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Chapter 18 : Risks and Regulations

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Risks and Regulations, Page 1 of 2

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Abstract:

This chapter compares emotion-based risk perception to science-based risk assessments, provides an example of the pitfalls of making decisions based on emotions and not facts and discusses the role that government regulatory agencies play in minimizing the potential risks associated with new products, including those developed using biotechnology. The uncertainty of exposure is one of the reasons risks are discussed in terms of probabilities instead of an absolute assessment of the seriousness of the hazard. (Bt) corn contains the gene from subsp. that encodes a protein specifically toxic to lepidopteran insects, including monarch larvae, that ingest any part of the plant expressing the Bt gene. The level of risk defined by the hazard and exposure can be decreased or managed by instituting safeguards that decrease either or both of these factors. In response to media attention and political pressure, government agencies and private companies funded additional research specifically targeted to the effect of Bt corn on monarch butterfly populations. This research provided scientific data to estimate risk mathematically by assessing the hazard (toxic dose) and the probability of exposure of monarch larvae to Bt corn pollen. The data reaffirmed the decision of the regulatory agencies that the benefits of Bt corn outweighed the risks. With regard to agricultural biotechnology products, the regulatory agencies review the product at various stages in development to assess its effects on the environment, agriculture, and human health.

Citation: Kreuzer H, Massey A. 2005. Risks and Regulations, p 443-473. In Biology and Biotechnology. ASM Press, Washington, DC. doi: 10.1128/9781555816094.ch18

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Figures

Image of Figure 18.1
Figure 18.1

Physiological effects of fearfulness. Rats that are chronically fearful age prematurely and die 15% sooner than those that are not. These brother rats are the same age, but the fearful rat on the left has a pituitary gland tumor. Researchers placed novel neutral objects, such as a bowl or brick, in their environment. The fearful rats avoided the objects, became anxious, and maintained chronically high levels of stress hormones after researchers removed the objects. The bold rats investigated the objects, and the surge of stress hormones returned to normal rapidly. (Photograph courtesy of Sonia Cagivelli, University of Chicago.)

Citation: Kreuzer H, Massey A. 2005. Risks and Regulations, p 443-473. In Biology and Biotechnology. ASM Press, Washington, DC. doi: 10.1128/9781555816094.ch18
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Image of Figure 18.2
Figure 18.2

Natural plant toxins. Beautiful wildflowers often contain chemicals to deter herbivory. In the western states, wild lupines ( spp.) and larkspurs ( spp.) inflict significant losses on free-ranging livestock. Both are highly palatable to livestock and sheep, even though they contain alkaloids, which are neuromuscular poison that lead to death from respiratory failure. Grazing sheep can die from consuming as little as 4 ounces of lupine each day for 3 days. (Photographs courtesy of William Cielsa, Forest Health Management International [http://www.forestry images.org] [A], and by Jack Dykinga, courtesy of the Agricultural Research Service, USDA [B].)

Citation: Kreuzer H, Massey A. 2005. Risks and Regulations, p 443-473. In Biology and Biotechnology. ASM Press, Washington, DC. doi: 10.1128/9781555816094.ch18
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Image of Figure 18.3
Figure 18.3

Monarch butterfly. (Photograph courtesy of Jennifer E. Dacey, University of Rhode Island [http://www.forestryimages.org].)

Citation: Kreuzer H, Massey A. 2005. Risks and Regulations, p 443-473. In Biology and Biotechnology. ASM Press, Washington, DC. doi: 10.1128/9781555816094.ch18
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Image of Figure 18.4
Figure 18.4

Monarch life cycle. Larvae emerge from eggs and immediately begin to feed on milkweed plant tissues. Like all lepidopteran larvae, monarch larvae molt a number of times as they grow. When the larva reaches a certain size, hormonal changes trigger the formation of the pupa. During the pupal stage, the adult butterfly forms. Adult butterflies feed on nectar through highly specialized mouthparts. (Photographs by Peggy Greb, courtesy of the Agricultural Research Service, USDA [A]; Herbert A.“Joe” Pase III, Texas Forest Service [http://www.forestryimages.org] [B]; Peter Wirtz [http://www.forestryimages.org] [C]; and John Mosesso, courtesy of the National Biological Information Infrastructure of the U.S. Geological Survey [D].)

Citation: Kreuzer H, Massey A. 2005. Risks and Regulations, p 443-473. In Biology and Biotechnology. ASM Press, Washington, DC. doi: 10.1128/9781555816094.ch18
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Image of Figure 18.5
Figure 18.5

Milkweed. There are approximately 100 species of milkweed plants in North America, and most prefer to grow in open habitats, such as along roadsides. Butterfly milkweed () is common in the southern United States. Common milkweed () is the monarch's preferred host plant in the area where almost all Bt corn is grown. (Photographs courtesy of David Stephens [http://www.forestryimages.org] [A] and Arnold Drooz, U.S. Fish and Wildlife Service [http://www.forestryimages.org] [B].)

