DNA has been randomly mutating for eons. That's one of the processes that drives evolution. I know of no "organic" foods that cause cancer, do you? GM just directs and speeds up the process. And GM crops go through a lot of testing before they are judged fit for human consumption.
(The first person to mention Thalidomide will need to remove my boot from his butt. You think they haven't improved testing standards in the decades since then?)
And could Mr Organic Will Save Us please answer how we're going to grow enough food "organically" to feed the teeming billions of humans crowding this planet? Without GM, without artificial pesticides and without artificial fetilizers? Just 'cause a niche market of wealthy Westerners can afford to indulge in their taste for organic veggies, doesn't mean that the Chinese or Africans, for example, can do the same.
Given how arid most of China and Africa are, they need to make the most of each square meter of fertile land, to get enough to feed themselves. Organic food, which requires more land for the same output, is a luxury to them.