Yes, well, even if there are not published scientific results regarding frontline use in poultry and egg consumption withdrawal periods, show people have been using frontline for years and have been able to establish some guidelines in use of frontline and determine what is safe.
Frontline has only been available just over 20 years. There have been many substances in history that were thought to not cause harm, but it took time to realize they do. Also, published scientific results don't always tell an accurate story either. I once heard someone say he could design an experiment to show anything he wanted. I also know several articles that are published that almost were not published due to a company not liking the results and threatening lawsuits. Also, just because someone does something does not mean it is safe. I have also seen people tell others they do a particular thing to mislead people. Be careful.