DALLAS (NewsNation) — As legal recreational marijuana use expands in the U.S., the number of workers testing positive for the substance in workplace drug screenings is reaching a 25-year high, according to an annual analysis by Quest Diagnostics, one of the country’s largest drug-testing labs.

Of the more than 6 million general workforce tests Quest analyzed for marijuana use in 2022, 4.3% came back positive, up 3.9% from the previous year.

More than 7% of drug tests after on-the-job accidents came back positive for marijuana and this has continued to rise since 2012.

In 2022, the percentage of employees who tested positive for marijuana following an on-the-job accident rose to 7.3%, an increase of 9% compared to the previous year. From 2012 to 2022, post-accident marijuana-positive tests went up more than 200%.

Thirty-eight states plus the District of Columbia have legalized either recreational or medical cannabis use; it still remains illegal on the federal level.

The U.S. Drug Enforcement Administration lists marijuana as a Schedule I substance, meaning it has high abuse risk and no safe medical use in treatment in the U.S.

Seth Berenzweig, an employment attorney, said companies have to consider safety standards and any potential legal challenges while also weighing best ways to retain workers in the current tight labor market. Also, businesses must be mindful of how laws or policies may vary from state to state regarding employees working remotely.

“It’s more important than ever that companies try to walk this delicate tightrope and figure out a way to balance the reality that while they want to have a safe workforce and clear policies, it has to be done in a way that’s HR-friendly to make sure that the rules of the road are set in place,” Berenzweig said.

Quest Diagnostics data also found that the positivity rate for all drugs and all drug tests, whether pre-hiring or on the job, was the highest it’s been in 20 years.

Though marijuana was the main driver of the rise in positive drug tests, screenings also came back positive for amphetamines. Positive tests for amphetamines rose to 1.5% in 2022, up from 1.3% in 2021, according to Quest. The data doesn’t differentiate between prescribed medications and illicit drugs.

Positivity rates for certain classes of opioids and barbiturates declined in 2022, according to the data.