一项刊登在PNAS上的研究发现，至少有一种转基因农作物——被改造成抵御常见昆虫害虫的棉花——已经显著提高了印度小型农户家庭的生活标准。在2002年到2008年间，Jonas Kathage 和 Matin Qaim对印度四个主要生产棉花的邦的533户家庭进行了调查。这些样本包括了种植称为Bt棉花的转基因作物的农民以及没有种植它们的农民。前一组报告说棉花产量和利润分别增加了24%和50%。
这组科研人员把这种增加归结为棉铃虫破坏的减少。他们进一步确定了一旦这些种植者意识到这种利润收益是可持续的，种植Bt棉花的农民的生活标准就提高了18%。由于这些农民大多数相对贫穷，这组作者报告说，这种收益已经对他们的生活产生了巨大的积极影响。
这些发现反驳了早先的一个主张，即转基因作物技术因为较低的和侵蚀性的经济收益而可能伤害到小型农户。这组作者说，由于Bt棉花是唯一一种已经被小型农户广泛种植的作物，这项研究可能影响更广泛的公众生物技术辩论。（生物谷Bioon.com）
doi:10.1073/pnas.1203647109
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Economic impacts and impact dynamics of Bt (Bacillus thuringiensis) cotton in India
Jonas Kathage1 and Matin Qaim1
Despite widespread adoption of genetically modified crops in many countries, heated controversies about their advantages and disadvantages continue. Especially for developing countries, there are concerns that genetically modified crops fail to benefit smallholder farmers and contribute to social and economic hardship. Many economic studies contradict this view, but most of them look at short-term impacts only, so that uncertainty about longer-term effects prevails. We address this shortcoming by analyzing economic impacts and impact dynamics of Bt cotton in India. Building on unique panel data collected between 2002 and 2008, and controlling for nonrandom selection bias in technology adoption, we show that Bt has caused a 24% increase in cotton yield per acre through reduced pest damage and a 50% gain in cotton profit among smallholders. These benefits are stable; there are even indications that they have increased over time. We further show that Bt cotton adoption has raised consumption expenditures, a common measure of household living standard, by 18% during the 2006–2008 period. We conclude that Bt cotton has created large and sustainable benefits, which contribute to positive economic and social development in India.
