One little-noticed aspects of sunscreen ointments is that the main
ingredient of some is the chemical  GUANINE  which is one of the bases of
nucleic acids (DNA & RNA).  Technical-grade guanine is, I expect, liable to
contain, or to produce over time, impurities causing mutations or cancer.
        Guanine admittedly absorbs UV very well, but technical guanine does
not seem to me a suitable material to put on your skin.

R

-
Robt Mann
consultant ecologist
P O Box 28878   Remuera, Auckland 1005, New Zealand
                (9) 524 2949