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Chicago Tribune: Mystery PCB Surfaces in Chicago, Baffling Researchers
Thursday, January 22, 2009
More than three decades after highly toxic PCBs were banned in the United States, an unusual PCB compound has turned up in the air outside several Chicago schools.
Polychlorinated biphenyls are a group of chemicals that once were widely used as coolants and lubricants but were outlawed after studies linked them to cancer, liver and kidney damage and other ailments.
Hundreds of sites around the nation are contaminated with PCBs, which are known as persistent chemicals because they don't break down in the environment and can build up in people and animals. PCBs move easily among land, water and air, and scientists know several of the chemicals tend to be present in the air Chicagoans breathe.
They were surprised to find it because PCB-11 isn't a chemical that was intentionally manufactured and marketed.
"We might have done a pretty good job shutting down direct sources of PCBs," said Keri Hornbuckle, a civil and environmental engineering professor who oversaw the study. "But this shows we aren't doing enough to shut down what's still out there."
The researchers speculated that the concentrations detected in the air in multiple Chicago locations could be coming from old paint, as other research has found the compound in wastewater from factories that produce yellow pigment.
Or, they said, it could be a previously unknown pollutant in smokestack emissions produced when paint is manufactured. The molecular structure of PCB-11 is similar to a chemical still used in yellow pigment, according to the study.
As part of a larger project examining PCBs in the Chicago area, Hornbuckle and her colleagues mounted air monitors atop two vans that provide medical services in low-income neighborhoods. Samples were collected outside nearly 40 schools.
The team found concentrations of several PCBs in the air, as expected, but they were surprised to find levels of PCB-11 in virtually every sample.
Most of the schools are in old industrial neighborhoods on the Northwest, West and Southeast Sides. The highest concentrations were found outside Casals Elementary in Humboldt Park and St. Gall Elementary in Gage Park.
Representatives from the Chicago Public Schools and the Chicago archdiocese said they were unaware of the study. Officials at the Illinois Environmental Protection Agency said they would need to conduct more air sampling and review scientific papers about PCB-11 before deciding whether to investigate further.
PCBs were dumped for years with little or no regulation and contaminated dozens of waterways around the country, including Waukegan Harbor in Illinois, the Grand Calumet River in northwest Indiana and Green Bay in Wisconsin. Scientists have known for years that PCBs accumulate in the fatty tissues of fish, leading to advisories throughout the Great Lakes region to limit eating most freshwater species.
Less is known about the potential health effects of airborne exposure to the chemicals, though steady levels of PCBs in fish can be attributed in part to pollution falling from the air into waterways."We haven't paid a lot of attention to this particular PCB before," said Victoria Persky, an epidemiologist at the University of Illinois at Chicago who helped arrange the testing methods the Iowa researchers used. "We need to see more data before deciding whether we should be alarmed."
More than 50 factories in Chicago list paint and pigment production as part of their manufacturing processes, but none report releasing PCBs into the air, adding to the mystery of where the PCB-11 is coming from.