What's Growing On?

• By Katherine L. Pace
• Jan 01, 2002

Agriculture uses seventy percent of the world's freshwater supply. Almost half of the world's food comes from irrigated cropland, but irrigation use is threatened by overpumping of ground water, diversion of water to the cities, and the buildup of salt in the soil. As water flows from its source to crops, it collects salt and minerals and can become unusable as irrigation water. The U.S. Department of Agriculture (USDA) estimates that crop production has fallen by 25 percent on irrigated land in the United States because of increased salt levels in water.

Supporters of genetically engineered crops claim that bioengineering could create plants that can absorb salty water or grow with less water. In its August 2001 edition, Nature magazine released an article about the development of a salt-resistant tomato capable of growing in water with 50 times more salt than normal. In June 2001, Nature described the discovery of how plants open and close their stomata, the pores through which they breath, which could pave the way for the development of drought-resistant crops.

Some proponents of bioengineering claim that herbicide-resistant crops and crops with built-in pesticides will result in decreased use of herbicides and pesticides and thereby reduce water pollution. Studies by U.S. Department of Agriculture (USDA) in 1999 found that the adoption of herbicide-resistant crop varieties reduced herbicide treatment in half of the studied cases. A 1999 study by the National Center for Food and Agricultural Policy concluded that the use of bacillus thuringiensis (Bt) mondified corn resulted in 2 million fewer acres being sprayed with pesticides and that without the use of Bt cotton, 5 million more acres would have been treated.

Opponents of genetically engineered crops point to an equally numerous amount of studies that correlate planting of herbicide-resistant crops to increased use of herbicides. Without the need to worry about the effects of herbicides on crops, farmers can use herbicides indefinitely.

Bioengineering opponents also maintain that a "Blue Revolution" aimed at water conservation, is needed to boost water productivity and create a long-term solution to water shortages. Advocates of such a revolution support strategies such as the use of drip irrigation systems, more efficient sprinklers, lining irrigation canals, recycling farm runoff, and reusing domestic wastewater for crop production.

Fulfilling a Need

From 1960 to 1990, the world's population increased from three billion to six billion people. According to United Nations (U.N.) demographic studies, if population trends continue, there will be more than 9 billion people by 2050.

U.N. statistics estimate that 800 million people are malnourished, most in underdeveloped countries where most population growth will take place. Forty-four percent of the world's children have stunted growth. Thirty-three percent are underweight. One hundred million children suffer from vitamin A deficiency, the leading cause of blindness. Four hundred million women of childbearing age suffer from iron deficiency, putting their children at risk of physical and mental retardation, premature births and natal mortality.

Within the next 25 years, food requirements in poor countries are expected to double. However, the annual rate of cereal yield increase is less than the population increase, farmable land is becoming increasingly scarce and 70 percent of the world's fresh water is already used for agriculture.

The International Food Policy Research Institute in Washington, D.C. estimates that crop yields will have to increase by at least one third to keep up with population growth. According to an article in the June 2001 issue of Science magazine, 40 percent of plant productivity in Africa and Asia and 20 percent in the developed world is lost to pests. The European corn borer alone destroys 40 million tons of the world's corn crop each year, enough calories to feed 60 million people.

The Council for Biotechnology Information, a council of leading biotechnology companies, maintains biotechnology, the genetic engineering of organisms, could increase crop production in the developing world by 25 percent without the use of more land or water. Crops could be engineered to better resist pests, weeds, bacteria and viruses, grow on less fertile lands and require less water. Furthermore, farmers could grow crops of better quality and higher nutrition.

Pest, Weed, Disease and Drought Resistance

Already, scientists have engineered crops to resist pests, weeds and disease. The most commonly used genetically engineered crops (GEC) in the United States are Bt-modified crops. Bt, is a naturally occurring pesticide that is activated by the stomach acids of insects. Once used in pesticide form, Bt has been introduced into crops such as corn, cotton and potato, causing the crops to produce increased levels of Bt. To prevent insect resistance to Bt, different strains of Bt are inserted into crops to produce different toxins, and unmodified crops are planted next to Bt-modified crops to serve as insect refuges.

