More U.S. workers are testing positive for illicit drugs than at any time in the last 12 years, according to data coming out today from Quest Diagnostics Inc., one of the largest workplace-testing labs in the nation.

The number of workers who tested positive for marijuana rose by 4%, while positive results for other drugs also rose. The increases come against a backdrop of more liberal marijuana state laws and an apparent resurgence in the use of drugs like cocaine and methamphetamine.

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