Hazardous substances are materials that can pose a risk to health, safety, or the environment. These substances can be chemical, biological, or physical agents that may cause harm through exposure, ingestion, or inhalation. Common examples include toxic chemicals, flammable materials, and infectious agents. Regulations often govern the handling, storage, and disposal of hazardous substances to minimize risks. Organizations must follow guidelines set by agencies like the Environmental Protection Agency (EPA) to ensure safety and compliance. Proper training and protective equipment are essential for those who work with or around these materials.