What unique feature is included in the Category A hazard label?

The unique feature included in the Category A hazard label is the WHMIS biohazard image and emergency contact details. This is significant because Category A materials are considered to pose a high risk to health and safety. The presence of the biohazard symbol immediately alerts individuals to the nature of the hazard, indicating that the material can pose biological risks such as infectious agents or harmful substances.

Furthermore, including emergency contact details is crucial for ensuring that in the event of an incident involving these materials, individuals can quickly reach out to appropriate responders or specialists trained to handle such situations. This feature of the label enhances safety protocols and ensures emergency preparedness is effectively communicated.

In contrast, the other options do not embody the specific characteristics relevant to Category A hazard labels. For instance, while barcodes or color codes may have various applications in hazardous materials handling, they do not carry the same specific meaning and importance as the biohazard symbol and emergency contacts in this context. Simple text warnings, while informative, lack the visual impact and direct identification that the biohazard image provides. Thus, the emphasis on the biohazard image and emergency information is integral to the labeling of high-risk materials.