Which of the following requires the use of personal protective equipment to prevent contamination?

Handling isotopes necessitates the use of personal protective equipment (PPE) to protect individuals from radiation exposure and contamination. Isotopes can be either stable or radioactive, but when dealing with radioactive isotopes, there is a risk of release of radioactive materials, which can contaminate the skin, clothing, or other surfaces. PPE, such as gloves, lab coats, and sometimes face shields or masks, serves as a barrier to prevent such contamination and minimize the potential for harm from the radiation emitted by these isotopes.

In contrast, radioactive decay is a natural process that does not require physical intervention or protective measures for the decay event itself. Environmental monitoring involves assessing radiation levels in the environment, which, while important for safety, does not typically involve direct handling of radioactive materials, thus lessening the need for PPE in that context. Similarly, the storage of safe materials refers to keeping materials that do not pose a contamination risk, so PPE is not necessary in these circumstances. Hence, the handling of isotopes stands out as the scenario that inherently requires proper protective equipment to ensure safety against contamination.