Modern pot also has very low levels of cannabidiol , or CBD , the compound that advocates say gives marijuana its medicinal properties . Colorado weed has THC levels of 18 to 20percent - sometime as high as 30percent . Marijuana 30 years ago had THC levels of less than 10percent . Findings come from Dr LaFrate , who tested 600 marijuana samples with liquid chromatography . Also found high levels of fungus , bacteria , heavy metals , pesticides and other contaminants in much of the pot .
Modern pot also has very low levels of cannabidiol , or CBD , the compound that advocates say gives marijuana its medicinal properties . Colorado weed has THC levels of 18 to 20percent - sometime as high as 30percent . Marijuana 30 years ago had THC levels of less than 10percent . Findings come from Dr Andy LaFrate , who tested 600 marijuana samples with liquid chromatography . Also found high levels of fungus , bacteria , heavy metals , pesticides and other contaminants in much of the pot .