Final answer:
DDT is a banned pesticide known for environmental harm, notably to bird populations. The chemical is categorized as a chemical agent due to its synthetic nature and intended use for pest control. Substances like 2,4-D and 2,4,5-T are herbicides used to kill broad-leaf plants in agriculture.
Step-by-step explanation:
DDT as a Pesticide
DDT is a well-known pesticide that has been banned in the United States due to its negative environmental impacts, especially on wildlife. It is infamous for causing thinner eggshells in birds like eagles, which affects their reproduction rates. DDT is considered a chemical agent because it is a synthetic compound designed to target and kill pests.
Herbicides and Their Use
Another class of chemicals used in agriculture is herbicides like 2,4-D and 2,4,5-T, which have been used since the end of World War II. These herbicides operate by causing uncontrolled hormonal growth in broad-leaf plants, effectively killing them. While not the focus of this question, understanding their mode of action provides context on the differences between various types of agricultural chemicals.
Implications for Human Health
Regarding human health, the use of pesticides and herbicides can have indirect effects. For instance, malnutrition is a significant contributor to child mortality, and while not directly related to chemical agents like DDT, it showcases the complex factors contributing to public health.