According to our local, nitrate free, butcher freshly slaughtered meat contains enoigh natural nitrate-alternatives to not require additional nitrate if ham, sausages and so on are prepared soon enough.
nitrate-free is a myth. They use celery powder which breaks down to sodium nitrate. The FDA allows the producers to call this "nitrate free" since they are not using sodium nitrate directly and the FDA considers the celery powder a flavoring agent.
Chemically it breaks down to sodium nitrate and has the same carcinogenic nitrates. Its just a legal labeling loop hole.