Eh, I learned it primarily by word of mouth from gardening enthusiasts who are buying homes. But here’s one article about the phenomenon: https://www.hgtv.com/outdoors/gardens/planting-and-maintenance/when-to-test-garden-soil-for-lead-contamination-and-how-to-garde

I don’t have a lot of statistics to back it up except that it seems worse on the East Coast and Rust Belt

As far as lawns go, thanks to lead paint and leaded gasoline from the mid-20th century, that land isn’t even one you’d consider suitable for growing food unless your house was built after the 1980s. At least, as long as you’re trying to avoid getting lead in your produce.

Really feels like our grandparents’ generation did a lot to fuck over our current generation. So many of these issues trace back to when even the Boomers were children.