Mercury in CFLs, unlike mercury in fish, is there on purpose. It helps fluorescent bulbs to produce light, and plays a role in the efficiency that makes it so good for the environment. It uses less energy, which means coal-fired power plants can produce less power and therefore emit less mercury into the air and into our fish supply. Ironically, though, the bulbs are themselves a source of the poison. But how much exposure are we talking about here?
On average, a compact fluorescent bulb has somewhere between 2.3 milligrams and 5 milligrams of mercury inside. That probably sounds like a lot, considering it's about 500 times the maximum ingestion amount recommended by the U.S. Environmental Protection Agency (EPA). But here's the thing: By running a CFL, you're not ingesting any mercury at all. The only time you even have a chance of inhaling the mercury vapor in a CFL is if it breaks, and even then, your risk is very limited. If you clean it up thoroughly and quickly (with a broom, not a vacuum, since vacuums can expel it into the air), seal all the debris in a plastic bag, and dispose of it at an approved site (see sidebar), there's barely any risk at all of inhaling a damaging dose of mercury.
To put the roughly 4 mg of CFL mercury in perspective, check out these other mercury numbers [source: CDPHE]:
- Watch battery -- up to 25 milligrams
- Thermometer -- up to 2 grams
- Tilt thermostat -- up to 3 grams
With CFL mercury exposure hinging entirely on breaking the bulb and not effectively cleaning up, fish definitely pose a greater risk when it comes to mercury poisoning. We actually eat the mercury in the fish. And even then, limiting your fish consumption to a couple of times a week is a perfectly logical balance between the proven health benefits of eating fish and the small amount of mercury you might be ingesting.
For more information on mercury sources and how to avoid them, look over the links below.
Related HowStuffWorks Articles
More Great Links
- CFL Bulbs Have One Hitch: Toxic Mercury. All Things Considered. NPR.org. Feb. 5, 2007. http://www.npr.org/templates/story/story.php?storyId=7431198
- Compact Fluorescent Light Bulb (CFL) FAQs. GE Lighting. http://www.gelighting.com/na/home_lighting/ask_us/faq_compact.htm#mercury
- Mercury in CFLs. n:Vision. http://www.nvisioncfl.com/mercury.aspx
- Mercury in Fish: Fact Sheet. New Mexico Department of Health. May 7, 1991. http://www.nmenv.state.nm.us/SWQB/MercuryQA.html
- Mercury in Fish. PBS.org. http://www.pbs.org/now/science/mercuryinfish.htmler
- Mercury Levels in Commercial Fish and Shellfish. FDA. http://www.cfsan.fda.gov/~frf/sea-mehg.html
- What You Need to Know about Mercury in Fish and Shellfish. EPA.gov. http://www.epa.gov/waterscience/fish/advice