Agricultural Research
Service scientist in Albany, Calif., harvests genetically engineered
potatoes. A gene from the giant silkworm moth was put into the potatoes in
an attempt to prevent bruising.As the 21st century approaches, the world is facing problems many experts see as intractable. All but four of the world's 17 major fisheries are seriously depleted. Irrigation water is in short supply in many parts of the globe, and erosion threatens the productivity of much farmland. While the amount of land under cultivation cannot be expanded greatly, almost 100 million people are expected to be added to the world's population each year for the next 30 years. As a result, per capita food production is likely to continue to decline in Sub-Saharan Africa and barely rise in South Asia.
Biotechnology - specifically that aspect involved in transferring genes from one species into the genome of another - has the potential to alleviate many of these problems. Genetically engineered (transgenic) fish that grow much faster than wild and traditional aquaculture varieties could relieve some of the pressure on the world's fisheries. Crops bioengineered for pest resistance could increase yield, eliminate the use of several insecticides now derived from fossil fuel, and reduce health risks and groundwater contamination from pesticides. In some areas, crops genetically modified for herbicide tolerance could decrease the amount of herbicide used and allow for no-till agriculture, which can minimize erosion. Crops engineered to produce oil-derived chemicals could relieve pressure on oil supplies. Recombinant bovine growth hormone already enables cows to use feed more efficiently and produce more milk.
Although each of these applications holds great promise, each also may cause harm to ecological systems, human health, or economic and social structures. Proponents of biotechnology claim that most transgenic agricultural products pose no unique hazards to health or to the environment. Critics say the advantages of bioengineered products have been exaggerated and that they involve potential dangers that have not been fully investigated. In general, it is molecular biologists, most of whom have a background in biochemistry, who see little reason to believe that transgenic organisms could injure ecological systems, while ecologists and experts in fisheries and marine biology think great caution should be used when releasing such organisms.
In the U.S., the Administration generally is confident that most uses of biotechnology will not cause undue harm and that, on an international basis, it can be used safely with voluntary and cooperative oversight. The U.S. takes the position that a legally binding international protocol governing uses and releases of genetically modified organisms - a biosafety protocol - would interfere with research and the development of the biotechnology industry.
In contrast, some European nations are quite leery about uses of biotechnology, especially in developing countries. Last month, the European Parliament passed a resolution saying that "a legally binding international biosafety protocol is necessary and a matter of urgency and must be immediately negotiated by the states party to the [United Nations] Convention on Biological Diversity," which was agreed to at the Earth Summit in Rio de Janeiro in 1992. To justify the need, the resolution states: "Deliberate releases of genetically modified organisms are being carried out in many developing countries, which have no legislation or infrastructure to ensure their safe use ... [and] this situation is putting the entire biosphere of the planet at risk."
Delegations from 80 countries met at a UN experts meeting in Madrid, July 24 to 28, to decide on the need for, and the issues to be addressed in, a biosafety protocol under the Convention on Biological Diversity. Even though the U.S. is not among the 120 nations that ratified the convention, it plays a strong role in the conferences of the parties and experts meetings.
At the Madrid meeting, the delegations reached consensus on a document calling on the parties to the convention to begin drafting a legally binding biosafety protocol. This document was approved, even though the U.S., Germany, Japan, and Australia officially took the position that a protocol is not needed and pushed instead for voluntary guidelines. The protocol issue will be dealt with further when the second conference of the parties to the convention meets in Jakarta, Indonesia, in November.
In its strong support for a binding protocol, the Madrid meeting represents an about-face from a report prepared by 15 UN experts at a meeting in Cairo last spring. The Cairo statement roughly equates genetically engineered organisms with organisms produced by traditional technologies - such as crop hybridization - implying that, therefore, no international control over the products of biotechnology is needed. The Madrid statement not only calls for a binding protocol, it also says the protocol should be based on the precautionary principle - the idea that a transgenic organism should not be released if there is significant uncertainty about its risk.
If a binding protocol is eventually adopted, international trade and corporate profits could be affected. The Biotechnology Industry Organization (BIO), a Washington, D.C.-based association of biotechnology companies, and other biotechnology industry groups lobbied strongly at the Madrid meeting to keep controls at the national, rather than the international, level.
Agricultural Research
Service scientist in Albany, Calif., harvests genetically engineered
potatoes. A gene from the giant silkworm moth was put into the potatoes in
an attempt to prevent bruising.After many years of development, agricultural bioengineered products are rapidly entering the U.S. marketplace. The first major product, Monsanto's recombinant bovine growth hormone, was approved for sale in February 1994, and since then nine other products have garnered regulatory approval. In addition, more than seven products are going through the approval process and likely will be on the market within two or three years.
