又会在哪里形成。面对这种破坏性的气候变暖,最好的应对策略是种植多种具有遗传多样性的高产作物。

转基因产品公司拥有各项已申请专利的作物基因,声称能对抗某一种不利环境,如干旱,炎热,洪水和高盐环境。但这些公司却不能利用专利基因培育出同时拥有上述优点的作物新品种,因为这些功能的实现极为复杂,需要不同的基因准确而协调地合作。而现有的转基因技术并不能构造出如此精密的、高度协调的基因网络来提高作物的抵抗力。

相反,传统的自然杂交属于整体作业,利用抗干旱、耐热、抗洪水和高盐分的普通作物进行基因整合,更有利于实现这一目的。

另外,植物育种领域依靠标记辅助选择技术也取得了进步。标记辅助选择,即MAS,是一项基本上被认可的生物技术,通过识别出重要的相关基因来加快自然育种的速度。而且标记辅助选择不涉及基因工程中的危险性和不确定因素。

涉及基因专利问题的MAS技术存在争议。MAS作物的专利权对于发展中国家而言意义非同一般。

特培作物的非转基因研究成效

如果说特培作物更能适应气候变暖,那么还有比基因工程更好的方式来培育这些作物品种。传统育种和标记辅助选择在这方面的优势不胜枚举,尽管相比于沸沸扬扬的转基因神话它们的优势鲜为人知。

长茎水稻就是非转基因技术的一项成果。这种水稻的茎比普通水稻要长,从而避免植株被洪水淹没。[81]基因工程作为一种研究手段用于识别目的基因,而只有在标记辅助选择技术的指导下,依靠传统育种才能培育出长茎水稻这种百分之百非转基因的作物品种。这很好地体现了包括转基因技术在内的一系列生物技术,通过与传统育种过程完美结合,能满足当前对作物新品种的高端需求。

转基因作物是否环保?

市场上占主导地位的转基因作物有两类:

·能抵抗全效除草剂(如美国的农达牌除草剂)的作物:这种作物可以减少喷洒除草剂的次数并且不会被除草剂杀死

·能生成杀虫剂中苏云金杆菌毒蛋白的作物:种植这种作物可减少化学杀虫剂的喷洒量

然而,上述两种说法都有待进一步分析。

转基因作物和除草剂

最普遍的抗杀虫剂型转基因作物对农达牌除草剂具有抗药性。但是随着农达牌除草剂的广泛使用,出现了无数种对这种除草剂免疫的杂草,[82]如藜[83],黑麦草[84]和抗草甘膦杉叶藻[85]等。美国刚引进转基因作物时,一般除草剂的用量开始下降,而出现抗药性杂草之后,除草剂重新升温。[86 87 ]农民不得不改变耕作习惯来对付这些抗药性杂草,疯狂加大农达的用量。并且市场上开始流行更强效的混合除草剂,而不仅限于农达。[88 89]

这些化学制剂都有毒性,危害到喷药的农民和食用染毒植物的人和牲畜。农达也不例外。事实证明,农达除草剂在杀伤植物细胞方面的毒性类似于抗药性转基因作物的细胞所遭受的破坏力。[90]

加拿大政府在2001年的一项研究表明,抗药性转基因油菜在商业化种植仅仅4-5年之后,通过交叉授粉已经导致了顽固性杂草的出现,这种杂草对三种不同的全效除草剂均有抗药性,成为困扰农民的一大问题,并波及相邻农田的主人。[91 92 93]

另有发现表明,转基因油菜能和其它植物(如野芥子和野萝卜)交叉授粉并把抗药性基因遗传给这些植物。这样一来,这些植物变种成顽固性杂草的可能性便会增加。[94]针对这一情况,业内的回应是增加除草剂的用量、使用复杂的混合除草剂[95 96]、培育能抵抗新型、混合型除草剂的作物。这种对策显然会导致化学药剂的恶性循环,难以让人接受,尤其对发展中国家的农民而言更是如此。

杀虫剂产生型的转基因作物

杀虫剂产生型的Bt转基因作物已经显示出能抵御害虫,是加大了化学药剂的应用的结果。[97 98 99]

在中国和印度,Bt转基因棉花最初在消灭棉花象鼻虫方面很有效。但是对第二代的害虫,特别是像粉蚧科的介壳虫是高度抵抗Bt毒素的,且迅速代替它的地位。农民们承受了大规模的作物减产,还不得不使用高成本的农药,从而抹掉了他们的的利润数字。[100 101 102 103]这样的发展在发展中国家是对农民非常有损害性的,因为发展中国家承担不起昂贵的投入。

那种声称Bt转基因作物能减少杀虫剂的使用的观点是愚蠢的,因为Bt作物是自我杀虫的。 法国科恩大学的吉尔斯•艾瑞克萨拉利尼说,Bt作物实际上是被设计出来要产生毒素来抵御害虫的,Bt转基因的茄子(茄子即紫色茄子)产生了大量的毒素,每公斤16-17毫克。它们能毒害动物,不幸的是,未能试验来确定它们对人类的的影响效力。[104]

转基因作物和野生动物

英国政府资助的农场层面农业方面的试验表明,抵制除莠剂(阻碍植物生长的化学剂)的作物的生长(例如糖萝卜、油菜籽油菜)可以消减野生物的种群数量。[105 106]

阿根廷的例子

在阿根廷,大量转型农业的转基因黄豆产品已经在农村社区和经济结构方面发生了灾难性的后果。它损害了食品安全并且引起了相当规模的环境问题,包括抵御除莠剂的杂草蔓延,土壤质量退化和害虫增加以及作物疾病频发。[107 108]

