What action should be taken with materials that have illegible labels and unidentified contents?

When dealing with materials that have illegible labels and unidentified contents, treating them as hazardous waste is the most appropriate action. This approach is crucial for safety reasons. If the contents of a container are unknown, their potential chemical properties and hazards cannot be assessed, which poses significant risks to personnel and the environment.

By classifying these materials as hazardous waste, proper protocols can be followed for disposal. This ensures compliance with regulatory requirements and protects everyone in the laboratory from exposure to potentially harmful substances. Treating unidentified materials as hazardous also emphasizes the importance of proper labeling and storage practices, fostering a culture of safety and accountability in the laboratory setting.

While other options may seem viable, such as using them for non-critical tasks or storing them for later identification, they carry substantial risks. Using unknown materials can lead to hazardous reactions or accidents, and merely storing them does not address the potential dangers they present. Donating them to other organizations is also inappropriate, as it could unintentionally pass on the risk associated with unidentified substances.