Although no variety of transgenic fish has been commercialized anywhere in the world, some companies are developing brood stocks of these fish and expect to begin marketing them within a few years. China plans to start selling its genetically modified fish as soon as it has produced stocks that grow fast enough to make the effort worthwhile.
Because the development costs have been so high, no company has yet made a profit on a transgenic agricultural product, despite the upsurge in commercial approvals; however, some firms expect to do so within a few years. BIO predicts that annual sales of such products will reach several billion dollars by 2000.
With the exception of recombinant bovine growth hormone, agricultural products with current or pending regulatory approval in the U.S. fall into six categories: plants engineered for herbicide resistance, plants designed for insect resistance, tomato plants engineered for delayed tomato ripening, plants modified to produce products now made from other crops, plants engineered so the crop can be processed more easily, and bacteria designed to enhance nitrogen fixation in alfalfa or to control insects. (The plants and animals that are genetically modified to produce pharmaceuticals are not discussed in this article.)
In the U.S., three different agencies regulate agricultural transgenic organisms under a patchwork of statutes. So far, Congress has not enacted a single new law to govern biotechnology research and commercial applications. Instead, the agencies have adapted the existing body of legislation to regulate recombinant DNA research and products. However, they have written some new guidelines for the conduct of research and for regulatory approval processes.
Currently, for product research and commercialization, companies must seek approval from one to three agencies, depending on the nature of the transgenic organism. Under the Food & Drug Administration's (FDA) transgenic plant food policy, few products will require agency approval under the Food, Drug & Cosmetic Act. However, most companies thus far have voluntarily consulted with FDA to gain its stamp of approval. The act has very few data requirements and specifies that consultations should go on behind closed doors, unless the company involved requests open meetings. Under the Plant Pest Act, the U.S. Department of Agriculture (USDA) regulates transgenic plants to be grown on a large scale. If the gene-modified organism expresses a pesticide or functions as a pesticide, the Environmental Protection Agency (EPA) regulates it under the Federal Insecticide, Fungicide & Rodenticide Act (FIFRA). Under the Toxic Substances Control Act (TSCA), EPA also controls genetically engineered microorganisms that have no pesticidal attributes. An example would be a bacterium engineered to produce ethanol from agricultural residue.
Corn that is genetically engineered to express an insect toxin from the soil bacterium Bacillus thuringiensis in its cells is an example of a crop that is regulated by all three agencies. Its insecticidal properties must be approved by EPA, its large-scale growing by USDA, and the corn as a food product by FDA.
Under the existing legal framework, environmental releases of most genetically engineered animals are essentially unregulated. Some varieties of transgenic fish have extra copies of a fish growth hormone gene, and FDA may decide to regulate them as new animal drugs. If FDA decides it does not have authority to regulate transgenic fish, no statute covers the environmental impacts of commercializing them, says James Maryanski of FDA's Center for Food Safety & Applied Nutrition. But he says FDA would be in charge of the quality of the fish in commerce.
Despite the frequent need for multiple approvals, industry is generally satisfied with the current regulatory structure. "The system is working pretty well," says BIO President Richard Godown. "Obviously, there are difficulties, but we're getting our products to market."
Agency officials also consider the current system effective. Janet L. Andersen, acting director of EPA's biopesticides and pollution prevention division, says, "The agencies have coordinated their efforts together well so they appropriately cover their mandate to regulate transgenic organisms."
However, the Union of Concerned Scientists (UCS) in Cambridge, Mass., and a number of environmental groups such as the Environmental Defense Fund have criticized the patchwork approach for years. Such groups prefer a new statute that would establish a comprehensive program administered by EPA to regulate the release of engineered organisms into the environment.
Jane Rissler, a UCS senior scientist based in Washington, D.C., says the use of USDA's Plant Pest Act is an especially weak part of the current system. This statute is vulnerable to legal challenge because it applies to plant pests, not plants, she says. "Furthermore, it is not a strong enough statute," she notes. "Unlike FIFRA, it is not a registration statute, which would allow USDA greater control over a product, and it does not require labeling. The product is simply approved or not approved."
Nearly all researchers in the biotechnology area agree that the techniques of recombinant DNA are a wonderful research tool for understanding plant and animal physiology. They say that with biotechnology the desired results in traditional breeding can be reached much more quickly and with less trial and error.
