"That sir is loss of sovereignty."
Please define 'sovereignty' since I don't think that we are talking about the same thing. One attribute of sovereignty is the ability to enter into binding agreements like treaties. Says so in the Constitution.
"US citizens did not vote on allowing a supranation agency to manage our trade."
Read the constitution. US citizens "vote" on treaties via their representatives.
"Many congressmen who voted for NAFTA apparently never read it or deny knowing what it would do."
What is your point? Most legislators only read summaries of legislation. And if the legislator is not a lawyer, it might not help even if they did read it.
"We have had our food security impaired because under NAFTA rejection of low standard or contaminated produce can be considered a trade violation, where before NAFTA it was only a health and safety issue."
Give an example, please. NAFTA allows for legitimate use of laws to protect safety. 10 to 1 any law that was ruled against in arbitration (a) went to far, and (b) was a giveaway to agricultural interests.
"Since your livelihood depends on NAFTA arbitrations..."
Small part of my practice. I work in the litigation department of my firm. But my job and expertise does put me in a better position to judge the truth of concerns about NAFTA than "other Americans".