Letters to the Editor: PDF OnlyDrug Use Association vs CausationRyan, James MD, MPH; Zwerling, Craig MD, PhD, MPH; Jones, Michael PhDAuthor Information East Boston Logan Health Associates Logan International Airport East Boston, Massachusetts Journal of Occupational Medicine: October 1993 - Volume 35 - Issue 10 - p 984-992 Free ©1993 The American College of Occupational and Environmental Medicine