Drug testing or drug screening is the clinical analysis of biological samples like urine, blood, saliva or hair to detect if the subject has been taking the drug or drugs in question.
Most employers carry out pre-employment or random drug testing of their staff, especially for persons manning sensitive positions like transportation, requiring use of heavy equipment or other responsibilities where public safety is of concern.
In the US, drug screening is now a standard practice to reduce the impact of substance and alcohol abuse and increase efficiency levels in the workplace. A study by the Surgeon General reported that alcohol and drug abuse cost the economy $524 billion annually, and 5.4% of all employees failed drug screening test in 1997.
Hospitals, universities, sports bodies and law enforcement agencies also conduct hundreds of drug tests every year.
What Kinds of Drugs to Test For
The drugs that are screened for in the workplace are often limited to substances that are prone to abuse, including prescription drugs and alcohol; or the guidelines set by the government or in the contract terms of the private employer.
Employers may adopt a standard five-panel test of commonly abused drugs such as cocaine, marijuana, opiates, PCP, and amphetamines. Others extend the scope to a ten-panel drug screening to include prescription drugs like propoxyphene, oxycodone, barbiturates, benzodiazepines, alcohol, and even newer substances of abuse like MDMA (ecstasy).
Professional sportsmen or college athletes may be required to test for performance-enhancing drugs like anabolic steroids, diuretics, erythropoietin; as well as alcohol.
What Samples Should You Use?
The various drug screening methods include blood test, urinalysis (urine test), swab (saliva analysis), and hair follicle test.
Urine test is the commonest drug screening method because it is the simplest and least expensive. Hair testing is relatively new but the most efficient as it can detect presence of drug in the body that go back up to 90 days. But its accuracy can be lowered by environmental contamination such as smoke or powder.
Swab tests can only spot drug or alcohol in the saliva that go back to three days. The test results are not always reliable as, for example, marijuana or nicotine from tobaccos is easily absorbed by the body and only very little amounts of these substances are released into saliva.
Blood test is the most invasive and most accurate, as it can spot the presence of parent drugs and not just their metabolites. But it is the costliest drug screening method and often has to be backed by a legal requirement for the post.
Accuracy and Reliability
The result of a drug screening can be misleading or rigged by the subject if not conducted properly. An employer must ensure that specimen collection follow a strict guideline and is done within the detection window of the drug or drugs being tested for.
A lot of drugs can stay in the body system for up to four days after use, although marijuana can be detected for up to three or four weeks in the system after ingestion if it is heavily abused. Therefore, test samples collected too early or too late may produce less accurate results.