Fw: #718: Biotech -- The Basics, Part 3

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: . RACHEL'S ENVIRONMENT & HEALTH NEWS #718 .

: . ---February 15, 2001--- .

: . HEADLINES: .

: . BIOTECH: THE BASICS, PART 3 .

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:

: BIOTECH: THE BASICS, PART 3

:

: By Massey*

:

: As we saw in REHN #716, genetically engineered crops now planted

: in the U.S. and worldwide are mostly designed to tolerate

: herbicides or to kill insects or other pests. A small percentage

: is designed for other purposes such as resisting infection by

: certain viruses. Here we will look at some of the threats

: genetically engineered crops pose to ecosystems.

:

: Pesticidal crops may be toxic to nontarget organisms - organisms

: they were not designed to kill. For example, BT corn designed to

: kill the European corn borer can also be toxic to other closely

: related insects, including butterflies and moths.

:

: Monarch butterfly larvae feed on milkweed, which often grows in

: or near corn fields. In a laboratory, scientists found that

: monarch larvae feeding on milkweed dusted with BT corn pollen

: grew more slowly and died at a higher rate than larvae that were

: not exposed to the toxic pollen.[1] Another study found these

: effects were likely to occur outside the laboratory as well.

: Researchers placed potted milkweed plants in fields of BT corn

: and measured the number of BT pollen grains that were deposited

: on the milkweed leaves. Monarch larvae exposed to BT corn pollen

: at these levels had high death rates compared with larvae exposed

: to non-engineered corn pollen or placed on milkweed leaves with

: no pollen.[2]

:

: The U.S. Environmental Protection Agency (EPA) now expresses

: concern about the effects of BT corn pollen on monarchs and other

: butterfly species, including the endangered Karner Blue

: butterfly.[3] EPA has asked companies to submit data on these

: effects, but this " data call-in " occurred four years AFTER EPA

: allowed BT corn to be used on U.S. farms.[2,pg.13]

:

: BT corn may also harm the green lacewing, a beneficial insect

: that eats agricultural pests. The lacewing may be affected by the

: toxin in the digestive systems of insects that have eaten BT corn

: but have not been killed by it.[4] This example shows how

: non-target effects may interfere with a chain of predator-prey

: relationships, disrupting the natural balance that keeps pest

: populations under control.

:

: BT crops may also affect non-target organisms by changing soil

: chemistry. A 1999 article in NATURE reported that the roots of BT

: corn plants released BT toxin into soil. The researchers found

: that 90 to 95% of susceptible insect larvae exposed to the

: substance released from the roots died after 5 days.[5]

:

: The use of BT crops can also promote the development of

: BT-resistant pest populations. As we saw in REHN #716, organic

: farmers use BT sprays occasionally as a natural insecticide to

: combat severe pest outbreaks. BT crops, in contrast, generally

: expose insects to BT toxins day after day, whether or not there

: is a major infestation. These conditions increase the likelihood

: that BT-resistant insects will evolve. The widespread appearance

: of BT-resistant insect pests would mean the loss of one of the

: most valuable tools available to organic farmers for dealing with

: serious pest outbreaks.[6,pg.139]

:

: Herbicide-tolerant crops are designed to make it easier for

: farmers to use certain herbicides. A 1999 study of soybean

: farming in the U.S. midwest found that farmers planting Roundup

: Ready soybeans used 2 to 5 times as many pounds of herbicide per

: acre as farmers using conventional systems, and ten times as much

: herbicide as farmers using Integrated Weed Management systems,

: which are intended to reduce the need for chemical

: herbicides.[7,pg.2] Glyphosate, the active ingredient in Roundup,

: can sometimes persist in soil over long periods of time[8] and

: may affect the growth of beneficial soil bacteria, among other

: environmental effects.[9] A recent, unpublished study conducted

: at the University of Missouri suggests that applications of

: Roundup to Roundup Ready crops may be associated with elevated

: levels of soil fungi that sometimes cause plant diseases.[10]

:

: More hazards may lie ahead as new products of genetic engineering

: come to market. According to the NEW YORK TIMES, s Company

: is collaborating with Monsanto to develop Roundup Ready grass for

: lawns.[11] Studies suggest that Roundup exposures can be harmful

: to human health. For example, exposure to glyphosate herbicides

: may be associated with increased occurrence of non-Hodgkins

: lymphoma, a cancer of white blood cells.[12] (See REHN #660.) And

: a study published last August in ENVIRONMENTAL HEALTH

: PERSPECTIVES found that in a laboratory, Roundup exposure

: interfered with sex hormone production in cells of testicular

: tumors taken from mice.[13] If the introduction of Roundup Ready

: grass leads to increased use of Roundup on lawns, children's

: exposure to the herbicide could rise.