转基因作物和非目标性的昆虫以及有机生物体

Bt转基因自生杀虫剂作物伤害无关昆虫群体,包括蝴蝶[109 110 111]和一些有益的扑食其他害虫的益虫。[112]从Bt转基因作物中生发出来的杀虫剂还会污染毒害水中生命[113]和土壤中的生物有机体[114]。有一项研究披露,Bt转基因自生杀虫剂作物对益虫是有更加负面的打击而不是正面的影响。[115]

转基因和非转基因作物能共存吗

一些搞生物工程的人反驳说,如果农民愿意,他们应该有能力来选择种植转基因作物,他们的理由是转基因作物和非转基因作物是可以和平共处的。然而在北美的经验已经表明,让转基因作物和非转基因作物“共同存在”很快会导致非转基因作物被大面积大规模的污染毒害。

这不仅对农业生态学方面有至关重要的影响,还对经济产生严重影响。损害了原始有机农业农民们收取红利的能力。也阻碍了国家间的出口市场发展,因为一些国家为防止基因污染有严格的进口规定。污染的发生通过植物之间的花粉传播,通过农具上的转基因种子播散,以及没有间隔分离的混合存储。转基因作物进入一个国家就取消了选择----每个人都会逐渐被迫培植转基因作物或者渐渐污染他们的非转基因作物。

这里就有一些转基因污染事件的典型:

·在2006年,转基因大米刚进行了一年的领域性试验,就被发现造成了大面积美国大米供应源和种子苗木[116]污染。被污染的大米甚至出现在了遥远的非洲,欧洲和美国中部。2007年三月路透社报道,美国出口大米的销售量比上一年锐减百分之20,原因就在于转基因污染。[117]

·在加拿大,污染的转基因油菜使得从根本上不可能去栽培有机的非转基因的油菜了。[118]

·美国法院推翻了对转基因紫苜蓿的批准,因为它通过交叉花粉传播威胁非转基因苜蓿。[119]

·由于转基因玉米产品以英亩为单位的增加种植,西班牙的有机玉米产品显著下降,也是因为交叉花粉传播问题造成的。[120]

·2009年,随着广泛散播的未经批准的转基因变种所带来的污染被发现,加拿大亚麻种子出口欧洲市场垮掉。[121]

·仅2007年,就有39例新出现的转基因污染事件发生在23个国家,而从2005年以来,216起相关污染事件被报道。[122]

对转基因的替代

许多权威机构,包括IAASTD关于农业前景123的报告,发现转基因作物对全球农业的改善和对抗贫穷饥馑气候变化几乎没什么贡献,因为存在更好的替代。它们多种多样可以列举很多,包括整合害虫管理,有机生物,有保障可持续的,低投入,非化学害虫管理和农业生物农场,它们的扩展可以超越彼此的特别的领域界限。在发展中世界专门项目应用这些经过证实的战略已经增加了相当的产量和粮食安全。[124 125 126 127 128 129]

这些战略应用包括:

·有保障可持续的,低投入,节省能源的实践,保持建设土壤,加强自然抗害虫和作物的回弹力。

·创新农耕办法,以减少和消除高成本的化学杀虫和施肥。

·应用成千上万种传统农业中每种主粮作物,这些作物自然地适应了各种自然压力例如干旱,燥热,恶劣天气条件,水涝,盐碱地,贫瘠土壤,害虫和疾病[130]

·应用现存的作物和它们的野生家族传统的育种项目,以实用的试验来发展多样性

·传播能使农民协作性地保持和改进的传统种子

·应用现代生物学有益的和高尚的方面。例如标记辅助选择,即用最新遗传知识来加速传统的繁殖。[131]不同于转基因技术,标记辅助选择可以安全地生产出新的多种作物,使之产生有价值地混杂嫁接体,提高营养,增加口感,提高产量,抵御害虫和疾病,以及培养其耐旱耐热,抗盐碱抗涝的性能。[132]

有机生物农业和低投入耕作在非洲改进了产量

好像没有什么理由来拿着贫穷农民的身家性命来赌博,即非要迫使他们种植试验性的转基因作物,因为现成地存在试验和尝试性的廉价的做法来增加粮食产量。许多最近的研究表明,在非洲国家低投入做法如有机生物可以大幅度地提升产量,同时还带来其他的益处。这样的做法的优势是以相关知识为基础,而不是以高投入为基础。结果是它们比那些昂贵的高科技(过去也毫无补益)更容易被贫穷的农民接受。

2008年联合国报告,“非洲的有机生物农业和粮食安全”,考察了在24个非洲国家。114组农业项目,发现有机的或者近似有机的实践,引来产量的增加超过100%。在东部非洲,发现产量增加了128%。[133]进一步的研究表述:“这些研究中的证据支持了这样的观点,就是在非洲,有机农业比非有机的农产品系统可以更有助于粮食安全,在长远上说,它也更会被人们所支持。[134]

有机和低投入的办法在发展中国家增进农民的收入

对于粮食无保障来说贫穷是主要的实质性因素,根据2008年的联合国报告,“非洲的有机农业和粮食安全”,有机农业耕作从多方面给予贫穷以正面的改善作用。农民主要收益于:

·现金储蓄,因为有机耕作不要求高成本的化学杀虫剂和化肥

·额外收入,来自于卖副产品(因为要改成有机耕作)

·对合格的有机产品的奖励价格,最初在非洲取得用于出口,同时也在国内市场出售。

·通过各种加工活动在有机产品上附加价值

这些优势被非洲和拉丁美洲的研究所证实。结论是有机农业可以环保地友善地减少贫穷最近的研究表明,合格的有机农场参与了产品出口,比那些常规的产品(指农民的净收入)更可以获取相当高的利润。[136]在这些例子中,87%的农民和家庭表明增加了收入得益于有机耕作,因此有机耕作和产品减轻了贫穷增加了区域性粮食安全。[135]

