Pennsylvania ranks second in U.S. natural gas production, accounting for about one-fifth of U.S. output in 2024, and has one of the most extensive histories of energy extraction in the country. A team of researchers from Penn State is trying to better understand the environmental impacts of these sites - specifically, if fracking is increasing radium content in local drinking water.
According to a new study recently published in Environmental Science and Technology, the answer is not a simple yes or no. The team recorded higher salt concentrations in samples taken closer to energy extraction sites, indicating that natural gas drilling might contribute to elevated salinity in the ground, in turn releasing radium - a radioactive chemical - and other heavy metals trapped in the surrounding rock into drinking water.
The team connected with homeowners across Washington and Greene Counties in southwestern Pennsylvania to collect samples from 91 private water wells and springs, testing if nearby fracking-based oil and gas operations contributed to higher concentrations of radium in the groundwater. The team found elevated radium content was associated with some drilling operations, as well as higher salt concentrations in the water. However, the recorded upticks in salinity and radium could also be associated with a host of other environmental factors aside from energy extraction.
Radium can be found in the ground at very low concentrations everywhere in the environment, explained Nathaniel Warner, associate professor of environmental engineering at Penn State. However, drinking water with elevated radium levels can pose serious health problems, including an increased risk for cancer.
"Radium has a chemical makeup sort of similar to other metals like calcium, so it follows in the body where those chemicals naturally go," Warner explained. "Your body says, 'I need calcium for my bones, so I'm going to send some calcium there, along with some radium that I'm drinking.' Over time, that radium will decay, releasing particles and energy that will damage your cells."
Oil and gas drilling traditionally involves mining into oil or gas pools miles underground. However, as these wells have depleted over decades of use, unconventional oil and gas (UOG) drilling has emerged to access previously untapped fuel reserves. UOG uses a process known as fracking to extract fuel from the ground, shooting a high-pressure mixture of water, sand and chemicals to break apart rock horizontally from the initial borehole.
"The big difference is really the scale of the operation - the amount drilled and the amount of water used to frack and break apart the rock," Warner explained. "In UOG, you're drilling miles down, but then also drilling miles out horizontally. With that said, there are a lot of similarities in the impacts you might see associated with UOG and conventional operations."
Previous research by another team at Penn State had associated elevated "hotspots" of salt content near UOGs, particularly in the Northern Appalachian Basin, stretching from Alabama to upstate New York. According to Warner, these areas of elevated salinity can carry up to 200% higher risk for radium-related health effects, because introducing salty chemicals can knock existing radium off surrounding rocks and into underground freshwater reservoirs.
However, little research had examined whether these drilling operations were specifically responsible for increased radium content in groundwater. Previous studies had focused on upticks in deep brine salts like sodium, chloride, barium and strontium in areas that had experienced oil or gas spills, but radium measurements were notably absent.
The team began by reaching out to homeowners living within different distances to UOG operations, specifically within about half a mile, just under two miles and slightly more than three miles. Embarking on several field campaigns to collect samples of drinking water from the homes, the researchers directly tapped into residents' private wells before the water was exposed to any type of treatment system, such as faucet filters. Once the samples were collected, they returned to the lab and analyzed the samples' radium and salt content.
