Over the years I've used a few different wormers; wazine, safeguard paste and liquid goat wormer, valbazen, pyrantel pamoate, zimecterin gold, equimax, ivermectin pour on, eprinex and moxidectin plus.
I've eaten eggs after treating my birds with most of these wormers with the exception of ivermectin pour on, moxidectin plus, z-gold and equimax. I'm still here typing. I used to recommend a 24 day (total) withdrawal period after the dosing for all these wormers.
If someone is allergic to any of the ingredients in these wormers or they think they might have an adverse reaction, eggs should be tossed in the garbage.
I dont recommend feeding the eggs back to chickens since there's residue in the eggs. The residue might help build worm resistance the next time you worm your birds.
There has been no residue testing in eggs after wazine use, only for slaughter. The reason there has been no egg testing is because of costs. They wont test eggs specifically for backyard chicken owners. Also, commercial operations have no need for wormers.
My understanding is that piperazine (wazine) use in Canada for chickens has no egg withdrawal.