Genetically engineered corn - is it safe?

New studies run over several years each confirmed concerns about the commercialisation of corn genetically engineered with Cry toxins.1,2,3

One study monitored the quantity of Cry toxins in a variety of genetically engineered corn developed by Monsanto (MON 810).1 This corn variety produces an artificial, truncated version of a Cry toxin derived from the bacterium, Bacillus thuringiensis, and was developed to control Lepidopteron insects.

What this study found was that instead of the Cry toxins acting as they would if sprayed on corn plants - releasing a small quantity of the toxin at a single or several occasions - the engineered plant produced the toxin protein during the whole period of its growth. It was also found that the toxin remained biologically active for several years in a dry plant under moderate temperatures. After harvest, the corn stubble was shown to contain a significant quantity of Cry toxin, which could still be detected in plant residues more than a year later. Traces of the toxin were also found in the soil where it could affect essential soil microorganisms.

The researchers looked at doses of Cry-toxins permitted for use in commercial bio-pesticides, including DIPEL. When they compared these with MON 810 Bt-corn, they found that the engineered corn produced 1500-3000 times more Cry1Ab toxin than the dose in a single treatment using DIPEL.

A second study2 analysed the spread of pollen from the MON 810 corn, choosing an area for the trials where no other corn was grown. It established that a conventional variety of corn grown closer than 800 metres was liable to cross-pollination by the MON 810 transgene/s. It also revealed that MON 810 pollen that settled on nearby weeds affected insects, potentially causing species to recede. The researchers established, for example, that the caterpillars of the Peacock and Comma butterflies were extremely sensitive to Cry toxins, and that the dose permitted for use against European corn borer, Ostrinia nubilalis, is 50-times larger than the sensitivity level of these butterflies.

A third study3 revealed that insects have developed resistance against Cry-toxin and that Bt-corn varieties (incorporating a Cry toxin) could have a relatively short 'viability' time. The extrapolation of this is that it will generate a growth in the number of insect populations on which Bacillus thuringiensis products would no longer work. This would pose a severe problem for organic farming, which relies on it almost exclusively.

References

1. 'Production and decomposition of DK-440 BTY corn,' András Székács, Erik Maloschik, Éva Lauber, László A. Polgár & Béla Darvas, Hungarian Academy of Sciences, Plant Protection Institute, Department of Ecotoxicology and Environmental Analysis, Budapest; Székács, A. et al. (2005) FEBS Journal, 272 Suppl. 1: 508;
http://www.blackwellpublishing.com/febsabstracts2005/abstract.asp?id=41771;

Székács, A. et al. (2006) Abs. 52th Hungarian Plant Protection Days,
52: 32;
http://www.fvm.hu/doc/upload/200602/ntn_2006_kiadvany_2006_02.pdf;

Granted by Hungarian Ministries of Education (BIO-00042/2000);
Environment & Water (K-36-01-00017/2002, NTE-725/2005).

2. 'Conflicts of DK-440 BTY corn pollen,' Béla Darvas, Éva Lauber &
László A. Polgár Hungarian Academy of Sciences, Plant Protection Institute, Department of Ecotoxicology and Environmental Analysis, Budapest.

Darvas, B. et al. (2004) Növényvédelem, 40: 441-449.

Lauber, É. et al. (2006) Abs. 52th Plant Protection Days, 52: 36;
http://www.fvm.hu/doc/upload/200602/ntn_2006_kiadvany_2006_02.pdf

Bálint, A. (1980) A vetomagtermesztés genetikai alapjai. Mezogazdasági
Kiadó, Budapest. 1-171.

Granted by Hungarian Ministries of Education (BIO-00042/2000);
Environment &
Water (K-36-01-00017/2002, NTE-725/2005).

3. Béla Darvas & Éva Lauber, Hungarian Academy of Sciences, Plant
Protection Institute, Department of Ecotoxicology and Environmental
Analysis, Budapest

Darvas, B. et al. (2005) Abs. 51. Növényvédelmi Tudományos Napok, 51:
9; http://www.omgk.hu/ntn2005.pdf

Darvas, B. et al. (2006) Abs. 52. Növényvédelmi Tudományos Napok, 52:
37;
http://www.fvm.hu/doc/upload/200602/ntn_2006_kiadvany_2006_02.pdf

Granted by Hungarian Ministries of Education (BIO-00042/2000);
Environment & Water (K-36-01-00017/2002, NTE-725/2005).

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