What amount of bpa would a human have to consume to be harmful?

Avoid it: There's more we don't know than what is clear about the effects of bpa. Public health agencies have set safe exposure levels, but those assumptions are based on looking for cancers or other obvious toxicity. It was originally designed as a birth control chemical so we know it affects hormones. Look here to get an idea of what it might do to us: http://www.ncbi.nlm.nih.gov/pubmed/?term=bisphenol+A