The lead we leave in the ground is microscopic compared to the mega-tons of toxic waste being dumped into our rivers by industries cheating to save money over EPA rules and regulations. And...if you think that is bad, go to Mexico, or any third world nation. San Diago bay and beaches are closed on a regular basis due to contamination from the Tijuana river spewing raw sewage, untreated toxic waste, and heavy metal contaminates into the ocean.
I'm not saying lead is a good or bad thing. What I am saying is there are a LOT more dangerous waste products that need our consideration, and action, before we start recovering a few grams of lead from our back yards.
Kindly 'Ol Uncle
"...war is the most widespread cause of fatal lead poisoning!"