Penta was banned by EPA in 2015 according to Google AI search. 10 yoa lumber exposed o elements, my swag, probably a lot of the chemicals have leached out ( using 2015 date ) . My understanding , may be completely off base , no expert , is that so called pressure treated , isn't truly "pressure treated " but only soaked in the preserving chemicals , allowing the chemicals to leach away fairly easily.
Take all my comments for what their worth , a little less than 1/2 what you paid for them .
