In two separate studies, 5 drug-free male volunteers with a history of marijuana use were passively exposed to the sidestream smoke of 4 and 16 marijuana cigarettes (2.8% delta-9-tetrahydrocannabinol [THC]) for 1 h each day for 6 consecutive days. A third study was similarly performed with 2 marijuana-naive subjects passively exposed to the smoke of 16 marijuana cigarettes. Passive smoke exposure was conducted in a small, unventilated room. Room air levels of THC and CO were monitored frequently. All urine specimens were collected and analyzed by EMIT d.a.u. assay, Abuscreen radioimmunoassay and GC/MS. The studies show that significant amounts of THC were absorbed by all subjects at the higher level of passive smoke exposure (eg., smoke from 16 marijuana cigarettes), resulting in urinary excretion of significant amounts of cannabinoid metabolites. However, it seems improbable that subjects would unknowingly tolerate the noxious smoke conditions produced by this exposure. At the lower level of passive marijuana-smoke exposure, specimens tested positive only infrequently or were negative. Room air levels of THC during passive smoke exposure appeared to be the most critical factor in determining whether a subject produced cannabinoid-positive urine specimens.
Chemical substances migrate outwards from within the body to the skin surface by diffusion from cutaneous capillaries across the epidermis. Heretofore, study of transepidermal chemical emissions have been restricted to substances which are in the vapor phase at skin surface temperature. We have investigated outward transcutaneous chemical migration of nongaseous chemicals by devising an occlusive transcutaneous chemical collection system, consisting of a tape-encased plug of gelled saline in which activated carbon is dispersed. Investigations of nine chemicals in ‘fuzzy’ rats, rhesus monkeys, and man provide data which are consistent with a general theory of outward transcutaneous chemical migration. This noninvasive continuous transcutaneous sampling technique provides a new method for investigating skin permeability in vivo and may provide a basis for convenient diagnosis and monitoring of chemical exposure.
Five drug-free male subjects ingested marijuana-laced brownies in a double-blind crossover study designed to test for behavioral effects, physiologic effects, and urinary cannabinoid metabolites produced as a result of consumption of marijuana plant material cooked in foodstuff. On three separate occasions, each subject consumed two brownies which contained 1.6 g of marijuana plant material. Placebo marijuana plant material (0% THC) was mixed with marijuana plant material (2.8% THC) so that each subject ingested equivalent marijuana plant material of 0, 1, and 2 marijuana cigarettes (2.8% THC). Subjects scored significantly higher on behavioral measures after consumption of brownies containing THC than with placebo; however, the effects were slow to appear and variable. Peak effects occurred 2.5 to 3.5 h after dosing. Modest changes in pulse and blood pressure also were noted. Urinalyses by EMIT d.a.u. assay and Abuscreen RIA for cannabinoids and GC/MS assay for THCCOOH indicated that substantial amounts of marijuana-related metabolites were excreted over a period of 3 to 14 days. No positives were produced as a result of ingestion of placebo brownies.
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