[Excretion of 11-nor-delta 9-tetrahydrocannabinol-9-carboxylic acid in experimental smokers. Duration of detection in urine].

: Cannabis cigarettes of comparable potency were smoked by experimental smokers. Peak excretion occurs between 2 to 7 hours and falls rapidly in the first 30 hours period. Elimination then goes on slowly over 5 days. Individual and interindividual variations are observed. The test can detect occasional use of cannabis no longer than 36 h to 48 h with good probability. Negative detected user can suddenly excrete metabolites to positive levels. This has a consequence on the use of the test to screen exposed group for epidemiologic studies.