But scientists' views are sharply divided over transgenic fish. Some experts regard such fish as the potential answer to the depletion of the world's fisheries and a practical way to increase protein intake for many malnourished people. They believe that even if some fertile transgenic fish manage to escape to oceans or freshwater bodies, the fish will not pose a severe ecological hazard. Others see gene-modified fish as a potential nightmare that could permanently eliminate many species of wild fish.
Currently, about 40 or 50 labs around the world are working on transgenic fish. About a dozen of them are in the U.S., another dozen in China, and the rest in Canada, Australia, New Zealand, Israel, Brazil, Cuba, Japan, Singapore, Malaysia, and several other countries. Some of these labs are associated with companies that expect to commercialize their fish in a few more years. Many of the fish under development are being modified to grow faster than their wild or traditionally bred aquaculture siblings. Faster growth is usually accomplished by transferring a fish growth hormone gene from one species of fish into another. The faster growing fish not only reach market size in a shorter time, they also use feed more efficiently, researchers say.
For example, Thomas T. Chen, director of the Biotechnology Center at the University of Connecticut, Storrs, transferred into common carp the growth hormone DNA from rainbow trout fused to a sequence from an avian sarcoma virus. The genetic material was injected into fertile carp eggs with microinjection. The offspring of the first generation of transgenic fish grew 20 to 40% faster than their unmodified siblings. Chen is also developing transgenic catfish, tilapia, striped bass, trout, and flounder.
Another example is work by Robert H. Devlin, a research scientist with Fisheries & Oceans, Canada, in West Vancouver, British Columbia. He has modified the growth hormone gene in coho salmon by developing a gene construct in which all the genetic elements are derived from sockeye salmon [Nature, 371, 209 (1994)]. The transgenic coho grew on average 11 times faster than unmodified fish and the largest fish grew 37 times faster. The growth hormone levels in the transgenic fish are high year-round, rather than falling off in the winter as occurs in ordinary salmon, Devlin says. The modified salmon are large enough to be marketed after one year, in contrast to standard farmed salmon that do not reach market size for at least three years.
Research associate Amy J. Nichols and professor Rex Dunham in the department of fisheries and allied aquaculture at Auburn University, Auburn, Ala., have developed transgenic carp and catfish that grow 20 to 60% faster than standard farmed varieties. They use microinjection and electroporation to inject another copy of a fish growth hormone gene into fertile fish eggs. The growth of the resulting modified carp and catfish is stimulated by extra fish growth hormone.
Transgenic fish are wild types or nearly so, often created from eggs hatched from gametes collected in the wild, so they are fully capable of mating with wild fish. Consequently, one important risk associated with transgenic fish is that, if they escape to fresh water or to the ocean and mate with wild fish, they could destroy the diversity of the wild population gene pool.
Such an event occurred in Norway with farmed salmon. Seals occasionally broke the net cages where the salmon were being raised in fjords and some of the salmon escaped and mated with Norway's wild salmon. Because the numbers of wild salmon had already been depleted as a result of acid rain on freshwater spawning grounds, the wild salmon were easily overwhelmed by aquaculture salmon. As a result, says Anne R. Kapuscinski, professor of fisheries and Sea Grant extension specialist at the University of Minnesota, the genes of the wild salmon were homogenized, and Norway lost one of its most important resources - a tremendous amount of genetic diversity in its wild salmon - and the associated commercial and sport fishing industries.
In addition, transgenic fish could also eliminate whole aquatic ecological systems by preying on and outcompeting native species, as many introduced exotic (nonindigenous) fish have done. In the U.S., the introduction of exotic species is responsible for 28 of the 86 endangered and threatened fish species and subspecies.
At U.S. and Canadian research facilities, elaborate precautions are being taken to prevent the release of transgenic fish into the environment. The fish are often raised in ponds covered with nets to keep birds out; enclosed by electric fences to keep muskrats, raccoons, and humans out; and the outlets are fitted with screened drains to prevent the loss of small fish or eggs.
USDA's Agricultural Biotechnology Research Advisory Committee recently developed voluntary performance standards for safely conducting research with genetically modified fish and shellfish. The committee wrote the standards in consultation with fish and shellfish researchers around the world and will publish them in a few weeks. Many researchers in the U.S. have expressed an interest in using the guidelines. The standards may also fulfill a real need in developing nations that lack expertise or resources to develop such guidelines. Eric M. Hallerman, associate professor of fisheries and wildlife sciences at Virginia Polytechnic Institute & State University, Blacksburg, surveyed countries around the world and found that only 12 have specific national policies or regulations on transgenic aquatic organisms.
Auburn Univ., Nichols
microinjects catfish eggs with growth hormone gene.
