The DOT definition of hazardous materials emphasizes that these materials must be?

The correct answer highlights that hazardous materials must be properly controlled to ensure safety in handling, storage, and transportation. The Department of Transportation (DOT) defines hazardous materials as substances that pose an unreasonable risk to health, safety, and property when not handled appropriately.

This definition underscores the importance of regulation and control measures implemented in the transport of these materials. Effective control measures include proper labeling, containment, adequate training for personnel, and adherence to safety protocols to minimize risks associated with exposure or accidental release.

Although proper labeling, correct storage temperatures, and usage in closed systems are important aspects of handling hazardous materials, the emphasis on being properly controlled reflects the broader regulatory framework that necessitates the management of all associated risks. It’s about ensuring that hazardous materials are managed in a way that mitigates danger to public health and safety.