en a standard sobriety test similar to a roadside sobriety test. The test showed that marijuana significantly impaired their ability to stand on one leg for 30 seconds or touch their finger to their nose. As the dose of THC increased, the subjects swayed more, raised their arms, and had to put their feet down in an attempt to maintain their balance. Subjects also committed 2.5 times more errors when they attempted to touch their nose with their finger. The data from these laboratory studies show that marijuana impairs balance and coordination - functional components important to driving - in a dose-related way, said Dr. Heishman. These effects may be related to reported marijuana-induced impairment of automobile driving, he stated. Highway and urban driving studies conducted in the Netherlands show less impact on actual driving. However, these driving studies used very low doses of marijuana for safety reasons, Dr. Heishman said. Future research using appropriate safety measures should test the effect of higher doses of marijuana on driving as well as the combined effect of marijuana and alcohol on driving, he concluded. In another study, Dr. Wayne Lehman of Texas Christian University looked at how marijuana affects job performance. A series of surveys he conducted among 4,600 municipal employees in four cities in the Southwest indicated that 8 percent of employees had smoked marijuana in the past year, and a large percentage of these users had smoked marijuana in the past month, Dr. Lehman said. "Employees who report marijuana use are different from nonusers," said Dr. Lehman. They are much more likely than nonusers to have arrest histories, low self-esteem, high rates of depression, and friends who are deviant. Many marijuana smokers also have alcohol-related problems. One-third of marijuana users in the surveys reported they drank frequently, one-half said they got drunk, and 60 percent reported a problem with alcohol use, according ...
