Itching Powder
This is a sample of the hairs collected from the base of
the "wing" part of the maple seed.
Transmitted Off Crossed Circular Polarized Light Illumination
Definition/Function:
Itching powder includes both mechanical and chemical irritants that induce itching when
applied to the human skin. This
may be the result of an attempt at humor (practical joke) or an unexpected exposure to
one of these agents. The seeds of
any of the Acer family of trees (Maples) has a large population of very stiff "hairs"
near the base of the "wing". These
hairs can be collected and used as an itching powder and are sold as such in novelty
shops. This is just one of the types
of itching powders available commercially.
Significance in the Environment:
Any of the mechanical agents that cause contact dermatitis can be collected by taking a
tapelift of the affected area of
skin. A Tapelift of clothing covering that area or of surfaces in the environment of
that individual may also detect the
presence of one of these mechanical agents. If the agent is clearly introduced
artificially then the exposure may be the
result of a practical joke. Rosehip pith and maple seed hair are two agents that
generally indicate a practicle joke.
Glass fiber, carbon fiber, bark fiber, and the like may be the result of an exposure
related to a specific activity or
the degradation of some material in the environment.
Characteristic Features:
The maple seed hairs tend to have a large basal attachement at one end and terminate in
a stiff, sharp point. The have
moderate birefringence and a large lumen running the length of the fiber. The lumen is
often divided as a result of the
fiber being composed of more than one cell, typically three cells or more.
Associated Particles:
When this material has been used as part of a practical joke it is clearly out of place.
There are no other similarly
elevated plant remains that would suggest an inadvertent exposure.
References:
1. http://en.wikipedia.org/wiki/Itching_powder
2. Rietschel, Robert L. and Joseph F. Fowler, Jr. (eds), FISHER'S CONTACT DERMATITIS,4th
EDITION, Williams & Wilkins, 1995
3. Marks, James G. and Vincent A. DeLeo (eds), CONTACT AND OCCUPATIONAL DERMATOLOGY,
Mosby-Year Book, 1992