The resulting fish grow faster
than their standard counterparts and..
.. are raised in ponds covered
with nets and surrounded by an electric fence.Commercialization of transgenic fish will occasionally involve some escapees, no matter how carefully pools or net pens are designed. So researchers are planning strategies to prevent the reproduction of transgenic fish. The main strategy is to raise triploid transgenic fish. Instead of having the usual two sets of chromosomes, triploid fish have three sets and are sterile. To produce triploid fish, eggs from diploid fish are given a heat or pressure shock at the appropriate time of development.
But this method has potential drawbacks. Using heat or pressure shock makes only 90 to 98% of the eggs triploid. This problem can probably be solved, however, by using an alternate method to produce triploid fish. The eggs are made tetraploid by using heat or pressure and the resulting tetraploid fish are then mated with diploid fish. The offspring are 100% triploid.
Even if 100% of the transgenic fish are triploid, however, there is another difficulty that has only recently come to light - the possibility that some of them will revert to diploid and thus become fertile. Standish K. Allen, associate professor of marine science at Rutgers University, New Brunswick, N.J., found that when individually tested triploid Pacific oysters were placed in the Chesapeake Bay, many of them reverted to diploid. Each oyster was tested twice - before it was put in the bay and shortly after - and all were triploid. But when tested several months later, 14% had reverted to diploid at one site and 20% at another.
Not enough testing has been done to rule out the possibility that some species of triploid fish might also revert, Allen says. "It's a little difficult to know whether fish will revert because the subject is not well documented in the literature," he says. One of the reasons might be that people have not looked carefully for reversion in many artificially induced triploid fish, he explains.
So much is unknown about transgenic fish that it is difficult to assess what risks their release might pose to the environment. Researchers do not even have a definitive answer to the simple question: Will transgenic fish ultimately grow larger than unmodified varieties? Chen believes that, in general, fish keep growing throughout their lives, so faster growing transgenic fish will end up larger than their standard counterparts. In contrast, Kapuscinski cautions that not enough has been published about the growth of modified fish to provide any general answers to this question.
Another unknown is how the fitness of fertile genetically modified fish would change through the generations. Researchers suspect that some species would become more fit as the generations proceed, while others would become less well adapted. But there are almost no experimental data. Some experts believe that nearly all varieties of transgenic fish would have a hard time surviving and reproducing in the wild.
William M. Muir, a population geneticist at Purdue University, is studying transgenic medaka, small fish with a 10-week generation time, to see how their fitness changes over generations. Muir does not yet have results on his medaka but he believes that some transgenic fish if allowed to reproduce will get more fit through the generations. "I suspect that when we first put the transgene in the fish that we are not seeing its worst face," Muir says. "Originally, the fish may be out of sync with its physiology, but natural selection may help the organism cope with this new functionality, and probably over time it will get more aggressive or more fit."
In China, fertile transgenic fish are being raised in large open ponds without nets or fences to keep out birds, or humans who might want to steal the fish and grow them in their own ponds. Marc Welt, assistant professor of molecular biology at Xavier University, New Orleans, who spent a month at Chinese facilities that develop transgenic fish, says this lack of security does not present an ecological risk because China's environment is so degraded that it supports few wild fish.
Alvin L. Young, director of the Office of Agricultural Biotechnology at USDA, agrees. "The Chinese have had a very disrupted ecosystem for 2,000 years," he says. "So how does one track the adverse effects of transgenic fish from the normal things that have gone on there for centuries?"
Hallerman admits that China no longer has commercial quantities of wild fish. For centuries, however, the Chinese have employed the genetic diversity in wild fish to replenish and revitalize the stocks used in aquaculture. If transgenic fish homogenize the wild fish in China, the nation will have lost a valuable source of genes, he says.
" There is a lot of talk now about how aquaculture, especially with transgenic fish, is a great answer because most commercial fisheries and wild populations are declining and increasingly are going extinct," Kapuscinski says. "But it may not be in the nation's best interests to totally turn our backs on wild populations and even on commercial fishing, and rely on aquaculture, because then we may be tempted to allow the genetic diversity of the wild populations to erode even further. And these are the populations we need to go to periodically to get new genes to infuse into our aquaculture stocks."
Scientists' views of transgenic plants, though not as polarized as their views about modified fish, vary greatly. USDA officials essentially consider transgenic plants as no different from standard varieties. Therefore, the plants require no more care in research and commercialization than standard varieties. A number of other scientists believe that genetically modified plants may pose more risks than traditionally bred crops.
