Across the board: 3.1% or 3.9 million workers -- but it's not evenly distributed. In some segments of the workforce it's 28%.

This U.S. national study explored the overall prevalence, frequency, and distribution of illicit drug use in the workforce and in the workplace during the preceding 12 months. Illicit drug use in the workforce involved an estimated 14.1% of employed adults (17.7 million workers). Illicit drug use in the workplace involved an estimated 3.1% of employed adults (3.9 million workers). Illicit drug use in the workforce and in the workplace is not distributed uniformly in the employed population. At-risk, though circumscribed, segments of the U.S. workforce were identified with prevalence rates up to 55.8% for any use of illicit drugs and up to 28.0% for illicit drug use in the workplace. The implications of these data for future theoretical research and for management policy and practice are discussed. (PsycINFO Database Record (c) 2006 APA, all rights reserved)