Misly,

Without a specifics given it is hard to comment on it.  This NG is anonymous
so no harm would come of it posting under an alias.
You can not untie the connection between the test and what it might mean to
you or anybody.  You need to have the proper test to evaluate a possible
problem.  There are many different tests and many different problems and
each needs to be thought of ahead of time.  The interpretation of the test
is always tied clinically to your problem and for that reason most high
complex testing is regulated by state and federal law as to who can perform
that test and always require a doctors order. You can not walk into a
clinical lab and demand a test.  There are environmental labs that do
environmental testing all the time from walk-ins but they do not do clinical
lab testing.  I would be suspicious of any lab doing so.
As far as GC/MS, it is an expensive piece of equipment so not all labs have
one. If for example, you found a syringe of a substance and wanted to know
what it was, then you have a problem in finding someone to do an analysis
for you.  The first is it is a biohazard with potential handling problems.
The next is billing questions.  The other concern is forensic or legal in
that what will you do with the findings? There is no "chain of custody".
Those are all issues that might make an environmental lab from doing
anything with it.
We have sent such samples to our toxicology lab for analysis and have billed
the doctor who sent it to us.  That is the only reasonable route one can
take under the above situation.
Hope that helps