What are the Environmental Disadvantages of BT Crops?

Bacillus thuringiensis (Bt) is a ubiquitous soil bacteria that produces a protein with insecticidal properties. This protein has been genetically engineered into crops, such as corn and cotton, to prevent damage by foraging insects. Concern over genetically modified food safety has been prevalent since its incorporation in the early 1990s. However, to date, there is no evidence to indicate that Bt crops pose a danger to human health or to the environment.

Cry Protein

• A protein expressed by Bacillus thuringiensis, the Cry protein, acts as an insecticide. An article included in the July 2009 issue of the "Bulletin of Environmental Contamination and Toxicology" explored the possibility of the Cry protein being leached into the soil and absorbed by other plants. The researchers found that the Cry protein was detected in basil, carrot, kale, radish, snap bean and soy bean in soil in which Bt corn was grown the previous year. However, other plants, such as beet and spinach grown in the same field did not produce the protein. The researchers cautioned, however, that more studies will need to be conducted to confirm these findings.

Bt Effects on Other Organisms

• Bt crops have been planted extensively throughout the world, but there is concern about the effects of these genetically-altered plants on nontarget organisms. A review article published in the May 2011 issue of the "Journal of Integrative Biology" analyzed data from studies over the previous five years with the aim to uncover the effects on organisms other than insect control. The authors concluded that no harm to nontarget organisms, including plants and animals, has been reported.

Bumblebees and Bt Crops

• Populations of bumblebees have experienced an unprecedented decline, which may be attributable to the use of insecticides. A study appearing in the May 2010 issue of "Pest Management Control" investigated the effects of two commercial Bt strains on the foraging behavior of bumblebees, Bombus terrestris. The researchers used colonies produced in their laboratory and found that exposure to either strain of the modified plants had no effect on the insects' foraging behavior. The researchers noted that "firm conclusions regarding the hazards of Bt to bumblebees would require more information on relevant concentrations of Bt products in the environment."

Effects on Soil

• To investigate the effects of Bt crops on soil, researchers collected samples from Bt cotton crops that were grown under nets to prevent cross pollination. The results of the experiment were published in the September 2009 issue of "Environmental Monitoring and Assessment." The researchers analyzed the amount of carbon, nitrogen and phosphorus as well as several enzymes from both patches of soil and concluded that there was no risk to ecosystems using Bt crops.