How do you know it doesn't enter the bloodstream? I've been using Frontline on birds for years,but not on hens producing eggs for human consumption. As far as I know, Frontline isn't even approved for use on chickens (though many poultry raisers use it), so it is unclear as to whether it is safe. However, from what I've heard and from how it works on other animals (dogs, cats, etc.), frontline does absorb into the body and kills bloodsucking parasites. Still, since it isn't approved/tested on chickens, I guess we can't know exactly what happens.
The breeder who told me about frontline said that it was fine to eat eggs after using frontline, and I trust him. He has been showing for years and using frontline after every show. I have always eaten the eggs too, sometimes laid a day afterwards.
Ok. It probably is fine, even if it does absorb into the bloodstream. I sometimes accidentally get frontline on myself when applying it to my chickens, and it hasn't seemed to hurt me yet.
