Which is worse for you, a can of tuna or a broken CFL bulb? Sorry, Charlie… image by Dave Lifson

A paper expected to be published in the August issue of the lighting industry journal, LD+A, may quiet some of the controversy over the dangers of mercury in compact fluorescent lights (CFL). I’ve argued in this blog that the cut in mercury emissions from power plants due to the electricity saved when traditional incandescent bulbs are replaced with CFLs, greatly outweighs the amount of mercury that could escape from broken CFLs, plus what is emitted during the making and transportation of CFLs. But the paper, by Robert Clear, Francis Rubinstein, and Jack Howells, who do research at Lawrence Berkeley National Laboratory (LBNL), goes a step farther by showing that even a person who breaks a lamp is more at risk from mercury in the environment than from the mercury in the lamp itself.

The researchers point out that there is a distinction between the kind of mercury that you are exposed to from broken CFLs—elemental mercury—and the mercury emitted from power plant smokestacks after it finds it’s way into waterways and oceans, where it becomes methyl mercury. Methyl mercury accumulates all up the food chain, so that large fish like tuna can contain a lot of it. Methyl mercury crosses the blood-brain barrier and passes through a pregnant woman’s placenta to her fetus. Methyl mercury is responsible for developmental problems, while elemental mercury, which is inhaled, appears to be more of a hazard for adults and children, and only then in the case of severe or prolonged exposures. In most mild cases, when the elemental mercury exposure ends, the bad effects diminish and go away. This is unfortunately not true for the developmental problems caused by methyl mercury.

The startling conclusion of the paper is that in a worse case scenario—you break a CFL in a closed, unventilated room; you vacuum the carpet, throwing mercury into the air; you set the vacuum in a corner; and then sit in the room breathing for eight hours—the amount of mercury exposure is about equivalent to the exposure you’d get from eating a can of Albacore tuna.

Eating a can of tuna has positive health effects as well as the negative health effects from the mercury. There are no positive health effects from a broken CFL, and you can reduce your exposure. The researchers suggest that in the case of a broken CFL, you should immediately open a nearby window. You can limit contamination by gathering up the large pieces of the broken bulb into a bag and set the bag outside. The room should then be left to air out for an hour or so. If the lamp broke on a carpet you can vacuum, but it should be done quickly while the room is being ventilated, the vacuum cleaner should be removed to an outside area, and again the room should be left vacated for an hour or so. Once the vacuum cleaner has cooled, you can empty the contents of the vacuum cleaner bag into the bag with the broken bulb. Take the bag to your nearest recycling center.

  • Ian

    I’ve never been concerned about the direct health effects of breaking a CFL bulb due to the relatively low contained mercury concentrations (though perhaps I should have considered the potential danger).

    My concern with respect to CFL bulbs has always had more to do with improper disposal: With the production of a few billion bulbs and the illegal disposal of a large fraction of these bulbs in traditional landfills, the tiny amount of mercury from a single bulb builds up to a significant amount. This can lead to major environmental damage due to leeching into wetlands or the water table.

    In my experience, a surprisingly large number of CFL consumers are unaware of the required methods for proper disposal of used bulbs. As we are nearing the predicted failure age of many old bulbs (based qualitatively on my memory of when CFL use became popular) and due to the continuingly increasing popularity of the bulbs, I expect the influx of mercury to traditional landfills to increase dramatically in the near future.

    Am I mistaken in thinking that this issue represents a major hazard to the environment?

  • Rafael

    All old, non-digital home thermostats have a switch filled with quite a bit of mercury (about two or three droplets), and those ones have been consistently disposed of in the trash for decades. There are other appliances that have had mercury-based switches, and those ones probably end up in landfills in large numbers as well. By comparison, a CFL has less than a tenth of the mercury that a thermostat has. The influx of mercury to landfills from CFLs is negligible compared to the amounts coming from old appliances, thermometers, and thermostats.

