Is teflon a poison if ingested?
I hope I am not breaking any rules of this forum by directly quoting, but here you go:

"The cold polymer is harmless on ingestion, in contact
with the skin, or implanted in living tissues. When
heated above 250° C. it begins slowly to give rise to
small amounts of decomposition products, some of
which are toxic.
The accidental inhalation of fumes from the overheated
polymer by workmen produces an influenza-like
illness which has been described elsewhere. The
illness follows a latent interval of a few hours and
resolves within a day or two with no subsequent illeffects.
This may happen, for example, when the
polymer is heated to comparatively high temperatures
(350-400 C.) in an oven, an extruder, or some other
equipment used to fabricate it, but it is easily prevented
by the intelligent use of exhaust ventilation."

In: Harris, Kenwin. “Toxicity of Polytetrafluoroethylene.” British Medical Journal 1.5285 (1962): 1146.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1958415/pdf/brmedj02864-0082a.pdf