Originally Posted by WPStrassburg
Once cured 100% silicone should be food safe. If you want one that has been tested you'll have to look for one that is nsf or fda certified. Dow 732 & 748 look to be listed for FDA & NSF applications.
The problem is that you're not applying 100% silicone. In order to make silicone liquid, some sort of volatile compound must be added. It's the VOC's that may be dangerous, and different manufacturers use different compounds for each line of products. Much of the compound is released into the air causing the silicone to "dry." But I have a hard time believing that you're left with 100% silicone after that, which is why I wouldn't use silicone sealant on any food contact surfaces.
There are, however, silicones approved by the NSF for "food zone areas," but I don't know of any kitchen where silicone sealant is used in direct contact with food.
I'm not saying that you can't find a safe sealant, I'm just saying that I would avoid using it to seal things that come in direct contact with the wort when there are better ways to achieve the same result.