Probably, because "people with breast implants" are not a protected class, but I'm not certain how one would be able to tell unless they were involved in some sort of business where they get to see their customers naked?
It is only illegal (federal law) to discriminate on the basis of race, color, religion, national origin, sex, pregnancy, familial status (with some exceptions, a landlord cannot legally refuse to rent to you simply because you have children), citizenship status (government services, not employment), disability, veteran status, or "genetic information" (an employer or insurer cannot require you to submit to genetic testing for predisposition to disease). Many states across the country have adopted additional protections, so one's rights can vary from state to state.