Despite worries that Bt-modified crops threaten monarch butterflies, recent studies revealed that the potential harm is minimal. Following a study by Cornell University in 1999 which revealed that 44 percent of monarch caterpillars died after being fed milkweed leaves dusted with pollen from Bt corn, Iowa State University in Ames, the U.S. Environmental Protection Agency (EPA), the U.S. Food and Drug Administration (FDA) and other scientists conducted their own studies. They concluded that Bt concentrations are usually too low to harm monarch butterflies. Bt is found in corn pollen. When given the choice of eating milkweed leaves with or without pollen, monarch larvae will chose the latter. Furthermore, because milkweed, monarch larvae's only food, does not grow abundantly in corn fields, butterflies tend to leave their larvae around the edge of corn fields where, according to the studies, pollen levels and therefore Bt concentration levels drop off rapidly.

Scientists have engineered herbicide-tolerant crops that could be better for the environment. Farmers could use postemergent methods instead of preemergement, meaning they could spray weeds after both weed and crop had begun to grow instead of spraying the soil before hand. As a result, farmers could use herbicides only as needed and fewer herbicides would be incorporated into the soil.

To protect crops against damage by bacteria and viruses, scientists have developed a way to vaccinate crops. By inserting bacterial or viral genes into a plant's genome, scientists can trigger the plant's defensive mechanisms that degrade ribonucleic acids (RNA), which hold the bacterial and viral genes, and thereby disable the bacteria or virus. Though questions remain about exactly how the vaccination method works, plant vaccinations have already been successful at saving the Hawaiian papaya industry from ringspot virus.

Engineering plants with increased drought resistance could also improve crop yields. Much farm land is not properly irrigated due to water shortages, and recent studies predict that water scarcity will become severe as the population continues to grow. Because scientists have recently found out how plants open and close their stomata, tiny pores through which they breathe and release water, scientists could engineer plants to close their stomata in response to a drought and better survive in dry climates.

Benefits to Human Health

As important as the potential to increase crop yields is the potential to improve the nutritional quality of plants. Following the sequencing of the rice genetic code, scientists developed new, nutritionally enhanced rice. The new rice, which appears to grow and reproduce normally, is the first crop genetically engineered for nutrition. After seven years of research, the Federal Institute of Technology in Zurich created rice with increased levels of vitamin A and iron. Because rice is the staple food for half of the world's population, and because the mapping of the rice genome could lead to an increased understanding and manipulation of the genomes of similar crops such as potatoes and corn, the development could significantly decrease malnourishment worldwide.

The FDA is aware of potential risks that GEC pose to human health. In 1992 it adopted a policy of labeling foods whose composition or nutritional content has been significantly altered due to genetic engineering. If genetic engineering increases toxin levels, varies a food's composition or introduces proteins, which commonly cause allergic reactions, the FDA conducts a premarket review of the engineered foods and determines labeling. Labeling of all GEC would require complicated and costly systems of food segregation and testing at all stages of production from seed development to packaging and would result in increased food costs for consumers.

Along with providing more nutrients, GEC could serve as edible vaccines. According to the Council for Biotech Information, one out of five children are not vaccinated against diseases such as diphtheria, tetanus and measles. Undeveloped countries cannot afford to provide conventional vaccines, and drug companies have little incentive to develop cheaper methods. Researchers are testing tomato and potato-based vaccines against viruses that cause diarrhea and hepatitis B virus among other edible vaccines. If successful, edible vaccines could save billions of dollars and millions of lives.

Environmental Impacts

Despite warnings of ecological destruction, recent studies support the claim that GEC have little chance of becoming invasive plants, highly aggressive weeds. A decade-long study published in the February 2001 edition of Nature magazine revealed that changes in crops to produce higher yields are not useful in the wild. Because insects and weeds do not significantly check plant growth in the wild, pest and herbicide resistance should not result in invasiveness. Researchers planted seeds of modified potatoes, beets, corn and oilseed rape in 12 different natural habitats with a variety of conditions in each. The modified plants proved as unsuccessful at spreading as the unmodified plants.

