https://digital.library.unt.edu/ark:/67531/metadc39955/m1/
Or google
"Technologies for Reducing Dioxin in the Manufacture of Bleached Wood Pulp"
Note how none of the paper samples exceed 50ppt, the average is much less.
Ppt. Parts per
trillion.
I have thought about fiber contamination. It would likely vary on pressing and collection method.
I have veered away from the higher temperature and pressure that results in bleeding, and collect rosin with itself, not a scrapper or dab tool.
I pick up a thick knob with a square of parchment and use that to wipe the remains.