More Mercury Factoids: Compact Fluorescent Light Bulbs

Note: part of a series. Other posts on CFLs are here and here.

So I’m online getting some consumer information about compact fluorescent light (CFL) bulbs, the latest weapon in the war on carbon dioxide, and I happen to run across this tidbit published last month from the Junkman himself, Steven Milloy. Mr. Milloy has used the misfortune of one Maine woman, who broke a mercury-containing CFL bulb in her home and got a raft of really bad advice for what to do about it, as a springboard for bashing all environmentalists about reducing greenhouse gas emissions.

The news media had taken up the chase on this issue, and from them we find that the facts in this matter were as follows: According to an article in the Ellsworth American, Brandy Bridges dropped one of about two CFL dozen bulbs she was installing in her home, which broke on a shag carpet. Alert to the potential hazards of mercury exposure, Ms. Bridges called Home Depot, where she had bought the bulbs. Home Depot warned her not to vacuum the glass and directed her to a poison control hotline, which in turn referred her to the Maine Center for Disease Control and Prevention and the Maine Department of Environmental Protection. The DEP sent a specialist to test the mercury vapor levels in her home.

Here’s where the story starts to become fact-free: In her daughter's room near the broken bulb the mercury level was in excess of six times the EPA standard. This is completely accurate as far as the journalist knows – but at the same time, an utterly useless piece of information for trying to understand if there is a real health risk associated with a release of mercury from a broken CFL. Mr. Milloy gratuitously adds that the “safe” level for mercury is 300 billionth of a gram per cubic meter of air, a framing that tells you he really isn’t that concerned about the mercury exposure, but this was just too good an opportunity to pass up to beat up again on the folks who are concerned about global warming. I guess he doesn’t own any Philips stock.

Back to our story. DEP specialist told Ms. Bridges not to clean up the glass herself, but to call an environmental clean-up firm. The firm gave Ms. Bridges an estimate of $2,000 to clean up the broken bulb. Keep in mind this advice was completely inconsistent with the recommendations that EPA and many other regulatory agencies provide for disposal of broken bulbs. If anyone should be scraping together the money to deal with this, it should be the state of Maine, not Brandy Bridges.

The final irony in this misfortunate episode is that there probably was no real risk to begin with. Think about it for a moment. Mercury is a substance that requires cumulative exposure over a period of months or years to produce its adverse effects. And, a CFL contains around 5 milligrams of mercury, scarcely a pinhead’s-worth. No doubt that it will volatilize into a room, but how much mercury could that produce in the air, and for how long?

Quite a number of investigators have examined the problem of indoor air pollution from elemental mercury resulting from breaking mercury-containing thermometers, ritualistic uses and just playing around with mercury beads. In 2005, EPA published a series of studies examining mercury emissions and indoor concentrations under controlled conditions. I used the empirical model published in that report to estimate the air concentrations potentially associated with emissions of the 5 mg of mercury that would be released from breaking a CFL light bulb in a small bedroom under “average” air exchange conditions. The modeled mercury concentrations slightly exceed the “EPA standard” (the Reference Concentration, or RfC – which is not a standard, but that’s a story for another day) for a couple of days, but then drop below it, and fall well below it within two weeks. I hear the objections now, “but that’s not what the news story said”, but the factoid “six times higher than the EPA standard” is so poorly described and poorly informed, as to not even qualify as a factoid, and scarcely the basis for making environmental health decisions around CFL light bulbs. It’s certainly not persuading me to avoid using them.

Part 2 of this post coming to a blog near you discusses why being exposed for a couple of days to mercury concentrations in air higher than the RfC isn’t a public health problem, certainly not one warranting scaring people off from using CFL light bulbs. In addition, we can further discuss the matter of the choices we make to optimize environmental health and climate protection. But until then, don’t be afraid of CFL light bulbs because of the mercury in them (particularly if you’re getting the news from the Junk Science guy himself; consider the source).