Cancer isn’t spreading from host to host via a medium like bacteria or viruses do. Something is carcinogenic or can cause cancer. But it isn’t spreading. The mechanism is already in the body - cell division. Carcinogenic factors increase the chance, that something goes wrong during the process. And the resulting cells failing to kill themselves. Or the immune system failing to kill them.

Although… Some say certain infections could lead to cancer. But nitrates are not microbes.

Q: …
A: use a test kit. Or send a sample to a lab to be sure.