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University of Iowa News Release


Dec. 4, 2009

UI researchers find likely source of Chicago air pollutant in paint pigments

Two University of Iowa researchers may have found a likely source of a polluting substance, a polychlorinated biphenol (PCB) called PCB11, that they previously identified in air samples throughout Chicago.

The pigments in some indoor and outdoor paints contain PCB11, according to a University of Iowa study published in the Dec. 3 online issue of the journal Environmental Science & Technology. (The article can be found at

Keri Hornbuckle, professor, and Dingfei Hu, postdoctoral fellow, in the Department of Civil and Environmental Engineering, conducted the study as a follow-up to their 2008 research that found PCB11 in 91 percent of 184 Chicago air samples. That study noted that although other PCBs had previously been found in Chicago air, PCB11 had no known Chicago source and had never been intentionally manufactured there.

The new study tested PCB concentrations in 33 commercial paint pigments purchased from three paint stores. Hornbuckle and Hu tested for the presence of all PCBs and found PCB11 to be the most frequent PCB in pigments used in indoor and outdoor paints, primarily in the colors green, blue, red and yellow. The study concluded that PCBs are probably present in commercial paints due to their inadvertent production during the manufacture of pigments.

The study noted that the pigments also have wide application in inks, textiles, paper, cosmetics, leather, plastics, food and other materials.

The possibility that PCBs in the air of Chicago, and other cities as yet untested, may pose a health hazard is an open question. Hornbuckle said there are very few studies on the potential toxicity of PCB11 or its metabolites.

The report noted that PCBs are a family of 209 compounds, including the commercially produced Aroclors that were marketed for use in electrical transformers, capacitors heat transfer systems and hydraulic systems. Aroclor is a mixture of PCBs manufactured between 1930 and banned from production in the 1970s and 1980s. PCB11, while not an Aroclor, appears to be a global pollutant, as others have recently found it in the air of Philadelphia, five sites around the Great Lakes, and Antarctica.

The study concluded by stating: "To our knowledge, pigments or dyes are the only significant source of PCB11. The elevation of PCB11 in air must be associated with human activity of utilizing pigments or dyes. The presence of PCB11 indicates paint should be an important source of airborne PCBs although the link of PCBs in paint pigments and PCBs in air is still not clear."

STORY SOURCE: University of Iowa News Services, 300 Plaza Centre One, Iowa City, Iowa 52242-2500.

MEDIA CONTACTS: Keri Hornbuckle, UI College of Engineering, 319-384-0789,; Gary Galluzzo, 319-384-0009,