1975 Science paper : 7% could not smell trimethylamine

With a systemic body odor problem, including TMAU, it is quite common for the person and their 'loved ones' (e.g. parents, partner, children) to be unable to smell the odor. Speculation as to why this would be varies in the community. Some feel that those close to the person become acclimatized and desensitized to the smell. Others feel that some people are totally anosmic to some smells (specific anosmia). Another theory is a genetic reason, with the 'loved ones' being carriers of the same problem being a factor for some reason.

One can only speculate as to what exactly is happening. There is one published paper of a study in which people's ability to smell a certain group of smells including trimethylamine were tested. Written in 1975, this paper is a study of a group of a couple of hundred people, which demonstrated that 7% of the group had difficulty detecting the smell of tertiary amines, particularly trimethylamine.

Apparently trimethylamine is usually detectable at a very lows level in humans, the lowest of 53 odors tested in one study, including mercaptans and hydrogen sulfide.

1975 full paper : 7% of a group has anosmia to trimethylamine

abstract : anosmia to trimethylamine

In another paper in 1990, 11.5% of children could not have their detection of TMA measured, which may indicate an anosmia, but the paper says this may be due to them losing interest in the study.

http://www.springerlink.com/content/jnt300916675x160/

http://www.springerlink.com/content/jnt300916675x160/fulltext.pdf

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other links of interest

http://chemse.oxfordjournals.org/cgi/content/short/2/3/267