Workplace drug testing has increased significantly in the UK, four leading screening companies have said.
They have seen rises in the number of annual tests carried out of between 40% and 470% over four years.
Workers cannot be made to take a drugs test, but if they refuse when the employer has good grounds for testing, they may face disciplinary action.
Business leaders' increased awareness of workplace drug use is a large factor behind the growth, said LGC Group.
It added that the adoption of a drugs-testing policy is "mainly due to insurance purposes".
The four companies are Alere, Synergy Health, LGC Group and BioClinics. The last two saw rises of 100% and 470% respectively over the four years in the number of drugs tests they conduct annually, although they started from a smaller base.
Wider business use
Lianne Gray, LGC Group's strategic account manager for occupational drug testing, said employees in safety-critical roles - such as operating heavy machinery or driving - and government agencies were most likely to be screened.
But she said there was a growing trend for drug testing to be conducted in "more normalised industries", including retail and health companies, as businesses look to "safeguard not only the business, but also the reputation in the field they work in".
Ms Gray said there had been changes in the types of drugs for which businesses wished to screen.
"Traditionally we see requests for amphetamines, cocaine, cannabis, opiates," she said. "Now we're seeing more requests for things like ketamine, steroids, and also for novel psychoactive substances - or legal highs as they're otherwise known."
Businesses are now testing employees for so-called legal highs more frequently
Under current law, businesses must have the consent of employees whom they wish to screen for drugs, and usually this will be in the contract or staff handbook.
Drugs testing is normally performed at random. It is also sometimes enforced prior to employment, on cause - following an accident or incident - or on suspicion.
Stobart Group, which includes the well-known Eddie Stobart haulage business, introduced a drugs-testing policy three years ago.
The services and infrastructure company, which operates London Southend Airport, screens not only its hundreds of truckers but all its employees, including shop workers.
Director of safety and compliance Neil Marston said: "We want to maintain a safe working environment for all our staff. But also for our customers, our visitors who pass through our premises. We're also very proud of our brand and want to protect it."
The increases in drug testing have angered civil liberties groups, who say that the practice is an invasion of people's privacy outside of safety critical roles.
Niamh Eastwood from the drugs advice charity, Release, said they frequently took calls from people who had falsely tested positive for drugs.
Eating poppy seed bread for instance can indicate the presence of opiates in some tests.
She said another problem is that although drug tests may indicate what substances are in the system, they do not indicate if a worker's performance is likely to be affected.