Of Cabbages and Cancer.

• Author: Robertson, Henry
• Position: Genetic engineering and health

Agribusiness corporations and their genetic engineers assure us that it's safe to grow and eat their products. But these biotechnological masters of the universe may be overlooking threats to human health. Two possible threats emerge in separate reports from the United Kingdom.

The Joint Food Safety and Standards Group of the British Ministry of Agriculture, Fisheries and Food (MAFF) warned the US Food and Drug Administration in a letter dated December 4, 1998, about the spread of antibiotic-resistant genes which are commonly used as markers in genetic engineering.

Because it takes place at the submicroscopic level, it's impossible to see if a gene splice is successful. A "marker" gene attached to the transgenetic material makes detection possible. In the case of an antibiotic resistance marker, you expose the target cells (e.g. bacteria) to an antibiotic. You then know that whichever cells survive have incorporated the transgene with its accompanying marker.

When genetically modified seeds are planted in fields, the marker gene will still be in every cell of the growing plant. MAFF warned, "The widespread use of transgenics carrying antibiotic resistance marker genes will involve a massive amplification of these genes in the biosphere." This is not a good idea at a time when doctors are finding a growing number of disease strains, including tuberculosis bacteria, that are resistant to all known antibiotics.

The MAFF letter reported that bacteria in the environment can take up the antibiotic resistance genes and "could also act as a gene pool that may interact with human pathogens." Recent publications show that pathogenic bacteria can carry transgenic DNA into mammalian cells. Bacteria in the human mouth and respiratory tract can also incorporate foreign DNA.

MAFF used the example of the ampicillin resistance marker gene, which deactivates penicillin and similar antibiotics. It is used in genetically engineered maize in a "disrupted" form, meaning that it is not expressed. However, it is highly mutable and so could be reactivated in bacteria and possibly become resistant to a wider spectrum of antibiotics.

The second development was reported by Dr. Mae-Wan Ho of the biology department of the Open University in a letter to the British Society of Plant Breeders dated July 13, 1999. Dr. Ho discussed the possible link between the cauliflower mosaic virus (CaMV) and human cancer.

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