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November 30, 1970

Marihuana Deterioration

JAMA. 1970;214(9):1709. doi:10.1001/jama.1970.03180090073023

To the Editor.—  Rodin et al (JAMA, 213:1300, 1970) expressed dismay that the marihuana they received from the National Institute of Mental Health "was supposed to have had a A9-THC [tetrahydrocannabinol] content of 1.312%. When samples of the same material were sent for assay to two independent laboratories, A9-THC contents of 0.5% and 0.2%, respectively, were reported. This indicates that the current assay techniques are either quite unsatisfactory or the material deteriorates merely by standing in a safe at room temperature." In a recent paper,1 Lerner demonstrated that the THC content of marihuana at room temperature decreases at the rate of 3% to 5% per month, and, that at 100 C for one month, all THC in a potent marihuana sample (2.32% THC) had disappeared. As pointed out by Lerner, because of the long-known decrement in the psychoactive potency of marihuana (now known to