Environmental benefits of GEC include less externally-sprayed pesticides, less destruction of wilderness for farming land, and crops that allow livestock to better digest minerals in feed and thereby reduce the harmful phosphorous in animal waste.

Though biotechnology does involve risks, testing and intelligent application of GEC can reduce the risks. The potential benefits of engineering crops cannot be ignored when deciding the fate of biotechnology. There is no question that crop yields will not be able to meet food demands in the future without new farming techniques. Biotechnology, if accompanied by adequate research and testing, could prove to be the next step in the green revolution.

Arguments Against GECs

Opponents of GECs emphasize that they are not inanimate objects. They are living organisms with the ability to interact, reproduce and migrate in uncontrollable and unpredictable manners. The critics point out that GECs cannot be recalled as one would recall faulty tires or dangerous toys.

The world's ecosystems have already been destabilized by the introduction of non-indigenous species. In the Great Lakes, the zebra mussel that came from Europe is out competing native mussel species. The Indian mongoose is wrecking havoc in Hawaii. According to the June 2001 Science magazine, invasive species of plants and animals are categorized as one of the three most serious environmental problems, along with global warming and habitat loss.

Critics of GECs argue that wide use of biotechnology risks introducing non-indigenous species around the world with catastrophic effects. Plant behavior is too complex to predict even with field tests. Field tests do not adequately deal with the potential spread of GEC because they are planted over small areas and surrounded by border rows of unmodified crops. Furthermore, field tests are carried out over short time periods (usually no more than two growing seasons) and deal with few ecological systems. If used commercially, GEC would be planted in numerous and diverse environments, over long time periods and without the same measures taken to prevent spread.

Though some researchers maintain there is a minimal threat of invasiveness, studies have not addressed the effects of drought or disease resistance. Furthermore, they have not dealt with the exchange of genes among similar plants. Natural hybridization occurs between 12 of the world's 13 most important crops, such as wheat, rice and soybean. Of these domesticated plants, numerous species are able to hybridize with wild relatives and could produce new weeds.

Herbicide-Tolerance

Another concern is that the development of herbicide-tolerant crops could increase use of herbicides, because farmers can spray higher levels of herbicides without worrying about the effects on crops. According to the Environmental Defense Biotechnology Working Group, a group of public interest organizations and citizen activists, at least 30 crops have already been modified to withstand previously damaging doses of herbicides. In its July 2001 edition, Sierra magazine said that Monsanto Company, a producer of herbicides, requested and received from the EPA a tripling of the allowed levels of glyphosate residue on harvested crops. Glyphosate, a herbicide, has been linked to non-Hodgkins lymphoma, cancer of the while blood cells.

Another risk posed by herbicide-resistant crops is the development of herbicide-resistant weeds, as modified crops may pass their genes to wild relatives.

Negative Side Effects

Other possible negative impacts on the environment include direct and indirect effects on non-target organisms. Bt, a naturally occurring pesticide that has been engineered in plants to occur in higher levels, targets not only the European corn borer, a common pest, but also butterflies, moths and beetles. Because modified plants produce higher levels of Bt, nearby soil contains higher concentrations of Bt that could affect soil ecosystems. According to Jeremy Rifkin in his book, The Biotech Century (Penguin Putnam Inc., 1998), Bt from modified plants remains toxic in the soil up to three times longer than if produced naturally. Because predators may eat plants and animals that have absorbed pesticides, GEC risks harming species that depend on pests for survival and reproduction.

Insect Resistance

Many critics of GEC assert that increased insect resistance and new plant diseases pose very real environmental threats. Bt, when it occurs naturally, is only produced by plants in response to attacks by pests. Bt-modified crops are engineered to produce Bt continuously, regardless of the number of pests. Farmers cannot decide when they will spray pesticides according to present pest situations. They are committed to continual pesticide use that increases the risk of insect resistance.

