Abstract: | Whenever small amounts of drugs are present in blood or urine samples, especially of substances that are preferentially smoked such as cannabinoids, the discrimination between active and passive inhalation may cause severe problems. The statement of a passive exposure by marijuana smoke has been scrutinized reviewing the literature. The pharmacokinetics of smoked marijuana as well as experimental data on cannabinoid concentrations in plasma and urine samples following passive exposure are summarized. As a conclusion it seems urgent to enlarge the existing data base. |