This line in the article got me.
The deal would, however, allow corporations to bypass domestic judicial systems and turn to international courts to challenge government regulations that they believe violate the deal.
One of the things that people don't always get is that some other countries have TOUGHER environmental regulations than the US.
Let's say Japan demands food grown in safe environmental conditions, and those are higher than the food grown in the US. If they agree to the TPP it will lower the conditions for everyone. Japan will have to say our frozen potatoes are safe, and they can't discriminate against our potatoes or we can sue them.
The US standards aren't always as great as they want people to believe. In some cases our levels of allowable chemicals (pesticides/antibiotics) are higher than other countries. We also don't have the precautionary principle as the base for our chemicals like in Europe.
We don't know what is going on in the food safety area of the TPP since nothing has leaked from there yet.
Would the big corporations want to buy the cheapest food possible from places that don't have pesky regulations? You bet. How do they get around it? Well they say, "Country A's food safety standards are the" equivalent" to the USs and we can't demand they be inspected by the USDA or FDA"
That allows other countries to sell tainted food to us and the US to sell, for example, pesticide loaded potatoes or older beef to Japan. The idea is to get food safety standards "harmonized" to a level that is lower than the highest country.