The Safety of Bt Corn

Genetically modified microorganisms (GMO) are not yet accepted universally especially by the organic patrons. Plant gene modifications cannot be considered as an organic practice. Plus, it may cause unknown harm to human beings and environment.


One of the widely used GMO plant is the Bt Corn. Series of studies had proven its safety. Philippine Department of Agriculture approved its propagation and use in December 2002 after six years of trial and evaluation. The rest of article was excerpted from their statement .

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Bt or Bacillus thuringiensis is a common soil bacterium that produces its own insecticidal protein. Its property was discovered in 1901 by a Japanese bacteriologist, S. Ishiwata but failed to make formal description of it. A decade later, a German, Ernst Berliner named the bacterium Bacillus thuringiensis after the Thuringia region of Germany, where he isolated the organism. The Bt protein has been used safely since 1950s by organic gardeners and farmers worldwide as biological insecticide.

Bt-protected plants meet the key criteria in developing new pest control product: technical feasibility, need, efficacy, and safety. Bt-protected plants offer promises of safe and effective insect control.

Bt corn is a variety of corn where a specific Bt gene is inserted to produce a protein that protects the corn plant from feeding by Asiatic corn borers (ACB). This makes the corn plant naturally resistant to attack by ACB.

1. Is Bt corn safe for humans?
Since Bt corn is very specific, it would not harm man. The Bt protein will only affect an organism with specific receptor sites in its alkaline gut where the proteins can bind. Human beings and many insects lack these receptors. Besides, the stomach of humans is acidic.

2. Will Bt corn cause allergy?
The Bt protein does not cause allergy because it is easily digested or degraded in heat.

3. Will Bt corn make humans antibiotic-resistant?
The approved Bt corn variety does not have an antibiotic resistant gene.

4. Can we feed Bt corn to other animals?
Bt corn is safe to poultry and livestock animals. They showed comparable performance when given Bt corn feeds.
Dogs, guinea pigs, rats, fish, frogs, salamanders and birds have shown no ill effects from eating the Bt protein.

5. Will Bt corn affect other non-target organisms?
Bt protein is highly specific and will only affect insects that have specific gut receptors to the protein. Similarly, honeybees and lady beetles, both beneficial insects, showed no harmful effects upon eating Bt protein.

6. Will corn borer develop resistance to the protein produced by Bt corn?
Available data show that after 5-year commercialization of Bt crops, no reported pest resistance occurred. Insect Resistance Management Plan will prolong the use of Bt crops and will guard against unintended consequence.

7. What is the effect of Bt corn on soil ecosystem and groundwater?
The Bt protein does not move or leach with groundwater because it binds to soil particles. The proteins do not particularly last in acidic soil conditions. Under sunlight, Bt protein is destroyed very rapidly.

8. What happens if Bt corn cross-pollinate with native varieties?
There is no harm in cross-pollination since Bt protein will only affect the target insects. There is also less probability for cross-pollination since corn has limited pollination period of 5-10 days. Pollen viability is at most 60 minutes and is affected by weather especially high temperature. Also, cross pollination declines with distance e.g. 1% at 33.3 m to 0.03% at 53.3 m at release point. Studies show that 200 m are enough to isolate, in space, one field from the other

Still, cross-pollination may be avoided by planting Bt corn 21 days before and after the non-Bt corn is planted. White and yellow corn farmers are also following this temporal isolation to avoid cross-pollination.

4 Replies to “The Safety of Bt Corn”

  1. It’s hard to believe the information presented, Marvin. No technology is problem free and you only present good things. A great amount of research is showing that the technology is a problem. It’s like inserting a tiny bit of wrong code in a web-page. Aside from this, the major producer, Monsanto, has a long history of knowing ill effects of its products and insisting that its employees should not release the data.

    How can I trust a company that cries wolf so often. It was mentioned that the corn is unlikely to cross, but Mexico is having a major problem keeping BT corn from crossing with their preferred blue corn. The cross-pollination is like forcing me to eat only what the company produces, because the patent right carries to anything the corn crosses.

    Even worse, it is taking my choice away to choose what I eat, because it is probable enough that the gene will enter my garden and turn the corn I wanted to plant, into their property. I live off of my land and do not want the corn.

    Dr. Ross Carlson

    1. In addition, while the corn itself won’t enter the ground, but the vast amount of weed-killers (and don’t tell me they’re not toxic) that are sprayed onto the ground, do affect the soil and any water they enter. Round up in water is another problem. If you’d like to challenge me on this, I will personally meet with you to watch you drink a cup of water with a teaspoon of round-up added to it.

  2. Pingback: corn farmers

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