:

: In some cases, genetically engineered crops might become problem

: weeds, disrupting existing ecosystems. A recent study published

: in NATURE found that some genetically engineered crops are

: unlikely to become problem weeds. Researchers planted genetically

: engineered crops that were available in 1990 and monitored their

: growth for ten years. Many of the plants simply died out, and

: those that did survive showed no signs of spreading.[14] But some

: crop plants, such as canola, survive well on their own without

: human intervention. In Canada, genetically engineered canola

: plants designed to resist various herbicides appear to have

: exchanged genetic material so that some canola plants now can

: survive exposure to two or three herbicides. These plants with

: multiple herbicide resistance can be difficult for farmers to

: control.[6,pgs.122-123]

:

: Genetically engineered virus-resistant crops are supposed to

: reduce problems from viral infections, but in some cases they

: could make those problems worse. Virus-resistant crops are

: created by adding virus genes to the plant's existing genetic

: material. If a genetically engineered crop resistant to one virus

: is infected by another virus, the genetic material from the two

: viruses may sometimes interact to produce new virus types, which

: could be more harmful or could infect a wider range of plants

: than the original.[15,pgs.59-68]

:

: All the hazards discussed above are compounded by the problem of

: genetic pollution. Many crop plants disperse genetic material

: through pollen, which may be carried by the wind or by

: pollinators such as bees. This means genetically engineered

: plants may " share " their genetic material with other,

: non-engineered plants. For example, pollen from genetically

: engineered corn can blow into a neighboring field and pollinate

: conventional corn. Because of genetic pollution, some organic

: farmers whose fields border genetically engineered crops may no

: longer be able to certify their crops as organic.[6,pg.127]

:

: In animals, sexual reproduction between different species is

: usually impossible. In a few cases, reproduction between closely

: related species can occur but the offspring are generally

: sterile. For example, a horse and a donkey can mate to produce a

: mule, but mules cannot reproduce. In contrast, many plants are

: able to reproduce sexually with related species, and the

: offspring of these combinations are often fertile. When crop

: plants grow near wild plants to which they are related, they may

: reproduce with these plants. This means that genetic material

: inserted into a crop plant can find its way into wild plant

: populations.

:

: A recent article in SCIENCE reviews the literature on " ecological

: risks and benefits " of genetically engineered crops and confirms

: what advocates of precaution have been saying for years: we lack

: basic information on how genetically engineered crops may affect

: ecosystems.[16] Here are a few examples of what scientists do not

: know about ecological effects of genetically engineered crops:

:

: ** No published studies have looked at whether novel genes

: introduced into crops have become established in populations of

: wild relatives.[16, pg. 2088]

:

: ** We know that BT toxin can be released from the roots of BT

: corn plants, but no published studies have looked at the

: ecological consequences of adding BT toxin to soil in this way.

: [16, pg. 2089]

:

: ** As we have seen, BT toxin in the digestive systems of

: plant-eating insects may affect the predator insects that eat

: them. Right now it is impossible to model how an ecosystem might

: change due to these effects on predators, the authors say.[16,

: pg. 2089]

:

: ** Scientists are currently unable to estimate the likelihood

: that planting genetically engineered virus-resistant crops will

: lead to the development of new types of plant viruses. [16, pg.

: 2089]

:

: A precautionary approach would require that we investigate these

: questions before, rather than after, permitting large-scale

: commercial cultivation of genetically engineered crops.

:

: [To be continued.]

:

: ==============

:

: * Massey is a consultant to Environmental Research

: Foundation

:

: [1] E. Losey and others, " Transgenic Pollen Harms Monarch

: Larvae. " NATURE Vol. 399, No. 6733 (May 20, 1999), pg. 214.

:

: [2] C. Hansen and J. Obrycki, " Field Deposition of BT

: Transgenic Corn Pollen: Lethal Effects on the Monarch Butterfly, "

: OECOLOGIA Vol. 125, No. 2 (2000), pgs. 241-248.

