In what situation would urine from a renal test be permissible for disposal in the sewage system?

The correct assertion regarding the disposal of urine from a renal test is that it is permissible with prior decay of isotopes used. In nuclear medicine, many procedures involve the use of radioactive isotopes that emit radiation. After these isotopes are administered to a patient, they gradually decay and lose their radioactivity over time.

When urine is collected after a renal study, it may still contain traces of the radioactive isotopes. The safety protocols in nuclear medicine recommend that any radioactive waste, including bodily fluids like urine, should be managed carefully to prevent unnecessary exposure to radiation. Waiting for a specified period allows the isotopes to decay to a level where the radiation exposure is minimal and considered safe for disposal in the sewage system.

Compliance with regulatory guidelines ensures that the levels of radioactivity remaining in the urine post-decay are significantly below permissible limits, mitigating any potential risks to public health or the environment.