The definition includes two meanings. One is that the dangerous *** is part of the solid *** (in other words, if a substance is not a solid ***, then the substance is definitely not a dangerous ***); the second is The hazard must have hazardous characteristics. There are five common hazard characteristics, namely toxicity (including leaching toxicity, acute toxicity, biological toxicity, etc.), corrosiveness, flammability, infectivity, and chemical reactivity. Solids with one or more hazardous properties are classified as hazardous.