I'm not familiar with FDA that much (I live in EU) and I believe it isn't anywhere near perfect, but you want to be conservative when it comes to public health. Look at case of Thalidomide from 50s https://en.m.wikipedia.org/wiki/Thalidomide

  In the United States, pharmacologist Frances Oldham Kelsey M.D. 
  withstood pressure from the Richardson-Merrell company 
  and refused Food and Drug Administration (FDA) approval 
  to market thalidomide, saying further studies were needed.