Aside from the lumber itself, the only other materials used in making your butcher block are all considered food-safe once cured:
1. Titebond III Wood Glue - FDA-approved and waterproof
2. Mas Epoxies' Marine Epoxy and Non-Blushing Hardener - Used to fill small knots, when present
3. Goodfilla's Water-Based Non-Toxic Wood Filler - Used to fill small knots, when present
4. And last but not least, your selected finish
That's the complete list. We hope this helps!