谁拥有高科技

关于农业高科技可以大有裨益于发展中世界的观点,要害是应当问谁拥有高科技。基因革命被引入非洲将去除本国的公共和私人的合作关系,这个合作关系中的公共方面将由是非洲方面提供,而私人方面将是美国和欧洲的生物技术公司

在转基因作物中应用的植入基因是生物技术公司的专利和所有。在美国和加拿大,许多公司打官司把农民告上法庭,指责他们的作物中有所谓这些公司的具有专利权的转基因。农民们辨白说他们不是故意地种植了转基因作物,但是没有办法阻止法庭对他们进行的巨额罚款。

如果农民们买转基因的种子,他们必须签一个高科技合同保证不私留和再培育种子。他们每年不得不从生物技术公司买新种子,从而把对粮食的控制权从自己手里转让给了种子公司,不断加强的种子产业意味着农民几乎没什么选择而只能买转基因种子。百年来农民的认识要建立当地适应的而且多样的种子苗木被轻易地抹掉了。

相反,低投入和有机农耕办法没有引入专利技术,粮食控制还保留在农民们手上,还可以保持农民的种植技术留存,而且对食品安全有利。

结论

转基因作物技术没有提供什么大不了的益处。相反,它们却凸现出了对人类和动物健康、对环境对农民,食品安全、出口市场的危害。迄今没找到一个有说服力的理由去拿农民的身家性命去冒险。特别是当被验证了的成功的和被广泛接受的替代方法容易地廉价地存在着。这样的替代方法将保持粮食供应的独立性,而不受外国跨国公司的控制,而且提供最佳的保险来反对气候变化的挑战性指责。

原文

GM CROPS – JUST THE SCIENCE

research documenting the limitations, risks, and alternatives

Proponents claim that genetically modified (GM) crops:

•   are safe to eat and more nutritious

•   benefit the environment

•   reduce use of herbicides and insecticides

•   increase crop yields, thereby helping farmers and solving the food crisis

•   create a more affluent, stable economy

•   are just an extension of natural breeding, and have no risks different from naturally bred crops.

However, a large and growing body of scientific research and on-the-ground experience indicate that GMOs fail to live up to these claims. Instead, GM crops:

•   can be toxic, allergenic or less nutritious than their natural counterparts

•   can disrupt the ecosystem, damage vulnerable wild plant and animal populations and harm biodiversity

•   increase chemical inputs (pesticides, herbicides) over the long term

•   deliver yields that are no better, and often worse, than conventional crops

•   cause or exacerbate a range of social and economic problems

•   are laboratory-made and, once released, harmful GMOs cannot be recalled from the environment.

The scientifically demonstrated risks and clear absence of real benefits have led experts to see GM as a clumsy, outdated technology. They present risks that we need not incur, given the availability of effective, scientifically proven, energy-efficient and safe ways of meeting current and future global food needs.

This paper presents the key scientific evidence – 114 research studies and other authoritative documents – documenting the limitations and risks of GM crops and the many safer, more effective alternatives available today.

Is GM an extension of natural plant breeding?

Natural reproduction or breeding can only occur between closely related forms of life (cats with cats, not cats with dogs; wheat with wheat, not wheat with tomatoes or fish). In this way, the genes that offspring inherit from parents, which carry information for all parts of the body, are passed down the generations in an orderly way.

GM is not like natural plant breeding. GM uses laboratory techniques to insert artificial gene units to re-programme the DNA blueprint of the plant with completely new properties. This process would never happen in nature. The artificial gene units are created in the laboratory by joining fragments of DNA, usually derived from multiple organisms, including viruses, bacteria, plants and animals. For example, the GM gene in the most common herbicide resistant soya beans was pieced together from a plant virus, a soil bacterium and a petunia plant.

The GM transformation process of plants is crude, imprecise, and causes widespread mutations, resulting in major changes to the plant’s DNA blueprint1. These mutations unnaturally alter the genes’ functioning in unpredictable and potentially harmful ways2, as detailed below. Adverse effects include poorer crop performance, toxic effects, allergic reactions, and damage to the environment.

Are GM foods safe to eat?

Contrary to industry claims, GM foods are not properly tested for human safety before they are released for sale3 4. In fact, the only published study directly testing the safety of a GM food on humans found potential problems5. To date, this study has not been followed up.

Typically the response to the safety question is that people have been eating GM foods in the United States and elsewhere for more than ten years without ill effects and that this proves that the products are safe. But GM foods are not labelled in the US and other nations where they are widely eaten and consumers are not monitored for health effects.

Because of this, any health effects from a GM food would have to meet unusual conditions before they would be noticed. The health effects would have to:

•   occur immediately after eating a food that was known to be GM (in spite of its not being labeled). This kind of response is called acute toxicity.

•   cause symptoms that are completely different from common diseases. If GM foods caused a rise in common or slow-onset diseases like allergies or cancer, nobody would know what caused the rise.

•   be dramatic and obvious to the naked eye. Nobody examines a person’s body tissues with a microscope for harm after they eat a GM food. But just this type of examination is needed to give early warning of problems such as pre-cancerous changes.

To detect important but more subtle effects on health, or effects that take time to appear (chronic effects), long-term controlled studies on larger populations are required.

Under current conditions, moderate or slow-onset health effects of GM foods could take decades to become known, just as it took decades for the damaging effects of trans-fats (another type of artificial food) to be recognized. ‘Slow poison’ effects from trans-fats have caused millions of premature deaths across the world6.

Another reason why any harmful effects of GM foods will be slow to surface and less obvious is because, even in the United States, which has the longest history of GM crop consumption, GM foods account for only a small part of the US diet (maize is less than 15% and soya bean products are less than 5%).

