[OldNavyVet]

Lead residue was probably left there after British forces burned the White House in the War of 1812.

Ref ... http://www.findingdulcinea.com/news/on-this-day/July-August-08/On-this-Day—British-Troops-Burn-White-House-and-Capital.html

[Rebelbase]

Lead mostly likely from decades of leaded gas exhaust on Penn. Ave.

[Gordon Greene]

“Lead residue was probably left there after British forces burned the White House in the War of 1812.”

That’s crazy talk... everybody knows the grounds of the Whitehouse were impregnated with poisons and hazardous materials by George W.!

Sometimes you folks surprise me with your naivity.