ETA: DDT was dusted directly on people for flea and lice control and typhus prevention and was primarily sprayed indoors for malaria prevention so there was a lot more direct human contact than even production plant workers have with insecticides currently.
Where is the evidence of direct DDT harm to human beings? I don't recall that ever being mentioned when DDT was banned in the United States (within my lifetime, so I remember the contemporary news reports on the issue). If there is a harm, how does it compare to the harm of insect-borne diseases?
http://www.edge.org/3rd_culture/wrangham/wrangham_index.html
The rest of your comment seems irrelevant. I'm not disputing in any way that plants have toxins or that we had to develop various practices to make us safer. I don't dispute that many man-made chemicals are safe and useful. I don't even dispute that pesticides could conceivably improve safety from a hypothetical insect-born contagion.
However genetically modified mono-crops sprayed with heavy loads of pesticides simply to increase yields does not strike me as something that goes towards food safety at all. It goes towards short-term profit, and you can bet the cost of any long term health effects is simply ignored until 30-40 years down the line when the soil is depleted and the effects of various pesticides have time to show up in the human population. At that point the industry will throw its hands up in the air and say "how could we have known?" while pushing the new and improved fertilizers and pesticides with a new batch of as-of-yet-unknown problems.
That's why I think it's a good idea to eat more traditionally raised food. It's not because I'm some hippie idealogue or because I don't believe in science or progress, it just strikes me as a safer bet given the severe holes in nutrition science, and in many ways, the intractability of solving the health "equation".