For what reason might pesticides be classified as "restricted use"?

Pesticides are classified as "restricted use" primarily because they require certification for safe application. This classification is in place to ensure that the application of these pesticides is managed carefully, as they may pose a greater environmental, health, or safety risk if handled improperly. Trained and certified applicators are knowledgeable about the potential hazards, proper handling techniques, and appropriate application methods required to minimize risks to human health and the environment.

In contrast, the other options do not accurately capture the reasons for the restricted use classification. For instance, being cheaper is not a criterion that connects with safety concerns. Similarly, while some pesticides may be effective, efficacy alone does not justify restriction; it's the potential risk associated with improper use that matters most. Lastly, all pesticides are subjected to safety regulations, so claiming that restricted use pesticides have no safety regulations is incorrect. Thus, certification ensures that only qualified individuals handle pesticides that could potentially cause harm if misapplied.