Citation: Kreuzer H, Massey A. 2005. Risks and Regulations, p 443-473. In Biology and Biotechnology. ASM Press, Washington, DC. doi: 10.1128/9781555816094.ch18
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Image of Figure 18.6
Figure 18.6

Monarch life history. Monarchs in most generations in North America live approximately 2 months. The first month consists of immature stages that are not reproductive. The last generation of a summer overwinters and gives rise to the next year's first generation.

Citation: Kreuzer H, Massey A. 2005. Risks and Regulations, p 443-473. In Biology and Biotechnology. ASM Press, Washington, DC. doi: 10.1128/9781555816094.ch18
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Image of Figure 18.7
Figure 18.7

Monarch roost. In North America, the last generation of adults migrates to a warm location, where they overwinter in large aggregations. The weight of the butterflies is significant enough to bend the branches of mature fir trees. (Photographs courtesy of Harry O. Yates, U.S. Forest Service [http://www.forestryimages.org].)

Citation: Kreuzer H, Massey A. 2005. Risks and Regulations, p 443-473. In Biology and Biotechnology. ASM Press, Washington, DC. doi: 10.1128/9781555816094.ch18
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Image of Figure 18.8
Figure 18.8

Monarch migration routes. At the end of the summer, monarch butterflies from North America migrate to overwintering sites in California and Mexico.

Citation: Kreuzer H, Massey A. 2005. Risks and Regulations, p 443-473. In Biology and Biotechnology. ASM Press, Washington, DC. doi: 10.1128/9781555816094.ch18
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Image of Figure 18.9a
Figure 18.9a

Bt protein. The toxins in Bt are proteins that form crystals under certain conditions. The Bt toxin genes vary slightly within each strain of the bacterium, as do the shapes of the crystallized proteins (Cry1A) they encode. The mechanism of action of Bt protein. (Step 1) An inactive form of the crystallized Bt protein enters the insect's gut. (Step 2) An enzyme produced by the insect binds to the Bt protein crystal and activates it. (Step 3) The activated form binds to receptors on the membranes of the cells in the intestinal lining. (Step 4) When the activated Bt protein binds to the receptor, the receptor's shape changes and the ionic contents of the cells lining the insect's gut spill into the intestinal lumen. The shapes of the Bt crystal, enzyme active site, and receptor-binding site are responsible for the specificity of the Bt toxins.

Citation: Kreuzer H, Massey A. 2005. Risks and Regulations, p 443-473. In Biology and Biotechnology. ASM Press, Washington, DC. doi: 10.1128/9781555816094.ch18
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Image of Figure 18.9b
Figure 18.9b

Bt protein. The toxins in Bt are proteins that form crystals under certain conditions. The Bt toxin genes vary slightly within each strain of the bacterium, as do the shapes of the crystallized proteins (Cry1A) they encode. The mechanism of action of Bt protein. (Step 1) An inactive form of the crystallized Bt protein enters the insect's gut. (Step 2) An enzyme produced by the insect binds to the Bt protein crystal and activates it. (Step 3) The activated form binds to receptors on the membranes of the cells in the intestinal lining. (Step 4) When the activated Bt protein binds to the receptor, the receptor's shape changes and the ionic contents of the cells lining the insect's gut spill into the intestinal lumen. The shapes of the Bt crystal, enzyme active site, and receptor-binding site are responsible for the specificity of the Bt toxins.

Citation: Kreuzer H, Massey A. 2005. Risks and Regulations, p 443-473. In Biology and Biotechnology. ASM Press, Washington, DC. doi: 10.1128/9781555816094.ch18
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Image of Figure 18.10
Figure 18.10

ECB damage. ECB larva inside corn stalk. These corn stalks were taken from plots of Bt and non-Bt corn grown adjacent to each other. ECB damage is clearly visible in the non-Bt variety on the right. (Photographs courtesy of Syngenta Agricultural Biotechnology Research Unit, Research Triangle Park, N.C.)

Citation: Kreuzer H, Massey A. 2005. Risks and Regulations, p 443-473. In Biology and Biotechnology. ASM Press, Washington, DC. doi: 10.1128/9781555816094.ch18
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Image of Figure 18.11
Figure 18.11

Forest pests and defoliation. Gypsy moth larvae feeding on an oak tree. The nun moth, a close relative of the gypsy moth, completely defoliated evergreen trees in this European forest.(Photographs courtesy of Terry McGuire, Animal and Plant Health Inspection Service, USDA [A], and Beat Forster, Swiss Federal Institute for Forestry [http://www.forestryimages.org] [B].)

Citation: Kreuzer H, Massey A. 2005. Risks and Regulations, p 443-473. In Biology and Biotechnology. ASM Press, Washington, DC. doi: 10.1128/9781555816094.ch18
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Image of Figure 18.12
Figure 18.12

ECB densities in Illinois, 1943 through 1999. (Source, Gianessi and Carpenter, National Council for Food and Agricultural Policy, 1999.)

Citation: Kreuzer H, Massey A. 2005. Risks and Regulations, p 443-473. In Biology and Biotechnology. ASM Press, Washington, DC. doi: 10.1128/9781555816094.ch18
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Image of Figure 18.13
Figure 18.13

Geographic distribution of corn-growing areas and monarch breeding range . (Maps redrawn from those of the USDA National Agricultural Statistics Service and the National Biology Information Infrastructure of the U.S. Geological Survey.)

