I think I know the answer to this question, but looking for extra insight. I built several garden boxes out of Pine (12x36x11). I used Polyurethane (common wood-floor sealant) to seal the outside of the boxes and prevent rot.

The boxes will be used to grow vegetables. Can I use Polyurethane on the inside of the boxes or will this this result in toxic produce (tomatoes etc)?

Or is it advisable to use polyurethane on the inside and then cover with weed barrier/landscape fabric? I have received conflicting advice. Gardenguides.com has a post suggesting its ok to use Poly inside wood containers. Any input appreciated

Here is a link that might be useful: Garden Guides.com