GENTECH archive


GM crops leak toxins, archive 2296

>GM crop toxin is leaking into the soil
>SOME genetically modified crops are leaking powerful toxins from
>their roots into the soil, scientists have found....

Still more sensationalist reporting. What the authors actually said in the conclusion of their paper:

"We have no indication of how soil communities might be affected by Bt toxin
in root exudates in the field. Bt toxin in the rhizosphere might improve
the control of insect pests, or it might promote the selection of
toxin-resistant target insects.... Further investigations will be necessary to shed light on what might happen underground."

In sum, all they know is that Bt toxin gets into the soil. Have you seen many caterpillars eating soil?

In fact, soil around and after cultivation of transgenic plants has been studied for some time, including

Donegan, Schaller, Stone, Ganio, Hann and Seidler. 1996. Microbial
populations, fungal species diversity and plant pathogen levels in field
plots of potato plants expressing the Bacillus thuringiensis var.
tenebrionis endotoxin. Transgenic Research 5:25-25.

Donegan, Palm, Fieland, Porteous, Ganio, Schaller, Bacao and Seider. 1995.
Changes in levels, species and DNA fingerprints of soil microorganisms
associated with cotton expressing the Bacillus thuringiensis var. kurstaki
delta-endotoxin. Appl Soil Ecol. 2:111-124.

Palm, Donegan, Harris and Seider. 1994. Quantitation in soil of Bacillus
thuringiensis var. kurstaki delta-endotoxin from transgenic plants. Mol.
Ecol. 3:145-151 (previously showed that Bt toxins could persist in soils)

Palm, Schaller, Donegan and Seidler. 1996. Persistence in soil of
transgenic plant produced Bacillus thuringiensis var. kurstaki
delta-endotoxin. Can. J. Microbiol. 42:1258-1262.

Palm, Seidler, Donegan and Harris. 1993. Transgenic plant pesticides:
fate and persistence in soil. Plant Physiol. Suppl. 102:166.

Yu, Berry and Croft. 1997. Effects of Bacillus thuringiensis toxins in
transgenic cotton and potato on Folsomia candida (Collembola: Isotomidae)
and Oppia nitens (Acari: Orbatidae). J. Econ. Entomol. 90:113-118

>It will raise fears among some scientists, regulators and
>environmental groups that beneficial soil organisms might be killed
>and that insects living in the soil might become resistant to the

Any specific examples that can be given?

>Other research found that lacewings that had fed on corn borers reared
>on BT corn had also died, raising concerns that such crops are harming
>more than just pests.

Only among some people, since the corn borers live inside the plant and the lacewings eat eggs and aphids on the outside.

>During the research, the team grew GM seedlings in the laboratory for
>25 days. Each plant produced on average 105 microgrammes of pro- tein
>and this was tested against larvae of the tobacco hornworm. Up to 95
>per cent of the larvae died after five days with 50 per cent killed at
>a dose of just 5.2 micro- grammes of protein.

Perhaps because the hornworm is about the most sensitive insect known.

>Dr Penny Hirsch, a soil expert at lACR-Rothamsted in Harpenden,
>Hertfordshire, said yesterday that the findings were "interesting" but
>added that field tests were needed to see whether the effects in the
>laboratory were happening in the real world.

Dead right!