  • Aimee

    Thank you, Ian, for saying exactly what is on my mind. I have heard reports that the elemental mercury from improperly-disposed CFLs will accumulate in the environment, eventually as methyl- or dimethyl mercury.

    While people may know of the proper disposal methods, I believe that many people are lazy or do not think that their one bulb will make a difference.

    It is important that people are educated as to the cumulative risk of these kinds of substances in the environment.

    While I am grateful that the media is pushing an “environmentally-beneficial” agenda by touting the energy benefits of CFLs, it seems prudent to also make it common knowledge that the use of these bulbs carries a risk.

  • Chip

    I agree with Ian in that the biggest threat to the environment from CFL’s is in the disposal of them. Granted there are appliances and thermostats out there but how often do you throw out an appliance or a thermostat? BTW most landfills will not accept appliances as “normal” landfill anyway. The problem is quantity. In CA alone PG&E sponsored a program that involved something like 14 million CFL’s. As a guess 90% of those will end up in landfills and even if the amount per CFL is small that amount times 12+ million becomes not so trivial.

  • jaapps

    The disposal of Hg into landfills may not be as hazardous to the environment as it is perceived to be. The interiors of most landfills are quite strongly reducing, leading to the immobilization of Hg on thio functional groups on organic matter and precipitation as a highly insoluble sulfide. Some Hg might be vented to the atmosphere as methyl mercury, but I am unaware of any studies that have identified this process or established its environmental significance. I would welcome feedback.

  • Yes,I agree Lan it’s true that Compact Fluorescent Lights contain tiny amounts of mercury. If a bulb breaks you will be exposed to the toxin that effects nerves.

  • John

    Ya ok. This is not exactly the same thing. But ok let’s just assume you’re right about the dose on the first day. What about your carpet, your hardwood floor, your couch, your kids bed’s and toys, your clothes. Yes, anything these awful things touch (and even things they don’t will be contaminated by the vapors recondensing on surfaces) will be contaminated with mercury and vapourize in your house for months. So you slowly poison your kids after the fact. If you think I’m overrating this look at a real study not some hypothesis. Read http://www.maine.gov/dep/homeowner/cflreport.html
    Try to do a little more research before you tell people it’s no big deal to break one of these in your home. Yes they can quite literally poison your kids, this is not debatable as 50 ug is enough per liter of blood for mercury poisoning. Considering a small child has about 1 liter of blood and the dose you are quoting is 50 ug, that is POISONING. So admit your ignorance and retract your false statements.

    • frankyburns

      The mercury cannot effuse to the air and also remain forever. It’s like water — it’s either sitting on the floor and not in the air, or it goes into the air, and then out the window. So really they are right, you are wrong.
      Another point is that no one ever worried out those long bulbs from olden times — but they are exactly the same, just in a different shape. So, it’s a lot of government hype. Not to say you shouldn’t crack a window, but if you clean up the glass and dispose of it, that’s it. You aren’t going to see huge amounts of mercury from a lightbulb. It’s mainly gas, and some in the powder.

      • Jason Williams

        This is a old article but he’s right. If a bulb breaks and it’s debris make contact with carpet, clothing ect those items WILL be contaminated and can off gas for years. I found a broken cfl bulb that had been hiding in my closet for over a year. All of my clothing was contanminated with vapors. I had to throw away $2000 worth of suits, jackets ect. Cost me $1000 to do a mercury analysis on my house because my girlfriend was showing signs of hand tremor and chronic headaches. I had insomnia and daytime sleepiness which are both mercury toxicity symptoms. Case and point; in certain circumstances such as a poor ventilated room and not cleaning up a broken bulb quickly enough it can result in health effects. Also, cfl bulbs or any mercury for that matter can stain practically anything and off gas for years and years, no lie! Good luck people keep those bulbs out of house forever buy LED bulbs.


Jim Gunshinan

Jim Gunshinan is the editor of Home Energy, the magazine of sustainable home building and renovation.

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