31 Pa. Stat. § 700j-808
It is hereby declared to be the legislative intent that the instant (whenever that may be) that the handling by a milk dealer or handler of milk produced outside of the Commonwealth becomes a subject of regulation by the Commonwealth in the exercise of its police powers, the restrictions set forth in this act respecting such milk so produced shall apply, and the powers conferred on the board by this act, and particularly by this article, shall attach; but such restrictions shall not apply to condensed or concentrated whole milk contained in hermetically sealed cans.
It is also hereby declared to be the legislative intent that the prices prescribed by the board for milk produced in this Commonwealth, and sold or delivered or made available on consignment or otherwise in this Commonwealth for shipment into and ultimate sale in another state, shall not be destructive of the price structure of producers in such other state.
31 P.S. § 700j-808