Cause Allergic Damage in Mice
(Beyond Pesticides, December 12, 2005) A decade-long project to develop genetically modified (GM) peas with built-in pest-resistance has been abandoned after tests showed they caused allergic lung damage in mice, reports NewScientist.com, based on results published in the Journal of Agricultural Food Chemistry (53:9023).
The researchers - at Australia's national research organization, CSIRO - took the gene for a protein capable of killing pea weevil pests from the common bean and transferred it into the pea. When extracted from the bean, this protein does not cause an allergic reaction in mice or people. But the team found that when the protein is expressed in the pea, its structure is subtly different to the original in the bean. They think this structural change could be to blame for the unexpected immune effects seen in mice.
The work underlines the need to evaluate new GM crops on a case-by-case basis, says Professor Paul Foster of the Australian National University in Canberra, who led the immunological work. He also calls for improvements in screening requirements for genetically engineered plants, to ensure comprehensive tests are carried out.
Jeremy Tager, Greenpeace Australia's campaigner on genetic engineering, agrees. "These results indicate the potential for unpredicted and unintended changes in the structure of transferred proteins. And I'm not aware of any country that requires feeding studies as part of its approval process."
Researchers found that mice that ate transgenic pea seed developed antibodies specific to the inserted protein. Some of these mice were later exposed to the purified protein, either through injection into the blood, or by putting the protein into their airways. This approach, which is a standard "multiple immune challenge" procedure, is designed to determine if the immune system is tolerant to a protein. The injected mice showed a hypersensitive skin response, while the airway-exposed mice developed airway inflammation and mild lung damage.
The effect was the same whether the protein was taken from raw or cooked peas - so whether the protein was active or denatured. "To my knowledge, this is the first description of inducing experimental inflammation in mice" with a GM food, Dr. Foster says. In the early 1990s, researchers engineered a more nutritious strain of soya bean by adding a gene taken from brazil nuts. But the project ended when it was discovered that the hybrid was likely to trigger a major attack in people with brazil nut allergies.
Further investigations by Foster's team revealed slight differences in the molecular structure of the protein when it was expressed in the bean and in the pea. They think this was caused by differences in the way the two plants produce proteins - particularly in a step called glycosylation, which involves adding saccharides to the protein.
According to Dr. Foster, slight differences in protein synthesis might also occur in other plants with other genes, meaning each new GM food should be very carefully evaluated for potential health effects. "If a GM plant is to go up for human consumption, there should be a detailed descriptive list of how one should go about analyzing that plant," he says.
A number of other recent studies have also shown worrisome health effects related to GM crops. In May 2004 a British newspaper leaked secret research done by Monsanto. The research showed that rats fed GE corn exhibit health problems including kidney abnormalities and blood changes. None of these abnormalities were present in rats that were fed non-GE corn for the study.
In addition to a small but significant number of studies showing adverse effects of GE food, many problems have been observed and reported over the years by farmers and other people who are in regular contact with GE products. According to Jeffery M. Smith, author of Seeds of Deception, “nearly 25 farmers in the US and Canada say that certain GM [genetically modified] corn varieties caused their pigs to become sterile, have false pregnancies, or give birth to bags of water. A farmer in Germany claims that a certain variety of GM corn killed 12 of his cows and caused others to fall sick. And Filipinos living next to a GM cornfield developed skin, respiratory, and intestinal symptoms and fever, while the corn was pollinating. The mysterious symptoms returned the following year, also during pollination, and blood tests on 39 of the Filipinos showed an immune response to the Bt toxin—created by the GM corn.”
TAKE ACTION: To protect yourself and your family, eat organic when possible. American consumers have a right to choose for themselves what kind of food they eat, and the U.S. government is acting irresponsibly by denying that knowledge and that choice. Take two minutes to take action on this issue by sending an online letter: go to The Center for Food Safety's website to automatically send a pre-written letter to the FDA demanding thorough safety testing and mandatory labeling of GE products. Also check out the Institute for Responsible Technology's website for information on how to pressure manufacturers and food providers to stop producing and providing GE food.