Which organization mandates laboratory decommissioning when radioactive materials are used?

The Canadian Nuclear Safety Commission (CNSC) is the correct choice because it is the regulatory body responsible for overseeing the use and safety of nuclear energy and radioactive materials in Canada. This includes setting and enforcing regulations concerning the handling, storage, and disposal of radioactive substances in various environments, including laboratories. The CNSC mandates the decommissioning of laboratories that have used radioactive materials to ensure that these sites are safely managed, preventing potential hazards to public health and the environment.

The CNSC's guidelines ensure that any facility that has worked with radioactive materials is appropriately cleaned, decontaminated, and decommissioned in accordance with established safety standards. This process is critical to maintaining safety protocols and ensuring that no residual radioactive contamination remains that could pose a risk after the laboratory's operational life has ended.

In contrast, the other organizations mentioned focus on different aspects of health and safety or have broader mandates that do not specifically address laboratory decommissioning in the context of radioactive materials.