I mention health issues to students so they keep clay out of their
mouths. I also tell them I have never actually heard of anybody getting
ill from the bacteria or worms in clay. Lots of things in life are for
external use only. My children and my grandchildren have all worked with
this clay at age 3 to make sculpture. Being a potter, I also begin
teaching then use the potter's wheel at age 3. They have never gotten sick
from it. I would hate to see people to stop working with clay because you
should avoid eating it.
Our science students, for class projects, go around campus looking
for stuff for lab work. They do report a fair amount of E' coli in our
reprocess can of clay. Our reprocess clay often sets around for a fairly
long time. We add the reprocess to every new batch of clay we mix. I am
not aware of anybody ever getting sick from it.
I do not know much about the intestinal worms hazard. I just
remember being told by Sheldon Carey, our ceramics prof at U. of Kansas,
that we could get worms if we got it in our mouth, but I have never seen a
documented case. Commercial clay and self dug clay all comes from similar
open pit sources where wild life could contaminate it with bacteria and
parasites. Commercial processing is not intended to remove bacteria or
parasites. We use primarily commercial clay, but we batch mix it ourselves.
I hope you all continue to enjoy using clay, even though it is for
"external use only" unless sterilized. Sterilized clay is used in the
manufacture of pills to help them stick together. Natural clay has been
safely used for thousands and thousands of years. This cannot be claimed
for any of the products being sold at higher prices as clay substitutes.
Just use good old commen sense.
The following web page is for those who want to learn more about
working with clay safely.