So far, transgenic crop plants with final regulatory approval include two varieties of tomato with delayed ripening, cotton resistant to the herbicide bromoxynil, insect-resistant potato, insect-resistant corn, herbicide-resistant soybean, virus-resistant squash, tomato engineered to have a higher solids content for easier processing into sauces, and canola with the oil composition altered to be high in lauric acid.
Monsanto developed the potato that resists the Colorado potato beetle. Monsanto spokesmen and most officials at USDA and EPA believe this crop is almost entirely risk free and, in fact, very beneficial to the environment. The crop will increase yield and protect workers, consumers, and the groundwater by eliminating or cutting back on the use of toxic insecticides.
The insect-resistant potato is created by using a modified virus as a vector to insert into the plant a truncated gene for the production of a potent insect toxin from Bacillus thuringiensis (Bt). The truncated gene is from the variety of Bt that produces a toxin for the Colorado potato beetle.
Organic farmers and other growers have employed bacterially produced insect toxins derived from Bt and the spores of Bt itself for 30 years as a tool in integrated pest management. Used in this manner, Bt stays on the plants for only a few days at a time before it is broken down by sunlight. Nevertheless, some insect resistance to Bt has already begun to show up in grain silos and in Hawaii where farmers have used it heavily. Unless precautions are taken, insects might also become resistant to the Bt plants - because the Bt toxin, which is very similar to that produced by the bacteria, is present in the plants throughout the growing season and can't be broken down in sunlight.
Because of this potential problem, Monsanto worked with EPA to develop a strategy that farmers can use voluntarily to ward off resistance. The plan involves making refugia available - that is, growing in the same field with the transgenic plants or nearby fields some unmodified plants that insects can eat. Thus, some nonresistant insects will be preserved to mate with resistant ones. The strategy also involves monitoring the crop so that if resistance develops in one area, action can be taken to keep it from spreading.
Rissler: unexpected harmful
effectsAn EPA science advisory panel of top entomologists approved the plan, says M. Lisa Watson, director of public affairs at Monsanto. However, UCS's Rissler says the resistance plan bears more resemblance to a work-in-progress with many unanswered scientific questions than to a concrete, well-worked-out strategy.
Early this month, EPA gave separate approvals to Mycogen and Ciba Seeds, a division of Ciba-Geigy, to market corn hybrid seeds, genetically engineered with a gene from Bt, to fight damage from the European corn borer. The seeds were developed in part by a collaboration between Mycogen and Ciba Seeds. Both companies have developed grower education materials to help farmers ward off insect resistance. To further reduce the likelihood that the corn borer will develop tolerance to a single control mechanism - the Bt toxin - the seeds Mycogen will be selling have both the Bt-based gene and a natural resistance gene acquired from a wild relative of corn and incorporated into the seed with traditional breeding.
Some scientists doubt that resistance can be avoided for more than a few years, even with carefully designed strategies, when thousands of acres of commercially grown crops are producing the Bt insect toxins throughout the growing season and when each crop has only one type of Bt. "Agricultural entomologists are well aware that the value of a' single-bullet' approach to insect control is likely to be short-lived," says Allison A. Snow, associate professor of plant biology at Ohio State University.
Charles M. Benbrook, a private agricultural consultant based in Washington, D.C., points out that if insects become resistant to Bt plants, they will also be resistant to the Bt used by organic farmers and this Bt will become useless.
Nearly all researchers agree that growing herbicide-tolerant plants in the U.S. will probably result in the use of less herbicide on some crops, at least in the short run, and, in most cases, the use of more environmentally friendly herbicides. And they do not expect herbicide-resistant crops with no wild relatives to pose a major risk to the environment.
The herbicide-resistant soybean developed by Monsanto will allow greater use of the herbicide glyphosate (Roundup), which breaks down quickly in soil, and will enable farmers to use fewer herbicides. In some areas, this soybean will allow elimination of all herbicides with detrimental properties, says Frank S. Serdy, director of regulatory affairs at Monsanto.
Critics do worry that growing Calgene's bromoxynil-tolerant cotton on U.S. cropland will lead to the use of more bromoxynil - a suspected cause of birth defects. On the other hand, according to Carolyn E. Hayworth, manager of public relations at Calgene, bromoxynil-tolerant cotton reduces by half the number of applications of herbicide required and decreases by about 40% the total amount needed.
Researchers are also concerned about the long-term effects of herbicide-resistant crops. "Evidence suggests the effects on the environment of herbicide-tolerant crops are not clear-cut," says Roger P. Wrubel, assistant professor in the department of urban and environmental policy at Tufts University, Medford, Mass. In the aggregate, the crops could help phase out environmentally damaging herbicides and reduce overall herbicide use, he says. Or they could promote reliance on chemicals that lead to weed resistance because they will encourage use of a few broad-spectrum herbicides.
