I have used wood from pallets and crates for years and not had any issues with the chem. I started with a dewalt planer and got years of great service from it. When it finally gave up the ghost 2 years ago I bought a Porter cable 12" at lowes for less than $300 figuring that would be fine for my needs. I have used it daily for those 2 years with very little problems. If I was to estimate how much wood I've run thru it would easily be over 100,000 linear ft. Most of the pallet wood I get is from a vinyl supply comp. and the boards are 12' long. every 2 weeks I pick up around 3-4 hundred boards and run them thru the planer after pulling the nails. I'm tough on my tools as far as working them hard, I don't give them much of a break!!! On the PC planer the blades cost $30 to replace vs $60 on the dewalt. I have resharpen my blades at least a dozen times. Most of my wood is pine but I do run Hardwoods as well thru the PC planer. There is one really nice feature with the dewalt in that it has a built in dust system that can be hooked up to a cyclonic collector. Hope this helps and wasn't to long winded.
sully