I’ve read that there have been many tests done around the country in the past 50 years. I don’t have the source unfortunately, but I believe it came directly from a 3 letter agency. The only one I can really control is water and insects to an extent, which is why I spray bifenthrin on my property every couple months to control bugs/mosquitoes. Also, my family drinks only RO or distilled water. I’d very much recommend both.