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What the Nose Knows - Avery Gilbert [14]

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dimethyl trisulfide. Despite this dramatic reversal of conventional medical wisdom, the gastroenterological community remained unmoved. Finally, in 1998, investigators at the Veterans Administration Hospital in Minneapolis took the next step and performed an exacting chemical and olfactory analysis of farts. Their experimental methods were straightforward: “To ensure flatus output, the diet of the subjects was usually supplemented with 200 g pinto beans on the night before and the morning of the study.” Gas capture was simplicity itself, though the details are squirm-inducing: “Flatus was collected via a rectal tube…connected to a gas impermeable bag.” When the bags of ass-gas were analyzed, the main contributors were once again sulfur-containing molecules: hydrogen sulfide, methyl mercaptan, and dimethyl sulfide.

By comparing bean-powered samples from men and women, the intrepid Minnesotans were able to settle a long-running dispute between the sexes. The data proved (as men have claimed for centuries) that the farts of women are stinkier, on a volume-for-volume basis, than those of men. Since men produce a greater volume than women, however, the overall gag factor remains about even. As part of their research, the team tested a device called the Toot Trapper, a fabric-covered foam cushion coated with activated charcoal. The cushion is worn inside one’s pants and, according to the manufacturer, absorbs the offensive odor of intestinal gas. The Minneapolis team tailored a pair of fart-proof pants from Mylar sheets and duct tape. When volunteers wore the pants along with a Toot Trapper, the captured gas was indeed less smelly. (“Toot Trapper” strikes me as a lame brand name for this useful product. If I were the marketing consultant, I’d go with something more robust, like “Blast Master 3000.”)

Lyrical accounts of child-rearing dwell on the wonderful smell of a baby’s head. Less sentimental observers note that infants are prodigious gas-factories. In 2001 a group of pediatricians found that diet affects the chemical composition of baby farts (technically, they analyzed the gas produced by poop samples stored at body temperature for four hours). The gas from breast-fed babies was heavy on (odorless) hydrogen and very low on stinky methyl mercaptan. Babies fed milk-based formula had intermediate levels on every gas measured. Infants fed soy-based formula produced a lot of hydrogen sulfide (rotten-egg smell) and also the most methane. The good news is that methane is odorless; the bad news is that it contributes to global warming.

Another cherished belief is that one’s own little bundle of joy produces better-smelling poop than the other kids. Remarkably, this belief holds up under strict scientific scrutiny. Mothers of fourteen-month-old babies contributed dirty diapers, which were sniffed from cardboard buckets. Each mother compared a diaper load from her kid to that of an anonymous sixteen-month-old who provided the reference sample. The other baby was stinkier when the dueling buckets were unlabeled; labeling the buckets (e.g., “Jason” versus “Other Baby”) didn’t increase the effect, nor did switching the labels reduce the effect; this means the mothers were not letting maternal pride interfere with their odor judgments—they really do find other children stinkier. This study also proves that some sensory psychologists have way too much time on their hands.

Reefer Madness

One complex botanical smell has had an outsized cultural impact on the nation. Rod Blagojevich captured it well when, during his campaign for governor of Illinois, he admitted that he had smoked marijuana, saying “it was a smell that we all, in our generation, are familiar with.” He added, “I didn’t like the smell of it.” In contrast, Andy Warhol allegedly said, “I think pot should be legal. I don’t smoke it, but I like the smell of it.”

I once received a phone call from a graphic artist when I worked for the fragrance company Givaudan Roure. He was designing the booklet for a solo CD by a member of a well-known rock band and wanted to print it with

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