Typical radioactive wastes – e.g., from a research hospital – might include:

• iodine-131 ( ¹³¹I ), a high-energy emitter of gamma and beta radiation;
• phosphorus-32 ( ³²P ), a pure beta emitter;
• mixed wastes containing both ¹²⁵I  (a low-energy gamma emitter) and ¹³¹I .

Producers of radioactive wastes often store isotopes with a half-life of 90 days or less until they have decayed enough for disposal. For medical wastes, "disposal" means incineration, because of the possibility of infectious substances.

The standard guideline is to store materials for 10 half-lives.

Some materials decay below background radiation levels in less than 10 half-lives. Others, however, are still quite radioactive after 20 half-lives.

The construction of storage facilities depends on the energy levels of radiation being emitted. For example, ¹³¹I  is shielded by two feet of solid concrete, which reduces radiation by a factor of 10, but does not completely contain it. In contrast, ³²P  can be completely shielded with a half-inch of high density polyethylene.