Nevertheless, there are signs that all is not well with the US food supply. A report by the US Centers for Disease Control shows that food-related illnesses increased 2- to 10-fold in the years between 1994 (just before GM food was commercialised) and 19997. Is there a link with GM food? No one knows, because studies on humans have not been done.

Animal studies on GM foods give cause for concern

Although studies on humans have not been done, scientists are reporting a growing number of studies that examine the effects of GM foods on laboratory animals. These studies, summarized below, raise serious concerns regarding the safety of GM foods for humans as well as animals.

Small animal feeding studies

•   Rats fed GM tomatoes developed stomach ulcerations8

•   Liver, pancreas and testes function was disturbed in mice fed GM soya9 10 11

•       GM peas caused allergic reactions in mice12

•       Rats fed GM oilseed rape developed enlarged livers, often a sign of toxicity13

•       GM potatoes fed to rats caused excessive growth of the lining of the gut similar to a pre-cancerous condition14 15

•       Rats fed insecticide-producing GM maize grew more slowly, suffered problems with liver and kidney function, and showed higher levels of certain fats in their blood16

•       Rats fed GM insecticide-producing maize over three generations suffered damage to liver and kidneys and showed alterations in blood biochemistry17

•       Old and young mice fed with GM insecticide-producing maize showed a marked disturbance in immune system cell populations and in biochemical activity18

•       Mice fed GM insecticide-producing maize over four generations showed a buildup of abnormal structural changes in various organs (liver, spleen, pancreas), major changes in the pattern of gene function in the gut, reflecting disturbances in the chemistry of this organ system (e.g. in cholesterol production, protein production and breakdown), and, most significantly, reduced fertility19

•       Mice fed GM soya over their entire lifetime (24 months) showed more acute signs of ageing in their liver20

•       Rabbits fed GM soya showed enzyme function disturbances in kidney and heart21.

Feeding studies with farm animals

Farm animals have been fed GM feed for many years. Does this mean that GM feed is safe for livestock? Certainly it means that effects are not acute and do not show up immediately. However, longer-term studies, designed to assess slow-onset and more subtle health effects of GM feed, indicate that GM feed does have adverse effects, confirming the results described above for laboratory animals.

The following problems have been found:

• Sheep fed Bt insecticide-producing GM maize over three generations showed disturbances in the functioning of the digestive system of ewes and in the liver and pancreas of their lambs22.

•  GM DNA was found to survive processing and to be detectable in the digestive tract of sheep fed GM feed. This raises the possibility that antibiotic resistance and Bt insecticide genes can move into gut bacteria23, a process known as horizontal gene transfer. Horizontal gene transfer can lead to antibiotic resistant disease-causing bacteria (“superbugs”) and may lead to Bt insecticide being produced in the gut with potentially harmful consequences. For years, regulators and the biotech industry claimed that horizontal gene transfer would not occur with GM DNA, but this research challenges this claim

•  GM DNA in feed is taken up by the animal’s organs. Small amounts of GM DNA appear in the milk and meat that people eat24 25 26. The effects on the health of the animals and the people who eat them have not been researched.

Do animal feeding studies highlight potential health problems for people?

Before food additives and new medicines can be tested on human subjects, they have to be tested on mice or rats. If harmful effects were to be found in these initial animal experiments, then the drug would likely be disqualified for human use. Only if animal studies reveal no harmful effects can the drug be further tested on human volunteers.

But GM crops that caused ill effects in experimental animals have been approved for commercialization in many countries. This suggests that less rigorous standards are being used to evaluate the safety of GM crops than for new medicines.

In fact, in at least one country – the United States – safety assessment of GMOs is voluntary and not required by law, although, to date, all GMOs have undergone voluntary review. In virtually all countries, safety assessment is not scientifically rigorous. For instance, the animal feeding studies that GM crop developers routinely conduct to demonstrate the safety of their products are too short in duration and use too few subjects to reliably detect important harmful effects.27

While industry conducts less than rigorous studies on its own GM products, 28 it has, in parallel, systematically and persistently interfered with the ability of independent scientists to conduct more rigorous and incisive independent research on GMOs. Comparative and basic agronomic studies on GMOs, assessments of safety and composition, and assessments of environmental impact have all been restricted and suppressed by the biotechnology industry.29 30

Patent rights linked with contracts are used to restrict access of independent researchers to commercialized GM seed. Permission to study patented GM crops is either withheld or made so difficult to obtain that research is effectively blocked. In cases where permission is finally given, biotech companies keep the right to block publication, resulting in much significant research never being published.31 32

The industry and its allies also use a range of public relations strategies to discredit and/or muzzle scientists who do publish research that is critical of GM crops.33

Are GM foods more nutritious?

There are no commercially available GM foods with improved nutritional value. Currently available GM foods are no better and in some cases are less nutritious than natural foods. Some have been proven in tests to be toxic or allergenic.

Examples include:

•       GM soya had 12–14% lower amounts of cancer-fighting isoflavones than non-GM soya34

•       Oilseed rape engineered to have vitamin A in its oil had much reduced vitamin E and altered oil-fat composition35

•       Human volunteers fed a single GM soya bean meal showed that GM DNA can survive processing and is detectable in the digestive tract. There was evidence of horizontal gene transfer to gut bacteria36 37. Horizontal gene transfer of antibiotic resistance and Bt insecticide genes from GM foods into gut bacteria is an extremely serious issue. This is because the modified gut bacteria could become resistant to antibiotics or become factories for Bt insecticide. While Bt in its natural form has been safely used for years as an insecticide in farming, Bt toxin genetically engineered into plant crops has been found to have potential ill health effects on laboratory animals38 39 40

•       In the late 1980s, a food supplement produced using GM bacteria was toxic41, initially killing 37 Americans and making more than 5,000 others seriously ill.

