Sodium nitrates and sodium nitrites

Almost every packaged meat has Sodium nitrates or Sodium nitrites these days.

There is solid evidence that consumption of processed meats cured with nitrates/nitrites is linked to a higher, about 32%, risk of certain cancers, especially colorectal.
There are plausible biological mechanisms (nitrosation → NOCs).

At the same time, the evidence is less clear for naturally occurring nitrates, e.g., from vegetables, such as celery salt.

Eating antioxidants helps mitigate some of the risk.