National Academies of Sciences
National Research Council
*The report is available on the NAS web site at:
U.S. Regulatory System Needs Adjustment As Volume and
Mix of Transgenic Plants Increase in Marketplace
The committee called on the U.S. Environmental Protection Agency (EPA), U.S. Department of Agriculture (USDA), and Food and Drug Administration (FDA) to quickly come to an agreement on each agency's role in regulating plants that have been genetically modified to resist pests. It also said that any new rules should be flexible so they can easily be updated to reflect improved scientific understanding.
"Public acceptance of these foods ultimately depends on the credibility of the testing and regulatory process," said committee chair Perry Adkisson, chancellor emeritus and distinguished professor emeritus, Texas A&M University, College Station. "The federal agencies responsible for regulating transgenic plants have generally done a good job, but given the current level of public concern and following our review of the data, it is the committee's belief that the agencies must bolster the mechanisms they use to protect human health and the environment. However, I must also emphasize that we believe it is the properties of a genetically modified plant -- not the process by which it was produced -- that should be the focus of risk assessments."
As the volume of transgenic products increases, more research will be needed to examine and better detect their effects on human health and the environment so that the agencies will have a more refined scientific basis for making decisions, the committee said.
Farmers have been trying to minimize their losses from crop pests for hundreds of years by using conventional breeding practices, such as hybridization, to develop crops with desirable traits. Some types of worms cause an estimated $7 billion in crop losses per year in the United States; the damage from insects is even more severe. In the past two decades, scientists have used the tools of advanced molecular biology to more precisely alter plants to be pest resistant. Scientists use these methods to introduce genes that endow plants with pesticidal traits, creating what are known as transgenic pest-protected plants. These genes may come from similar, sexually compatible species or from completely unrelated organisms. Transgenic plants have been grown commercially since 1995, and their use has increased dramatically since then. In 1999 alone, more than 70 million acres of transgenic crops were planted in the United States.
But some scientists and members of the public have expressed concern that the genetic engineering of plants could result in unsafe foods, do irreparable harm to beneficial organisms, and spur the uncontrollable growth of weeds. Given the dramatic increase in commercial planting of genetically engineered crops and the safety concerns they raise, the Research Council decided to initiate a review of the scientific data on potential health and environmental risks and the use of this data in the regulatory process.
Thus far, only in very rare circumstances have pest-protected plants caused obvious health or environmental problems. For example, although a human allergic reaction to a new gene product has never been documented for a commercially available transgenic pest-protected plant, one such incident did occur at the research stage. In that study, people with a known allergic reaction to Brazil nuts experienced a similar reaction when they were exposed in skin-prick tests to soybeans containing a gene transferred from the Brazil nut.
Priority should be given to developing improved methods for identifying potential allergens, specifically focusing on new tests relevant to the human immune system and on more reliable animal models, the committee said. Changes in plant physiology and biochemistry should be monitored during the development of pest-protected plants. And because the potential exists for transgenic plants to have increased levels of toxic plant compounds, EPA, USDA, and FDA should create a coordinated database that lists information about natural plant compounds of dietary or toxicological concern, to aid researchers who monitor concentrations of these compounds in such plants.
In examining ecological concerns, the committee looked at the possibility that transgenic plants could affect organisms which are not the target of the pesticidal trait, the potential transfer of novel genes from one type of plant to another, and the evolution of new strains of immune pests.
Both conventional and transgenic pest-protected crops could impact so-called nontarget species, such as beneficial insects, but that impact is likely to be smaller than that from chemical pesticides, the committee said. In fact, when used in place of chemical pesticides, pest-protected crops could lead to greater biodiversity in some geographical areas. The committee called for more research to examine these issues.
The highly publicized report of monarch butterflies being poisoned by pollen from genetically engineered corn is an example of an issue that needs to be researched further and will require rigorous field evaluations, the committee said. In that particular report, researchers showed that pollen from corn which had been genetically engineered to produce Bacillus thuringiensis (Bt) toxins -- a type of insecticide -- slowed the growth, and sometimes killed, monarch caterpillars when enough pollen was placed on milkweed leaves fed to them in a laboratory. Follow-up studies are needed in the field where pollen density might be lower and the toxin might be deactivated by environmental factors.
Concern also surrounds the possibility that genes for resisting pests might be exchanged among cultivated crops and their weedy relatives, potentially exacerbating weed problems -- a high-cost nuisance for farmers and potential threat to the ecosystem. The committee recommended further research to identify plants with weedy relatives, to assess rates at which pest-resistance genes might spread, and to develop techniques that decrease this likelihood.
Another ecological concern is the potential for pests to evolve and develop a resistance to plants that have been genetically modified to kill them. The committee concluded that the ability of pests to adapt and develop resistance should continue to be evaluated. Such an occurrence could have a number of potential environmental and health consequences, including a return to the use of more harmful chemical pesticides. Strategies to manage the development of resistance in pests should be encouraged for all uses of a pesticide, be it in a spray form or produced by a plant.
To improve coordination, EPA, USDA, and FDA should develop a memorandum of understanding for regulating transgenic pest-protected plants that identifies regulatory issues within the purview of each agency as well as issues for which more than one agency has responsibility, the committee said. The memorandum also should establish a process to ensure appropriate and timely exchange of information between agencies. For 14 years, the agencies have formulated policies for genetically modified foods under guidelines set forth in the 1986 Coordinated Framework for the Regulation of Biotechnology. The framework gives each agency a role in setting safety standards based on legal jurisdictions at the time. But the committee said the scope of each agency's oversight needs to be clarified, especially when a new product is to be reviewed by more than one agency.
Additionally, the committee took issue with exemptions in EPA's proposed 1994 rule for regulating certain transgenic pest-protected plants. EPA proposes to grant categorical exemptions for all plants that have been given a new gene from a sexually compatible plant, and for plants expressing proteins that are derived from a virus, known as viral-coat proteins. But in the first instance, the committee said that in some cases the transfer and manipulation of genes between sexually compatible plants could potentially increase human and environmental exposure to high levels of toxins. Secondly, while plants with viral-coat proteins may be safe to eat, there are environmental issues to consider because of their potential to crossbreed with weedy relatives. The committee urged EPA to reconsider its plans to grant categorical exemptions for these transgenic plants.
The committee also recommended that the agencies monitor ecological impacts of pest-protected crops on a long-term basis to ensure the detection of problems that may not have been predicted from tests conducted during the registration and approval process.
A more open and accessible regulatory process is needed to aid the public in understanding the benefits and risks associated with transgenic pest-protected plants, the committee concluded. To increase access to the process, existing Web sites for the coordinated framework should be expanded to include more detailed information and to link all of the agencies' decisions for any particular product.
The committee's work was funded by the National Research Council, which is the principal operating arm of the National Academy of Sciences and the National Academy of Engineering. The three, along with the Institute of Medicine, constitute the National Academies. They are private, nonprofit institutions that provide science, technology, and health policy advice under a congressional charter. A committee roster follows.
Pre-publication copies of Genetically Modified Pest-Protected Plants: Science and Regulation are available from the National Academy Press at the mailing address in the letterhead; tel. (202) 334-3313 or 1-800-624-6242. The cost of the report is $50.00 (prepaid) plus shipping charges of $4.50 for the first copy and $.95 for each additional copy. Reporters may obtain a copy from the Office of News and Public Information at the letterhead address (contacts listed above).
NATIONAL RESEARCH COUNCIL
Committee on Genetically Modified Pest-Protected Plants
Perry Adkisson* (chair)
RESEARCH COUNCIL STAFF
* Member, National Academy of Sciences
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