Before the electric light bulb ended the Gaslight Era, one of the biggest advances in illuminating Chicago and other cities was the development of a lantern wick that could withstand intense heat while burning brighter than ordinary lamps.
The wicks, known as Welsbach gas mantles, were made of gauze soaked in a radioactive element called thorium. To meet demand, several long-forgotten lantern factories north of the Chicago River ground tons of thorium-laced ore during the early 1900s, then gave away the sandy leftovers to shore up soggy areas around Streeterville, at the time a heavily industrialized neighborhood.
Nobody kept track of where the radioactive sand from Lindsay Light Co. ended up. But today, developers and street crews confront the company’s toxic legacy every time they dig foundations for hotels and high-rise condominiums that have made Streeterville a magnet for upscale living and tourism.
Experts say the radiation doesn’t pose dangers as long as contaminated soil remains below newer layers of concrete, asphalt and dirt that cover most of the neighborhood. Environmental regulators start to worry only when old buildings, parking lots and parks are dug up for new development — work that is on the increase again after the economic downturn.
Inhaling thorium-contaminated dust increases the risk of developing lung and pancreatic cancer, according to the U.S. Environmental Protection Agency. Even small amounts can deposit in bones and stay in the body for years.
The two Chicago-area sites are among dozens nationwide where toxic waste was dumped by companies associated with Kerr-McGee Corp., which took over the former Lindsay Light factories in the 1960s. Most of the settlement money will pay for cleaning up radioactive waste from uranium mining in the Navajo Nation, rocket fuel spilled into Lake Mead near Las Vegas and cancer-causing creosote from wood treatment factories in the Midwest, East and South.
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