Safety of Bt Proteins to Non-Target Organisms: Vindicating Evidence
Prof. C Kameswara Rao
Foundation for Biotechnology Awareness and Education,
Bangalore, India krao@vsnl.com, www.fbae.org, www.fbaeblog.org

'The anti-agribiotech lobbies insist that the proteins of Bacillus thuringiensis (Bt), in pest resistant transgenic crops are not safe to non-target organisms, ignoring a host of detailed scientific studies which have shown that these proteins are safe to non-target organisms. 

The book ‘Bacillus thiringiensis: biology, ecology and safety’, published in 2000, refers to over 8,000 research publications, in over 60 years.  It contains extensive data on the safety of diverse Bt proteins to non-target organisms.    

The activists conveniently ignore that for Bt proteins to be toxic to any organism, a set of
physico-chemical and biological pre-requisites are essential.  In the absence of the pre-requisites in a particular organism, Bt proteins are safe to that organism.

What blew up the issue out of proportion was the much-publicized study by Losey, et al.,
(1999) which indicated that transgenic Bt corn pollen might harm monarch butterfly larvae, a conclusion immediately questioned.  Sears et al., (2001) re-examined the issue, avoiding the flaws in the experimental design in the earlier study and concluded that impact of Bt corn pollen on monarch butterfly populations was insignificant.   But the activists paid this only a Nelson’s eye.

In spite of all the evidence that Bt proteins were not the cause for a) the death of farm animals in the State of Andhra Pradesh (AP) in India, and b) the collapse of bee colonies in the US and Europe, both the instances were much publicized in support of anti-GE activism.  Recent developments, however, seem to vindicate the safety of Bt proteins. 

1. Death of farm animals in AP

Anti-GE activists in AP have a pathological compulsion to attribute any untoward incident in the farm sector to Bt crops.  Two years ago, Bt proteins in Bt cotton seeds were blamed for the death of 24 peacocks in AP, while the real cause was the pesticide Goucho, routinely used in seed dressing.  Subsequently, numerous reports of sheep, goats and cattle dying allegedly on consuming Bt cotton plants in the Warangal, Khammam and Adilabad Districts of the Telengana area of AP (Deccan Herald, February 7, 2007; The Hindu, March 2, 2007; GM Watch, March 4, 2007; Hindustan Times, June 17, 2007; GM Watch, June 18, 2007; Hindustan Times, June 18, 2007), became a never dying story, raising the question ‘Why do cattle die eating Bt cotton plants only in the Telengana region of Andhra Pradesh?’
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The causes of death of cattle and sheep were analyzed on this blog earlier.  Bt proteins were repeatedly established to be non-toxic to mammals on the basis of their mode of chemical action and experimental studies.  Yet, the activists want the world to believe that Bt cotton plants cause these alleged animal deaths and so Bt transgenic crops should be banned.

Official vindication of Bt proteins in the farm animal death imbraglio in AP has now come.  On August 17, 2007, the Minister for Environment and Forests, (MoEF) Government of India, cited an AP Government’s report and said that Bt cotton samples analyzed by four public sector laboratories contained high levels of nitrates, nitrites, hydrogen cyanide residues and organophosphates, which may be common constituents of soil or fertilizer or pesticides used in cotton cultivation, were the cause for farm animal deaths. The Minister reportedly said that ‘the MoEF had not received any scientific report attributing sheep mortality to grazing on Bt cotton fields per se’.  Since the farmers use significantly lower quantities of insecticides on the Bt cotton crop, nitrates and nitrites are more likely to be the toxicants.  The sources and symptoms of nitrate and pesticide poisoning were analyzed on this blog earlier.

2. Collapse of Honey Bee Colonies in the US and Europe

There has been a collapse of Honey Bee colonies in the US and Europe early this year, causing enormous losses.  The anti-GE activists attributed this to the pollen of GE crops.  While there are several GE crops in the US, it is absurd to attribute bee colony collapse to GE pollen in Europe and elsewhere, where there is a distinct lack of GM pollen in the environment.

Colony Collapse Disaster (CCD), the desertion and death of almost all the bees in a colony, occurs now and then, sometimes in epidemic proportions, in all countries.    While several causes for CCD were identified, no specific reason or reliable remedies are known.  Poisoning by agricultural chemicals, an unusually higher than normal winter damage and natural age dependent colony degeneration, are often confused with CCD.

 
Christian Evans analyzed in News Target (March 2007) the various possible causes for the bee colony disaster and concluded that the heavy chemical inputs in modern agricultural practices were responsible for the problem.

At a hearing of the US House Subcommittee on Horticulture and Organic Agriculture on CCD on April 5, 2007, three experts testified that the pollen from GE crops was not one of the causes for the disaster.  Nicotinoid pesticides, which may affect honey bee’s learning ability, may be one of them.  The general impression at these hearings was that the problem was overblown from the level of normal over-winter losses.

Irish Times (April 06, 2007) attributed bee colony losses to either to the CCD or a new form of Varroa destructor, a mite that attacks bees, which was prevalent for the past four or five years in Ireland.

On April 15, 2007, Omega News raised the question if mobile phones are wiping out the bees, by scrambling their signals and the same was reiterated in June 2007, by The Independent (UK).

So far not even a single peer reviewed report has proved that the products of new genes in GE crops are harmful to honey bees, bumble bees or such other insect pollination vectors.

3. OECD consensus document

The Organization for Economic Cooperation and Development, Paris, has released a peer reviewed consensus document (July 2007, Document No. 42) on the safety of transgenic Bt insecticidal proteins.  This document does not show any serious adverse effects of Bt proteins on non-target organisms under normal field conditions of Bt crops, which is also the experience of a decade of cultivation of transgenic crops in different parts of the world.

August 25, 2007