A lot of info on the internet state that glow sticks are made from non-toxic chemicals. Here’s the real deal (from Wiki):

Glow sticks contain hydrogen peroxide, and phenol is produced as a by-product. It is advisable, therefore, to keep the mixture away from skin and to prevent accidental ingestion if the glow stick case splits or breaks. The glow stick contains two chemicals and a suitable fluorescent dye (sensitizer, or fluorophor). The chemicals in the glass vial are a mixture of the dye and diphenyl oxalate. The chemical inside the plastic tube is hydrogen peroxide. By mixing the peroxide with the phenyl oxalate ester, a chemical reaction takes place: the ester is oxidized, yielding two molecules of phenol and one molecule of peroxyacid ester (1,2-dioxetanedione). The peroxyacid decomposes spontaneously to carbon dioxide, releasing energy that excites the dye, which then relaxes by releasing a photon. The wavelength of the photon—the color of the emitted light—depends on the structure of the dye. The decomposition is a reverse [2 + 2] cycloaddition, which is a forbidden transition; so the reaction cannot release its energy as heat, but only as a single photon with an exact energy quantum.

Jasmin

When you mix light (not paint), you need red, green, and blue.

This small change is a world of difference between mixing paint and mixing light. It’s just the way the universe is wired. I do recommend getting a yellow light stick and seeing what happens when you substitute it for green…