We all eat antibiotics, unknowingly. I leave my butter out, always have, plus when the push was on to switch to margarine, my family never did. It turns out that butter is better for you than margarine. Margarine contains trans fat which raises bad cholesterol.
Also, when I was young and went to the movies when asked if I wanted butter on my popcorn, I always answered, no just put that yellow stuff on it.
I have been into organic foods for quite a while now, they are more expensive but they taste better and are better for you.
http://www.thealternativedaily.com/organic-butter/