More than you probably needed to know

Passing gas: A modern scientific history - Salon.com

This is a really long extract about flatulence, and other related intestinal facts.  There is quite a bit to be amused by, such as this about early research into smells:

I ask Levitt whether it was difficult to recruit volunteers for the flatus studies. It wasn’t, partly because the subjects were paid for their contributions. People who sell their flatus are more or less the same crowd who turn up to sell their blood.

“What was hard,” Levitt says, “was finding the judges.” Levitt needed a pair of odor judges to take “several sniffs” and rate the noxiousness — from “no odor” to “very offensive” — of each of the sixteen people’s flatal contributions. The hypothesis was that noxiousness would correlate with the combined concentrations of the three sulfur gases. And it did.

Curious as to which olfactory notes the different sulfur gases contributed to the overall bouquet of flatus, Levitt purchased samples of the three gases from a chemical supply house. The judges agreed on the following descriptors: “rotten eggs” for hydrogen sulfide, the gas with the strongest correlation to stink; “decomposing vegetables” for methanethiol; and “sweet” for dimethyl sulfide. Though lesser players like methylmercaptan contribute as well, it is for the most part these three notes, in subtly shifting combinations and percentages, that create the infinite olfactory variety of human flatus. To quote Alan Kligerman, “A gas smell is as characteristic of a person as a fingerprint is.” But harder to dust for.

But I did learn things I didn't know:  there is a tablet that is available that is very effective at removing the smell - Devrom.  But even in America - home of the TV advertisement for douching, for goodness sake - no one likes to see or hear advertisements for curing smelly farts.   Hard to believe:

Bismuth pills, on the other hand — and Levitt has tested these, too — reduce 100 percent of sulfur gas odor. Bismuth is the “bism” in Pepto-Bismol. Daily doses of Pepto-Bismol can irritate the gut, but not bismuth subgallate, the active ingredient in Devrom “internal deodorant” pills.

I had never before heard of Devrom. This may be because mainstream magazines often refuse to run the company’s ads. Devrom’s president, Jason Mihalopoulos, e-mailed me a full-page ad he had hoped to run in Reader’s Digest and AARP magazine. A smiling gray-haired couple stand arm in arm below the boldface headline “Smelly Flatulence? Not since we started using Devrom!” Mihalopoulos was told he could not use the phrases “smelly flatulence” and “stinky odor,” or the word “stool.” One of the magazines suggested changing the copy to say that the product “eliminates intestinal gas,” but that’s not what Devrom does. That’s what Beano does. So unless you read the Journal of Wound Ostomy & Continence Nursing or the International Journal of Obesity Surgery, you won’t see the happy, internally deodorized Devrom couple.

 And as for the hydrogen sulfide component, we get this useful bit of information, showing that the worst flatulence won't kill you:

The concentration of hydrogen sulfide in offensive human flatus is around 1 to 3 parts per million. Harmless. Ramp it up to 1,000 parts per million — as can exist in manure pits and sewage tanks — and a few breaths can cause respiratory paralysis and suffocation. Workers die this way often enough that a pair of physicians, writing in a medical journal, coined a name for it: dung lung. Hydrogen sulfide is so swiftly lethal that farm- and workplace-safety organizations urge anyone who enters a manure pit or attempts to clear a blocked sewage pipe to wear a self-contained breathing apparatus. ...

It is fitting that the Devil is said to smell of sulfur. Hydrogen sulfide is a diabolical killer. Its telltale rotten-egg smell, screamingly obvious at 10 parts per million, disappears at concentrations above 150 parts per million; the olfactory nerves become paralyzed.

 What a sneaky gas...