Transportation Safety: DOT Has Taken Steps to Verify and Publicize Drug and Alcohol Testing Data but Should Do More, Report to Congressional Committees [open pdf - 1MB]
From the Highlights: "Since 1988, DOT [Department of Transportation] has regulated the process by which employers in the different transportation industries (aviation, trucking, rail, transit, pipeline, and maritime) are required to test their employees for drug and alcohol use. Employers must self-report these test results annually to DOT or when requested by DOT. In a 2018 statute, Congress required DOT to publish the aggregate drug and alcohol testing data on DOT's website and included a provision for GAO [Government Accountability Office] to review the website and these data. This report examines: (1) how DOT uses drug and alcohol testing data, (2) how DOT verifies that data are reliable, and (3) whether DOT follows key actions for transparently reporting drug and alcohol testing data."
Government Accountability Office: https://www.gao.gov/