Not sure if I can cite examples, but H2O2 (Hydrogen-Peroxid) is found in nature. I know that the so-called healing waters at various springs around the world have been shown to have a high concentration of H2O2. This idea is documented further in McCabe's book.

Hydrogen peroxide is prepared commercially by oxidation of alkylhydroanthraquinones and by electrolysis of ammonium bisulfate. It can also be prepared by reaction of barium peroxide with sulfuric acid and is prepared (with acetone) by oxidation of isopropanol.

From what I have learned, h2O2 is purely natural. It is 2 atoms of hydrogen and 2 atoms of oxygen. Water is 2 atoms of hydrogen and 1 atom of oxygen. it's that extra oxygen atom that helps us.

Evidently, before pollution, we would get hydrogen peroxide in the rain - so it seems to be purely natural and normal and something that we USED to get but now, because of pollution, we are stopped from getting. That tells me that we need it. Just like our soil is depleted of nutrition, so our rain and air is depleted too.

My benchmark is that if nature concocts the chemical get togethers, as in h2o (water), or ozone (h203) or hydrogen peroxide (h202) then it's fine. If humans concoct it, as in aspartame, or genetically modified whatever, vaccines, then avoid it if you can.