CGRER member investigates synthetic fragrances, freshwater mussel decline

Not to scare you, but they’re everywhere. Misting from perfume bottles. Drifting in the air. Dripping down your bare leg and spiraling down the shower drain.

And, contrary to what most would believe, they may not be so harmless.

 With her analysis of the Great Lakes, researcher Keri Hornbuckle has spent roughly eight years studying how common fragrances found in everything from detergent to body spray affect the world around us.

“Fragrances can be non-biodegradable,” said Hornbuckle, a civil and environmental engineering professor at the University of Iowa and a member of the Center for Global and Regional Environmental Research (CGRER) in Iowa City. “They retain their smell a long, long time. You can ship them all around the world, put them on the shelves at a grocery store and five years later they still smell the same. Then, when they get in the environment, they degrade slowly or not at all. So if they do anything, they continue to do it.”

To discover the effects of fragrances, Hornbuckle worked with Theresa Newton, a fishery biologist for the U.S. Geological Survey. Newton specializes in the conservation of freshwater mussels, organisms that line the floors of bodies of water. In some riverbeds, Newton has found anywhere from 10 to 100 mussels per square meter of river bottom. Despite these high numbers, mussel populations continue to decline in the U.S., with approximately 70 percent of mussels either threatened or on the verge of extinction.

 These two trends — the upsurge of products featuring fragrant compounds and the waning of mussel populations — formed the backbone of the project. While other factors such as urbanization and habitat degradation account for mussel loss, most mussel biologist would agree that contaminants such as fragrances contribute to the reduced population, according to Newton.

For the tests, Hornbuckle and Newton captured pregnant mussels from Iowa’s Boone River and placed them in beakers containing various concentrations of fragrances.

“After working with these studies long enough, some of my graduate students know the respective smells of those two chemicals,” Hornbuckle said. “They could walk by a dryer and say ‘Oh, that’s AHTN right there.’”

 

“The concentrations where we observed adverse effects on mussels were much higher than are normally seen in surface waters but close to the concentrations of fragrances in wastewater effluent,” Hornbuckle said.

These adverse effects included stunted growth and reproductive damage. Newton said that while the fragrance concentrations were higher than what most mussels are exposed to, most mussels live anywhere from 30 to 100 years, leaving much room for longer-term effects through prolonged exposure. The population decline has had one primary result: a loss of biodiversity.  

“Mussels are habitat,” Newton said. “They provide habitat for other insects. Where you have mussel beds you have insects, where you have insects you have fish, where you have fish you have fishery.”

Hornbuckle and Newton looked at two primary fragrances in their researching, the compounds HHCB and AHTN. Such fragrances, according to Hornbuckle, appear in mostly inexpensive products such as deodorants and shampoos.

 

For further information contact:

Keri Hornbuckle: 319-384-0789

Theresa Newton: 608-781-6217

Soheil Rezayazdi: 319-331-4013