» drug testing _

The Argument

‘Impairment’ is all about being unfit, often only temporarily, for a specific purpose. For instance, no one argues that it is OK to drive a car while drunk (DUI) even though alcohol is a drug that is usually licensed by governments. Same argument applies for driving under the influence of certain drugs (DUID). Typically most drugs, even medicinal ones, can cause impairment if taken to excess.

Most countries that have laws against DUI also have laws against DUID. Many of these countries have so far not enforced these laws unless it’s after the fact of the accident and people are either dead or damaged. However, all of the countries are actively testing devices that can be used by the road-side or in the workplace. One country that is now routinely testing drivers for impairment due to certain drugs is Australia. The States of Victoria, New South Wales, South Australia and Tasmania are all randomly testing drivers for being under the influence of cannabis or methylamphetamines.

What is being discovered is that twice as many drivers are proving positive to these two drugs than to alcohol.

The key issue here is impairment. These Australian drivers are not being booked for having taken drugs at some time in the past (which is not the point here) but for currently being impaired. For both drugs that probably means having taken the drug in the previous few hours. The tests that are employed can only detect recent (means the last few hours) drug taking above a certain ‘legal limit’, just like the breath alcohol tests for DUI. Whatever there are arguments about the definition of impairment and no doubt the legal limits will be refined as time goes by, no one argues that it is OK to drive while impaired and there is a good argument to actively discourage DUID and so reduce road or workplace accidents.

The Devices

All devices that are currently used to detect drug impairment by the roadside use a small sample of saliva. Urine and blood tests may still be used for legal evidence (just as they frequently are for DUI) but these are impractical and invasive at the roadside. All devices collect this saliva sample by using something that approximates a cotton bud, or a tongue depressor: something that is not difficult to use and can be handed back to the person administering the test. How much of a sample is needed varies from product to product and clearly one that needs only a small sample has an advantage.

Once the sample is collected, it is introduced to testing medium. Some devices require that the sample is mixed with a buffer solution, some not. Using a buffer solution adds an additional layer of complexity for the operator.

Most devices available today use a technology called ‘immunoassay’. Typically this results in a colour change if the target drug is present. There are many examples of immunoassay testing, for instance pregnancy tests often use this technology. In testing for drugs, the assay time is typically in the region of several minutes during which time the testing device may have to be held horizontally. Other devices use different technologies which give far faster results with far less care and attention required. For instance, the Oxtox’ Drugsensor uses electrochemistry.

The Ideal Device

The ideal test would collect a small amount of saliva and deliver a result in seconds. It would be cost effective. It would be easily transportable and not affected by extreme temperature variations. It would be ergonomic to use.