Hundreds of Detroit home demolition sites may have been filled with toxic dirt

Toxic chemicals like lead and asbestos are likely in dirt used to backfill demolished structures in city, experts say

Hundreds of Detroit home demolition sites were potentially backfilled with toxic construction debris from a demolished shopping mall and other sources, creating an unfolding public health threat in the city's neighborhoods.

Detroit, the nation's lowest income big city, is in the US industrial heartland. It was left with tens of thousands of empty structures as industrial plants closed and people left the city in past decades - Detroit's population dropped from nearly 2 million people around 1950 to fewer than 700,000 today. The city's demolition program is widely considered the largest ever in the US.