"The higher oral fluid detection rate for marijuana strongly suggests that observed oral fluid collection curbs evasive donor behavior," said Dr. Sample. "Simply put, it is extremely difficult to cheat an oral fluid collection when someone is observing."While both urine and oral fluid testing are highly effective in detecting recent drug use, urine specimen collection is unobserved, affording donors seeking to evade detection with the means to adulterate the specimen. In contrast, oral fluid specimens are collected when the donor places a swab in his or her mouth under direct observation of the drug test administrator. Marijuana Continues to Be the Most Commonly Abused Drug Data from DTI for January to June 2012 show that marijuana continues to be the most commonly detected drug. Data from urine drug tests show that marijuana positives in the U.S. general workforce (2.0%) are nearly twice that of amphetamines (0.86%), which ranked as the second most commonly detected drug. This finding is corroborated by data from the U.S. Substance Abuse and Mental Health Services Administration (SAMHSA), which estimated that in 2011, 7% percent of Americans (18.1 million people) were current users of marijuana -- up from 5.8% (14.5 million people) in 2007. Pre-employment oral fluid drug testing data showed a sharp increase (15.7%) in the positivity rate from 2011 to the first-half of 2012 (4.4% vs. 5.1%). This increase is likely related to the increase in marijuana positivity rates, which was driven by changes in testing technology. The positivity rate in random oral fluid drug testing is up 12.1% from 2011 to the first-half of 2012 (3.3% vs. 3.7%). This increase reversed the 8.3% decline seen between 2010 and 2011. Substance misuse negatively affects the workplace through lost productivity, workplace accidents and injuries, employee absenteeism, low morale and increased illness and can have a serious impact on business operations.