Pesticides, which include insecticides, herbicides and fungicides, are a group of poisons used for killing or repelling unwanted organisms. Each year, more than 4 billion pounds of pesticides are used worldwide. Although law requires that all new pesticides undergo a series of testing before being marketed, a 1984 study by the National Academy of Sciences found that 90 percent of all pesticides have never been tested for long term health effects. Less than one percent of the U.S. food supply is tested for pesticides.
Many pesticides can be indiscriminate in what they kill and often harm non-targeted animals that may be beneficial to crops. In areas of heavy pesticide use, poisoning of birds, mammals and fish are common. Some of the more persistent pesticides may remain dangerous for up to 20 years, slowly leaching into underground water supplies. In the United States, pesticides have been found in groundwater supplies in 26 states. Nearly half of all Americans rely on groundwater for home use.
Every year up to two million people suffer from pesticide poisoning worldwide, resulting in about 40,000 deaths. In the United States 50,000 cases of pesticide poisoning are recorded annually. Pesticide exposure can cause cancer, birth defects and damage to a number of body organs. Children often receive greater pesticide exposure because of their greater consumption of food and air, pound per pound, than adults. One study found that in households where pesticides are used, children are much more likely to suffer from leukemia.
Over the years, many insect species have become resistant to insecticides, necessitating higher doses and increased applications of more dangerous pesticides. Over the last 40 years, pesticide use has increased 10-fold, yet crop loss has almost doubled from 7 to 13 percent.
U.S. law currently allows any pesticide to be exported as long as the importing country is notified of its regulatory status. As a result, many pesticides that are banned or restricted in the United States because of their danger to health and the environment are exported to developing countries. In many cases pesticides are applied by farmworkers who are unable to read instructions or warnings on product labels (which are frequently written in English). These laborers are often inadequately protected and are exposed to heavy doses of dangerous pesticides. Ironically, 70 percent of the pesticides exported to developing countries are used in the production of food imported by the United States. Between 1979 and 1985 six percent of all agricultural imports to the U.S. carried unacceptably high levels of pesticides.
John Adams, Executive Director, National Resources Defense Council, explains that "more needs to be done to reform pesticide legislation and enforcement. Scientific evidence now shows that in most cases chemical-free agriculture is as productive as methods using pesticides. As consumers, everyone can help encourage a transition to environmentally-sensitive agricultural practices through thoughtful shopping and eating habits."
STS Actions.
• Have students make lists of the advantages and disadvantages of using pesticides. You might want to tell the students that a pesticide is a general word for poisons that control or kill insects, fungi, weeds, and rodents. Use the lists as way to identify student misconceptions.
• Have the students investigate pheromones, which are natural sex attractants, as a safe, biological alternative to chemical pesticides.
• Have students find out what effect the following actions have on chemical pesticides:
1. Wash fruits and produce.2. Buy domestically grown produce in season.
3. Buy organically grown produce.
4. Grow your own food.
5. Tend the lawn without chemicals.
• Have students find out about organic gardening.