Pesticide levels are heavily regulated and kept to well below harmful levels. Levels are recorded and can be found at the EPA's website
Example Cereal grains are restricted to no more than 1 part in 20 million. Not exactly a high dose.
What are your concerns with GM foods?
I've not seen one report of any harm from genetically modified foods.
Supplement companies are not required to prove their products work, are safe or even contain the ingredients claimed. There can be possible interaction with prescription medication.