SOFT 2004 Meeting Abstracts - Society of Forensic Toxicologists

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COMPARISON OF BLOOD AND BRAIN CANNABINOIDS CONCENTRA nONS IN 11 HUMAN
CASES. CONSEQUENCES ON TRAFFIC SAFETY.
Mura p.l', Raul S.B. 2 ,Dumestre V. 3 , Brunet B.l,4, Cavagna v.2, Hauet T.l.4, Kintz p: I Laboratoire de
Toxicologie, University Hospital, Poitiers, France 2Forensic Toxicology Institute, Strasbourg, France
3Toxgen laboratory, Bordeaux, France 4, INSERM ERM 324, University Hospital, Poitiers, France
It is known that cannabis effects on cognitive and psychomotor tasks are proportional to the delta 9­
tetrahydrocannabinol (THC) amount consumed but that such impairments are not directly related to THC
concentrations in blood. Some studies have also indicated that impairing effects could still be present while
THC blood concentrations had dropped to a few ng/ml, but this assessment has never been confirmed by
biological data. However, in a number of circumstances such as traffic safety or homicides, forensic
toxicologists have frequently been asked to answer this question: according to the blood cannabinoids
concentrations, was the subject under influence of cannabis In order to document this important question,
we compared cannabinoids concentrations in blood and brain human samples.
Blood and corresponding brain corresponding samples were provided from legal autopsies performed to
determine the cause of death. In 11 cases, cannabinoids were found in blood: these 11 cases were
consequently included in this study. All samples were stored at -20°C until analysis. THC, 11-hydroxy­
THC (II-OH-THC) and 11 nor-9-carboxy-THC (THC-COOH) were investigated by a gas chromatography
mass spectrometric procedure derived from the method of Kemp et aL (1). Brain samples were initially
grinded in pH 7.4 Tris buffer. In 10 cases, the precise location of brain sampling was not known. The
results, expressed in ng/g, are indicated in the following table:
I
I Case number 1 2 3 4 5 I 6 7 8 9 10
ITHC Blood 0.5 0.6 1.8 2.3 3.0 ! 4.4 11.5