I totally understand where you're coming from and acknowledge the necessity of specific scientific review. I'm very glad you brought this up to help people consider such things carefully.  I mean it when I say your good sense is invaluable to many of us! And I admit a certain lala guesswork attitude to my original response here, lol.
But, in this case, anthelmintics are generally considered safe.
Fenbendazole seems to be undergoing current or pending clinical trials for a potential anti-cancer affect.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7458798/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6966614/