Prescription drug misuse could be slipping through the cracks at Illinois workplaces, this article warns. No study has assessed whether the state has a prescription drug problem in the workplace, and state law does not require employers to conduct drug tests. The Illinois Work Injury Resource Center tests thousands of employers throughout central Illinois for marijuana, cocaine, amphetamines, PCP, and opiates. Employers can upgrade the test to include six additional prescription medications. It can still be difficult to identify those who misuse drugs because opiates can clear an employee’s system in about a week. Also, many opiates sometimes go untested because employers are unaware of advanced testing options.