Tianying, China

Correction Appended: Sept. 13, 2007

Number of people potentially affected: 140,000
Type of pollutant: Lead and other heavy metals
Source of pollution: Mining and processing

An industrial city — though China doesn't really have any other kind —in the country's northeastern rust belt, Tianying accounts for over half of China's lead production. Thanks to poor technology and worse regulation, much of that toxic metal ends up in Tianying's soil and water, and then in the bloodstream of its children, where it can cause lowered IQ. Wheat has been found to contain lead levels up to 24 times Chinese standards, which are even more stringent that U.S. restrictions on lead. "China has a commitment to environmental protection, but it also has a commitment to industry," says Fuller. "It's a constant push that's mostly won by industry."

— by Bryan Walsh

Due to incorrect information from The Blacksmith Institute, an earlier version of this story mistakenly referred to the Chinese city of Tianjin. The correct city is Tianying.