Kevin Drum makes a strong case for spending the money to remove the remaining sources of environmental lead: old lead paint and residential water pipes. Eliminating lead paint an lead pipes each would have costs in the tens-of-billions range. In each case that would mean either (1) requiring private parties to spend substantial amounts of money or (2) spending substantial amounts of public money to fix up private property, somewhat unfairly to those who prudently spent their own money to fix it.  But neither problem could possibly justify allowing the ongoing damage from lead exposure; those are one-time expenditures, and the flow of damage from lead is a continuing cost.
One source Kevin doesn’t mention is smelters, which used to be a major source. I’m not current enough to know whether most of the smelter business has moved abroad, but I’m sure there are still some domestic smelters, and they’re inevitably bad news on the lead front.
As Kevin notes, one consequence of lead exposure is higher crime: lead reduces IQ and also specifically attacks some of the brain functions that support self-control. But consider what a horse-laugh a politician would get if he listed de-leading among his crime-control proposals.