Environmental concerns

...in debate

Disruption of the Ecosystem -- Researchers and farmers work to segregate transgenic plants and animals from their wild relatives, but it's tough to ensure that transgenic and wild populations don't mix. In some cases, this means that farmers don't plant certain types of GMO crops.

Transgene Spread by Pollen -- When genetically engineered plants are grown in fields, they produce pollen that might spread their DNA to native plants. It's nearly impossible to confine pollen from a crop to the field where that crop is grown. In addition, many of the crops we grow have wild relatives that grow as weeds near crop fields. A GMO crop might pollinate a nearby weedy plant. If it did, genes from a GMO crop could move into closely related, wild plants.
Transgenic animals-- As with plants, transgenic animals grown in the wild may mix with wild animal populations and change the genetic composition of the wild group. Interestingly enough, Purdue animal scientist Bill Muir thinks those genes might contribute to the decline of wild animal species. (See: Transgenic fish could threaten wild populations -- this link opens a new window)

Pests Overcoming Pest Resistance -- As soon as researchers genetically engineer a crops to be resistant to a certain kind of pest, the pest starts finding ways to overcome that resistance. For example, widespread use of genes for production of the Bacillus thuringiensis toxin could render Bt toxin ineffective in the future. The toxin will kill susceptible caterpillars, leaving only Bt caterpillars to pupate, reach adulthood and multiply. The more we use Bt, the faster we create a large population of Bt-resistant caterpillars. As a result, people will lose the use of an effective insecticide that's considered organic.

Keep in mind that pests develop the same sort of resistance to pesticides. Whether we apply pesticides or genetically engineer plants to resist insects and disease, pests find away around our efforts.

For more information, see Field of Genes: A smarter way to kill bugs and Field of Genes: The dismal science of resistance from the University of Wisconsin's The Why Files. Also, visit lesson 18, "Insect-resistant Transgenic Crops" at Purdue's "Introduction to Agricutural Biotechnology" Web site. (These links open new windows.)

Contamination of Organic Crops -- The organic farming community doesn't use GMO crops. If a GMO crop is grown near an organic crop, there's a chance that pollen from the GMO crops will fertilize the organic crop...and with it will come the additional GMO genes.

Monoculture Leading to Epidemic -- If the adavantages of certain GMO crops cause most farmers start using them, and if those crops are genetically similar, crops across the nation could be wiped out by a single disease or pest.