Environmental Experts Speak: UI’s Keri Hornbuckle discusses PCBs and other toxins

Keri Hornbuckle is a professor in the University of Iowa’s Department of  Civil and Environmental Engineering. She is also a member of the Center For Global & Regional Environmental Research. Much of Hornbuckle’s research involves measuring and studying toxins in the environment. She recently discussed some of her current projects with Iowa Environmental Focus.

Hornbuckle began by giving an overview of her work:

“My work is part of the Iowa Super Fund Research Program, which focuses on PCBs – in particular, airborne PCBs or potentially airborne PCBs. I’ve been interested in [questions about PCBs] for about 25 years. I did my PHD work on questions like, ‘How do these chemicals get into the air?’ and, ‘What drives the processes where these chemicals are distributed worldwide?’ I’m also a Great Lakes researcher partially because these chemicals are a big problem in the Great Lakes. They accumulate in fish to a level that’s possibly harmful to the people eating the fish. Airborne PCBs are a problem because the surface area of the Great Lakes is large enough that airborne PCBs deposit into the Great Lakes and end up in fish, and therefore in humans. It turns out that PCBs in the air drive many of the potential human hazards associated with long-banned chemicals. A particular focus of this long-term project is figuring out where they’re coming from and how we can fix it.”

Next, Hornbuckle detailed her research on siloxane chemicals:

“We’re interested in toxic chemicals or potentially toxic chemicals in natural systems. That is, we’re interested in them when they’re in places where they shouldn’t be, or places where they can no longer be controlled very easily. PCBs are one of the chemicals we’re interested in, but not the only ones. We’re also interested in chemicals that are in large production, which may not be banned at all, and aren’t necessarily toxic. For instance, personal care products are interesting to me. I’ve been studying synthetic fragrances in the environment. Most recently we started looking at siloxanes, which are used in some industrial products, but also in deodorant and hair care products. These kinds of chemicals are interesting because they have no natural sources and they’re nearly non-biodegradable. So, they get into the environment and decay very slowly, and in the meanwhile they have the potential to exert some hazards to ecosystems. Fragrances aren’t harmful to humans, but there does appear to be some organisms that are vulnerable to them and it affects their ability to survive in nature. For example, we studied the effect of fragrances on fresh water mussels from Iowa rivers and it showed that the larva grow slower, move less and die faster with exposure to higher concentrations of fragrances.”

The interview concluded with Hornbuckle describing her recently published research project on PCBs in the Indiana Harbor and Ship Canal:

“We did a series of field studies in the Indiana Harbor and Ship Canal, which is in the southwest corner of Lake Michigan. Running through that town is a human-made canal. The canal was created around the turn of the last century to support expansion of industrial development in that area. It was hugely successful, and it is still a very busy harbor and canal. There are billions of dollars of economic activity that requires barges to go in and out of that harbor and canal system. Over time the canal filled with sediment, and it needs to be dredged in order for the barges to get through. Our study looked at the presence of PCBs in the sediments, which were going to be dredged. There are PCBs on the top of the sediment at the sediment-water interface, but as you dig down deeper in the sediment the concentrations of these chemicals get higher and higher. We hypothesized that after the dredging occurs, a higher level of PCBs will be left on the surface of the sediment. We already know from previous studies that the PCBs diffuse from the top sediment into the water, and from the water into the air. Exposing this amount of PCBs from dredging could lead to a very long-term, very large increase in PCB emissions.”

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