The old kind of treated lumber had arsenic in it and there was legitimate concern about it leaching into the soil/compost and about kids and pets being exposed to the wood -- especially since kids tend to put their hands into their mouths a lot.

The new version has no arsenic.

I don't bother with bins anymore. The kids who take the compost out can't reach to get the scraps into the back and onto the top when they have to stretch over the sides of a bin. Its actually tidier looking to have unbinned piles than to have all the mess spilling out the front of the bins.

Why not paint the outsides of the pallets? Make em look purty.

Keep in mind that it took many years, even after many people started reporting Arsenic poisoning, for the EPA to finaly ban the sale of the old CCA PT lumber. It could take as many years to find out that the copper is leaching out of this newer PT lumber and poses as much a problem as the Arsenic does.