Driving under the influence of marijuana is likely to increase, with law enforcement battling to deal with the problem. Picture: 3dman_eu /Pixabay

Johannesburg - There is a silent killer stalking South Africa’s roads that is difficult to trace and, for the most part, slips under the radar.

Drunk driving is easily detected through a breathalyser or a blood test, but there are South Africans who are taking to the road under the influence of a multitude of illicit drugs.

It is difficult to know just how many are drugged driving, but experts believe that figure is high.

In a recent article in the SA Crime quarterly journal, the authors mention a study that was done at routine roadblocks in 2008. It was found that recreational drugs, excluding alcohol, were detected in 14% of drivers stopped.

“However, the prevalence of road users in South Africa who use and/or abuse non-alcoholic impairing substances, which may impair driving ability, remains mostly unknown.

“This is primarily due to the little to no routine drug screening performed on drivers during random stops, and drivers who have been involved in accidents are seldom tested”, the authors wrote.

What is likely to add to the problem of drugged driving is South Africa’s move towards the legalisation of dagga.

Driving under the influence of marijuana is likely to increase, with law enforcement battling to deal with the problem.

The problem, according to criminologist Dr Lawrence Barit is that many people who use dagga don’t realise the effect that it has on their driving abilities. However, tests have shown otherwise.

“In a careful, well controlled study of driving in city traffic after smoking both large and small doses of dagga, 42% of those who had taken small doses and 63% of those who had taken large doses, showed a decline in their driving abilities,” said Barit.

“Unusual behaviour included missing traffic lights, stop signs passing manoeuvres without sufficient caution, poor handling of a vehicle with respect to traffic and unawareness of pedestrians or stationary vehicles.”

Research has shown that driving under the influence of cannabis is worsened when alcohol is consumed.

But the problem with dagga is that it can be difficult to detect. Unlike a breathalyser test, methods of detecting recent marijuana use has to be done through saliva or urine tests.

These, says Howard Dembovsky, chairman of the Justice project, can be expensive. “You are looking at a test to screen for THC, the active ingredient in cannabis costing about R250 a test.”

Dembovsky believes that South Africa needs to borrow what traffic officials in the UK and Australia are doing - giving officers training in how to spot drivers under the influence of drugs.

Barit has another suggestion - getting the drivers to pay for the drug tests themselves. This is a system that is used successfully in the UK, and has been successful in securing drunk driving convictions.

In South Africa, he says, only about 6% of arrested drunk drivers are convicted.

The problem, he points out is that state pathology laboratories take months to complete blood tests, which often results in cases been thrown out of court. In the UK, private pathology labs are used to test the blood of suspected drunk drivers.

“These results are returned in a matter of hours and the test is paid for by the driver” says Barit.

The irony, he says, is that South Africa has good legislation when it comes to drunk and drugged driving, the problem is in enforcing it.

There is another problem that needs to be sorted out, say the authors of the study that appeared in the SA Crime quarterly: “At present, our knowledge of the extent of drugged driving in South Africa is very limited. More studies should be conducted in South Africa to adequately define the problem and to provide accurate data to underpin policy initiatives and resource allocation.”

Saturday Star