Mercury in MarijuanaSome of the problems arising from marijuana use might result from the intake of bioaccumulated mercury

Plants are known to accumulate metals a d metall ids from the environment. Often the metal content of vegetation is used to indicate local ore deposits or to detect pollutants (Cannon 1960, 1971, Vinogradov 1959, Warren et al. 1968). Mercury and its inorganic derivatives in plants have become increasingly recognized as coming from a variety of natural sources including thermal springs and volcanoes (Siegel and Siegel 1982, 1987a, Siegel et al. 1985, 1987). Without minimizing the significance of anthropogenic release of mercury into the biosphere by fossil fuel burning (Andren and Nriagu 1979) or the microbial formation of organic mercury compounds Jensen and Jernelov 1969), abundant evidence now exists for natural volcanic and geothermal sites as major sources of environmental mercury available for uptake by vegetation (PhelanKotra et al. 1983, Siegel and Siegel 1984, 1987b, United States Geological Survey 1970, Varekamp and Buseck 1986). Plants take up elemental mercury vapor (Hgo) through their leaves from the atmosphere, and the ionic forms of mercury enter via the roots from the soil solution. Subsequently the plants return part of this mercury as Hgo to the environment (Anelli et al. 1973, Siegel and Siegel 1985, 1987 a, b, c). Mercury uptake occurs in primary producers at the base of the food chain, and it is a major human dietary concern. But the efficiency of mercury absorption by the gut is only approximately ten percent as efficient as that of the lungs (WHO Task Group 1976). Therefore, mercury in vegetation that is inhaled through smoking can have a far more significant impact than that that is ingested. Generally, tobacco (Nicotiana sp.) is grown in clay solids low in mercury. However, the best-quality marijuana