SOURCE: Quest Diagnostics Incorporated

Quest Diagnostics Introduces New Lab Procedure to Thwart Nitrite
Tampering in Workplace Drug Tests

TETERBORO, N.J., May 11 /PRNewswire/ -- Quest Diagnostics Incorporated (NYSE: DGX - news) today announced the availability of a new testing procedure designed to detect the presence of high levels of nitrite in drug testing specimens. Nitrites, in the form of potassium nitrite powder, are sometimes added to urine samples at the time of collection by drug abusers attempting to obtain a negative drug test result.

One of the most effective chemical agents used for this purpose is sold under the KlearŪ trademark. Quest Diagnostics’ experimental laboratory data indicates that 1,000mg of Klear nitrite added to a urine sample that is positive for cannabinoids will cause the test for cannabinoids to produce a negative result in immunoassay testing. Those specimens, adulterated with nitrite, will not screen positive for cannabinoid marijuana (THC) metabolites and will escape detection.

However, the addition of Klear also elevates nitrite levels to unnaturally high levels in the sample. An automated procedure devised by Quest Diagnostics screens the original urine sample to detect unnatural levels of nitrite.

Specimens containing these unnaturally high levels will be flagged on the result report as "Specimen Adulterated - Presence of Nitrite Detected," giving employers the option to reject the sample as contaminated.

Kenneth W. Freeman, Chairman and Chief Executive Officer of Quest Diagnostics, said, "We are offering this new service to our employer customers to ensure the integrity of the lab test results they rely on for vital information regarding employee drug use. These companies must be certain that their employees, especially those entrusted with public safety, such as airline pilots and train conductors, are not subverting the urine testing program. We perform millions of drug tests every year in our labs. This additional measure ensures the integrity of the data we provide to customers."

Quest Diagnostics Incorporated is one of the nation’s leading providers of diagnostic testing, information and services with laboratories across the United States. The wide variety of tests performed by Quest Diagnostics on human tissue and fluids help doctors and hospitals diagnose, treat and monitor disease. Its Nichols Institute unit, located in San Juan Capistrano, California, conducts research, specializes in esoteric testing using genetic screening and other advanced technologies, performs clinical studies testing, and manufactures and distributes diagnostic test kits and instruments. Quest Informatics collects and analyzes laboratory, pharmaceutical and other data to help large health care customers identify and monitor patients who are at risk for certain diseases. Visit our web site at: www.questdiagnostics.com.

The statements in this press release which are not historical facts or information are forward-looking statements. These forward-looking statements involve risks and uncertainties that could cause the outcome to be materially different. Certain of these risks and uncertainties are listed in the Quest Diagnostics Incorporated 1997 Form 10-K.

SOURCE: Quest Diagnostics Incorporated