The impact of employee marijuana use is seen in the workplace in lower productivity, increased workplace accidents and injuries, increased absenteeism, and lower morale. This can and does seriously impact the bottom line.
Links
[1] http://www.drugfreeworkplace.org/10-facts-about-marijuana/
[2] http://rethinkpot.org/tags/drug-free-workplace
[3] http://rethinkpot.org/tags/workplace
[4] http://rethinkpot.org/tags/employees
[5] http://rethinkpot.org/tags/business