Pesticide handler employees are not required to wear chemical-resistant gloves when:

The correct answer highlights a key aspect of pesticide safety regulations. When the pesticide label specifically states that gloves must not be worn, it overrides general safety requirements. This scenario is typically based on the formulation of the pesticide in question. Certain products may be designed to be safe for handling without gloves due to their low toxicity or the nature of their chemical formulation. Therefore, when a label provides such a directive, it is crucial for handlers to adhere to the manufacturer's instructions to ensure their safety and compliance with regulations.

In contrast, the other scenarios involve situations where the use of gloves is usually required due to the high risk of exposure to hazardous chemicals. Mixing or loading pesticides and repairing contaminated equipment present increased exposure risks, which warrant the use of protective gear for safety. Additionally, using a backpack sprayer for herbicides commonly involves handling potentially hazardous substances, making gloves a necessary protective measure.