The percentage of positive tests for methamphetamine among U.S. workers and job applicants dropped more than 22 percent between 2006 and 2007, reports Quest Diagnostics, a national drug testing service. Quest Diagnostics also says its data show that positive tests for cocaine in the general U.S. workforce were down 19 percent between 2006 and 2007, and that overall drug use among workers subject to drug testing remains at an all-time low.

Although positive methamphetamine tests have decreased, the data also indicate that the use of amphetamine has increased slightly among workers, by about five percent. "Although some may conclude that there is a reduced availability for methamphetamine, the fact that our data show an increase in amphetamines suggests that some workers might be replacing one stimulant drug for another in the larger drug class of amphetamines,” says Quest Diagnostics spokesman Barry Sample.