Bt-corn

Zwahlen, C., Hilbeck, A., Howald, R. and Nentwig, W. (2003). Effects of transgenic Bt corn litter on the earthworm Lumbricus terrestris . Molecular Ecology, 12(4), 1077-1086. 

Long before Bt crops were developed, Bt toxins in sprayable formulations were used to control insects. This fact allowed the EPA and FDA to consider twenty years of human exposure in assessing human safety before agreeing to register Bt corn for commercial use. In addition to these data, numerous toxicity and allergenicity tests were conducted on many different kinds of naturally occurring Bt toxins. Based on these tests and the history of Bt use on food crops, it was concluded that Bt corn is as safe as its conventional counterpart and therefore would not adversely effect human and animal health or the environment (Opinion on..., EFSA 2004). 

Bt corn can improve human and animal health by reducing contamination of food by mycotoxins, which are toxic chemicals produced by fungi (Wu 200 >). This is possible because Bt corn reduces insect damage that promotes fungal growth. 

In the United States, adoption of certain Bt crop plants by U.S. farmers has resulted in the application of fewer pounds of chemical insecticide, and thereby has provided environmental benefits, but the size of the reduction is dependent on the particular crop. Overall, the USDA Economic Research Service found that insecticide use was 8% lower per planted acre for adopters of Bt corn than for nonadopters (Fernandez-Cornejo and Caswell 2006). 

It seems to me that these tortillas made from corn from Bt-corn plants fit well within the ecological farming framework we try to support. First, the global environment is being spared more than a hundred million pounds of much more toxic pesticides each year (Toenniessen 2006). Second, the tortillas likely contain reduced... 

Bt crop A crop plant genetically engineered to produce insecticidal toxins derived from the bacterium Bacillus thuringiensis. Current commercial Bt crops include Bt cotton, Bt corn, and Bt soybeans. 

Kershen, Drew. 2006. Health and food safety The benefits of Bt corn. Food and Drug Law Journal 61 197. 

Wu, F. 2006. Mycotoxin reduction in Bt corn potential economic, health, and regulatory impacts. Transgenic Research 15 277-289. 

Pimentel, DavidS., and Peter H. Raven. 2000. Bt corn pollen impacts on nontarget Lepidoptera Assessment of effects in nature. Proceedings of the National Academy of Sciences USA 97(15) 8198-8199. 

Concerns over the safety of transgene introduction into environment was sensitized early in the GMO debate with significant focus on the potential toxicity of Bt endotoxins to monarch butterfly [Danaus plexippus) larvae exposed to transgenic pollen. Early data suggested that Bt corn pollen could result in potentially significant reactions in the monarch gut. 

Ecological concerns are real as we do not know what may occur with the widespread propagation of transgenic plants. There were initial fears that Bt corn was toxic not only to the European corn borer but also to the monarch butterfly larvae that may eat milkweed leaves laced with Bt corn pollen. However, EPA studies dismissed this threat. It is possible that other insects, not intended as targets of bioengineered proteins, may also be affected. It is absolutely essential that these ecological issues be addressed. However, these are not food safety issues. The same concerns occur with the widespread use of organic pesticides relative to runoff and water pollution. Both must be addressed on their own merits. 

Jaffe G (2003). Planting Trouble Are Farmers Squandering Bt. Corn Technology An Analysis of USDA Data Showing Significant Non-Compliance with EPA s Refuge Requirements. Center for Science in the Public Interest. Available www.cspinet.org. Accessed 27 May 2005. 

In response to public concerns raised by recent monarch butterfly/Bt-corn pollen studies [26, 27], tests are also under way to compare the respective effects of purified lepidopteran-active Bt toxins, of a Bt biopesticide preparation, and of a conventional chemical pesticide commonly used on corn and potentially present when pollen is produced (M.H. Pham-Delegue, unpubhshed data). Such work is expected to assess the biosafety correlates of the different methods used for crop protection, rather than simply comparing the effects of GM plants versus control plants, which is not agronomically realistic. 

Saxena, D., Flores, S. and Stotzky, G. (1999). Insecticidal toxin in root exudates from Bt corn. Nature 402,480. 

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