To improve nutrition for the world's population.

The genetic engineering of rice grains to produce provitamin A (β-carotene), described by X. Ye et al. (Reports, 14 Jan., p. [303][1]), is an example of the best that agricultural biotechnology can offer society. In the Perspective by Mary Lou Guerinot that accompanies Ye et al. 's report (“The green revolution strikes gold,” p. [241][2]), however, there are two points that are of concern. First, Guerinot says that corn expressing Bacillus thuringiensis (Bt) toxin minimizes the application of insecticides for corn insect control. In fact, insecticide applications are little reduced because Bt corn only controls the European corn borer, which is a relatively minor pest on corn, especially as compared with the corn rootworm pest complex ([1][3], [2][4]). More than 90% of the insecticide applied to corn is applied for control of the rootworm complex. Furthermore, the environmental effects of Bt corn pollen on the monarch butterfly and other beneficial insects, as demonstrated by laboratory research, need to be carefully assessed under field conditions ([2][4]). Second, about half the world population eats rice daily, so as Guerinot points out, adding vitamin A to rice will benefit many people, particularly those suffering vitamin A deficiency. However, looking at the broader picture, the World Health Organization recently reported that the number of malnourished is more than 3 billion people ([3][5])—more than half the current world population of 6 billion. Not mentioned by Guerinot is that per capita cereal grain production has been declining since 1984 ([4][6]), due in large measure to rapid population growth. This trend can be expected to continue if—as projected on the basis of the current population growth rate—the world population doubles to 12 billion in about 50 years. Other factors contributing to the decrease (grains provide about 80% of world food) are a per capita decline in cropland per person of 20% during the past decade, a 10% per capita decline in irrigation, and a 23% per capita decline in fertilizer use ([4][6]). Developing more nutritious food to reduce the number of malnourished people is admirable, but in addition, strategies to increase the food supply are critically needed. These include conserving cropland resources; improving the disparity between human population numbers and their food supply; and conserving freshwater, energy, and biological resources. We need to use science and technology to improve all aspects of the global food supply. 1. [↵][7]1. D. Pimentel 1. P. H. Schwartz, 2. W. Klassen , D. Pimentel, Handbook of Pest Management in Agriculture (CRC Press, Boca Raton, FL, 1981), p. 15, 77. 2. [↵][8]1. D. Pimentel, 2. P. Raven , “Commentary: Increase in genetic engineering means less reliance on chemicals,” St. Louis Post-Dispatch , 1 August 1999, p. B3. 3. [↵][9]World Health Organization, The World Food Summit: Micronutrient Malnutrition: Half of the World Affected (press release WHO 78, Geneva World Health Organization, Geneva, 1996), pp. 1-4. 4. [↵][10]1. D. Pimentel 2. et al. , Environ. Dev. Sustainability 1, 19 (1999). [OpenUrl][11][CrossRef][12] # Response {#article-title-2} The Pimentels raise several important issues. I used Roundup Ready soybean and Bt corn as examples of crops that benefit the farmers that grow them but, as such, do not offer added value for the people who consume them. Concerns about Bt corn will continue to be debated until lab results, such as those obtained with the monarch butterfly ([1][13]), and well-controlled field studies have been conducted and replicated. Regarding how to feed the world while preventing further degradation of our environment, it is precisely the magnitude of this problem that suggests we want to take as many different approaches as possible. A more varied diet is one way to improve nutrition, but changing people's behavior takes time. In addition, water availability, soil characteristics, and climatic conditions often limit agricultural options. For these reasons, the practice of fortifying foods after harvest with essential minerals and vitamins is in wide use, for example, the addition of vitamin D to milk and various vitamins and minerals to flour ([2][14]). Ye et al. 's “golden rice,” on the other hand, is an example of how we can fortify foods before harvest using transgenic technology. Unfortunately, too much of the focus has been on how such beneficial traits are introduced into crops. As the Pimentels suggest, we need to broaden the discussion and examine all aspects of global food production, not just the issues concerning transgenic crops. As responsible scientists, we must be willing to weigh the pros ands cons of various agricultural practices and to ask who ultimately benefits and who, in the end, gets to decide. 1. [↵][15]1. J. E. Losey 2. et al. , Nature 399, 214 (1999). [OpenUrl][16][PubMed][17] 2. [↵][18] . [1]: /lookup/doi/10.1126/science.287.5451.303 [2]: /lookup/doi/10.1126/science.287.5451.241 [3]: #ref-1 [4]: #ref-2 [5]: #ref-3 [6]: #ref-4 [7]: #xref-ref-1-1 "View reference 1 in text" [8]: #xref-ref-2-1 "View reference 2 in text" [9]: #xref-ref-3-1 "View reference 3 in text" [10]: #xref-ref-4-1 "View reference 4 in text" [11]: {openurl}?query=rft.jtitle%253DEnviron.%2BDev.%2BSustainability%26rft.volume%253D1%26rft.spage%253D19%26rft.atitle%253DENVIRON%2BDEV%2BSUSTAINABILITY%26rft_id%253Dinfo%253Adoi%252F10.1023%252FA%253A1010008112119%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx [12]: /lookup/external-ref?access_num=10.1023/A:1010008112119&link_type=DOI [13]: #ref-5 [14]: #ref-6 [15]: #xref-ref-5-1 "View reference 1 in text" [16]: {openurl}?query=rft.jtitle%253DNature%26rft.stitle%253DNature%26rft.aulast%253DLosey%26rft.auinit1%253DJ.%2BE.%26rft.volume%253D399%26rft.issue%253D6733%26rft.spage%253D214%26rft.epage%253D214%26rft.atitle%253DTransgenic%2Bpollen%2Bharms%2Bmonarch%2Blarvae.%26rft_id%253Dinfo%253Apmid%252F10353241%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx [17]: /lookup/external-ref?access_num=10353241&link_type=MED&atom=%2Fsci%2F288%2F5473%2F1966.atom [18]: #xref-ref-6-1 "View reference 2 in text"