Quantification of Human Health Risk Reduction Following the Introduction of Bt Cotton

Abstract

Genetically modified (GM) crops were first grown on commercial scales in the mid 1990’s. By 2002, 58.7 million hectares of genetically modified crops were planted worldwide [1]. The number of hectares planted has been increasing rapidly since the first commercial introduction. During the five-year period 1996-2000 the number of countries growing GM crops more than doubled, increasing from 6 in 1996 to 16 in 2002. Figure 1 gives the global area of GM crops during the period 1996-2002. The rapid adoption rates reflect the claims given by the biotechnology industry that GM crops will yield overall benefits. One such claim is that GM crops can bring financial and environmental benefits to farmers and consumers as a safe replacement for traditional synthetic chemical pesticides. Synthetic chemical pesticides have played an important role in crop protection since they were first introduced in the mid 1940’s. After Rachel Carson published her controversial book Silent Spring, regulatory agencies initiated a process of implementing stricter legislation to restrict the use of pesticides. Reduction of pesticide use following the introduction of GM crops has been well documented in the scientific literature after the first commercial introduction of GM crops [2]. However, its implications with respect to environmental and public health have yet to be well studied and little quantitative information is available on human health risk reduction resulting from the reduction of pesticide uses [3]. In this paper, the human health risks associated with reduced pesticide uses following the introduction of genetically modified crops are quantified. In this study, Bacillus thuringiensis (Bt) cotton, a genetically modified crop, is chosen as the research focus based on its global popularity. Additionally, one of the most important benefits associated with Bt crops is to reduce insecticide uses. In 2002 the global area of GM cotton was 6.8 million hectares, of which 4.6 million were sown with the Bt trait [1]. Bt is a bacterium that produces insecticidal proteins. Bt’s toxins are very specific to certain harmful insects and are relatively safe to most beneficial insects and humans. Additionally, Bt toxins are biodegradable and not persistent in the soil [4]. GM cotton carrying the insect-resistant Bt gene was commercialized in 1996 in the United States. Figure 2 gives cotton statistical data during the period 1996-2000 in the United States [5]