The National Safety Council, a nonprofit organization whose stated mission is to eliminate preventable deaths at work, in homes and communities through leadership, research, education and advocacy, published a Position/Policy Statement on October 21, 2019 addressing cannabis (marijuana) impairment in safety-sensitive positions. NSC stated that “it is clear that cannabis impacts psychomotor skills and cognitive ability,” and concluded that “there is no level of cannabis use that is safe or acceptable for employees who work in safety-sensitive positions.” (“Safety-sensitive” refers to jobs that impact the safety of the employee and the safety of others as a result of performing that job). You can read more about it here.