•       Several experimental GM food products (not commercialised) were found to be harmful:

•       People allergic to Brazil nuts had allergic reactions to soya beans modified with a Brazil nut gene42

•       The GM process itself can cause harmful effects. GM potatoes caused toxic reactions in multiple organ systems43 44. GM peas caused a 2-fold allergic reaction  –  the GM protein was allergenic and stimulated an allergic reaction to other food components45. This raises the question of whether GM foods cause an increase in allergies to other substances.

Can GM foods help alleviate the world food crisis?

The root cause of hunger is not a lack of food, but a lack of access to food. The poor have no money to buy food and increasingly, no land on which to grow it. Hunger is fundamentally a social, political, and economic problem, which GM technology cannot address.

Recent reports from the World Bank and the United Nations Food and Agriculture Organisation have identified the biofuels boom as the main cause of the current food crisis46 47. But GM crop producers and distributors continue to promote the expansion of biofuels. This suggests that their priority is to make a profit, not to feed the world.

GM companies focus on producing cash crops for animal feed and biofuels for affluent countries, not food for people.

GM crops contribute to the expansion of industrial agriculture and the decline of the small farmer around the world. This is a serious development as there is abundant evidence that small farms are more efficient than large ones, producing more crops per hectare of land48 49 50 51 52.

“The climate crisis was used to boost biofuels, helping to create the food crisis; and now the food crisis is being used to revive the fortunes of the GM industry.” Daniel Howden, Africa correspondent, The Independent (London), 200853

Do GM crops increase yield potential?

At best, GM crops have performed no better than their non-GM counterparts, with GM soya beans giving consistently lower yields for over a decade54. Controlled comparative field trials of GM/non-GM soya suggest that 50% of the drop in yield is due to the genetic disruptive effect of the GM transformation process55. Similarly, field tests of Bt insecticide-producing maize hybrids showed that they took longer to reach maturity and produced up to 12% lower yields than their non-GM counterpart56.   

A US Department of Agriculture report confirms the poor yield performance of GM crops, saying, “GE crops available for commercial use do not increase the yield potential of a variety. In fact, yield may even decrease.... Perhaps the biggest issue raised by these results is how to explain the rapid adoption of GE crops when farm financial impacts appear to be mixed or even negative57.” 

The failure of GM to increase yield potential was emphasised in 2008 by the United Nations International Assessment of Agricultural Knowledge, Science and Technology for Development (IAASTD) report58. This report on the future of farming, authored by 400 scientists and backed by 58 governments, stated that yields of GM crops were “highly variable” and in some cases, “yields declined”. The report noted, “Assessment of the technology lags behind its development, information is anecdotal and contradictory, and uncertainty about possible benefits and damage is unavoidable.”

Failure to Yield

The definitive study to date on GM crops and yield is “Failure to Yield: Evaluating the Performance of Genetically Engineered Crops”. Published in 2009, the study is authored by former US EPA and Center for Food Safety scientist, Dr Doug Gurian-Sherman. It is based on published, peer-reviewed studies conducted by academic scientists and using adequate experimental controls.

In the study, Dr Gurian-Sherman distinguishes between intrinsic yield (also called potential yield), defined as the highest yield which can be achieved under ideal conditions, with operational yield, the yield achieved under normal field conditions when the farmer factors in crop reductions due to pests, drought, or other environmental stresses.

The study also distinguishes between effects on yield caused by conventional breeding methods and those caused by GM traits. It has become common for biotech companies to use conventional breeding and marker assisted breeding to produce higher-yielding crops and then finally to engineer in a gene for herbicide tolerance or insect resistance. In such cases, higher yields are not due to genetic engineering but to conventional breeding. “Failure to Yield” teases out these distinctions and analyses what contributions genetic engineering and conventional breeding make to increasing yield.

Based on studies on corn and soybeans, the two most commonly grown GM crops in the United States, the study concludes that genetically engineering herbicide-tolerant soybeans and herbicide-tolerant corn has not increased yields. Insect-resistant corn, meanwhile, has improved yields only marginally. The increase in yields for both crops over the last 13 years, the report finds, was largely due to traditional breeding or improvements in agricultural practices.

The author concludes: “commercial GE crops have made no inroads so far into raising the intrinsic or potential yield of any crop. By contrast, traditional breeding has been spectacularly successful in this regard; it can be solely credited with the intrinsic yield increases in the United States and other parts of the world that characterized the agriculture of the twentieth century.”59

Critics of the study have objected that it does not use data from developing countries. The Union of Concerned Scientists responds that there are few peer-reviewed papers evaluating the yield contribution of GM crops in developing countries – not enough to draw clear and reliable conclusions. However, the most widely grown food/feed crop in developing countries, herbicide-tolerant soybeans, offers some hints. Data from Argentina, which has grown more GM soybeans than any other developing country, suggest that yields for GM varieties are the same or lower than for conventional non-GE soybeans.60

“If we are going to make headway in combating hunger due to overpopulation and climate change, we will need to increase crop yields,” says Dr Gurian-Sherman. “Traditional breeding outperforms genetic engineering hands down.”61

If GM cannot improve intrinsic (potential) yield even in the affluent United States, where high-input, irrigated, heavily subsidized farming is the norm, it would seem irresponsible to assume that it would improve yields in the developing world, where increased food production is most needed. Initiatives promoting GM crops for the developing world are experimental and appear to be founded on expectations that are not consistent with data obtained in the West.

In the West, crop failure is often underwritten by governments, which bail out farmers with compensation. Such support systems are rare in the developing world. There, farmers may literally bet their farms and their entire livelihoods on a crop. Failure can have severe consequences.

