Itching Powder
This is a tapelift sample from the office chair of a person suffering from contact dermatitis. The dermatitis in this
case was caused by exposure to the bristle hairs from maple tree seed pods. This is a form of itching powder commercially
available. Three of the bristle hairs can be seen lying near horizontally at the center of the field of view. One of these
extends out of the field of view on the right center of the image. There are a total of eight of these stiff fibers in this
field of view.
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, as in this case. There are no
other similarly elevated plant remains that would suggest an inadvertent exposure. The other particle in this sample are
consistent with a normal office environment.
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
