Drug screening has been implemented for more than twenty years in many companies to determine if company's employees are on drugs. The most commonly abused drugs detected by drug screening are marijuana, hashish, cocaine, herion, ecstasy etc.

There are different types of drug tests run now. As a rule, urine, oral fluids, hair samples are taken and examined in a testing laboratory. Drug testing can be also run on-site, which lessens company's expenditure and is more convenient for employees.

Thus, one of the most commonly administered on-site drug test is the oral swab. It is very cheap. The company wastes about $1.00 per test. Besides, it is less embarrassing for employees compared to gathering urine specimens. Moreover, saliva tests are fast. So, the results get ready in a few minutes. In addition, these drug tests are harder to adulterate than urine drug tests, as specimens are obtained under sstrict direct supervision. Despite being donor friendly, non-invasive and easy to run, saliva drug tests detect very recent drug use. More than six types of drugs can be determined in this way.

One more way of drug screening is examination of urine samples. About 10 types of drugs can be determined by means of urine drug tests. There are three kinds of a urine drug test: dip form, cassette form and cup form. The employee's urine is gathered in a specially made secure cup and sealed with a tamper-resistant tape. After that the cup is sent by express delivery service to a clinical laboratory where it is examined for drugs.

Hair testing is believed to be very accurate and can determine drug use as far back as ninety days. Since hair grows out, any drugs used are encased in the hair shaft. Longer hair can reveal an individual's drug history spanning a longer period of time than shorter hair. Human hair grows, on average, 0,5 inches a month. Clinical laboratories generally require about 0,5 - 1,5 inches for a test. It represents around 30 - 90 days of drug use.

Spray drug tests are also simple to carry out. They are very reliable and difficult to adulterate as well. Yet, the range of drugs detected by means of a spray drug test is very limited.

Although many employees and privacy advocates consider drug tests a ruthless invasion of privacy and violation of one's rights and freedoms, drug tests continue to be carried out by employers, since drug use is frequently the cause for absenteeism, on-the-job accidents and health problems.