Elvira Dommisse: Risks still outweigh benefits of genetics

COMMENT

Genetic modification of crop plants was going to solve problems that plant breeders have been grappling with for years. Crops were going to be pest- and disease-free and yield more highly. They were going to be healthier and taste better.

During the late 1980s and early 1990s, when GM food crops were being produced and field-tested in New Zealand, food safety was simply not an issue at Crop and Food Research. Those same scientists are still saying, "it's only DNA, and people have been eating GM food for years". They are forgetting to say that DNA codes for proteins, and a foreign protein in a plant could fundamentally alter its nutritional status.

Genetic modification of plants is unlike plant breeding. It involves alterations to the DNA of crops by the insertion of transgenes - for example, animal, bacterial or viral DNA into plant cells.

During the 1990s, when widespread commercial cultivation of GM crops began in the United States and Canada, a concept of "substantial equivalence" was promoted by biotech companies and governments. This concept claims that GM crops are equivalent in nutrition and potential toxicity to established conventional crops.

But GM crops are not the same because of the random nature of the DNA integration and the uncertain consequences of the introduction of foreign proteins into the cell. Biotech firms acknowledge this when it suits, arguing that GM varieties are different enough to be patented. On the basis of their substantial equivalence, GM crops have not been comprehensively tested for their toxicity, and labelling on food packaging has been discouraged.

There have been no independent, controlled clinical trials looking at the effects of short or long-term ingestion of GM foods by humans. The failure to adequately test and label GM foods has meant that any health problems arising from their consumption will be difficult, if not impossible, to trace. Human consumers are test organisms in this badly designed experiment.

The consumption of GM foodstuffs has raised three major areas of health concerns with medical and scientific experts alike.

Adverse reactions to altered food components: Several independent scientists have warned that the viral gene promoter (a promoter switches on a gene) used in the genetic modification of most plants could be especially unstable and prone to two DNA events - horizontal gene transfer (HGT) and recombination.

These scientists are concerned that the two DNA events come with risks of cancer, gene mutations resulting from random insertion, reactivation of dormant viruses and generation of new viruses.

"Growth factor-like" effects in the stomach and small intestine of young rats fed with various GM foods have been attributed to transgenic DNA constructs and may well be found in virtually all GM food.

The first GM food in the US, the Flavr Savr tomato, was approved by Government officials against the advice of its own scientists, who were concerned about unexplained stomach lesions in rats fed on the tomato. GM insect-resistant (Bt) crops containing a "Cry" protein known to be a potent attacker of the immune system and to bind to the gut have been commercialised by the US Government.

Since the introduction of GM soy into food, doctors in Britain, Ireland, the US and Canada have independently reported a 50 per cent increase in allergies to soy. This increase coincided with the introduction of transgenic soy into food. The British Royal Society has urged caution in feeding transgenic soy to young children.

Antibiotic resistance: Genetic modification could make disease-causing bacteria resistant to antibiotics. Antibiotic-resistance genes are used as "markers" to identify transgenic plant tissue. A study last year commissioned by Britain's Food Standards Agency showed that antibiotic-resistance marker genes from GM food can make their way into human gut bacteria after just one meal.

The British Medical Association has warned that the risk to humans from antibiotic resistance developing in micro-organisms is one of the major public health threats that will be faced in the 21st century.

Accidental ingestion of industrial and pharmaceutical crops: Since 1991, more than 300 field trials of crops genetically modified to produce drugs and vaccines have been conducted in secret locations in the US. Some of these include abortion-inducing chemicals, growth hormones, a blood-clotting factor and human and animal vaccines. The majority of engineered biopharmaceuticals are in corn, a prolific pollinator. Corn pollen can be blown for long distances, contaminating non-GM crops.

Even if these "pharm" crops were genetically modified to produce sterile seed, the sterility mechanism has been shown to be only about 90 per cent effective. One mistake by a biotech company could have people eating drugs and vaccines in their cornflakes.

Those who say we will be left behind if we don't proceed with the field release of GM crops have failed to acknowledge the ever-increasing body of peer-reviewed research from overseas that documents food and environmental safety risks. These risks outweigh any promised benefits of GM crops.

Scientists in New Zealand remain divided on the field release of GM organisms. I have spoken to a number of scientists in crown research institutes and universities who have expressed serious concerns about the food safety and environmental impacts of GM crops.

New Zealand has an international reputation for exporting safe food of the highest quality. Let's keep it that way.

* Dr Elvira Dommisse is a former Crop and Food Research scientist.