Water Resources Research
Strontium Found in
Eastern Wisconsin Wells
Young children in high-strontium areas at risk
By Marie Zhuikov
Hundreds of millions of years ago, geologic forces squirted massive layers of hot salty water underground through aquifers from Michigan to Wisconsin. As the hot brine raced along, it carried dissolved minerals, such as arsenic, iron, strontium and sulfur. Just like when hot salt water cools and forms crystals, when the hot brine came into contact with cooler rocks, it either mixed with other fluids—diluting itself—or cooled and deposited its minerals for later discovery by enterprising miners or scientific researchers.
One such ancient hydrothermal brine migration occurred in eastern Wisconsin, and University of Wisconsin Water Resources Institute researchers have discovered it is impacting drinking water quality for thousands of people. The element they found is strontium. Not to be confused with the radioactive version that is a byproduct of nuclear fission, this type of strontium is contained within a mineral known as celestine, which is white or light blue in color. Strontium dissolves in water and has no taste or odor.
The study, by John Luczaj, associate professor in the Department of Natural and Applied Sciences at the University of Wisconsin-Green Bay, with UW-Green Bay graduate student Joseph Baeten and Associate Professor Michael Zorn, involved collecting 115 water samples from municipal and private wells in Brown and Outagamie counties near Green Bay.
In preliminary findings, 73 samples (63 percent) contained strontium levels higher than the Environmental Protection Agency’s lifetime health advisory limit of 4 mg/L, which means people drinking the water over the long term face an increased risk for health problems. Six water samples (five percent) contained levels above 25 mg/L, which exceed the short-term exposure levels identified by the EPA. Children who drink the water for more than between one and 10 days face an increased risk of developing health problems.
The researchers also determined that the source of the strontium is natural. In addition to the water samples analyzed, they examined the chemistry of more than 100 rock samples collected during other studies. Their analysis showed the primary source of dissolved strontium in the groundwater originates from celestine and possibly strontianite, another mineral.
On the periodic table, strontium’s upper and lower neighbors are calcium and barium. Strontium’s similarity to calcium and its behavior in water is what makes this mineral problematic for humans, especially children.
“When children’s tooth enamel and bones are developing, exposure to strontium can cause tooth mottling and strontium rickets,” said Luczaj.
While tooth mottling is mainly a cosmetic issue, causing white spots or brown stains to be deposited on the teeth, rickets can affect bone development and quality of life. The body mistakes strontium for calcium and tries to incorporate it into developing bones. This softens the bones, leading to bowed legs, widened wrists, skull abnormalities, spinal deformities, and an increased likelihood for bone fractures.
Luczaj has suggestions for readers in the areas that have high strontium. (See map.) “If they are drinking water-softened water or reverse-osmosis water, there’s probably little strontium in it,” he said. “But if they have young children and they are in the high-strontium area, they should definitely have their water tested.”
Although evaluating the distribution and sources of strontium in Brown and Outagamie counties was the focus of the study, the researchers also tested several household samples of water treated with water softeners and found them effective at removing 97 percent of the dissolved strontium. Municipal systems were less effective in removing strontium because they are designed to remove radium. In two municipal samples, 57 percent and 74 percent of strontium were removed.
Dennis Rohr, a science teacher at Seymour High School, encourages people to be aware of strontium in the water supply. “Many people think that when the water comes out of their tap, it’s clean and fresh. If they don’t smell anything bad, they assume everything’s okay,” he said. Rohr was among the first to realize that strontium was an issue in local drinking water.
“Our study confirms there’s a significant problem in eastern Wisconsin for strontium levels in drinking water,” Luczaj said. “The public needs to be aware of this, and we recommend that a strontium advisory area be established for the region.”
According to the Outagamie County Public Health Division, rickets is not a reportable illness, so data on its prevalence are not available.
To learn more, read the Wisconsin Department of Health Services’ “Strontium in Drinking Water” fact sheet. (dhs.wisconsin.gov/eh/Water/strontium.htm)
Why Look for Strontium?
Researcher John Luczaj said people have known there is a significant amount of strontium in the water since the 1950s, but the issue simply fell by the scientific wayside.
Luczaj credits Dave Johnson, a hydrogeologist with the Wisconsin Department of Natural Resources for resurrecting the investigation. Johnson credits Dennis Rohr, a science teacher at Seymour High School. Rohr credits Michael Hanton, general manager with Clean Water Testing in Appleton.
In 2007, Rohr and his high school science club students were awarded a prestigious Toyota TAPESTRY grant to study the connection between 23 heavy metals that are found in well water along with naturally occurring arsenic, a known contaminant in the area. “Often, other heavy metals increase when you have increasing amounts of arsenic in the water,” Rohr said. He worked with Hanton’s company, which provided professional testing of the water samples.
“Hanton had tested water in Brown County and suggested we get samples from there, and that’s where we discovered the high levels of strontium,” Rohr said. “It was our grant that found it, but it was Hanton’s insight that led us to it. I really can’t take credit for it.”
In the meantime, Johnson had seen the mineral celestine in local quarries and heard about strontium levels in water in conversations with Rohr. “Then Luczaj came to me looking for an issue that needed research. I suggested he look at strontium and told him about Rohr’s findings. I didn’t do anything other than that,” Johnson said.
No matter whose idea it was, the project turned out to offer valuable insight into Wisconsin’s water quality.