The people most at risk, however, are among the least likely to be aware of the problem.
"There is a subpopulation that eats more fish than the general population," she said. "They're the ones doing the sustenance fishing."
As part of her senior thesis, the Mount Holyoke College student from Augusta is surveying and testing anglers to measure how much mercury they have absorbed from eating fish -- and also trying to determine whether government consumption advisories are effective.
Her studies focus on the portion of the river from New Savannah Bluff downstream.
So far, Smith has located almost two-dozen anglers who eat plenty of fish, and who were willing to donate hair samples that will be tested for mercury.
"They usually think its a natural thing, that fish are healthy," she said. "A lot of people eat catfish and mullet from the river, but bass are the most common."
She has posted fliers in restrooms and fish-cleaning stations at New Savannah Bluff Park, hoping to find even more subjects.
"I'm asking them things like, how much fish they eat, the frequency of meals, how big the fish are and if they are sharing the fish with someone who is or may become pregnant," she said. "I'm also asking them what they know about fish advisories."
Mercury is categorized as a persistent bio-accumulative toxin because it can build up in the tissue of fish or animals that ingest it, and it can cause an array of health problems.
Georgia and South Carolina have ongoing advisories suggesting limits on the number of meals per week anglers should consume from Savannah River fish.
Those limits are clearly exceeded in some cases, Smith said.
"One thing that has surprised me so far is how much fish some of the fishermen eat," she said. "I didn't know some people actually eat fish for breakfast."
As a medical anthropology major with an emphasis on maternal and child health, the impact of mercury in fish on pregnant or nursing women is particularly important to explore, she said.
Smith is no stranger to mercury issues in the Savannah River.
As a Davidson Fine Arts Magnet School student in 2006, her science fair project that involved testing of sediment near Olin Corporation's Augusta plant yielded elevated concentrations of mercury.
The resulting inquiry from Georgia's Environmental Protection Division led to a $3 million cleanup plan that involved damming up Olin's drainage canal and filling it in with clean dirt to prevent the spread of mercury sediment.
Reach Rob Pavey at (706) 868-1222, ext. 119, or email@example.com.