Well, there ya go, Bill. Its 100% silicone with somethin' else added, there's 110% of something in the tube, just like the colored silicone. I think by "100% silicone" they mean no latex or other caulking material, so read the label and ingredient list carefully. For sure avoid anything with any kind of "-cide" in it.
As for other ingredients, sometimes we may worry more than we need too. If you have an older Innes book, you can read how to seal leaking corners with old fashioned spar varnish. Yup, linseed oil and turpentine based varnish. You do have to let it cure for a few days. ( Not a bad idea with silicone, let it "gas off" that smell the crew noticed, which is acetic acid among other things.)
Those of us old enough can remember the metal framed tanks and the asphaltum and other tar and petroleum based sealants. Innes gives a formula for making the stuff, heating it up with parrafin and turpentine and other spirits.
So there are most likely several products that are safe but not specifically listed as such. I don't recomend pouring a shot of kerosene in the tank, use common sense, do rsearch, ask around
( there is probably some forum or something on line where you could do that) test with some feeder guppies for a while. When in doubt spend extra for exact same product labelled for aquarium use.
100% silicone with mildicide AND color is 120% ,