What does the term "hazardous waste" refer to?

The term "hazardous waste" refers to any waste that may pose substantial or potential threats to public health and the environment. This definition encompasses a wide variety of waste types, including solid, liquid, and gaseous waste, as long as it exhibits hazardous characteristics such as being ignitable, corrosive, reactive, or toxic. The potential harm that such waste can cause makes it a concern for proper management and disposal to prevent adverse effects on human health and ecosystems.

In contrast to the other choices, which have specific limitations or definitions that do not capture the full scope of what constitutes hazardous waste, this answer encapsulates the broader implications of waste management and safety. Hazardous waste can indeed include ignitable materials, but it is not limited to just those. It can encompass a range of substances beyond just liquids or materials that are recyclable. Therefore, the definition of hazardous waste is comprehensive and considers the potential danger it poses more broadly.