Stalking the Wild PCB

Tuesday, April 1, 2008

“The level of these toxins in the Great Lakes fish is so high that the federal government has banned commercial fisheries there. And yet the manufacture of PCBs has been banned for 30 years. So where are they coming from?”
Keri Hornbuckle, professor of Civil and Environmental Engineering

Text by Jean Florman

When Keri Hornbuckle talks about her research on the fate and transport of pollutants in the Great Lakes, she leans forward, gestures broadly, and begins to pepper her speech with words like “opportunity,” “pride,” and “public good.” The professor of civil and environmental engineering and newly minted departmental executive officer of the Department of Civil and Environmental Engineering articulates an explicitly humanistic vision of the 21st-century engineer.

“Whether it’s designing stronger buildings, more effective water treatment, safer roads and bridges, or environmentally friendly fish ladders, all civil engineers work for the public good,” says Hornbuckle, recently appointed Robert and Virginia Wheeler Faculty Fellow. “While each individual faculty member must decide his or her own research mission, we still share a fundamental commitment to improve the lives of others.”

Hornbuckle’s own commitment to the common good is reflected in her research on persistent organic pollutants, including the synthetic musk fragrances added to many household products, fluorinated compounds used as surface protectants such as Scotchgard™, and polychlorinated biphenyls (PCBs), a class of about 200 chemicals used widely in the manufacture of paints, caulking compounds, and electrical transformers. All these chemicals are common contaminants in surface water, and PCBs in particular have been linked to carcinogenic effects in humans.

In 2006 Hornbuckle and other researchers—16 from The University of Iowa and three from other schools—formed the Iowa Superfund Basic Research Program (isbrp) to study the consequences of atmospheric sources and exposures to PCBs. The team is attempting to determine the sources, transport mechanisms, distribution, and environmental exposure of PCBs as well as their metabolism and toxicity in humans and other animals. The group also will research novel methods of phytoremediation—the use of plants to clean contaminated sites. Funded by a $12 million ($18 million including indirect costs), four-year grant from the National Institute of Environmental Health Sciences (National Institutes of Health), the program focuses on PCBs associated with contaminated bodies of water, former industrial sites, and atmospheric sources.

“The project harnesses the expertise of researchers from an array of disciplines to tackle a complex environmental, health, and engineering problem,” Hornbuckle says about isbrp, which is directed by Professor of Occupational and Environmental Health, Larry Robertson. “Existing data indicate that PCBs and other semi-volatile pollutants can be found in the air of many big cities, including Chicago,” Robertson says. “But where these pollutants come from, how much of them people breathe, and the impact of exposure are challenging questions.”

Six isbrp research teams focus on individual but related research problems, including the genetic impact of PCBs in lab rats, the processes by which humans inhale and metabolize PCBs, and whether poplar trees can be used to clean up sites contaminated by PCBs. Hornbuckle and her team of two postdoctoral fellows, three graduate students, and two undergraduate students are conducting a major field study to determine the prevalence, distribution, and sources of atmospheric PCBs in the Chicago area. Hornbuckle believes that atmospheric modeling will provide a critical key to answer those research questions.

“The level of these toxins in the Great Lakes fish is so high that the federal government has banned commercial fisheries there,” Hornbuckle says. “And yet the manufacture of PCBs has been banned for 30 years. So where are they coming from?”

Her answer: “off-gassing” into the atmosphere from the soil of former production and dump sites. Like many large cities, Chicago is riddled with sites—some large, but many small—where paints and other PCB-rich products were manufactured or disposed of from the 1930s until the mid-1970s, when the Environmental Protection Agency (EPA) banned their production. Although the EPA can dredge and seal sites that are known to be contaminated, many sites remain unidentified and continue to throw PCBs into the atmosphere. As the atmosphere moves around the globe, so, too, do the pollutants it carries, contaminating water sources as they go.

“Polar bears exhibit considerably elevated concentrations of PCBs,” Hornbuckle says, “even though they of course live nowhere near industrial operations. These chemicals tend to concentrate particularly well in cold water, where they are taken up by the fish, which are eaten by the polar bears.”

The PCBs in Great Lakes fish also come from the atmosphere. Hornbuckle notes that left to its own devices, water will release PCBs, so “if we can stop the atmospheric source of PCBs, the Great Lakes will cleanse themselves quickly.”

But researchers must first identify the sources of the PCBs. Using an innovative sample technique, Hornbuckle’s team will collect more than 2,000 air samples during the four-year study.

“PCBs are measured in air around the world,” she says, “but it’s expensive to install and operate a single monitoring device in one place. So we designed and installed devices on two mobile health clinic vans that visit 40 Chicago area public schools each month. Because the vans move around, we’ll get better geographic range, as well as increased sample size.”

Describing this novel idea as “a real breakthrough,” Hornbuckle adds that isbrp epitomizes her vision of good science. It is hard to believe, then, that years ago she came very close to abandoning PCB research entirely.

After earning a Bachelor of Arts degree in chemistry from Grinnell College (1987), the Cedar Rapids, Iowa, native worked for a year analyzing PCBs as a lab technician. Far from challenging the young woman who had a penchant for math and science, lab work bored her. “Analyzing PCBs was a real pain,” Hornbuckle says. “And at the end of the year, I swore I would never have anything to do with them again.”

The experience, however, did allow her to observe environmental engineers solving real-world problems, collecting and analyzing data, talking to clients, and conducting fieldwork—all of which intrigued her. Her mentor at the University of Minnesota was working on PCBs in the Great Lakes and her graduate studies in environmental engineering (Ph.D. 1996) gave her the opportunity to apply the full panoply of critical thinking skills to tease apart real problems and create real solutions.

“I had a fantastic experience apprenticing in graduate school,” Hornbuckle says. “Now that I’m a professor myself, I understand that one of the great privileges of being a faculty member is serving as a mentor to students.”

Hornbuckle’s latest role as department executive officer for civil and environmental engineering has given her another new perspective on the discipline, particularly in light of the collegiate reaccredidation process, which begins with departmental self-appraisals and includes a site visit from members of the accreditation team in 2008.

“I’ve thought a lot about who we are at Iowa and where the department and the college should be heading,” she says, “and one of the things we must do is find a way to tell our success stories better. “And, of course, we focus our efforts on research for the public good—something we must continue to say loudly and often.”