Three GM crops for Africa

GM sweet potato

The virus-resistant sweet potato has been the ultimate GM showcase project for Africa, generating a vast amount of global media coverage. Florence Wambugu, the Monsanto-trained scientist fronting the project, has been proclaimed an African heroine and the saviour of millions, based on her claims about the GM sweet potato doubling output in Kenya. Forbes magazine even declared her one of a tiny handful of people around the globe who would “reinvent the future”.62 It eventually emerged, however, that the claims being made for the GM sweet potato were untrue, with field trial results showing the GM crop to be a failure.63 64

In contrast with the unproven GM sweet potato variety, a successful conventional breeding programme in Uganda had produced a new high-yielding variety which is virus-resistant and has “raised yields by roughly 100%”. The Ugandan project achieved success at a small cost and in just a few years. The GM sweet potato, in contrast, in over 12 years in the making, consumed funding from Monsanto, the World Bank, and USAID to the tune of $6 million.65

GM cassava

The potential of genetic engineering to massively boost the production of cassava – one of Africa’s most important foods – by defeating a devastating virus has been heavily promoted since the mid-1990s. There has even been talk of GM solving hunger in Africa by increasing cassava yields as much as tenfold.66 But almost nothing appears to have been achieved. Even after it became clear that the GM cassava had suffered a major technical failure67, media stories continued to appear about its curing hunger in Africa.68 69 Meanwhile, conventional (non-GM) plant breeding has quietly produced virus resistant cassavas that are already making a remarkable difference in farmers’ fields, even under drought conditions.70

Bt cotton

In Makhatini, South Africa, often cited as the showcase Bt cotton project for small farmers, 100,000 hectares were planted with Bt cotton in 1998. By 2002, that had crashed to 22,500 hectares, an 80% reduction in 4 years. By 2004, 85% of farmers who used to grow Bt cotton had given up. The farmers found pest problems and no increase in yield. Those farmers who still grew the crop did so at a loss, continuing only because the South African government subsidized the project and there was a guaranteed market for the cotton.71

A study published in Crop Protection journal concluded, “cropping Bt cotton in Makhathini Flats did not generate sufficient income to expect a tangible and sustainable socioeconomic improvement due to the way the crop is currently managed. Adoption of an innovation like Bt cotton seems to pay only in an agro-system with a sufficient level of intensification.”72

How will climate change impact agriculture?

Industrial agriculture is a major contributor to global warming, producing up to 20 per cent of greenhouse gas emissions, and some methods of increasing yield can exacerbate this negative impact. For example, crops that achieve higher intrinsic yield often need more fossil fuel-based nitrogen fertilizer, some of which is converted by soil microbes into nitrous oxide, a greenhouse gas nearly 300 times more potent than carbon dioxide. Minimizing global agriculture’s future climate impact will require investment in systems of agriculture less dependent on industrial fertilizers and agroecological methods of improving soil water-holding capacity and resilience.

GM seeds are created by agrochemical companies and are heavily dependent on costly external inputs such as synthetic fertilizer, herbicides, and pesticides. It would seem risky to promote such crops in the face of climate change.

Peak oil and agriculture 

According to some analysts, peak oil, when the maximum rate of global petroleum extraction is reached, has already arrived. This will have drastic effects on the type of agriculture we practise. GM crops are designed to be used with synthetic herbicides and fertilizers. But synthetic pesticides are made from oil and synthetic fertilizer from natural gas. Both these fossil fuels are running out fast, as are phosphates, a major ingredient of synthetic fertilizers.

Farming based on the current US GM and chemical model that depends on these fossil fuel-based inputs will become increasingly expensive and unsustainable. The statistics tell the story:

In the US food system, 10 kcal of fossil energy is required for every kcal of food consumed.73

•       Approximately 7.2 quads of fossil energy are consumed in the production of crops and livestock in the U.S. each year.74 75

•       Approximately 8 million kcal/ha are required to produce an average corn crop and other similar crops.76

•   Two-thirds of the energy used in crop production is for fertilizers and mechanization.77

Proven technologies that can reduce the amount of fossil energy used in farming include reducing fertilizer applications, selecting farm machinery appropriate for each task, managing soil for conservation, limiting irrigation, and organic farming techniques.78

In the Rodale Institute Farming Systems Trial (FST), a comparative analysis of energy inputs conducted by Dr David Pimentel of Cornell University found that organic farming systems use just 63% of the energy required by conventional farming systems, largely because of the massive amounts of energy required to synthesize nitrogen fertilizer, followed by herbicide production.79

Studies show that the low-input organic model of farming works well in African countries. The Tigray project in Ethiopia, part-funded by the UN Food and Agriculture Organisation (FAO), compared yields from the application of compost and chemical fertilizer in farmers’ fields over six years. The results showed that compost can replace chemical fertilizers and that it increased yields by more than 30 percent on average. As side-benefits to using compost, the farmers noticed that the crops had better resistance to pests and disease and that there was a reduction in “difficult weeds”.80

GM crops and climate change

Climate change brings sudden, extreme, and unpredictable changes in weather. If we are to survive, the crop base needs to be as flexible, resilient and diverse as possible. GM technology offers just the opposite – a narrowing of crop diversity and an inflexible technology that requires years and millions of dollars in investment for each new variety.

Each GM crop is tailor-made to fit a particular niche. With climate change, no one knows what kind of niches will exist and where. The best way to insure against the destructive effects of climate change is to plant a wide variety of high-performing crops that are genetically diverse.

GM companies have patented plant genes that they believe are involved in tolerance to drought, heat, flooding, and salinity – but have not succeeded in using these genes to produce a single new crop with these properties. This is because these functions are highly complex and involve many different genes working together in a precisely regulated way. It is beyond existing GM technology to engineer crops with these sophisticated, delicately regulated gene networks for improved tolerance traits.

