The Skeptical Teacher

Musings of a science teacher & skeptic in an age of woo.

CFLs and Mercury Militia Hysteria

Posted by mattusmaximus on March 6, 2009

Yesterday I taught my students about the dissipation of energy in electrical circuits. As part of the lesson we calculated how much energy it takes to use a compact fluorescent lightbulb (CFL) in comparison to a standard incandescent bulb. CFLs are great: they provide the same amount of visible light for about 1/4 the energy input, they don’t produce much waste heat, and while they are a bit more expensive to buy they last about 10 times longer than incandescents. So replacing old incandescents with CFLs is a great way to save both money & energy, the latter of which helps to combat carbon emissions and global warming.


So, given all of these great benefits of using CFLs, you would think that everyone would be falling all over themselves promoting the technology, right? Sadly, the answer is no, and the following story illustrates why not.

Later in the day I was hanging around in my science office, talking with some of my colleagues. I brought up the subject of my lesson with a couple of them and how I was encouraging the kids to replace old bulbs with CFLs. One of my colleagues, a science teacher, went a little nuts and said she’d never put CFLs in her house. The reason why not: the mercury in CFLs… argh!

While mercury can be a toxic substance (if a lot is inhaled while in it’s vapor form), the levels of mercury found in CFLs is very small. According to the Energy Star program (a joint effort of the U.S. Environmental Protection Agency and the U.S. Department of Energy)…

CFLs contain a very small amount of mercury sealed within the glass tubing – an average of 4 milligrams. By comparison, older thermometers contain about 500 milligrams of mercury – an amount equal to the mercury in 125 CFLs. Mercury is an essential part of CFLs; it allows the bulb to be an efficient light source. No mercury is released when the bulbs are intact (not broken) or in use.

Most makers of light bulbs have reduced mercury in their fluorescent lighting products. Thanks to technology advances and a commitment from members of the National Electrical Manufacturers Association, the average mercury content in CFLs has dropped at least 20 percent in the past year. Some manufacturers have even made further reductions, dropping mercury content to 1.4 – 2.5 milligrams per light bulb.

So, the amount of mercury contained in these CFLs is extremely small, far smaller than what would be needed to harm a human. But if you happen to break one, what do you do? Well, it’s pretty easy to clean up a broken CFL, according to the EPA – it pretty much consists of ventilating the room for about 15 minutes and cleaning up the broken parts.

Why is it that some people, even supposedly well-educated folks with a background in science, get so damned freaked out by mercury? Well, many whackjobs in the environmental movement have been making pseudoscientific hay about mercury for many years – these folks are what I like to call the “Mercury Militia”. They glom onto mercury as the cause of all manner of nastiness, regardless of dosage levels & concentrations, including blaming mercury amalgam fillings for teeth for various health problems and insisting that some vaccines containing minute amounts of mercury cause childhood autism. And none of that nonsense is true!

And then, of course, another reason why some people get roped into the anti-mercury hysteria is because of bogus stories like this one from WorldNet Daily, which scares the hell out of people who might use CFLs in their house. Unfortunately, just because someone forwards a scary sounding “news” article to your email doesn’t mean it has any real validity. For example, has a great analysis & debunking of many claims made by the anti-mercury crowd in that WND article.

But the fear-mongering by some extreme nutjobs is worse than just spreading a lack of critical thinking, because it actually results in more mercury being released into the environment – that’s right, more mercury! According to this fact sheet from Energy Star…

EPA estimates the U.S. is responsible for the release of 104 metric tons of mercury emissions each year. Most of these emissions come from coal-fired electrical power. Mercury released into the air is the main way that mercury gets into water and bio-accumulates in fish. (Eating fish contaminated with mercury is the main way for humans to be exposed.)

Most mercury vapor inside fluorescent light bulbs becomes bound to the inside of the light bulb as it is used. EPA estimates that the rest of the mercury within a CFL – about 14 percent – is released into air or water when it is sent to a landfill, assuming the light bulb is broken. Therefore, if all 290 million CFLs sold in 2007 were sent to a landfill (versus recycled, as a worst case) – they would add 0.16 metric tons, or 0.16 percent, to U.S. mercury emissions caused by humans.

So, long story short, by not using CFLs we are actually pumping more mercury into the environment because using a less-efficient incandescent bulb wastes so much more energy that is mostly generated by coal-fired power plants in the United States. And those coal-fired plants spew way more mercury into the environment than all the CFLs on the planet could ever come close to doing!

Thus, the Mercury Militia and those whom they have frightened into buying their bogus b.s. are actually making the situation worse. It is not only costing people more money to use wasteful incandescents, but it is also contributing to higher mercury emissions!

The irony is so thick you could cut it with a knife.

2 Responses to “CFLs and Mercury Militia Hysteria”

  1. Jim said

    One thing worth mentioning: the concern I have generally heard about the CFLs is not about individual breakage but the aggregate effect in landfills. Generally people expressing this concern follow it up by expressing admiration for LED lighting. Of course, LEDs generally offer more directional lighting, which can be off-putting for some. Anyway, just thought I’d throw that out there.

  2. Karen said

    I think you may need a lesson in toxicity my naive friend. I disagree that there is a ” little” amount of mercury in these. The mercury in these is being downplayed. My child broke one and because there are no warnings on the packaging who would know that there is hazmat cleanup instructions and that you need to evacuate the room for a broken lightbulb. The levels measured in the Maine cfl study show that levels above the workplace limits for acute exposure are possible. Yes limits to not be passed for the workplace for adults not for children. The workplace limit is 100,0000 ng/m3 and the cronic exposure limit for a home are 300 ng/m3 (yes I realize that is a chronic limit). California is the only one who has a limit for an acute exposure in the home for children and pregnant women. It is 600 ng/m3 for one hour. The maine cfl study had some levels in the 1000’s for days. Comparing the size of the mercury to the head of a pen to show how small it is has NOTHING to do with the toxicity of something. The proponents of these things also mislead you with the following comparisons as well. Comparing it to a thermometers amount of mercury being 500-3000 mg so it can’t be that bad. But they’ve stopped making mercury thermometers and thermostats because they are too toxic. Also mercury vapor is what is toxic (you could eat mercury and it is basically mon toxic as tour body cant absorb much) and a thermometer would only evaporate about 50 ug of mercury vapor per hour being diluted by air as it does making levels of mercury in air quite low but still dangerous . A cfl puts many many times this into the air right away because it sprays mercury droplets into the air that evaporate instantly (evaporation rate based on surface area/temp). They also contaminate everything they touch. How can these even be legal without warnings plastered all over them. Please don’t say “we’ll there are no warnings on tubes and those have been used for years safely”. Well, no they haven’t, people just didnt know how toxic they actually were. As well, tubes in people’s kitchens are usually covered and tubes are harder to break. Cfls fit in lamps and low places that are easily knocked over or accidentally hit. 50 ug of mercury per litre of blood is enough to poison you. A child has 1 litre of blood. There are 5000 ug average in a bulb (but up to 20,000 ug (5-20 mg)). These are dangerous and they can contaminate your floor,couch,bedding, clothing, etc. floors in the Maine cfl study emitted mercury for months after a spill.

    Read some studies ( not just the government websites and “green” websites) before making claims of them having little mercury and giving the impression that because of this they are safe.
    Here is your reading list since everyone seems to only get the information that the proponents of these bulbs tell them. Research for yourself.

    Click to access scher_o_124.pdf

    Click to access Mercury_postSRP3.pdf

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