title: The nature of navel fluff.
abstract: Hard facts on a soft matter! In their popular scientific book (Leyner M, Goldberg B. Why do men have nipples - hundreds of questions you'd only ask a doctor after your third martini. New York: Three Rivers Press; 2005), Leyner and Goldberg raised the question why "some belly buttons collect so much lint". They were, however, not able to come up with a satisfactory answer. The hypothesis presented herein says that abdominal hair is mainly responsible for the accumulation of navel lint, which, therefore, this is a typically male phenomenon. The abdominal hair collects fibers from cotton shirts and directs them into the navel where they are compacted to a felt-like matter. The most abundant individual mass of a piece of lint was found to be between 1.20 and 1.29 mg (n=503). However, due to several much larger pieces, the average mass was 1.82 mg in this three year study. When the abdominal hair is shaved, no more lint is collected. Old T-shirts or dress shirts produce less navel fuzz than brand new T-shirts. Using elemental analysis, it could be shown that cotton lint contains a certain amount of foreign material, supposedly cutaneous scales, fat or proteins. Incidentally, lint might thus fulfill a cleaning function for the navel.
authors.affiliation: Vienna University of Technology, Atominstitut der Osterreichischen Universitäten, Stadionallee 2, 1020 Vienna, Austria. georg.steinhauser@ati.ac.at
authors.forename: Georg
authors.initials: G
authors.lastname: Steinhauser
mesh_terms: D000005:Abdomen / Q000502:physiology*; D019317:Evidence-Based Medicine; D006197:Hair / Q000502:physiology*; D006801:Humans; D013784:Textiles; D014472:Umbilicus / Q000502:physiology*