Granted, the results do point that pine dust causes a stronger reaction than some other woods. I am not saying pine is good or bad just there is evidence that points to an issue with the phenols and that there is a reduction in the phenol content after drying. I still question are you sure that the chips you are buying have been dried after chipping. In my area the one wood yard I used to work with told me they don't dry pine chips at all they just chip the branches and end cuts.