To : Regina
Re : Pyrethroid insect sprays

The pyrethrin insect sprays have become quite popular in the last decade
because they are quite safe around humans.  Actually, these are "Natural-
like" products as they were originally derived from the chrysanthemum
flower.

A pyrethroid derivative, permethrin is used in Nix, or A200 pyrinate which
we use for lice and scabies.

First,  the oral bioavailability is extremely low, and first pass uptake in
the liver is extremely high. Thus very little ever reaches the plasma
compartment.   Also,  the transcutaneous absorption is virtually nil.   We
simply don't seem to absorb the stuff through the skin.  We can even use
this stuff on infants.   The estimated lethal dose in humans is greater than
1 gram/Kg.  Now thats a lot of pure stuff.

Secondly, it is not stored in fat, or retained in the human like the older
family of hydrocarbon pesticides.  Maybe a little, but nothing like the
older products.

Lastly,  the biggest problem in using this stuff, is that it doesn't stay
around very long,  so its residual abilities is poor.  Thus we have to spray
often.

So to be honest,  I can't think of a safer, better, more environmentally
friendly pesticide (if there is such).



Regards

Tom Hale, Ph.D.
http://www.perinatalpub.com

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