It seems there are some silicone sealants that are "pure". This is one I found. It seems to have only two ingredients, which seem to be essential for the silicon sealants (siloxanes). They are found in cosmetics which are supposed to be Ok for people.
BDLN7WH-LN7Silicone-SDS.pdf (bonditgroup.com)
CYCLOPENTASILOXANE & CYCLOHEXASILOXANE
BDLN7WH-LN7Silicone-SDS.pdf (bonditgroup.com)
CYCLOPENTASILOXANE & CYCLOHEXASILOXANE