The Federal Motor Carrier Safety Administration (FMCSA) released a detailed report on substance use violations compiled by their new national drug and alcohol database.The FMCSA recently released a summary report for the month of May that broke down the data on the types of drugs that were identified in positive CDL holder drug tests that were reported to the Drug & Alcohol Clearinghouse.As of June 1, 2020, here are the top 8 substances that were identified in positive substance use tests reported to the Clearinghouse.