Pressure cookers can't be used as pressure canners because canners are larger (16 qt. and larger is what I have read before). Because of their size, they heat up and cool down much more slowly. This is calculated into the processing time. In a cooker, you can't determine how much longer you have to process at pressure to make up the difference, so it is not recommended.
Life is too short to eat processed, artificially-colored, chemically-preserved, genetically-modified food. Or maybe that IS why life's too short.