Monday, March 28, 2016
In a toxicology lab at Southern Illinois University Carbondale, a team of scientists is getting ready to test 50 sediment samples collected across the Northeast. The samples are slated to arrive courtesy of the U.S. Geological Survey (USGS) this summer, and their coming will set in motion a flurry of testing, quality control, and lab-to-lab communication.
The results will reveal whether a relatively-new testing method using Tenax resin can help scientists and natural resource managers more accurately predict the threat of pyrethroid insecticides to aquatic life. The approach makes it possible to hone in on the insecticides' bioavailability—the amount that could enter an animal's system instead of just how much total chemical is in the waterway—at a fraction of the time and cost of more traditional monitoring methods.
But first, the SIU researchers need to learn how to apply the Tenax technique to pyrethroids found in sediment.
Kara Huff Hartz, an associate scientist working in Michael Lydy's lab, has worked as an environmental and analytical chemists for years. Her experience with toxicology testing broadly and Tenax specifically, though, began in December.
"It definitely takes a little shift," she said. "It's more of a culture and a language shift. The principles are the same, and I have made shifts like this before. That's how science works these days. We're all overlapping and interdisciplinary.
I see myself as working between Dr. Lydy and the team. I will be in the lab making sure things are getting done on time and the quality assurance is good. Then I will be the one bringing the data back to Dr. Lydy."
Timing is especially key in this project. According to Federico Sinche, a PhD student working with Lydy, pyrethroids in the samples may break down quickly enough to affect their results.
"We have to make sure the Tenax is capturing the amount available for uptake by animals before degradation has taken place," he said. "The temporal component is a big one with this project. We will have to keep testing the sediment to see if biodegradation has occurred and keep track of the rate of degradation."
"And we're trying to coordinate all this with five or six other USGS labs," Huff Hartz added. "We are trying to do direct comparisons, so we need to start on the same day to account for the degradation issue."
Despite these challenges, Sinche and Huff Hartz say they are excited to tackle the three-year project—albeit for different reasons.
Sinche is no stranger to the Tenax technique, but his work till now has primarily focused on polychlorinated biphenyls (PCBs) and how their bioavailability is affected by saw dust, black carbon, and other types of organic matter found in sediment. Commonly found in electrical equipment, motors, and hydraulic systems before they were banned in the 1970s, these chemicals are unusually stable and can persist in the environment for decades. As such, they're a far cry from pyrethroids and other emerging contaminants.
"Learning more about pyrethroids will be interesting, especially given how wildly-used they are in the U.S." Sinche said. "I am excited to see how well we will be able to determine the bioavailable concentrations."
For Huff Hartz, it's the method that holds the most excitement.
"This is a very different analytical method for me. It enables us to step away from a biological endpoint and do something that is a little more reproducible and more widely applicable. Chemicals behave the same way. And they won't die on you. So this seems like a nice way to use chemistry to get answers to biological questions."
To learn more about pyrethroids, bioavailability, and the team's USGS project, check out UpClose with Michael Lydy.