Perhaps "very dangerous" was an inappropriate characterization.
The idea is that this drug kills cells in the human body and, for that
reason, I think of it as dangerous.  In fact, the more dangerous the
drug, the more effective it is because the more deadly it is to
tumor cells.

I guess the danger question boils down to: What would happen
if the Tookad were light activated in some other part of the body
that didn't have cancer in it?  Would it hurt us?  A lot?  Or a little?

I don't know the answer to that.  If the answer is that it would only
hurt us a little, then my characterization of the drug as dangerous
is overstated.

Most of the chemotherapy drugs are dangerous in the sense
that they are cell killers.  The trick in using them is to either find
chemicals, or delivery mechanisms, that kill more tumor cells
than non-tumor cells.

A lot of conventional chemotherapy drugs kill all dividing cells.
Cancer cells divide a lot and so may be killed.  But the lining
of the stomach also has actively dividing cells (which is why
people get nauseous and vomit with chemotherapy) the hair
grows by dividing to produce more cells (which is why people
lose hair on chemotherapy).  One reason chemotherapy is
less effective with prostate cancer than with fast growing cancers
is that, with prostate cancer, the rate of tumor cell division is
lower.

One day there will be very precisely targeted drugs that can
kill just the cells we want to kill.  But we have a way to go
before we get there.

   Alan