Which organization’s mission is to save lives, prevent injuries, and protect the health of US workers?

The mission to save lives, prevent injuries, and protect the health of U.S. workers is primarily associated with OSHA, the Occupational Safety and Health Administration. Established under the Occupational Safety and Health Act of 1970, OSHA is responsible for ensuring safe and healthy working conditions by setting and enforcing standards and providing training, outreach, education, and assistance. The agency conducts inspections, investigates complaints, and monitors workplaces to ensure compliance with safety regulations, thereby directly protecting the health and safety of workers.

While other organizations mentioned have important roles—NIOSH focuses on research and recommendations for the prevention of workplace injuries, MSHA regulates mines to ensure miner safety, and the CDC is involved in public health more broadly—OSHA is specifically tasked with workplace safety enforcement and protection in a wide array of industries. Thus, it is the organization that aligns most closely with the mission described in the question.