Human Heredity 11th Edition by Michael Cummings

تمرين 22

What About Irradiated Food?
During the past 50 years, research has demonstrated that radiation can help preserve food and kill contaminating microorganisms. Irradiation prevents sprouting of root crops such as potatoes; extends the shelf life of many fruits and vegetables; destroys bacteria and fungi in meat, fish, and grain; and kills insects and other pests in spices.
For irradiation, food is placed on a conveyor and moved to a sealed, heavily shielded chamber, where it is exposed to a radioactive source. An operator views the process on a video camera and delivers the dose. The food itself does not come in contact with the radioactive source, and the food is not made radioactive. Relatively low doses are used to inhibit the sprouting of root vegetables such as potatoes. Intermediate doses are used to retard spoilage in meat, poultry, and fish. And high doses can be used to sterilize foods, including meats. The amount of food irradiated varies from country to country, ranging from a few tons of spices to hundreds of thousands of tons of grain.
NASA routinely has fed irradiated food to astronauts in space since 1972, and irradiated foods are sold in more than 40 countries, including the United States. The U.S. Food and Drug Administration (FDA) approved the first application for food irradiation in 1964, and approval has been granted for the irradiation of spices, herbs, fruits and vegetables, pork, beef, lamb, chicken, and eggs. All irradiated food sold in the United States must be labeled with an identifying logo (see inset).
Studies by U.S. government agencies have shown that there are benefits to irradiated foods. Irradiation kills all or most disease-causing organisms and does not change the nutritional value of the food. However, these studies also show that irradiation does not destroy toxins produced by bacteria before irradiation and does not prevent aging of fruits and vegetables.
Public concern about radiation has prevented the widespread sale of irradiated food in this country. Advocates point out that irradiation can eliminate the use of many chemical preservatives, lower food costs by preventing spoilage, and reduce the 76 million cases of food-borne illnesses and 5,000 deaths caused by contaminated food each year in the United States. For example, irradiation of lettuce has been shown to eliminate contamination with Escherichia coli O157:H7, a deadly bacterial strain responsible for over 70,000 cases of food-borne illness and over 60 deaths per year. Those opposed to food irradiation argue that irradiation produces mutation- and cancer-causing compounds in food and that the testing of irradiated food to detect cancer-causing effects is inadequate. Opponents also point out that treatment may select for radiation-resistant microorganisms. Whether food irradiation will find widespread adoption will depend on consumer education and other factors such as price and availability.
Consumer products including bandages, cotton balls, diapers, and contact lens solutions are routinely irradiated. There is no opposition to these products in the marketplace. Given this, why are irradiated foods not more accepted when they can prevent illness from E. coli and other pathogens?