Which organization is primarily responsible for establishing the standards of drug testing for the transportation field?

The Department of Transportation (DOT) is primarily responsible for establishing the standards of drug testing within the transportation field. This organization has specific regulations and guidelines that govern the drug and alcohol testing processes for various modes of transportation, including aviation, railways, highways, and mass transit. The DOT's regulations are designed to ensure safety and compliance, which are critical in the transportation industry where safety-sensitive positions are common.

Through its Office of Drug and Alcohol Policy and Compliance, the DOT sets forth the criteria for testing, including the substances to be tested, the procedures for collection, and the responsibilities of employers. This framework aims to create uniformity across the industry, ensuring that transportation workers are fit for duty and that public safety is prioritized.

The other organizations listed, like the Environmental Protection Agency (EPA) and the National Institute of Health (NIH), have different areas of focus that do not encompass drug testing standards for the transportation sector. The Department of Defense (DOD) does have its own drug testing protocols, but they are not specific to the transportation field, making the DOT the clear authoritative body in this context.