America’s prescription drug epidemic is a growing problem at work.

Workers with substance use disorders miss nearly 50% more days than their peers, and up to six weeks of work annually, according to a recent analysis from the National Safety Council, a nonprofit and nongovernmental agency promoting safety in the workplace, NORC at the University of Chicago, a nonpartisan, independent research organization. and Shatterproof, a national nonprofit dedicated to fighting drug abuse. There is a big gap between how many American workers are dealing with this problem while holding down a job and how many employers see it as a problem, Deborah Hersman, president of the National Safety Council, said.

In fact, 75% of adults struggling with substance abuse are in the workforce, although they are more likely to be unemployed than those who don’t have an opioid problem. Construction, entertainment, recreation and food service businesses have twice the national average number of employees with substance use disorders, the study found. Drug addictions in general cost taxpayers more than $440 billion annually, and the cost of untreated substance abuse ranges from $2,600 per employee in agriculture to more than $13,000 per employee in the information and communications sector.

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More than 70% of U.S. employers are dealing with the direct impact of prescription drug misuse in their workplaces, according to a separate survey of more than 500 companies with 50 or more employees released by the National Safety Council earlier this month. The survey, billed as the first of its kind in the U.S., also found that although a similar percentage of employers agree that prescription drug misuse is a disease that requires treatment, 65% feel it is a justifiable reason to fire an employee.

In the most recent survey by the National Safety Council, 88% of the companies surveyed said they are interested in their insurer covering alternatives to pain relief treatment, and nearly 60% believe the insurance company will be responsive. But 30% of those employers will not act on that interest. And just one-fifth of employers said they feel “extremely prepared” to deal with prescription drug misuse in the workplace. But 70% of the employers surveyed said they would like to help employees who are struggling with prescription drug misuse.

The percentage of workers testing positive for illicit drugs such as cocaine, amphetamines and methamphetamines among the U.S. workforce increased to the largest percentage in a decade in 2015, according to a workplace urine drug test of more than 9.5 million tests of urine samples, among other tests, by Quest Diagnostics, a company that provides national clinical laboratory tests on potential and/or current employees. The positivity rate for 9.5 million urine drug tests in the U.S. workforce increased to 4% in 2015 versus 3.9% the year before.

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Drug poisonings, largely from opioid painkillers, in the last decade eclipsed car crashes as the leading cause of preventable death among adults. People addicted to drugs are buying them on the street, as they’re often cheap. People with genuine need for pain medication leave drugs lying around where others have access them, or they are simply sold on. More often, they develop an addiction to pain medication after being prescribed drugs, said Leland McClure, medical science liaison of medical affairs at Quest Diagnostic. Quest found that opioid use is falling among workers.

People who work in fields where they’re at risk of injury and, therefore, are more likely to take pain medication, also surged in recent years, Quest found. They include medical workers who do heavy lifting, manufacturing and retail workers, and factory and warehouse workers. Lifting and carrying material accounts for nearly one-third of all accidents, according to an analysis of more than 1.5 million workers compensation claims released last year by Travelers Companies Inc., an insurance company. The most frequent employee injury (strains and sprains) averaged 57 days off work.

(This story was updated.)