In some of our field trips and lab work (I have been working on a
second baccalaureate in marine bio over the last six years), we were
cautioned to be sure our hands were very clean of things like lotions,
soap, sunscreen, and the like, before handling amphibians, for fear
that these substances would do them harm. There is also an
opposite side to the matter; some amphibians secrete substances toxic
to predators -- and incidentally to us -- through their skins, so we
had to be careful for our own sake.
-- Jay Freeman, First Extropian Squirrel