Compared to the light users, heavy marijuana users made more errors and had more difficulty sustaining attention, shifting attention to meet the demands of changes in the environment, and in registering, processing, and using information. These findings suggest that the greater impairment among heavy users is likely due to an alteration of brain activity produced by marijuana. When the early effects fade, over a few hours, the user can become very sleepy. Skeletons, skulls, aliens, marijuana leaves, and the number 420 are common symbols. One well-known type of water pipe is the bong.
Some users mix marijuana into foods or use it to brew a tea.
Another method is to slice open a cigar and replace the tobacco with marijuana, making a blunt. A B-40 is when the blunt is smoked with a 40 oz. The clearest health risk posed by post is the danger to the lungs. Marijuana smoke contains the same cancer causing chemicals found in tobacco smoke. Since pot smokers hold marijuana smoke in the lungs longer, one or two joints a day may do more damage than may more cigarettes.