CHICAGO, Illinois, September 29, 2008 (ENS) - For the first time, a new study of Chicago air sampled between November 2006 and November 2007 found a toxic pollutant that is a byproduct of paint pigment manufacturing to be present throughout the city.
The substance is PCB11, one of a class of toxics called polychlorinated biphenols, PCBs, a mixture of individual chemicals which are no longer produced in the United States, but are still found in the environment.
The distribution of PCB11 throughout residential areas of Chicago suggests that the compound is a past or current component of consumer paint products.
Although PCBs have been found in previous air samples collected in Chicago, the presence of PCB11 has never before been documented.
"To the best of our knowledge, this is the first published report of PCB11 in ambient air," said Keri Hornbuckle, a University of Iowa professor of civil and environmental engineering who led the study. It is published in the current online issue of the journal "Environmental Science & Technology."
"This compound is ubiquitous in air throughout the city of Chicago," said Hornbuckle, who is also a researcher at the Iowa research institute IIHR-Hydroscience and Engineering.
The prevalence of PCB11 in Chicago air suggests that there are either multiple current sources in the city or that this compound is widespread in background air. This has important implications for human exposure to this potentially toxic compound, Hornbuckle says.
"While inhalation is not widely considered to be a major exposure route for higher molecular weight PCBs, it may be an important route for PCB11," she said. "Not only is PCB11 one of the most volatile PCBs, if it is present in interior paints, then indoor concentrations may be much higher than reported here."
"We do not know if there are any health concerns associated with this compound but there are very few published studies of its toxic properties," she said.
The federal Agency for Toxic Substances says, "Health effects that have been associated with exposure to PCBs include acne-like skin conditions in adults and neurobehavioral and immunological changes in children. PCBs are known to cause cancer in animals."
The U.S. Environmental Protection Agency and the International Agency for Research on Cancer have determined that PCBs are "probably carcinogenic to humans."
To conduct the test, University of Iowa researchers mounted air sample collection devices on platforms attached to the rear of two medical clinic vans provided by the Mobile C.A.R.E. Foundation of Chicago, more formally known as Comprehensive Care for Chicagoland's Children with Asthma.
The samples were collected during the six to eight hours each day that the vans visited elementary schools where the mobile clinics provide service to students and their families.
Upon analysis, researchers found PCB11 in 91 percent of the 184 samples collected.
"The wide distribution of PCB11 in Chicago air is consistent with volatilization of this compound from painted surfaces although the actual source of PCB11 is unknown," wrote Hornbuckle and her University of Iowa research colleagues Dingfei Hu and Andres Martinez.
Historically, PCB11 is one of 209 polychlorinated biphenol compounds manufactured between the late 1920s and the 1970s. They were primarily marketed as mixtures called Aroclors by chemical companies until U.S. production ceased in the late 1970s.
The University of Iowa report says the historical trend for PCB11 is unknown and probably different from that for Aroclors - particularly if PCB11 is produced as a by-product of current paint manufacturing.
Hornbuckle and her team says that Aroclor-PCBs in the environment are decreasing worldwide, but that this may not be the case for PCB11.
Concluding that further study is needed, Hornbuckle and her colleagues said, "Consumption of paint chips could be also a direct exposure route for children. It is also possible that PCB11 is present not only in Chicago, but in air elsewhere and also in fish, soil, water, food and humans."
Funding for the research project was provided by the National Institute for Environmental Health Sciences Superfund Basic Research Program.
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