In the July 2001 Sierra magazine, Charles Benbrook, the former executive director of the National Academy of Sciences Board on Agriculture and Natural Resources, estimated that up to 10,000 times more Bt toxin is produced with the use of Bt-modified crops than with external applications. Once produced, the Bt toxin binds to soil particles and resists biodegrading. In June 2001, Science magazine said that ten moth species, two beetle species and four fly species developed resistance to Bt toxins under laboratory conditions. Though planting a mix of genetically modified crops and non-modified crops could slow resistance, it could not stop it.

Ending Genetic Diversity

The trend towards monocultures, the planting of single species of plants, being continued by biotechnology is equally unnerving as the environmental risks of GEC. Agricultural blights, such as the one that destroyed the Irish potato crops in the 1840s, are the result of planting monocultures. The lack of varied genetic material leaves plants vulnerable to pests and diseases that can wipe out entire crops. As in Ireland, where the blight was ended by the introduction of potatoes from Mexico and the Andes, the planting of various species of crops best stops blights. However, biotechnology, with its search for the perfect crop, is only continuing the move towards genetic conformity.

The U.N. Food and Agricultural Organization (FAO) estimates that approximately 40,000 plant species will be extinct by the middle on the 21^st century as farmers continue to plant fewer species of each plant. Soon, crops will be limited not only to single species, but to a single genetic makeup. Ironically, biotechnology relies on the very genetic diversity it is eliminating. Engineers are able to reproduce and manipulate existing genes, not create entirely new genes. The less genetic material available, the fewer tools genetic engineers have to work with.

Human Health

The risk of GEC to human health cannot be ignored. An exchange and manipulation of genes that produce proteins modify crops. Nearly all known food allergens are proteins; therefore, genetic modification could cause individuals to become allergic to foods that were previously safe. Though the FDA claims to review and label all foods whose composition have been altered to contain increased toxins or proteins commonly known to cause allergic reactions, there is no requirement that foods be reviewed. Instead, companies voluntarily submit their products for review, creating the potential for harmful goods to reach the market.

Alternatives

Biotechnology is not the only means by which to increase crop yields. Many agriculturists and environmentalists have chosen to work with the environment to manage pests and diseases. In its July 2001 edition, Sierra magazine stated the International Center of Insect Physiology and Ecology (ICIPE) in Kenya used a "push-pull" system to successfully increase crop yields. Farmers planted grasses outside the cornfields to attract pests and planted legumes inside that both repel pests and add nitrogen to the soil to prevent erosion. In China, farmers in the Yunnan province successfully experimented with planting two rice varieties instead of one to prevent rice blast, a fungal disease.

Other options for pest and disease control include interspersing more and less-resistant plants varieties, slowly exposing plants to diseases to build resistance, introducing incest-killing fungi and changing cultivation processes by altering light, temperature and planting and harvesting times.

Each alternative approach involves working with local resources and conditions.

It places the type and amount of pesticides and herbicides used under the farmers' control. Furthermore, farmers do not depend on companies to provide modified seeds. Some critics argue that, to ensure continued profits, biotechnology companies are creating sterile seeds, thereby forcing farmers to buy new seeds after each harvest. Companies who are mapping genetic sequences are withholding their research from the public domain for commercial reasons by patenting segments and variations of plant genomes. Opponents to GECs argue that in an attempt to monopolize the biotechnology industry and much of the agricultural industry, the producers of GEC are taking control from the farmers and giving it to corporations whose aim is to make money. As a result, many fear that both farmers and consumers may face increased food costs, and that the promise of an end to world hunger through biotechnology may never be realized.

This article originally appeared in the January/February 2002 issue of Water & Wastewater Products, Volume 2, Number 1, page 40.

This article originally appeared in the 01/01/2002 issue of Environmental Protection.