Final answer:
The item not required on a container label for biological materials is potential residues of processing agents. Labels include a tissue identification number, expiration date, and processing date to ensure sample integrity and traceability.
Step-by-step explanation:
Container labels for biological specimens are required to include documentation to maintain the integrity and traceability of the samples. This usually entails having a tissue identification number, which ensures that the specimen can be accurately identified and matched to data. Additionally, the expiration date, including month and year, is critical as it informs the user of the sample's viability period.
The processing date, also including the month and year, is necessary to track when the sample was prepared, which can affect its usefulness for certain tests or experiments. However, the information about potential residues of processing agents, while important for safety and compliance reasons in some contexts, is not typically a standard requirement for a specimen container label, unless specified by particular regulations or laboratory protocols.