Under what condition may an employee mix, load, or apply pesticides with the signal word "DANGER" at night?

The correct answer pertains to the requirement of making hourly contact with a responsible adult. This regulation is in place to ensure continuous communication and safety oversight when an employee is handling hazardous materials, like pesticides labeled with the signal word "DANGER." The signal word indicates that the pesticide is highly toxic and poses significant health risks.

By maintaining direct contact with a responsible adult, the employee can have immediate access to assistance or emergency protocols if an incident occurs during the application or mixing of the pesticide at night. This measure is crucial in ensuring a safety net is in place, reducing the likelihood of accidents and enhancing the effectiveness of emergency response should it be necessary.

Training specific to night operations or carrying a personal locator device, while potentially useful in enhancing safety, do not specifically address the immediate communication requirements that are crucial when working with hazardous materials at night. Having a first aid kit is also important for emergency preparedness but does not substitute for the need for oversight and guidance from a responsible adult in this context. Thus, the requirement for hourly contact is the key safety measure highlighted in this regulation, reinforcing the importance of communication in hazardous work environments.