Answer to Question 1
For several reasons, however, nonpersistent pesticides are not as environmentally sound as they might appear. First of all, they are persistent enough to ride the food supply from farmer to consumer.' Second, many of the nonpersistent pesticides are far more toxic than DDT. This higher toxicity, combined with frequent applications needed to maintain control, presents a significant hazard to agricultural workers and other exposed to these pesticides. Nonpersistent pesticides may still have far-reaching environmental impacts. For example, to control outbreaks of grasshoppers that eat sunflowers, farmers in Argentina began spraying monocrotophos, an acutely toxic organophosphate pesticide, in 1995 . Shortly afterward, thousands of dead Swainson's hawks were seen in the sunflower fields. It was estimated that 20,000 hawks died in one year, about 5 of the world's population of the species. Another problem is that desirable insects may be just as sensitive as pest insects to nonpersistent pesticides. Finally, nonpersistent chemicals are just as likely to cause resurgences and secondary-pest outbreaks as are persistent pesticides, and pests become resistant to nonpersistent pesticides just as readily, too.
Answer to Question 2
Several examples of environmental injustice were given in this chapter. Students may refer to international trade (discrimination against developing countries via taxes and restricting imports), placement of waste sites, and the disproportionate distribution of improvements to white areas of a city or country.
Lithotripsy. The direction of a sound pulse crushes the stones into smaller fragments that can be pa
Physical and Perceptual Dimensions of Sound Waves
Sound Localization
Albert Bierstadt, Puget Sound on the Pacific Coast.
The relation between the physical and perceptual dimensions of sound.
Examples of Look Alike Sound Alike Drugs