there is available independent research, but since it's an expensive endeavor and industrial complexes funding "their own" research to say "it's fine" (insert meme here) chances of quality research dropping into our laps are slim-to-none. So best we can do is by experimentation and observation ourselves. Several chronic conditions magically disappeared for me by paying more attention to my food origins and methods of preparation, moving away from pollution centers etc. People around me report very similar outcomes so I'm willing to trust those scarse and rare "contradictory" reports pitting industrialized lifestyle against "simpler" life.