About 20 years ago, there was a study about this. It said that there were such high levels of metals, lead and chromium in particular, and organic solvents that they recommended not eating stuff that was grown there. They recommended growing some specific plants that had high uptake of metals and disposing of them.
Call the venture Superfund Farms.
I retired from the agricultural business. I wouldn't be afraid to eat what is grown on these plots of land.
One should look at any study with skepticism since, as we have found out with 'global warming hoaxes' that sometimes the studies are intentionally directed. Incjdentally for all of your information, many of the products labeled for 'organic' use are as deadly, or more deadly than conventional insecticides is improperly used. The only difference is that 'organically labeled products' generally have less efficacy which means that there is more applications. Like every week as apposed to once a month with conventional products.