Does a mattress double its weight due to dust mites and their debris?

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Dear Cecil: An article in the February 18 Wall Street Journal says, “The average mattress will double its weight in ten years as a result of being filled with dust mites and their detritus.” This sounds impossible. Is it true? Who figured this out, and how? Nicki, via the Internet


Illustration by Slug Signorino

Cecil replies:

Jeepers. You know how at night, when everything is still, you hear this faint roaring sound? Some people say it’s the blood rushing in your ears. Uh-uh. It’s the dust mites, chewing on your sloughed-off skin.

I contacted the Wall Street Journal reporter who wrote the article in question (“Those Costly Weapons Against Dust Mites May Not Be Worth It”). She said she’d gotten this amazing-if-true-but-don’t-bet-the-rent story from a source at Ohio State University who was quoted elsewhere in the article. I tried reaching Emmett Glass, described in the story as “an OSU research associate leading the university’s ongoing Dust Mite Management Study.” So far he’s eluded my clutches, but one of his colleagues told me, “I did hear Paul Harvey say that a person sheds 40 pounds of skin scales in a lifetime.” Not to cast aspersions on a fellow media luminary, but my feeling is: Paul Harvey quotes scientist = good; scientist quotes Paul Harvey = bad.

Next I got in touch with a bunch of bug, allergy, and dust-mite experts, some of whom had been quoted in the Wall Street Journal article. Unsurprisingly, all dismissed the idea that there were mounds of mites in mattresses. “It’s nonsense,” said mite authority Larry Arlian, professor of biological sciences, microbiology, and immunology at Wright State University. “I don’t know where that originated. They’re not that prolific.”

Thomas Platts-Mills, professor of medicine and dust-mite guru at the University of Virginia, agreed. “I’ve heard that kind of stuff,” he said. “I don’t believe it. I’m sure there’s an added weight but I don’t think anyone has ever actually measured it.” He suggested that perhaps someone vacuumed up a sample of dust-mite-laden household crud and extrapolated from that to the total weight of a mattress. Extrapolation can be a funny thing. You’ll remember the column I did extrapolating from the reproduction rate of houseflies, in which I concluded that if Joe Letter Writer hadn’t swatted a bunch one day, they’d have reproduced ad infinitum and filled up all the space in the universe. So extrapolations are something you want to take with a grain of salt.

Why is this silly story about mattresses full of dust mites (various species of the subclass Acari, to get technical) being bruited about all of a sudden? Because there’s a buck in it. Some folks are allergic to dust mites (actually dust-mite feces), and it may make sense for them to buy filters, vacuum cleaners, and other gimmicks that promise to get rid of the little bastards. Most people aren’t allergic, but what the heck, if the hucksters can scare the pants off you, maybe you’ll buy all that stuff anyway. One commercial Web site  claims that a double bed contains over two million dust mites, that “a six-year-old pillow can have a tenth of its weight consisting of old skin, mold, dead mites, and mite dung,” etc. An OSU fact sheet backs up these claims, but the experts I spoke to doubted them. This same commercial site, run by a pest control company, also says:

[A] man from Clondalkin, Co. Dublin [Ireland] was playing golf when he was unwittingly infected with Weil’s disease by a rat that ran up his leg and urinated on him. Three weeks later he became severely jaundiced and died shortly after when his kidneys collapsed.

So let’s not get overly concerned about mites.

The trouble with journalists

Just heard from a somewhat ticked-off Emmett Glass, the OSU research associate that the Wall Street Journal reporter said was the source of the claim that a mattress will double its weight due to dust mites: Emmett writes:

I never quoted that statistic. I told [the reporter] that Internet web sites have statistics that try to strike fear in the consumer, thus promoting their products. I gave her a few off the top of my head (two million mites in an average mattress, mattress doubling in weight, etc.) that I read over the years. She asked me if any of these statistics have any scientific merit and I told her that none of them are in the literature. To the layman that is NO! In fact I asked the Wall Street Journal writer to call an expert on mattresses at the internal sleep products association. She did and was told that the statistic on mattresses doubling in weight was far from the truth. The journalist choose to include it in the story anyway. She liked the statistic because it made her story more interesting.

Glad to set the record straight, Emmett. As a bit of practical advice, when dealing with journalists it is never wise to speak in terms that may go over a layman’s head, e.g., that certain statements “aren’t in the literature.” Express yourself unambiguously, by stating politely that this is the kind of TOTAL CRAP found only in stories written by COMPLETE MORONS who ought to be working for SUPERMARKET TABLOIDS. She may still get it wrong, but hey, you tried.

Cecil Adams

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