By the time the birds are giving you eggs and meat, they are no longer eating medicated feed. It's only fed to baby chicks. So the point is moot. But even if they did eat medicated feed when full grown, it's safe to eat the eggs and meat as per the FDA. You're using the word "chemicals" to make it sound all scary and evil. But that's what the vaccine is, too, and you don't seem to have a problem with that. You also seem to equate medicated feed with pesticides, which just makes no sense. "Chemicals" aren't intrinsically evil and aren't all in the same bucket.