Oral fluid testing for driving under the influence of drugs: history, recent progress and remaining challenges

In recent years the demand for drug testing in oral fluid in cases of driving under the influence has been increasing. The main advantages of saliva/oral fluid are the possibility for non-medical personnel to collect it without embarrassment and a better correlation between presence of drugs in oral fluid and impairment. Several surveys have been performed since the 1980s using saliva, and researchers encountered problems related to insufficient sample volume and insufficient sensitivity of the analytical methods. Steady progress has been shown in sample collection, knowledge of toxicokinetics in oral fluid, reliability of on-site and laboratory-based immunoassays and confirmation methods. In a few countries, legislation was passed that allows the use of saliva as a matrix for screening or confirmation. Despite this progress, some more work needs to be done, principally in the areas of the sensitivity and reliability of on-site screening devices, particularly for cannabis and benzodiazepines, knowledge about passive contamination and more generalised proficiency testing before oral fluid testing for DUID will have the reliability needed to be used forensically.