Doctor develops new cannabis blood test

Press, 21 September 1977, Page 11

Doctor develops new cannabis blood test

PA Dunedin New Zealand scientists have made a breakthrough in the detection of cannabis in the blood—and cannabis tests could well become as common as bloodalcohol tests. Dr Neill McCallum of the D.S.I.R. in Wellington, in collaboration with Mr Don Ferry of the Medical Research Council in Dunedin, have developed a technique for measuring the level of tetrahydrocannabinol (TJI.C.), the major active ingredient of cannabis, which is claimed io be far simpler and cheaper than any of a variety of other techniques available. The technique could well pave the way to widespread cannabis testing both in New Zealand and overseas.

The new method uses a gas chromotographic technique and it is far simpler and cheaper than the other two or three techniques available.

It is capable of measuring one part of T.H.C. to every 1000 million parts of blood.

The method of measuring the cannabis in blood has been developed over several years but it has only been recently, since the research has involved the use of the highly sensitive measuring equipment in Dunedin, that positive results K.ve started to emerge with lower concentrations.

It is a refinement of a method developed by Dr

McCallum in Wellington three years ago. It was discovered completely by accident. Dr McCallum said from Wellington.

Dr McCallum said that Mr Ferry wanted to use the technique on the Dunedin machinery. At that stage the method was extremely quick but not too sensitive.

“When he put it through his machine he was amazed. It was about 500 times more sensitive.” Dr McCallum said he hoped that it was possible to extend the detection of the concentration from two to three hours to a maximum of 24 hours, after the cannabis had been smoked.

The new method involves the extraction of the T.H.C. constituent and the formation of a phosphate derivative. It is then possible to determine at what concentration the cannabis is present in the blood. Mr Ferry said the major advance was the simplicity of the new method. However, he said, the degree of concentration had not yet been related to the level of intoxication. The next move was now to establish how long the T.H.C. remained in the body and if there was a build-up of the levels over a long period.

He said that further experiments with animals would begin shortly to try and find how long T.H.C. lingered in them.