Specific anosmia, or why I can’t smell farts

What if you couldn’t smell your own farts? Would you consider it a disability, or a blessing in disguise?

I was about ten years old when I noticed I couldn’t smell certain things. I remember walking through the woods at summer camp when other people began making faces. “Eww,” they said, “it smells like skunk!” But I could barely smell anything.

It’s not that my sense of smell is completely absent. Rather, there are certain odors that I’m not sensitive to. Mostly bad scents, fortunately.

For example, I often can’t smell farts. Again, it’s debatable whether or not this is a blessing in disguise, but I will say it’s a little unnerving to flatulate (is that a word?) and have no idea whether or not the people around me can smell it.

I used to just write this off as an interesting quirk, but over Christmas break I had the following conversation with my sister and her fiance:

Fiance: Watch out, I’m a little gassy today.
Me: Don’t worry about it, I can’t smell it anyway.
Sister: Wait, you don’t smell things either?
Me: What, you too?
Fiance: Yeah, it’s great, she can use the bathroom right after me and it’s no problem.

Apparently fart-insensitivity is genetic. And so, having recently discovered one wacky congenital disability in myself (see my post I’m learning to live with faceblindness) I embarked on further research.

According to Wikipedia, anosmia is “the lack of olfaction, or an absence of the ability to smell”. I don’t have that – I can smell most things – but there is also specific anosmia, an insensitivity to a certain odor. And specific anosmia (aka selective anosmia, I think) may be genetically based. Winner!

Interestingly, it is just about impossible to describe the concept of an odor to someone who has never had a sense of smell. But there are support and advice forums available, where sad but hilarious stories are traded of anosmic life in a world of smellers. One unfortunate guy recalls trying to cover up the smell of an “accident” with a heavy application of cologne, not realizing that deodorant doesn’t actually cancel out odors. More information on anosmia can be found at the Anosmia Foundation, including links to purchase smell tests.

My handicap is far less serious, though apparently still an active area of research. I found one Nature article particularly interesting. The abstract for Odour-Blindness to Musk: Simple Recessive Inheritance states:

The rare anosmia to the n-butyl mercaptan of skunk, and more commonly the scent of freesia flowers, may be inherited as autosomal recessive traits.

So that’s it! Mystery solved! I’ve got a rare, genetic, specific anosmia to n-butyl mercaptan, or possibly some other mercaptan. Mercaptans, also known as thiols, are the volatile sulfurous compounds that give skunk its stink. And guess where else mercaptans can be found?

Dr. Ed Poliness has this to say on the subject: “Mercaptans are found in your smelliest farts”. Thank you for your frankness, Dr. Poliness. For further information on farts, readers may also contact Dr. Michael Levitt, the world’s leading authority on flatulence, according to this article. The article doesn’t mention mercaptans, but it’s an entertaining read anyway.

There are less obvious effects, as well. Anyone who has traveled in Asia is familiar with the durian, a gourmet fruit widely regarded as delicious, but with a scent so foul it is banned from the premises of many airports and luxury hotels. The mercaptans in durian likely explain why I am the only person my mom has ever heard of who likes the smell of durian but not the taste.

27. February 2008 by Niels
Categories: Life, the universe, and everything, Personal | Tags: , , , , , , , , , , , , , , , | 53 comments

Comments (53)

  1. I have this too, my friends and family said that I am lucky if I told them that I can’t smell any bad smells, but sometimes I can smell good even weaker. For that reasons, all stuff around me are always cleaned, everything has to be clean in order to avoid the judgment.

  2. Niels, I share your olfactory shortcoming. I cannot, in general, sense bad smells. I pass by garbage heaps that people cross streets to avoid. I cannot smell mercaptan. That is a dangerous shortcoming because the chemical is mixed with bottled LPG which is odorless. The presence of the flammable LPG in the atmosphere is detected by the presence of the offensive smell of mercaptan. I could end up burnt to the crisp by striking a match in a room full of LPG because I cannot smell mercaptan. Fortunately, I can feel the fragrance of good things like flowers, fruits and food. My loss of the sense of smell occurred when I was in my fifties and for no apparent reason. So, I wonder if it is hereditary.

  3. Wow, I’m not alone. Recently, we changed water heaters in my house, and somebody mentioned that the water stunk. I was surprised, and after a little investigation, I found out that I had been showering in and occasionally drinking sulfuric water for sixteen years. Later that month, I got sprayed by a skunk and couldn’t smell it. Oddly enough, I can smell farts, so I don’t have the exact condition previously mentioned, but I know where to look now. Also, now that I’ve stopped eating milk and eggs, I don’t get sick anymore. So that’s nice.

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