Safe Food_ Bacteria, Biotechnology, and Bioterrorism - Marion Nestle [110]
These early reports on environmental risks were based on single studies and needed further confirmation, but others soon followed. For example, preliminary studies showed that bees and other beneficial insects die when exposed to the Bt toxin, but certain harmful moths and tobacco budworms resist it. The Bt toxin remains stable in soil for many months, meaning that it exerts continuous pressure to encourage the growth of resistant insects. Herbicide-resistant plants transfer resistance to related weeds, sometimes over great distances through pollen drift.30 Many such problems can be unintended consequences of large-scale plantings of transgenic crops, and they greatly trouble environmentalists. As I will soon explain, effects on monarch butterflies are the most political of such consequences, but let’s look first at the environmental benefits claimed for transgenic crops.
Environmental Benefits
As evidence for the benefits produced by genetically engineered crops, the industry notes how quickly growers have adopted them. In theory, the crops should help growers. At the time farmers first began to plant transgenic crops, they were using more than 80 million pounds of conventional pesticides (a term that includes both insecticides and herbicides). Reducing the use of these chemicals should produce economic as well as health benefits, and a major argument for the value of transgenic crops is that they eliminate the need for hazardous pesticides—except Roundup, of course—by millions of pounds annually. This idea is central to the biotechnology industry’s public relations efforts. The advertisement shown in figure 17, for example, promotes the ecological advantages of transgenic crops. This advertisement, which much resembles those for the cigarette-selling Marlboro Man, is clearly meant to suggest that genetically engineered crops will save family farms.
As with all issues related to food biotechnology, its benefit to farmers is subject to debate. Also like the other issues, this one is complicated and lacks a firm research base on which to resolve outstanding questions. By 2001, most observers agreed that transgenic cotton required less use of pesticides than conventional cotton, but only in certain areas. In Arizona, for example, the use of transgenic cotton led to a breathtaking decline in the need for pesticides against budworms and bollworms: from 400,000 pounds in 1995 to just 2,000 pounds in 2000. In other states growing such cotton, however, the overall use of pesticides increased.31 When it comes to corn and soybeans, however, the evidence is wide open to interpretation. Here are just a few observations: U.S. farmers who planted Bt corn in 1997 did much better economically than farmers who planted conventional corn, but in 1998 they did worse, largely because so much corn was produced that prices fell and the costs of seeds and pesticides increased. Transgenic crops—cotton as well as corn and soybeans—contributed to an overall decline in pesticide use of 2.5 million pounds from 1997, or just 1% of total pesticide use. Infestations with the European corn borer were relatively low that year, suggesting that fewer pesticides would have been applied anyway.32 In contrast, an analysis of data from 1999 found that Roundup Ready soybeans alone saved $216 million in the costs of controlling weeds and required 19 million fewer applications of herbicides. The contradictions in these results are due to the large number of variables that have to be considered in such analyses, many of them constantly changing, and some easier to measure than others.33 What seems most evident from attempts to evaluate benefits is that it is still too early to do so. We do not yet know the overall effects of transgenic crops on cost, productivity, and use of pesticides.
FIGURE 17. In 2001, the biotechnology industry’s public relations campaign featured the equivalent of the Marlboro Man. Rather than cigarettes,