Which department of the Federal Government primarily regulates domestic land shipments of hazardous materials?

The Department of Transportation (DOT) is primarily responsible for regulating domestic land shipments of hazardous materials. This includes establishing regulations to ensure the safe transportation of hazardous materials by road, rail, and other means. The DOT sets guidelines for packaging, labeling, and handling to minimize risks during transportation.

The Environmental Protection Agency (EPA) focuses on environmental protection and regulating hazardous waste but does not specifically regulate the transportation of hazardous materials. The Occupational Safety and Health Administration (OSHA) is concerned with workplace safety and health regulations, and while it may touch on hazardous materials in the context of employee safety, it does not directly regulate shipments. The Food and Drug Administration (FDA) is involved with food safety and pharmaceuticals, not hazardous materials transport. Thus, the focus of regulation for hazardous materials during transportation falls under the purview of the DOT, making it the correct choice.