Some experts warn that herbicide-resistance or insect-resistance genes could spread from the transgenic crop to its wild relatives and create new weeds that are especially difficult to control, or that the crop itself could become a weed. Corn, potato, and soybean do not have wild relatives in the U.S., but canola - the rapeseed plant - has six wild relatives in the mustard family (Brassica), some of which are already rather troublesome weeds in regions where canola is grown. Monsanto, Hoechst, and Rhone-Poulenc are developing herbicide-resistant canolas, which will probably be commercialized in a few years.
Jack Brown, a plant breeder geneticist at the University of Idaho, has been studying the spread of herbicide-resistance genes from transgenic canola to its relatives in the mustard family. He has found that the resistance gene moved through pollination from the canola to a small fraction of one type of Brassica weed (birdscrape mustard), and that gene then moved to wild mustard, a weed that is much more troublesome. Even though the fraction of weeds affected was low, so much herbicide-resistant canola will soon be growing in the U.S. that a large number of herbicide-resistant weeds could potentially be created in a few years, he says. "We need to know much more about gene movement in nature and what steps to take if gene introduction into weeds occurs," Brown says. "Modern agriculture has happened at a price," he warns. "We should learn from our experiences what disasters could befall us before we jump into large-scale production of gene-modified plants."
USDA's Young admits that herbicide-resistance genes move from canola, but he does not think this will have" great ecological consequence. We just asked Brown to come up with a worst case scenario," Young says. "But that doesn't say it would be a bad case in reality."
The delayed-ripening tomato developed by Calgene, called either Flavr Savr or MacGregor, is already in supermarkets, and the one designed by DNA Plant Technology, Endless Summer, has been test marketed in New York State. Except for those researchers who are opposed to all bioengineered foods, few expect these tomatoes to have a harmful effect on the environment or on the development of weeds.
Most tomatoes are picked in the green hard-ball state so that they can be shipped long distances without rotting. Both of these transgenic tomatoes are designed so that they ripen more slowly and can be picked later in the ripening process. Calgene's tomato has an extra gene - a reverse copy of the gene responsible for an enzyme, polygalacturonase, that breaks down cell walls. As a result, Calgene's tomato softens more slowly. DNA Plant Technology's tomato has a gene that controls the enzyme 1-amino-cyclopropane-1-carboxylic acid (ACC) oxidase, which is necessary for the production of ethylene, one factor that makes a tomato soft.
A crookneck squash with virus resistance developed by Asgrow Seed Co., Kalamazoo, Mich., is now being grown and will be sold as frozen squash. It is modified by inserting into the genome genes coding for viral coat proteins of two viruses that often infect squash. For reasons not fully understood, the expression of low levels of viral coat proteins in the plant prevent infection by the original virus. The yield of the Asgrow squash is about five times greater than it is with standard seed because the virus that reduces yields cannot infect the crop, BIO's Godown says.
Transgenic high-laurate
canola plants (rapeseed) developed by Calgene were modified with a gene from
the California bay tree. The oil from this rapeseed is often more than 40%
laurate.Despite its advantageous yields, the squash is a subject of scientific controversy. Some experts worry that when the squash is infected with other viruses, recombinational events could occur that would generate new viral strains. Plant biologists Anne Green and Richard Allison of Michigan State University found that recombinational events occurred in transgenic cow pea plants modified with a virus coat protein. When the plants were inoculated with a different virus, viral RNA or DNA recombined with genetic material from the invading virus to form a new more virulent strain [Science, 263,1423 (1994)]. However, it is not known whether this would happen with squash plants. Nor is it known whether the widespread use of transgenic crops would increase the rate at which pathogens evolve, Snow says.
Calgene's genetically engineered canola, which will produce large amounts of lauric acid, was modified with one gene from the California bay tree. The gene shuts off fatty acid synthesis at 12 carbons instead of the usual 18-carbon length normal for the plant. The oil from some of the plants is more than 40% laurate. Currently, laurate oils are obtained from imported coconut and palm kernel oils produced in Southeast Asia.
One risk some see in high-laurate canola is that after harvest, the seeds will get mixed up with the seeds from the unmodified edible crop, since they are identical. As a result, some people might unknowingly eat high-laurate canola, which in large quantities is hard to digest. The problem will be further exacerbated when other types of transgenic canola, such as one now under development producing the industrial oil erucic acid - a feedstock for making nylon 13-13 - are also grown commercially.
