What safety measure is advised when filling a DOT container?

The correct choice emphasizes the importance of checking dates and purging the container before filling it. This practice is essential for safety and compliance with regulations when handling hazardous materials. By checking the dates, you ensure that the container is still within the acceptable limits for use, reducing the risk of accidents caused by using outdated or compromised containers. Purging the container helps eliminate residual substances that may react with the new material being added, thereby preventing chemical reactions that could lead to leaks or spills.

This safety measure ensures the integrity of the materials being handled and the safety of personnel involved in the filling process. It's a critical step in maintaining a safe working environment within facilities that handle potentially hazardous materials. The other options do not adequately address the specific safety procedures necessary for filling a DOT container.