Your first problem is that you have pressure-treated lumber, which generally contains toxic heavy metals that can leach into the earth and get on your skin.
I suggest you:
- first, switch base materials, then
- use a nontoxic sealer and finish from Vermont Natural Coatings or SafeCoat from AFM.
For more information:
Read "What are the best green alternatives to wood for decking?" a Q&A answered by Marian Keeler.