Another risk is an economic and social one. High-laurate canola could displace some of the coconut and palm kernel oils used in coffee whiteners and hair products, and as a result it could displace some exports from Southeast Asia. So rather than feeding or helping economically developing nations, high-laurate canola may simply cause more poverty among farmers who now grow or harvest coconuts and palm trees, say some experts.
Hundreds of field trials of transgenic plants are now being carried out each year, and for most of them, USDA requires only that the researcher give notification. It does not usually require a permit, nor does it request data showing a probable lack of harmful environmental effects. "Using the data from all the field studies done in the U.S., we've concluded that transgenic plants represent minimal risk," says USDA's Young. "They are no different from traditionally bred plants." Such plants do present some risk "but we have in place a very sophisticated agricultural system that monitors new varieties. Every time a new variety is introduced, researchers from the Agricultural Research Service and companies track those varieties to see if there are any unique problems," he adds. Transgenic plants will be monitored under this system as well.
UCS's Rissler disagrees. USDA's field tests of transgenic plants have not been conducted in a way that could assess environmental risks, she says." We did an analysis of the field test reports about a year ago," she explains." They showed very little attention to the experimental analysis of risks. USDA relies too much on intellectual arguments and not enough on field data."
Sheldon Krimsky, professor of urban and environmental studies at Tufts University, also analyzed USDA's field trials. He says USDA does not require sufficient precautions to prevent the spread of genes from transgenic plants to wild relatives in its field trials. USDA accepts the level of cross pollination acceptable to plant breeders, which provides only about 95 to 98% pure seed, he explains. This means that the department is allowing in its field trials about as much pollen dispersal from transgenic plants as plant breeders would permit in producing seed [BioScience, 42, 280 (1992)].
Kapuscinski: maintain
genetic diversityThose who see important risks in agricultural biotechnology say USDA should spend less money on biotechnology research and more on sustainable agriculture research. In the past five years, USDA has spent a total of about $28.5 million for sustainable agriculture research and about $640 million for biotechnology research. And for risk assessment of biotech research, USDA has spent only 1%, or $6.4 million, of the biotechnology budget. "We think that biotechnology is not a very good long-term solution to problems in agriculture - that, in fact, sustainable agriculture methods are a better long-term investment," says UCS's Rissler.
Many biotechnology companies have branches or joint ventures around the world and are prepared to introduce transgenic plants globally. For example, Pioneer Hi-Bred International, Des Moines, Iowa, which has large biotechnology investments, has branches in 31 countries.
Transgenic plants can be a mixed blessing for developing nations. Plants that are more nutritious or productive than standard varieties could be one factor that helps feed the world. China, for example, is now cultivating thousands of acres of Bt rice, which may increase its rice yields if insects do not become resistant to the crop.
On the other hand, Rissler explains, if genetically modified crops are grown in areas where they have not been adequately field-tested, they could have unexpected harmful effects, such as the spread of genes to wild relatives or the creation of new weeds or new viruses from virus-resistant plants.
For those countries that are so-called centers of diversity - areas that have high concentrations of traditional crop varieties and their wild relatives - transgenic plants pose special risks. Crop breeders from around the world often go to these areas to find new genes for disease or insect resistance. Crop varieties are already disappearing rapidly from these areas because of the green revolution and population pressure. For example, according to the Ottawa-based Rural Advancement Foundation International, about 30,000 rice varieties have been lost in India, largely because farmers have abandoned traditional varieties in favor of the more productive seeds introduced by the green revolution.
Transgenic crops may accelerate this loss of species by gene spread to wild relatives. If a transgene gives one wild relative an advantage, such as insect resistance, this relative may outcompete the others or itself become a weed.
Furthermore, some bioengineered products could wipe out the major exports of some developing nations. For example, a genetically modified bacterium is under development that produces vanilla flavoring. If this bacterium is commercialized, say many researchers, it could eliminate markets for vanilla beans, one of Madagascar's major agricultural products.
After more than a decade of controversy, recombinant bovine growth hormone (rBGH) was first marketed in February 1994 amid threats of boycotts by many consumer groups. At the time, a number of supermarket chains and milk wholesalers said they would not accept milk from cows injected with rBGH, and opponents predicted that milk consumption would go down.
Since then, the controversy has subsided in most regions, and some businesses that said they would not accept rBGH milk now do so. Total milk consumption increased 4% in the first 10 months of 1994, compared with the same period the previous year, and fluid milk consumption rose 1%.
