Belly button fluff, or more formally navel lint, is an accumulation of fluffy fibres in one's navel.

Many people find that, at the beginning and end of the day, a small lump of fluff has appeared in the navel cavity. The reasons for this have been the subject of idle speculation for many years but in 2001, Dr. Karl Kruszelnicki of the University of Sydney, Australia undertook a systematic survey to determine the ins and outs of belly button fluff. His primary findings were as follows:

• Belly button fluff (BBF) consists primarily of stray fibres from one's clothing, mixed with some dead skin cells and strands of body hair.
• Contrary to expectations, BBF appears to migrate upwards from underwear rather than downwards from shirts or tops. The migration process is the result of the frictional drag of body hair on underwear, which drags stray fibres up into the navel.
• Women experience less BBF because of their finer and shorter body hairs. Conversely, older men experience it more because of their coarser and more numerous hairs.
• BBF's characteristic blue tint is due to the existence of blue fibres in most clothing.
• The existence of BBF is entirely harmless, and requires no corrective action other than making sure that one picks it out every now and again.

Dr. Kruszelnicki was awarded the Ig Nobel prize for Interdisciplinary Research in 2002.

Graham Barker of Perth, Western Australia, is in the Guinness Book of Records as the record holder for collecting belly button fluff. He has been collecting belly button fluff almost every day for 20 years since January 17 1984. He collects about 3.03 mg per day. Contrary to the research of Dr. Kruszelnicki, his fluff is in a particular shade of red, even though he rarely wears red clothes.

See also

• Lint

External links

• Belly Button Lint - The Hole Story (Dr. Karl Kruszelnicki) (http://www.abc.net.au/science/k2/lint/)
• Graham Barker Homepage (http://www.feargod.net/fluff.html) (Guinness world record holder for collecting Belly Button Fluff)

es:Pelusilla del ombligo nl:navelpluis no:Navlelo