Sequestering Toxic Wood Chip

My city has very high lead levels.
I have been going around and composting/collecting plant material that grew in this polluted soil. I wouldn't personally eat kale that grew in that soil but I am importing kale/wood chip/plant material that grew in this soil.

Mostly I am importing wood chip from these polluted soil and I am wondering if I am not raising the amount of heavy metal in my soil, and esp the amount of bio-available heavy metal.

Would you eat mushroom that grew on these plant material? How about vegetables or nuts, is it only safe for low mineral fruits?

I do radiator repair among other things so I have a bit of familiarity with heavy metals, hygiene and their dangers in the environment. Far from professional on this. My answers is: To many variables to know by indirect means. Different species have different uptakes. Soil pH, climate and amount of water also have major effects on the amount of heavy metals plants take up from soils. Same thing applies on your end if it is putting lead in your soil. Under the right conditions it can be high risk or low risk. Have the wood tested and see is the only answer I can give. Best guess is that you will find very little in the wood itself. But remember that dirt/dust is splashed on the bark too. Guessing most of the lead will be there not in the wood but instead on the bark if there is a problem. Check with the lab to see how to best get results. Just guessing but likely they will suggest wood from several sources and areas in roughly the same ratios of species that you normally get it in. Take a known quantity of that wood and burn it in a slow fire then measure the lead in the ash.(gives a broader sampling and gets lead that may be a surface contaminate instead of in the wood.)

Radical mycology talks about this. There are species of shrooms that will concentrate heavy metals. One or two fruitings will pull 90% or the heavy metals out. Dispose of those fruits and then you are back to normal. The mycoremediation turned a tons of material problem into a few five gallon buckets problem.

Additional info:

Thousands of sample across my city has shown that our avg lead level is 2 times the EPA recommend limit of 400ppm.
Additionally, the city used to make and give out compost but after researcher backed up the numbers that gardening groups and non-profits have been finding, the city has now halted their composting operation. The finish compost had lead levels in the 300-400 range. http://www.wellesley.edu/news/stories/node/30659