Farmer acceptance is also fairly high. Monsanto estimates that farmers who purchase rBGH - about 11% of U.S. dairy farmers - own about 30% of total U.S. dairy cow herds and use it on some of the cows in their herds. Cows injected with the recombinant hormone produce about 10% more milk per day than cows without the hormone.
Thomas Lyson, professor of rural sociology, and coworkers at Cornell University surveyed all the dairy farmers in one New York county and found that 40% use rBGH. The users tend to be the larger farms with other advanced technologies, such as computers. However, 28 of the 46 respondents said that rBGH is "not a good thing for the [dairy] industry in New York or in the U.S."
One of the opponents' concerns is that rBGH will cause increased mastitis in cows and lead to greater use of antibiotics and higher levels of antibiotic residues in the milk supply. Critics are also concerned that treated cows will experience reproductive problems. But based on the 806 complaints FDA received about the hormone as of March 1995, the agency said in a press release, "FDA does not find any cause for concern." However, the agency is continuing to monitor herds treated under field conditions.
Despite U.S. commercialization of rBGH, opposition remains fairly strong in Europe. The European Union (EU) has in place a moratorium on the use of rBGH. It contends that the hormone may put small dairy farmers out of business, that it may have adverse effects on cow health, and that there are unresolved questions about human health, such as the possible adverse effects of increased levels of insulin-like growth factor-I (IGF-1) present in the milk from treated cows. And last month, the Codex Alimentarius Commission, the World Trade Organization's intergovernmental panel that develops global standards to protect health and the environment, voted to delay action on rBGH until it meets again in 1997. Technically, the panel could overrule EU, so this decision to delay action means that EU's ban on rBGH remains in place.
Agency scientists and observers also have widely divergent opinions about whether genetically engineered food should be labeled. FDA has decided not to require labeling unless the food contains a known allergen or its composition is substantially different from the standard food. For example, high-laurate canola is labeled because it has a high concentration of lauric acid. But under FDA's policy, most genetically engineered food will not be labeled.
Young: transgenic plants a
minimal riskPhilip Bereano, a professor of engineering technology and public policy at the University of Washington, Seattle, strongly disagrees with FDA's labeling policy. "Consumers have an absolute right to know the processes by which their foods are made," he says. And there are precedents for that, he adds. Even though many kosher products are chemically the same as nonkosher products, the process by which they are made is identified, he says. Dolphin-free tuna is a similar example.
FDA's Maryanski counters: "FDA is not saying that people don't have a right to know how their food is produced. But the food label is not always the most appropriate method for conveying that information. The Food, Drug & Cosmetic Act is not a comprehensive right-to-know act."
Another argument is one over allergens. Not all allergens are known, and a genetically modified food could contain an unknown allergen, Krimsky says. Therefore, if a problem arises, he adds, it would be much easier to track epidemiologically if the food is labeled.
Maryanski admits the question of allergens in transgenic food is a difficult one. FDA convened a conference on the issue, he explains, and decided that it was very unlikely that people would become allergic to the possible allergens in genetically modified food, largely because they are expressed at such low levels, and because the vast majority of allergic people are sensitive to a very limited number of proteins.
Rita R. Colwell, a marine biologist who is president of the Maryland Biotechnology Institute at the University of Maryland, Baltimore, sees a real urgency to use agricultural biotechnology. For example, she says, the world's oceans can produce at most 100 million metric tons of fish annually, and the harvest has dropped to 80 million metric tons. Soon, the world's population will require 135 million metric tons of fish. "It is no longer a question of should or shouldn't we raise transgenic fish," she says. "It is a necessity."
Simon G. Best, chief executive officer and managing director of Zeneca Seeds, Wilmington, Del., has a similar view of transgenic crops: "Without biotechnology, we will simply fail to meet the challenge" of dramatically increasing the availability of affordable basic food.
In contrast, David R. MacKenzie, who until last month was head of USDA's biotechnology risk assessment program and is now executive director of the Northeastern Regional Association of State Agricultural Experiment Station Directors, urges much more restraint before transgenic organisms are commercialized on a large scale. He is convinced that transgenic organisms may present some risks. "We're still unsure of what is going to happen with transgene spread into wild species," he says. "Some people say it doesn't matter because they are wild species and who cares. But people who do care about the ecology of natural systems get very upset at the idea that we would be spreading these genes.
" The chorus of people, especially at USDA," he continues," who say there is no risk in biotechnology subscribe to what I think is the wrong notion that DNA is DNA. I think there are barriers between species. I think there are aspects of these revolutionary [transgenic] designs that we don't understand yet. Before we start messing around too much, we ought to understand what happens when we jump these barriers, not just put things out there and see what happens."
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