Citation: Kreuzer H, Massey A. 2005. Risks and Regulations, p 443-473. In Biology and Biotechnology. ASM Press, Washington, DC. doi: 10.1128/9781555816094.ch18
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Image of Figure 18.14
Figure 18.14

Milkweed habitat and distribution. Roadsides are a preferred habitat for milkweed plants (arrow). USDA scientists in Iowa found common milkweed () growing in 71% of the roadside plots they surveyed. In Iowa and other Midwestern states, many roadsides occur adjacent to cornfields, and on average, 30% of the corn grown in Iowa is a Bt variety. However, even during corn pollen shedding, the leaves of this milkweed plant would not contain enough Bt corn pollen to harm young monarch larvae, because very little corn pollen travels outside of the cornfield. (Photograph by Peggy Greb, courtesy of the Agricultural Research Service, USDA.)

Citation: Kreuzer H, Massey A. 2005. Risks and Regulations, p 443-473. In Biology and Biotechnology. ASM Press, Washington, DC. doi: 10.1128/9781555816094.ch18
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Image of Figure 18.15
Figure 18.15

Corn pollen dispersal. Many studies to measure corn pollen dispersal from cornfields to milkweeds surrounding the field have consistently demonstrated that pollen levels decrease rapidly as the distance from the cornfield edge increases.

Citation: Kreuzer H, Massey A. 2005. Risks and Regulations, p 443-473. In Biology and Biotechnology. ASM Press, Washington, DC. doi: 10.1128/9781555816094.ch18
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Image of Figure 18.16
Figure 18.16

Corn pollen shedding and larval feeding. The timing of corn pollen shedding and monarch egg laying affects the probability that young larvae will be exposed to Bt corn pollen. The red lines indicate the areas where overlap occurs between pollen shedding and larval feeding.

Citation: Kreuzer H, Massey A. 2005. Risks and Regulations, p 443-473. In Biology and Biotechnology. ASM Press, Washington, DC. doi: 10.1128/9781555816094.ch18
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Image of Figure 18.17
Figure 18.17

Mycotoxins. Some molds and fungi that infect plants produce harmful substances know as mycotoxins. The fungus shown produces aflatoxin. A number of studies have shown that Bt corn has significantly lower levels of mycotoxins than non-Bt corn. (Photograph courtesy of Gary Payne, North Carolina State University.)

Citation: Kreuzer H, Massey A. 2005. Risks and Regulations, p 443-473. In Biology and Biotechnology. ASM Press, Washington, DC. doi: 10.1128/9781555816094.ch18
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Image of Figure 18.18
Figure 18.18

Field testing. Before inserting the new gene into the crop that will be commercialized, researchers often use other plants as hosts to see if the gene will produce sufficient amounts of the new protein under field conditions. Tobacco is often the host crop that is used in early stages of transgenic-crop development, because regenerating tobacco plants from plant callus is much easier than it is for other plants, such as corn. This 1989 field test of Bt tobacco (left), which the company had no intention of commercializing, measured the efficacy of a transgene that was eventually used in a transgenic Bt corn variety. As you can see, the Bt gene did an excellent job of deterring lepidopteran pests of tobacco compared to tobacco without the Bt gene (right).

Citation: Kreuzer H, Massey A. 2005. Risks and Regulations, p 443-473. In Biology and Biotechnology. ASM Press, Washington, DC. doi: 10.1128/9781555816094.ch18
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References

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Tables

Generic image for table
Table 18.1

Natural toxins

Citation: Kreuzer H, Massey A. 2005. Risks and Regulations, p 443-473. In Biology and Biotechnology. ASM Press, Washington, DC. doi: 10.1128/9781555816094.ch18
Generic image for table
Table 18.2

Carcinogenic substances

Citation: Kreuzer H, Massey A. 2005. Risks and Regulations, p 443-473. In Biology and Biotechnology. ASM Press, Washington, DC. doi: 10.1128/9781555816094.ch18
Generic image for table
Table 18.3

Relative risks

Citation: Kreuzer H, Massey A. 2005. Risks and Regulations, p 443-473. In Biology and Biotechnology. ASM Press, Washington, DC. doi: 10.1128/9781555816094.ch18
Generic image for table
Table 18.4

Specificities of Bt subspecies

Citation: Kreuzer H, Massey A. 2005. Risks and Regulations, p 443-473. In Biology and Biotechnology. ASM Press, Washington, DC. doi: 10.1128/9781555816094.ch18
Generic image for table
Table 18.5

Bt toxicity

Citation: Kreuzer H, Massey A. 2005. Risks and Regulations, p 443-473. In Biology and Biotechnology. ASM Press, Washington, DC. doi: 10.1128/9781555816094.ch18
Generic image for table
Table 18.6

Biotechnology product regulation

Citation: Kreuzer H, Massey A. 2005. Risks and Regulations, p 443-473. In Biology and Biotechnology. ASM Press, Washington, DC. doi: 10.1128/9781555816094.ch18

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