What do shark teeth have to do with Indiana's groundwater? Researcher digs for answers

Shark teeth buried in the sands of Florida’s warm sunny beaches and new lab equipment at Indiana University are helping a Hoosier geologist dig into research that could explain dangerously high fluoride levels in some Indiana groundwater.

Tracy Branam, a research scientist at the Indiana Geological and Water Survey, began analyzing groundwater in southern Indiana in the late 1980s as part of his doctorate degree.

During Branam’s investigation he discovered fluoride levels exceeding federal drinking water standards and set out to discover what the cause could be. In Indiana, most groundwater as well as surface water, has a fluoride concentration of 0.1-0.2 milligrams per liter, which is well below the U.S. EPA’s standard of 4.0. The high fluoride levels, he noticed, seemed to only occur in samples taken from at least 200 feet deep.

Branam was aware of similar research in South Carolina that indicated fluoride in the water came from a specific mineral in fossilized shark teeth called apatite and wanted to see if that could be a factor in his Indiana water samples.


The research is important because certain levels of fluoride in drinking water can be beneficial to dental health, reducing the ability of plaque bacteria to produce acid and damage teeth. But long-term exposure to high levels like those Branam found could put adults at higher risk of bone fractures. Children are even more likely to be adversely affected, he said, particularly their teeth during the formative period.

Branam wanted to investigate further, but in 1994 oversight of the IGWS was shuffled from the Indiana Department of Natural Resources to a research institute within Indiana University. With the move funding dried up for some projects, including his fluoride research. To move forward, he’d have to find help from outside funding.

“I submitted my proposal to federal government agencies and bureaus, including EPA and Department of Health, but at that time they were not interested in groundwater studies as much as surface water research,” Branam said.

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“Thus ended my dissertation project and my PhD," he said, "but my desire to still conduct this research never faded.”

For the next two decades, Branam focused his research on treatment systems for abandoned coal mine sites and conducted groundwater surveys in other parts of the state, but he still kept up with research on fluoride in groundwater.

During this time, Branam and his wife would visit Venice, Florida, and collect shark teeth. One beach, called Caspersen, is known as the shark tooth capital of the world due to the abundance of teeth found there. The town even hosts an annual Shark Tooth Festival each spring. The teeth the couple found there were added to those his mother had previously collected from Florida.

As Branam’s groundwater research simmered on the back burner, IGWS went through a changing of the guard.

New director brings new opportunities

Six years ago, Todd Thompson became the director of the institute that researches and collects geologic data and information related to energy, mineral and water resources in the state. The survey funding comes partially from a biennial state appropriation as well as federal and state grant programs.

Thompson brought a different view on how to conduct research. Generally, there are two concepts when it comes to research requiring specialized lab equipment, Thompson explained. You can have your own equipment and conduct work in-house or send samples out to private labs.

He preferred, when feasible, to keep the work in-house. But there was a problem.

“A lot of our lab equipment and field equipment was long in the tooth and we were not able to do what we needed,” Thompson said. “One important thing I wanted to do was get back into doing our own processing of data and material.”

Under Thompson’s guidance, the survey’s building went through some renovations, brining lab designs from the ‘50s and ‘60s up to date. That made the space more flexible for modern day equipment. Early on, a piece of lab equipment could be as big as a refrigerator, leaving little room for multiple pieces. Today’s equipment could be as small as a toaster, providing more room in each lab for various machines.

“I like to brag,” Thompson said, “and say we went from mid-20th century to state of the art 21st century labs.”

Thompson and the IWGS first brought in equipment to help researchers determine the age of quartz. Next came a machine called X-Ray Fluorescence that provides an analysis of the elements within a sample to determine chemical compounds.

Another recent addition, an instrument called an autotitrator, replaced a manual machine that only worked sporadically. The new equipment measures different aspects of groundwater, including hardness and fluoride levels. It also can determine the amount of apatite present in samples.

The new autotitrator will allow Branam to revive his decades-old research into fluoride and groundwater. More than 25 years after his research began, he will finally have a chance to put his shark-tooth theory to the test.

But what do sharks teeth have to do with water in Indiana?

Fossil records show researchers have found fossilized shark teeth throughout a good part of the state, Branam said. About 300 million years ago, during the Pennsylvanian age, part of southern Indiana was a marine environment while the northern part of the state was land. It was then that sharks swam in what we today call the Midwest.

That area filled in relatively quickly — at least in geological terms — with sediment, which Branam explained preserved those fossils quite well.

Even though Indiana is home to these fossilized shark teeth, it’s impractical to use them in the lab as they’re very fragmented and the core samples geologists pull from those depths are small. So to test his long-held hypothesis, Branam will use a mortar and pestle to crush some of his own fossilized shark tooth collection.

In the simplest terms, he plans to create synthetic groundwater that mimics those samples he found below 200 feet. Then, with the new equipment and a dash of powdered shark tooth, he'll conduct tests to see if fluoride levels change.

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But first, sort of like breaking in a new vehicle, Branam said the new lab equipment needs to be calibrated. That’s what he's working on now. Once the machinery is dialed in, he will begin working to prove or disprove his hypothesis.

“You don’t really know (the results) if nobody’s tested this,” Branam said. “I just want to test and verify and make sure we are correct.”

Karl Schneider is an IndyStar environment reporter. You can reach him at Follow him on Twitter @karlstartswithk

IndyStar's environmental reporting project is made possible through the generous support of the nonprofit Nina Mason Pulliam Charitable Trust.

This article originally appeared on Indianapolis Star: Are shark teeth introducing fluoride to Indiana waters?