关于转基因食品的安全性,最近有很多激烈的讨论和争论。而关于它带来的好处,如提高产量和减少农药使用,则较少有人质疑。那么这些优势是否毋庸置疑呢?
去年纽约时报上的一篇文章,通过对比美加和西欧的农产品数据(来自联合国粮农署的报告),说明转基因食品尚未实现其提高产量和降低杀虫剂用量的承诺。
https://www.nytimes.com/interactive/2016/10/30/business/gmo-crops-pesticides.html
大家知道,西欧国家很少种植转基因作物,而美加两国则广泛种植,最普遍的是大豆和玉米。尽管如此,西欧国家的玉米产率这30年来几乎和美加相同,见下图:
Genetically modified varieties introduced in the U.S.
The New York Times|Source: Food and Agriculture Organization of the United Nations | Note: Western Europe is France, Germany, Belgium, Luxembourg, Switzerland, the Netherlands and Austria.
而甜菜的产率,美加即使转了基因,也远远赶不上欧洲;连增长率都赶不上,越落越远:
Genetically modified varieties
introduced in North America
Genetically modified varieties introduced in the U.S.
The New York Times|Source: Food and Agriculture Organization of the United Nations | Note: Genetic modification penetration reached 95 percent by 2010, according to the United States Dept. of Agriculture.
最尴尬的是农药(杀虫剂)用量,不用转基因的法国在大幅下降,而大用转基因的美国不降反升。橘色曲线是法国,蓝色是美国
thousand metric tons of active ingredient
The New York Times|Source: Union of Industries of Plant Protection (France)
Pesticide use in the United States
INSECTICIDES AND FUNGICIDES
The New York Times|Source: U.S. Geological Survey
事实上,孟山都的产品加大了除草剂Glyphosate的用量,从下图可以看到2000-2010年的暴涨:
percentage of acres treated
Herbicides applied to corn in the United States
The New York Times|Source: U.S.D.A. National Agricultural Statistics Service
由此可见,转基因的优势尚未被实践证实,也许在小规模种植对比中有优势,可是放到一国的规模比较,优势尚不明显。
至于安全性,虽然目前尚未发现问题,但可以看出对于人们大量食用的粮食作物,即使是美国也是比较慎重的。比如小麦,尚无转基因的产品:“https://en.wikipedia.org/wiki/Genetically_modified_wheat As of 2015, no GM wheat is grown commercially, although many field tests have been conducted.”
而转基因玉米,则多用于食品添加剂和动物饲料;超市里卖的玉米棒子,则比较少有转基因的。http://www.ewg.org/enviroblog/2014/04/corn 虽然并非绝对没有,但2013年的调查中在71例抽样中只查到两例。
综上所述,在转基因的产量和抗病虫害的优势尚未明确的情况下,对转基因食品还是应该采取慎重的态度为佳。
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