News,Views & Insights on Biotechnology

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Some interesting facts: 3

GM tomatoes: The first and only safety evaluation of a GM crop, the FLAVR SAVRTM tomato, was commissioned by Calgene, as required by the FDA. This GM tomato was produced by inserting kanr genes into a tomato by an ‘antisense’ GM method. The test has not been peer-reviewed or published but is on the internet. The results claim there were no significant alterations in total protein, vitamins and mineral contents and in toxic glycoalkaloids. Therefore, the GM and parent tomatoes were deemed to be “substantially equivalent.”

In acute toxicity studies with male/female rats, which were tube-fed homogenized GM tomatoes, toxic effects were claimed to be absent. However: Some rats died within a few weeks after eating GM tomatoes.

  • The unacceptably wide range of rat starting weights (±18% to ±23%) invalidated these findings.
  • No histology on the intestines was done even though stomach sections showed mild/moderate erosive/necrotic lesions in up to seven out of twenty female rats but none in the controls. However, these were considered to be of no importance, although in humans they could lead to life-endangering hemorrhage, particularly in the elderly who use aspirin to prevent thrombosis.
  • Seven out of forty rats on GM tomatoes died within two weeks for unstated reasons.
  • These studies were poorly designed and therefore the conclusion that FLAVR SAVRTM tomatoes were safe does not rest on good science, questioning the validity of the FDA’s decision that no toxicological testing of other GM foods will in future be required.

GM maize: Two lines of Chardon LL herbicide-resistant GM maize expressing the gene of Phosphinothricin Acetyltransferase Enzyme (PAT-PROTEIN) before and after ensiling showed significant differences in fat and carbohydrate contents compared with non-GM maize and were therefore substantially different. Toxicity tests were only performed with the PAT-PROTEIN even though with this the unpredictable effects of the gene transfer or the vector or gene insertion could not be demonstrated or excluded. The design of these experiments was also flawed because:

Rats’ ability to digest was decreased after eating GM corn.

  • The starting weight of the rats varied by more than ±20% and individual feed intakes were not monitored.
  • Feed conversion efficiency on PAT-PROTEIN was significantly reduced.
  • Urine output increased and several clinical parameters were also different.
  • The weight and histology of the digestive tract (and pancreas) was not measured.

Thus, GM maize expressing PAT-PROTEIN may present unacceptable health risks.

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Bt- MagicIn a significant move, the Ministry of Agriculture in China has granted safety certificates to three genetically modified crop plants;two strains of GM rice and one strain of GM maize. This green signal will enable the commencement of small-scale field trials of these crops in China. This is interesting to those who have been following the intense debate raging over the GEAC’s approval to Bt  Brinjal in India. Though these approvals are only to start field trials and the actual cultivation of GM crops in China is still a far-cry, it will be interesting to see whether this move will have an impact in Asia as a whole with respect to GM technology. The two rice strains have been engineered to carry pest-resistant genes and the maize strain carries a gene that will improve phosphate digestion in animals resulting in better growth and reduction of Phosphate pollution. The former has been developed by Huazhong Agricultural University, and the latter by the Chinese Academy of Agricultural Sciences. The approval had been granted in the month of August but it has become public only lately after recieving local media attention.

The move has drawn criticism from Greenpeace and other environmental groups that are strongly opposed to the use of GM technology. This also happens to be the first time that such a certificate has been granted to a staple food in China. The chair of the International Service for the Acquisition of Agri-biotech Applications, Clive James, wrote in Crop Biotech Update that this is a move that will have a huge impact in Asia. Deeming the move as Global Leadership, he has envisaged an increase in adoption of feed crops as well as food crops in the region as other countries could be expected to follow China. Once again this reminds us that there are relatively few GM crops in the world that are produced for direct human consumption.

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