I don't have a source, because I'm not even sure if a study has ever been done. But my basic common sense tells me that putting hot (to boiling) water through

I don't have a source, because I'm not even sure if a study has ever been done. But my basic common sense tells me that putting hot (to boiling) water through plastic intended to be cheap enough it is disposable is likely going to leach some sort of plastics into the resultant beverage. BPA is not the only thing that can leach out of plastic.