Final answer:
Materials regulated by Hazard Class 4 include flammable solids, substances susceptible to spontaneous combustion, and substances that react dangerously with water. Hazardous materials also encompass listed and characteristic wastes, which are categorized based on specific hazardous properties and require careful management under various regulations to ensure environmental and human health safety.
Step-by-step explanation:
Materials regulated by Hazard Class 4 include substances that are flammable when dry, substances that are spontaneously combustible, and substances that are dangerous when wet. Hazard Class 4 is part of the classification system used by the United States Department of Transportation to categorize hazardous materials based on their inherent dangers during transportation. Amongst these, Class 4 specifically deals with flammable solids, substances liable to spontaneous combustion, and substances that emit flammable gases when they contact water.
According to United States regulations, hazardous materials include listed, characteristic, and mixed wastes. Listed wastes can be found in Table 22.7.1 of the US EPA where hazardous wastes are catalogued from specific sources, such as non-specific sources or discarded chemical products, and are grouped into four lists known as the F, K, P, and U lists. On the other hand, characteristic hazardous wastes have specific properties that make them hazardous, such as ignitability, corrosivity, reactivity, or toxicity, summarized in Table 22.7.2 by the US EPA.
In summary, proper handling of hazardous waste, including those in Hazard Class 4, is critical to protect human health and the environment. The management of these materials falls under various regulations, which include the Resource Conservation and Recovery Act (RCRA) and guidelines from the Environmental Protection Agency (EPA) for safe recycling, treatment, storage, and disposal.