The Skeptical Teacher

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

Posts Tagged ‘cfl’

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.

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