Much of the push toward drug testing has come from the federal government. In 1982, the Navy began the first broad-scale random drug testing after an aircraft accident aboard the USS Nimitz uncovered widespread drug use about the ship. The practice soon spread to other branches of the military. Then drug testing was introduced in safety-sensitive government agencies such as the Nuclear Regulatory Commission, and mandated for government contractors with contracts worth more than $25,OOO.

Several horrific accidents spurred drug testing in the transportation industry. In 1987, two trains collided in Chase, Md., causing 16 deaths, and it was later revealed that one of the trains engineers had been smoking marijuana before the collision. And in 1991, eight people were killed in a New York subway train crash; the train’s driver later tested positive for alcohol.

These incidents led to the passage of the Omnibus Transportation Employee Testing Act of 1991 which required the Department of Transportation to mandate drug and alcohol  testing of employees in safety-sensitive transportation positions in private companies.

A snapshot of how drug testing works comes from Tom Warner, president of three D.C-based plumbing, heating and air conditioning companies that together employ 92 workers.  He wasn’t pushed to his drug-testing policy because of any big disaster. Instead, it was little things such as recurring minor accidents and foolish mistakes.  He remembers one experienced technician, for example, who had used his bare hands on a sewer-contaminated piece of machinery, rather than use his gloves. “It wasn’t something a rational person would do” he recalled thinking at the time.

Warner decided to introduce drug testing, and the first results startled him.  About half of a group of new trainees failed. as did the worker who had failed to use his safety gloves. Some drug users quit rather than be tested. Warner decided to clean out the problem workers by simply firing people who tested positive for drug use.  They are invited to reapply after one year and will be rehired if they pledge to remain drug-free.  Few drug users either apply or reapply now, Warner said. “It’s known we’re a drug-free company,”  he said. “People who do drugs want to do drugs — and want to be in a place where they can.” The percentage of major firms requiring employee drug tests has escalated in the past decade, … and the percentage of employees who test positive has declined significantly.

Construction workers are among the category of employees reporting the highest usage rate of Illegal drugs. Percentage of employees, 18-49, reporting use of illicit drugs in the past month :-