Certainly is something to think about!
Is your employee "official" (i.e., you're paying her social security
and workman's comp, taking out taxes, and reporting her salary)? If
so, your employment agreement with her should set forth specific
rights and responsibilities, including safety issues.
In any case, the workplace you provide for her should be compliant
with OSHA standards, including things like posted MSDS for all of the
chemicals, quick access to first aid, eye-wash, etc., appropriate
safety equipment (goggles, protective gear), good ventilation, etc.
You should ensure that your policy on workplace safety is explicitly
made known to her (a periodic review of your safety policy and
expectations isn't a bad idea) and documented in writing. "Training"
her in safety techniques periodically isn't a bad idea, either.
This may sound very "formal," but it doesn't have to be... it just
has to be done. Reminding her to wear the safety goggles when
polishing, if you see her without them, is appropriate.
That doesn't mean that she CAN'T sue you if something happens, but
it does mean that her chances of winning a negligence case against
you go down significantly. A previous employer of mine had a policy
that all new employees had to sign on their first day. It said,
basically, "you have the right to sue us, but if you do you forfeit
your pension and our contribution to your 401(k)." To the best of
my knowledge, no one ever challenged them on that (a real catch-22
to do so), but I always wondered about the actual tenability of that
clause. And, it was definitely an indicator of the type of employer
they were - SOOOO glad I don't work there anymore!
Hope this helps,