:

: [3] U.S. Environmental Protection Agency, " Biopesticide Fact

: Sheet: BACILLUS THURINGIENSIS Cry1Ab Delta-Endotoxin and the

: Genetic Material Necessary for Its Production (Plasmid Vector

: pCIB4431) in Corn [Event 176], " April 2000. EPA Publication No.

: 730-F-00-003. Available at

: http://www.epa.gov/pesticides/biopesticides/factsheets/fs006458t.htm.

:

: [4] A. Hilbeck and others, " Effects of Transgenic BACILLUS

: THURINGIENSIS corn-fed prey on Mortality and Development Time of

: Immature CHYSOPERLA CARNEA (Neuroptera: Chrysopidae). "

: ENVIRONMENTAL ENTOMOLOGY Vol. 27, No. 2 (April 1998), pgs.

: 480-487.

:

: [5] Deepak Saxena and others, " Insecticidal Toxin in Root

: Exudates from BT Corn, " NATURE Vol. 402, No. 6761 (December 2,

: 1999), pg. 480.

:

: [6] Royal Society of Canada, ELEMENTS OF PRECAUTION:

: RECOMMENDATIONS FOR THE REGULATION OF FOOD BIOTECHNOLOGY IN

: CANADA (Ottawa: Royal Society of Canada, January 2001). ISBN

: 0-920064-71-X. Available from the Royal Society at (Ottawa,

: Canada) phone: (613) 991-6990 or at

: http://www.rsc.ca/foodbiotechnology/-GMreportEN.pdf.

:

: [7] Benbrook, " Evidence of the Magnitude and Consequences

: of the Roundup Ready Soybean Yield Drag from University-Based

: Varietal Trials in 1998, " AgBioTech InfoNet Technical Paper #1,

: July 13, 1999. Available at

: http://www.biotech-info.net/RR_yield_drag_98.pdf.

:

: [8] U.S. Environmental Protection Agency, " Pesticide and

: Environmental Fate One Line Summary: Glyphosate, " May 6, 1993.

:

: [9] See T. B. Moorman and others, " Production of Hydrobenzoic

: Acids by BRADYRHIZOBIUM JAPONICUM strains after treatment with

: glyphosate. " JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY Vol. 40

: (1992), pgs. 289-293. For a review of other relevant studies, see

: Caroline , " Herbicide Factsheet: Glyphosate (Roundup) " JOURNAL

: OF PESTICIDE REFORM Vol. 18, No. 3 (Fall 1998), updated October

: 2000, available at http://www.pesticide.org/gly.pdf

:

: [10] R.J. Kremer and others, " Herbicide Impact on FUSARIUM spp.

: and Soybean Cyst Nematode in Glyphosate-Tolerant Soybean. "

: American Society of Agronomy study abstract, available at

: http://www.biotech-info.net/fungi_buildup_abstract.html. Also see

: University of Missouri press release, " MU Researchers Find Fungi

: Buildup in Glyphosate-Treated Soybean Fields " (December 21,

: 2000), available at

: http://www.biotech-info.net/fungi_buildup.html.

:

: [11] Barboza, " Suburban Genetics: Scientists Searching for

: a Perfect Lawn, " NEW YORK TIMES July 9, 2000, pg. A1.

:

: [12] Lennart Hardell and Mikael sson, " A Case-Control Study

: of Non-Hodgkin Lymphoma and Exposure to Pesticides, " CANCER Vol.

: 85, No. 6 (March 15, 1999), pgs. 1353-1360.

:

: [13] Lance P. Walsh and others, " Roundup Inhibits Steroidogenesis

: by Disrupting Steroidogenic Acute Regulatory (StAR) Protein

: Expression, " ENVIRONMENTAL HEALTH PERSPECTIVES Vol. 108, No. 8

: (August 2000), pgs. 769-776.

:

: [14] M. Crawley and others, " Transgenic Crops in Natural

: Habitats. " NATURE Vol. 409, No. 6821 (February 8, 2001), pgs.

: 682-683.

:

: [15] Jane Rissler and Margaret Mellon, THE ECOLOGICAL RISKS OF

: ENGINEERED CROPS (Cambridge, Mass.: MIT Press, 1996).

:

: [16] L. L. Wolfenbarger and P.R. Phifer, " The Ecological Risks

: and Benefits of Genetically Engineered Plants. " SCIENCE Vol. 290

: No. 5499 (December 15, 2000) pgs. 2088-2093.

:

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