Employees increasingly are testing positive for marijuana, cocaine and methamphetamines at work, driving the rates of positive drug tests in the United States to the highest level in 12 years.
Illinois' positive drug test rate matched the national average, though employees' drugs of choice vary widely in different parts of the state.
Cocaine is big in Chicago's south suburbs while opiates dominate at the southern end of Illinois, according to a local breakdown based on the first three digits of the ZIP codes. Heroin is concentrated around Rockford.
Marijuana, the most common drug for which workers test positive, has a steady presence throughout much of northern and central Illinois but leads to a particularly high positive rate in Sangamon County, home of the state capital.
Illinois has nearly double the national rate of positive heroin tests — 0.055 percent versus 0.028 percent — and the rate is even higher south of Chicago around Will and Kankakee counties. The rate of positive heroin tests is highest around Rockford, where it exceeds 0.12 percent.
Positive cocaine tests also have have increased, for the fourth consecutive year in the general workforce and the second year for safety-sensitive workers.
Illinois' rate of positive cocaine tests, 0.37 percent, was higher than the national average of 0.28 percent, and locally the rate exceeds 0.45 percent in ZIP codes starting with 604, such as Will County and parts of southern Cook County, and 609, which includes Kankakee.
Quest Diagnostics, a leading lab services company based in Madison, N.J., released its annual analysis of more than 10 million workforce drug test results nationwide.