Commercial cured meat generally prohibits use of nitrates. Residual nitrates in cooked meats turn into nitrosamines (no U)
Nitrosamines is on the carcinogenic hot list which is very true and got cured meats on the bad list for many years.
This is also why injected meats with nitrites requires adding sodium eythrobate (SE). SE neutralizes any residual nitrites.
No evidence that residual nitrites convert to nitrosamines, but politics get involved...
Remember a majority of the USDA policy is political not practical.
SmokinEdge
gave the quick answer.
Some state that naturally derived nitrAtes is better than synthetic.
I don't have a clue.
Thankfully USDA labeling is supposed to get updated and the celery powdered products will be listed as "cured" to stop deceiving the populous.