Conventional natural cross-breeding, which works holistically, is much better adapted to achieving this aim, using the many varieties of virtually every common crop that tolerate drought, heat, flooding, and salinity.

In addition, advances in plant breeding have been made using marker-assisted selection (MAS), a largely uncontroversial branch of biotechnology that can speed up the natural breeding process by identifying important genes. MAS does not involve the risks and uncertainties of genetic engineering.

The controversies that exist around MAS relate to gene patenting issues. It is important for developing countries to consider the implications of patent ownership relating to such crops.

Non-GM successes for niche crops

If it is accepted that niche speciality crops may be useful in helping adaptation to climate change, there are better ways of creating them than genetic engineering. Conventional breeding and marker-assisted selection have produced many advances in breeding speciality crops, though these have garnered only a fraction of the publicity given to often speculative claims of GM miracles.

An example of such a non-GM success is the “Snorkel” rice that adapts to flooding by growing longer stems, preventing the crop from drowning.81 While genetic engineering was used as a research tool to identify the desirable genes, only conventional breeding – guided by Marker Assisted Selection – was used to generate the Snorkel rice line. Snorkel rice is entirely non-GM. This is an excellent example of how the whole range of biotechnology tools, including GM, can be used most effectively to work with the natural breeding process to develop new crops that meet the critical needs of today.

Are GM crops environmentally friendly?

Two kinds of GM crops dominate the marketplace:

•       Crops that resist broad-spectrum (kill-all) herbicides such as Roundup. These are claimed to enable farmers to spray herbicide less frequently to kill weeds but without killing the crop

•       Crops that produce the insecticide Bt toxin. These are claimed to reduce farmers’ need for chemical insecticide sprays.

Both claims require further analysis.

GM crops and herbicide use

The most commonly grown herbicide-resistant GM crops are engineered to be resistant to Roundup. But the increasing use of Roundup has led to the appearance of numerous weeds resistant to this herbicide82. Roundup resistant weeds are now common and include pigweed83, ryegrass84, and marestail85. As a result, in the US, an initial drop in average herbicide use after GM crops were introduced has been followed by a large increase as farmers were forced to change their farming practices to kill weeds that had developed resistance to Roundup86 87. Farmers have increased radically the amounts of Roundup applied to their fields and are being advised to use increasingly powerful mixtures of multiple herbicides and not Roundup alone88 89. 

All of these chemicals are toxic and a threat to both the farmers who apply them and the people and livestock that eat the produce. This is the case even for Roundup, which has been shown to have a range of damaging cellular effects indicating toxicity at levels similar to those found on crops engineered to be resistant to the herbicide90.

A Canadian government study in 2001 showed that after just 4-5 years of commercial growing, herbicide-resistant GM oilseed rape (canola) had cross-pollinated to create “superweeds” resistant to up to three different broad-spectrum herbicides. These superweeds have become a serious problem for farmers both within91 92 and outside their fields93.

In addition, GM oilseed rape has also been found to cross-pollinate with and pass on its herbicide resistant genes to related wild plants, for example, charlock and wild radish/turnip. This raises the possibility that these too may become superweeds and difficult for farmers to control94. The industry’s response has been to recommend use of higher amounts and complex mixtures of herbicides95 96 and to start developing crops resistant to additional or multiple herbicides. These developments are clearly creating a chemical treadmill that would be especially undesirable for farmers in developing countries.

Insecticide-producing GM crops

Bt insecticide-producing GM crops have led to resistance in pests, resulting in rising chemical applications97 98 99.

In China and India, Bt cotton was initially effective in suppressing the boll weevil. But secondary pests, especially mirids and mealy bugs, that are highly resistant to Bt toxin, soon took its place. The farmers suffered massive crop losses and had to apply costly pesticides, wiping out their profit margins100 101 102 103. Such developments are likely to be more damaging to farmers in developing countries, who cannot afford expensive inputs.

The claim that Bt GM crops reduce pesticide use is disingenuous, since Bt crops are in themselves pesticides. Prof Gilles-Eric Séralini of the University of Caen, France states: “Bt plants, in fact, are designed to produce toxins to repel pests. Bt brinjal (eggplant/aubergine) produces a very high quantity of 16-17mg toxin per kg. They affect animals. Unfortunately, tests to ascertain their effect on humans have not been conducted.”104

GM crops and wildlife

Farm-scale trials sponsored by the UK government showed that the growing of herbicide-resistant GM crops (sugar beet, oilseed rape) can reduce wildlife populations105 106.

The case of Argentina

In Argentina, the massive conversion of agriculture to GM soya production has had disastrous effects on rural social and economic structures. It has damaged food security and caused a range of environmental problems, including the spread of herbicide-resistant weeds, soil depletion, and increased pests and diseases107 108.

GM crops and non-target insects and organisms

Bt insecticide-producing GM crops harm non-target insect populations, including butterflies109 110 111 and beneficial pest predators112. Bt insecticide released from GM crops can also be toxic to water life113 and soil organisms114. One study reveals more negative than positive impacts on beneficial insects from GM Bt insecticide-producing crops.115

Can GM and non-GM crops co-exist?

The biotech industry argues that farmers should be able to choose to plant GM crops if they wish. It says GM and non-GM crops can peacefully “co-exist”. But experience in North America has shown that “coexistence” of GM and non-GM crops rapidly results in widespread contamination of non-GM crops.

This not only has significant agroecological effects, but also serious economic effects, damaging the ability of organic farmers to receive premiums, and blocking export markets to countries that have strict regulations regarding GM contamination.

Contamination occurs through cross-pollination, spread of GM seed by farm machinery, and inadvertent mixing during storage. The entry of GM crops into a country removes choice – everyone is gradually forced to grow GM crops or to have their non-GM crop contaminated.

