Fears Pharmaceutical Drug Genes
Could Enter Food Chain

By Philip Cohen

The rules the US government is proposing for field tests of crops that have been genetically modified to produce pharmaceutical products are not strict enough to prevent the contamination of food crops, experts have told New Scientist.
They say the proposed rules are based on flawed science, that there are loopholes allowing them to be bypassed, and that companies do not even have to disclose what genes have been added. And they warn of severe environmental consequences if a drug-laced plant were to breed with other crops or wild relatives.
Biotech companies plan to produce a vast range of products, from drugs to vaccines, in plants. "These plants have the potential for more benefit than any other agribiotech product," says Jane Rissler of the Union of Concerned Scientists in Washington DC. "But to realise those benefits we have to be very careful about the risks." The US Department of Agriculture's (USDA) plans don't come close, she says. What scares Rissler and others is that there could be a rerun of the Starlink debacle, in which GM corn strictly not intended for human consumption ended up on grocery shelves. If any contamination involved a crop producing a potent drug, the consequences could be far more serious, she says.
The proposed rules require the "pharmed" plants to be separated from other crops in time as well as space. For example, pharmed maize must be grown at least 400 metres away from other maize. It must also be planted two weeks before or after nearby crops, so that it isn't fertile at the same time. Similar regulations have been outlined for other plants that have been engineered to make drugs, including barley, corn, rice and sugar cane. But when it comes to keeping harvested products separate, the rules are vague, talking only of "adequate identification, packaging and segregation".
Companies that violate these procedures can be fined $250,000, and individuals could face jail sentences of up to five years. James White, the USDA's branch chief for biotech evaluations, is confident the rules will do their job: "The chance of gene flow is essentially zero."
"These rules are more stringent than prior recommendations, and I applaud that," says Norman Ellstrand of the University of California, Riverside, who sat on a National Academy of Sciences committee that reviewed the regulations for GM crops. "But there are big holes in the system."
The NAS report points out that some of the USDA's rules have no clear scientific rationale. For instance, the isolation distance for corn is simply double the 200 metres it recommends for the production of GM seeds. The assumption is that this spacing will reduce contamination to 0.1 per cent, but there is no evidence that the contamination risk drops off with this increase in distance. Only last week, Australian researchers reported that pollen from oilseed rape had contaminated fields up to 3 kilometres away, and that there was no obvious drop-off with distance (Science, vol 296, p 2386).
Another serious concern is that the USDA focuses on the intended use of a crop product and ignores its other possible impacts. For instance, the Texas-based company Prodigene applied to grow maize that produces a chicken-egg protein called avidin, which is known to kill or harm 26 species of insects. But because avidin is not classed as a drug, the crop doesn't come under the pharming regulations. Nor did the USDA look at the maize's environmental impact because the crop wasn't being grown in order to kill insects. "If they had used the same protein as an insecticide, they would have called in the Environmental Protection Agency to regulate it," says Ellstrand.
While avidin's properties are well known, that is not the case with every drug that might end up being grown in crops. Ellstrand and his colleagues were disturbed to discover that the publicly available descriptions of genes spliced into some plants are incredibly vague.
White says the USDA will start posting fact sheets on genes in transgenic plants later this month. When a company wants to keep the identity of a gene secret, it will give it a code name and a general description, such as "Gene S is a hormone in humans. It is harmless to invertebrates," and so on.
He also says the only drugs so far being grown in crops are proteins that would simply be digested if accidentally eaten by humans or animals. "The risks are minimal," White says. "No one is making Viagra in a field." But there's nothing to stop companies producing a Viagra crop if they want to. "It's a disaster waiting to happen," says Doreen Stabinsky, a science adviser for Greenpeace. "Grow this stuff in a greenhouse or a cave, not in an open field where animals can grab the seeds."
Ellstrand agrees that stricter containment is needed. Pharmed plants could be genetically engineered to prevent gene flow using methods such as the infamous Terminator technique, which makes seeds sterile, or a newly proposed one dubbed the Exorcist (see "Begone! evil genes"). And to be absolutely certain the food supply is safe, he argues that only plants that aren't grown for food should be used to make drugs.
White points out that when the long-awaited regulations are finally published, the public will have 120 days to respond. "I wouldn't be surprised if we got thousands of letters telling us: not in food."


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