I am sending the summary of the work we have done on the environmental risk associated to BT maize. The work was conducted as part of the EU grant INCO Nº ERB3514PL961239.

I include an abstract of the work in English. Although this work was presented in 2 national meetings in Spain, we have not published the work. The document named: Persistencia de Cry1Ab.PDF (NB text in Spanish; 140kb) was presented at:

V Congreso Nacional del Medio Ambiente. Madrid, 27 de noviembre-1 de diciembre, 2000
- González, P., Fereres, A. Persistencia de la toxina BT procedente de maíz transgénico en suelos y restos de cosecha. Presentacion de Comunicación, pag- 24-25

The document named BTk-transg.doc (NB text in Spanish; 15kb) was presented as an oral presentation at:

II. Congreso Nacional de Entomología Aplicada. Pamplona, 12-16 de noviembre del 2001.
- González P., Duque M. y Fereres A.. Persistencia de la toxina Bacillus thuringiensis var. kurstaki (Berliner) procedente de maíz transgénico en suelos y restos de cosecha.

Unfortunately, the work has not been published in a refereed journal. This is a summary of the main conclusions:

Abstract

Cry1Ab toxin released from Bt corn was not detectable in the clay fraction of the soil when using a soil-sample specific extraction and detection method based in a DAS-ELISA protocol. The failure for detection was likely due to the impossibility for recovering the toxin from clays because detection was possible when the toxin was extracted from the original soil samples. However, the clays adsorbed Cry1Ab toxins from the soil where transgenic Bt corn plants were grown as revealed by their insecticidal activity against the target species Trichoplusia ni. The clay fraction of the soil exhibited insecticidal properties up to a period of 8 weeks after the crop was harvested. The level of Cry1Ab toxin present in BT-corn leaf, and root crop residues that were incubated without soil contact under greenhouse conditions declined rapidly over time and dropped down below the levels of detection by DAS-ELISA seventeen and thirteen weeks after harvest, respectively. Leaf residues exhibited high insecticidal activity against T. ni 4 weeks after starting incubation. However, the insecticidal activity of such leaf residues declined very fast thereafter. Our findings show that adsorption of toxins released from Bt corn on soil colloidal fractions can increase their persistence, although there is low risk for long-term accumulation of potentially active toxin.

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