_____ is one of the four types of regulated waste that requires special handling.

Liquid or semi-liquid blood or potentially infectious materials is recognized as a type of regulated waste due to its potential to harbor bloodborne pathogens, such as viruses and bacteria that can pose significant health risks if exposure occurs. This category of waste requires special handling to prevent incidents of exposure among healthcare workers and waste management personnel. Proper disposal procedures are essential to mitigate the risk of infection and ensure safe management of such hazardous materials.

The other choices, while relevant to the overall conversation about waste management and safety, do not fall into the same category of regulated waste requiring the same special handling protocols as liquid or semi-liquid blood or potentially infectious materials. For instance, populations of infectious organisms are typically managed under biosafety regulations, used personal protective equipment is often treated as general waste unless contaminated, and sharps containers, while needing careful management, are classified separately from fluids and materials.