Pat Howard is associate professor of communication at Simon Fraser University. She teaches courses on scientific controversies and government regulation related to genetic engineering.

Since 1995, I have studied the scientific debates regarding the potential hazards of genetically modified plants, animals, and micro-organisms. The concerns expressed by ecologists, agronomists, microbiologists, veterinarians, physicians, toxicologists, and immunologists in the scientific literature are considerable. Coverage in the media, on the other hand, has been very inadequate. The one study that received a brief flurry of media coverage was conducted by a research team in Scotland, led by Dr. Arpad Pusztai, an international expert on lectins, which are insecticidal molecules produced by plants. In 1995, Pusztai’s team received a $3.2 million research grant to investigate the safety of genetically engineered potatoes producing such an insecticidal molecule. Pusztai had already spent six years studying this lectin. He had fed it to rats in very large quantities without any deleterious effects. He did not expect to uncover any health hazards. The rat-feeding study was meticulously designed to maximize the reliability of the findings. One group of rats ate the genetically modified potatoes, a control group consumed unmodified potatoes, and a third group ate unmodified potatoes laced with the lectin. To everyone's surprise, the rats that ate the genetically modified potatoes suffered serious health effects. The study used young, growing rats.

After only 10 days, a significant number of the rats that ate the GM potatoes showed signs of arrested development of their livers, testicles, and brains. Some suffered damage to the thymus and spleen, which are both crucial to immune system function. The rats' white blood cells also appeared to have been affected. The cells lining their stomachs and intestines had begun to proliferate and undergo structural change, an ominous sign of the possibility of an increased risk of cancer. The feeding continued for 110 days, the equivalent of the first 10 years of a child's life.

To rule out any other causes, the researchers repeated the tests with boiled, baked, and raw potatoes and varied the amount of food and percentage of protein. The results were consistent; the GM potatoes alone damaged the young rats' organs and immune systems. On October 16, 1999, The Lancet reported the study. Pusztai, however, went public with his findings before publication in this peer-reviewed journal. He appeared on television and expressed his concern for the public, which was already eating genetically modified potatoes, tomatoes, corn products, and soy. He was subsequently fired and his computer and research data confiscated. He and his colleague Stanley Ewen later obtained all the data and published their analysis in Britain's most prestigious medical journal.

Since the lectin did not damage the rats' organs and immune systems, what did? Is there something about the genetic modification process itself that makes the feed immunogenic, toxic, or carcinogenic? Feeding studies involving rats, mice, pigs, and cows, conducted in Mexico, Brazil, Cuba, Japan, Egypt, Slovenia, and Russia have produced comparable, negative health effects. In fact, a rat-feeding study of the first commercial GMO, the FlavorSavr tomato, also revealed lesions that caused FDA scientists to protest the agency's approval of the product in 1994. How do genetic engineers manage to get foreign DNA into the genome of a host plant and enable the plant to utilize it to produce proteins that confer the ability to tolerate a particular herbicide or antibiotic, or to kill insect pests? The fact is that they exploit the infectious capacities of viruses and bacteria. One commonly used vector is a soil bacterium, a plant pathogen that causes galls or tumours. Only the DNA coding for proteins involved in inducing tumours is used. It is taken from a plasmid; plasmids are small, free-floating circles of DNA that provide bacteria a greater capacity to deal with environmental changes than any other life form. They are able to exchange and share plasmids, which contain genes for adaptive capacities. This is how they spread antibiotic resistance. There is evidence that antibiotics may function as sex hormones stimulating gene transfer via the exchange of plasmids, among even different species of promiscuous bacteria.