In the UK, the respected Forensic Science Service does much of the testing for private companies. But a number of smaller private testing services are also vying for business. Earlier this year, Howard Taylor, director of laboratory services at the US National Safety Alliance, a firm which runs drugs testing programs for over 5000 companies, tested five commonly used commercial kits for testing urine samples on site. All the manufacturers claimed their tests were as accurate as any done in a lab. But that's not what Taylor found.
Sex is a more bizarre reason for failing a cocaine test.
NIDA studies have shown cocaine can be passed on in semen and absorbed through the vagina, although the amounts are too small to register in most tests. However, if drugs such as cocaine are placed on the lips or other areas of the body, the risk is higher. It's quite likely that enough could be transferred to another person through kissing or other oral contact to produce a positive drugs test, says Dan Berkable, president of the American Toxicology Institute in Las Vegas. The problems associated with urine testing have sparked interest in alternative techniques, mainly hair, sweat and saliva testing, says Huestis. Proponents of hair testing argue that it is less invasive and offers a much larger window of detection, as drugs stay in hair long after they have been metabolised by the body.