MADISON, N.J., March 7, 2013 /PRNewswire/ -- Job candidates subject to pre-employment drug screening tested positive for illicit drugs at a greater rate in the first six months of 2012 than in all of 2011, according to Drug Testing Index™ (DTI) data released today by Quest Diagnostics (NYSE: DGX), the world's leading provider of diagnostic information services. The positivity rate from pre-employment urine drug screening in the U.S. general workforce increased by 5.7% in the first half of 2012 compared to 2011, while the positivity rate from random urine drug testing in the U.S. general workforce was down 5.8%. The positivity rate in pre-employment urine drug screening for the federally mandated, safety-sensitive workforce remained unchanged from 2011 through the first half of 2012, but the positivity rate from random testing among these workers was down 6.7% in the first six months of 2012 compared to 2011. "The uptick in U.S. general workforce pre-employment data suggests that employers should be mindful of illicit drug use among prospective employees," said Dr. Barry Sample, Director of Science and Technology for Quest Diagnostics Employer Solutions. "These findings align with recent news reports citing some employers facing increasing drug positives when recruiting new workers." Gap Between Oral Fluid and Urine Positivity Rates Grows DTI data also reveal a jump in positivity rates for marijuana in oral fluid vs. urine in the U.S. general workforce. While marijuana positivity rates in oral fluid and urine changed little between 2008 and 2011, the gap between oral fluid and urine positivity rates for marijuana increased during this time from a 29% higher positivity rate in oral fluid in 2008 to a 42% higher positivity rate in 2011. Due in part to advances in oral fluid testing technology implemented in late 2011, the oral fluid marijuana positivity rate was 70% higher than that of urine (3.4% vs. 2.0%) in the first half of 2012 as compared with 2011.