Which regulatory body defines hazardous chemicals under the Health and Safety regulations?

The correct choice is OSHA, the Occupational Safety and Health Administration. OSHA is responsible for ensuring safe and healthy working conditions for employees by setting and enforcing standards. One of its key roles is to define what constitutes hazardous chemicals within the framework of health and safety regulations. This includes setting limits on exposure to various hazardous substances, requiring proper labeling, and developing safety data sheets to inform workers about the risks associated with these chemicals.

Understanding hazardous materials is crucial in maintaining workplace safety, as these definitions help employers implement appropriate safety measures. The other options may regulate certain aspects of chemicals—like the EPA overseeing environmental protection, the DOT focusing on transportation safety, and the CDC addressing public health concerns—but when it comes to defining hazardous chemicals specifically within the context of workplace safety, OSHA is the regulatory body that provides that specific definition.