Here are a few examples of GM contamination incidents:

•     In 2006 GM rice grown for only one year in field trials was found to have widely contaminated the US rice supply and seed stocks116. Contaminated rice was found as far away as Africa, Europe, and Central America. In March 2007 Reuters reported that US rice export sales were down by around 20 percent from those of the previous year as a result of the GM contamination117.

•     In Canada, contamination from GM oilseed rape has made it virtually impossible to cultivate organic, non-GM oilseed rape118

•     US courts reversed the approval of GM alfalfa because it threatened the existence of non-GM alfalfa through cross-pollination119

•   Organic maize production in Spain has dropped significantly as the acreage of GM maize production has increased, because of cross-pollination problems120

•   In 2009, the Canadian flax seed export market to Europe collapsed following the discovery of widespread contamination with an unauthorized GM variety121.

•   In 2007 alone, there were 39 new instances of GM contamination in 23 countries, and 216 incidents have been reported since 2005122.

 Alternatives to GM

Many authoritative sources, including the IAASTD report on the future of agriculture123, have found that GM crops have little to offer global agriculture and the challenges of poverty, hunger and climate change, because better alternatives are available. These go by many names, including integrated pest management (IPM), organic, sustainable, low-input, non-chemical pest management (NPM) and agroecological farming, but extend beyond the boundaries of any particular category. Projects employing these sustainable strategies in the developing world have produced dramatic increases in yields and food security124 125 126 127 128 129.

Strategies employed include:

•   Sustainable, low-input, energy-saving practices that conserve and build soil, conserve water, and enhance natural pest resistance and resilience in crops

•   Innovative farming methods that minimise or eliminate costly chemical pesticides and fertilizers

•   Use of thousands of traditional varieties of each major food crop, which are naturally adapted to stresses such as drought, heat, harsh weather conditions, flooding, salinity, poor soil, and pests and diseases130

•   Use of existing crops and their wild relatives in traditional breeding programmes to develop varieties with useful traits

•   Programmes that enable farmers to cooperatively preserve and improve traditional seeds

•   Use of beneficial and holistic aspects of modern biotechnology, such as Marker Assisted Selection (MAS), which uses the latest genetic knowledge to speed up traditional breeding131. Unlike GM technology, MAS can safely produce new varieties of crops with valuable, genetically complex properties such as enhanced nutrition, taste, yield potential, resistance to pests and diseases, and tolerance to drought, heat, salinity, and flooding132.

Organic and low-input methods improve yields in Africa

There seems little reason to gamble with the livelihoods of poor farmers by persuading them to grow experimental GM crops when tried-and-tested, inexpensive methods of increasing food production are readily available. Several recent studies have shown that low-input methods such as organic can dramatically improve yields in African countries, along with other benefits. Such methods have the advantage of being knowledge-based rather than costly input-based. As a result they are more accessible to poor farmers than the more expensive technologies (which often have not helped in the past).

A 2008 United Nations report, “Organic Agriculture and Food Security in Africa”, looked at 114 farming projects in 24 African countries and found that organic or near-organic practices resulted in a yield increase of more than 100 percent. In East Africa, a yield increase of 128 percent was found.133 The Foreword to the study states: “The evidence presented in this study supports the argument that organic agriculture can be more conducive to food security in Africa than most conventional production systems, and that it is more likely to be sustainable in the long term.”134

Organic and low-input methods improve farmer incomes in developing countries

Poverty is a major contributory factor to food insecurity. According to the 2008 United Nations report, “Organic Agriculture and Food Security in Africa”, organic farming has a positive impact on poverty in a variety of ways. Farmers benefit from:

•       cash savings, as organic farming does not require costly pesticides and fertilizers;

•       extra incomes gained by selling the surplus produce (resulting from the change to organic);

•       premium prices for certified organic produce, obtained primarily in Africa for export but also for domestic markets; and

•       added value to organic products through processing activities.

These findings are backed up by studies from Asia and Latin America that concluded that organic farming can reduce poverty in an environmentally friendly way.135

A recent study found that certified organic farms involved in production for export were significantly more profitable than those involved in conventional production (in terms of net farm income earnings).136 Of these cases, 87 per cent showed increases in farmer and household incomes as a result of becoming organic, which contributed to reducing poverty levels and to increasing regional food security.

Who owns the technology?

In considering which agricultural technologies will most benefit the developing world, it is crucial to ask who owns those technologies. The “Gene Revolution” that is proposed for Africa will be rolled out via public-private partnerships. The public side of such partnerships will be provided by Africa, whereas the private side will be provided by biotechnology companies based in the United States and Europe.

The transgenes used in creating GM crops are patented and owned by biotech companies. In the United States and Canada, companies have launched lawsuits against farmers whose crops were alleged to contain a company’s patented GM genes. Farmers’ claims that they have not intentionally planted GM crops have proved no defence in court against large fines being imposed.

When farmers buy GM seed, they sign a technology agreement promising not to save and replant seed. They have to buy new seed each year from the biotech company, thus transferring control of food production from farmers to seed companies. Consolidation of the seed industry increasingly means that farmers have little choice but to buy GM seed. Centuries of farmer knowledge that went into creating locally adapted and varied seed stocks are wiped out.

In contrast, low-input and organic farming methods do not involve patented technologies. Control of food production remains in the hands of farmers, keeping farmer skills alive and favouring food security.

Conclusion

GM crop technologies do not offer significant benefits. On the contrary, they present risks to human and animal health, the environment, farmers, food security, and export markets. There is no convincing reason to take such risks with the livelihoods of farmers when proven successful and widely acceptable alternatives are readily and cheaply available. These alternatives will maintain the independence of the food supply from foreign multinational control and offer the best insurance against the challenges of climate change.

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