In the energy efficiency industry, customers often ask about the mercury used in compact fluorescent light bulbs (CFLs), since the element is a known neurotoxin. Our usual response is a small amount of mercury, about the size of the period at the end of this sentence, can be found in today’s CFLs. But how much mercury is toxic? And when should we start to worry about it? How Stuff Works outlines these answers in their article: Is the amount of mercury in CFLs more dangerous than the amount in fish?
The safe upper limit of mercury consumption is about 0.1 microgram per kg of body weight per day, according to the U.S. Environmental Protection Agency (EPA). Both the U.S. Food and Drug Administration and the World Health Organization think the safe dose is higher than that, more like 0.3 micrograms/kilogram/day. So if you weigh 150 pounds (68 kilograms), that’s somewhere between 6.8 and 20 micrograms per day, or 48 to 140 micrograms per week, as a safe amount.
On average, CFLs contain between 2.3 milligrams and 5 milligrams of mercury to help them produce light. Which may seem high compared to the amounts recommended above, but when bulbs are running they are not emitting mercury. Customers only risk ingesting mercury from CFLs if the bulb breaks, and even then the risk is limited if it is cleaned up quickly and disposed of properly. All CFLs can be recycled and usually local hardware stores offer free CFL disposal. Websites like “Recycle a Bulb” can help you find your nearest recycling location.
So how does this compare to fish mercury levels?
For most types of fish, you’re going to end up well below that limit as long as you don’t eat it every day. Smaller fish typically contain very little mercury — canned tuna contains about 4.8 micrograms per ounce, scallops have about 1.4 micrograms per ounce and flounder has only about 1.1 microgram per ounce.
When it comes to fish, it’s the large ones you have to be careful about. Tiny organisms absorb methylmercury that develops in bodies of water through pollution. Small fish eat these organisms and eventually the large ones eat those, accumulating the largest amounts of the element in their bodies.
The bigger the fish, the more methylmercury-containing organisms they eat, until something like a swordfish is sporting 28.4 micrograms per ounce, and a tilefish can have up to 41 micrograms per ounce. Just one 4-ounce serving of tilefish per week is nearing the EPA’s top dose for a 150-pound person.
So CFLs contain more mercury, but have less chances of being ingested. Just handle broken bulbs carefully and recycle all CFLs at proper disposal sites. When it comes to fish, stick to smaller fish if you are going to eat it every day or indulge in the big fish only once a week.
Read the full article here.