Every granite sink I ever installed was done with silicone and I've never had a recall or a leak. I checked my manufacturers web site for the right sealant with a granite sink and it lists silicone. For alternate sealants you can use anaerobics, cyanoacrylates, polyurethanes, acrylics, epoxies, and latex. If indeed you have been told that your kitchen sink will not take silicone, because of the composite bonding material, then you will have to verify all of the sealants to make sure they comply with the manufactures guidelines. I have used acrylic and latex sealants when I can't use silicone.

Good Luck

Raymond VinZant Plumbing Prof.