While compact fluorescent light bulbs (CFLs) do contain a small amount of mercury, the amount is typically less than 5 milligrams per bulb. This amount is significantly lower than the levels of mercury found in some fish, such as tuna, swordfish, and shark, which can contain up to several parts per million of mercury. Additionally, the mercury in CFLs is contained within the glass envelope of the bulb, which prevents it from being released into the environment. In contrast, the mercury in fish can be more easily absorbed by the body when consumed. Therefore, the amount of mercury in CFLs is generally considered to be less dangerous than the mercury found in fish.