Employees are cheating on workplace drug tests at record rates—and legalized cannabis could be to blame

A rise in the use of recreational marijuana use in states that have legalized cannabis appears to be behind a spike in falsified workplace drug tests.

According to figures from Quest Diagnostics cited by the Wall Street Journal, workers are cheating on drug screens at a rate not seen in over 30 years.

While the number of Americans testing positive for listed substances remains stable for the third year in a row, that is potentially because more are resorting to extreme measures to mask their consumption habits particularly for jobs like heavy machinery operators or vehicle drivers.

“Some American workers are going to great lengths to attempt to subvert the drug-testing process,” said Suhash Harwani, Quest senior director of science for workforce health solutions, who pointed to pot as the leading cause.

One increasingly popular method is substituting urine samples to use either someone else’s, synthetic urine that can be purchased online or even animal urine. Quest data showed a sixfold increase last year in substituted samples to mark the highest rate ever recorded by the company.

Another common example that can, however, invalidate results and cause a subject to fail drug screening is not to swap urines but to blend in additives.

Amphetamines rank second after marijuana

According to Quest, out of more than 8.4 million urine samples tested last year, 4.6% came back positive.

States where recreational marijuana use has been legalized, such as New York and Colorado, have seen the largest swing with 5.8% of the tests positive last year, up from 2.4% in 2015.

By comparison, those states that hadn’t followed saw a much less pronounced increase, with the positivity rate only increasing to 3.3% from 2.6% in 2015.

As a result, employers are reconsidering what drug test policies may need to be changed to reflect the patchwork of different laws on statute books.

After marijuana, amphetamines rank as the second most common substance to be discovered during drug screening with a positivity rate that increased only marginally to 1.5% last year from 1.3% in 2019.

This story was originally featured on Fortune.com