A good many farm friends of mine have passed away with cancer. Including my former father in law.
Atrozine and all that stuff is nasty. But, here is the ticker. They have to go to school and get training on the usage of that stuff and then have the farm licenses to use it, yet you or I can go down to Home Cheapo and buy that stuff right off the shelf.
We never used it on the small farm I grew up on. You can get corn to grown pretty well if you get it up above the weeds by cultivation. These chemicals are used to help save on the costs of cultivating. It would be near impossible to cultivate corn, and other row crops, on a large corporate farm. Costs would be unreal.
Atrazine became common in the early 1960s on farms. My Dad says the local elevator hosted a meeting for farmers with a representative of CIBA-Geigy explaining atrazine. He also explained how safe it was all the while he was mixing some up. At the end of the meeting he DRANK it. If he was using the real thing his grave is probably still glowing.