The author of today's post, John Balbus, M.D., is Chief Health Officer at Environmental Defense.
Compact fluorescent light bulbs (CFLs) use dramatically less energy than incandescent bulbs and reduce greenhouse gas emissions. But they also contain mercury – a dangerous toxin.
What if you drop a CFL and it breaks? How much trouble are you in?
Despite some alarming news reports, you don't have much to worry about. If a CFL breaks, some of the mercury that's contained in the bulb will evaporate into the air. How much? It's hard to be certain, but one study [PDF] looking at long tubular fluorescent bulbs found that over a two week period, only 17 to 40 percent of the mercury in the bulb evaporated. The rest remained stuck in the bulb. Roughly one-third of the mercury that evaporated did so in the first eight hours after the breakage; the rest seeped out slowly over the remainder of the study period.
The amount of mercury in a CFL is very small, only 4-5 milligrams. This is almost one thousand times less than what was in mercury thermometers! So, let's assume that what happens with CFLs is comparable to what happens with tubular fluorescents. If a bulb breaks, only 0.67 milligrams of mercury (one-third of 40 percent of 5 milligrams) might become airborne in the room during the first eight hours, and only a fraction of that would be breathed in. In short, the exposure from breaking a compact fluorescent bulb is in about the same range as the exposure from eating a can or two of tuna fish. (See our list of "Best and Worst Seafood Choices" for more on mercury in fish.)
The tiny amount of mercury you're exposed to when breaking a CFL is extremely unlikely to cause any ill effects, noticeable or otherwise. But how do you minimize even this tiny amount of risk?
Remove children and pets from the room, and then clean up the broken bulb as quickly as possible. First, increase the ventilation in the room where the bulb broke by opening windows and doors. Then use index cards or other stiff paper to pick up the broken pieces of glass and any visible mercury. Don't use your bare hands, and don't use a vacuum cleaner because this can disperse the mercury more widely. Once you've gotten up the big pieces, use something sticky like duct tape to get up smaller pieces and dust. To be extra safe, stay out of the area for a few hours to let any remaining mercury disperse.
So what does mercury poisoning do to you, anyway? The symptoms are primarily neurological. A low level exposure (like if you broke a dozen CFLs in your house every day for a couple of weeks) would cause insidious symptoms – fatigue, memory problems, difficulty concentrating, and perhaps some mild clumsiness. Higher exposures could give tremors, and mood or emotional disturbances. But this is never going to happen from dropping one CFL!
Because they contain mercury, it's best to recycle CFLs (Earth911.org can tell you how), or bring them to your local Household Hazardous Waste (HHW) collection site. I've got five bulbs wrapped in bubble wrap in my basement, waiting for me to get a chance to take them to the county HHW site. But if you can't do that, you should seal used bulbs in a plastic bag before placing them in your regular trash.
And if despite your best efforts the bulbs end up breaking in a landfill, using CFLs should still cause a net decrease in mercury in the environment. Why? Because they so dramatically reduce energy use, and coal-generated electricity releases much more mercury than a CFL ever could.
The phrase "contains mercury" sounds alarming, but there is very little risk in the tiny amount of mercury in CFLs, and the benefit to the environment of using them is huge. To learn more about switching to CFLs, visit our guide to making the switch.