A toxic chemical used in the controversial drilling practice known as fracking has been detected in the drinking-water supply of Pennsylvania homeowners, according to a paper published Monday in the journal Proceedings of the National Academy of Sciences (PNAS).

According to the Pittsburgh Post-Gazette, the chemical—2-Butoxyethanol or 2BE, known to have caused tumors in rodents—showed up as "white foam," which one researcher "likened to dishwashing suds."

The PNAS study, Evaluating a groundwater supply contamination incident attributed to Marcellus Shale gas development, suggests that drilling fluid escaped the narrow, vertical borehole while crews were first drilling the gas well, and then moved laterally along intermediate depth fractures to the aquifer used as a potable water source.

"This is the first case published with a complete story showing organic compounds attributed to shale gas development found in a homeowner's well," said Penn State geoscientist Susan Brantley, one of the study's authors.

Explaining further, she told Lancaster Online: "This is the first documented and published demonstration of toxic compounds escaping from uncased boreholes in shale gas wells and moving long distances" into drinking water.

In other words, Andy Rowell explained in a blog post for Oil Change International, "the scientists believe that the pollution may come from a lack of integrity in the well which passes through the drinking aquifer and not the actual fracking process below."

Rowell continued:

If this is the case, it reinforces the concerns of communities from the US to the UK that the fracking industry often has to drill through drinking aquifers to reach the shale oil or gas. SCROLL TO CONTINUE WITH CONTENT Never Miss a Beat. Get our best delivered to your inbox.





And many people believe that the issue of well integrity could be the fracking industry’s Achilles heel.

On Twitter, environmental groups and activists said the news confirmed what fracking opponents already know—that the drilling practice is bad for public health and local ecosystems.

Even the oil-soaked government in Pennsylvania says that fracking contaminates drinking water: http://t.co/zpVwa9nD4c pic.twitter.com/jA1QECMSlq — 350 dot org (@350) May 5, 2015

Fracking #chemicals found in PA water confirms what we know: to protect health & communities, we must #banfracking http://t.co/GCIuNQJnEE — Environment America (@EnvAm) May 5, 2015

This is what we have always said. Well casings will fail. Fracking Chemicals Detected in Pennsylvania Drinking Water http://t.co/yYH0wv7zDm — Mark Ruffalo (@MarkRuffalo) May 4, 2015

Just last month, researchers in Pennsylvania discovered that the prevalence of radon—a radioactive and carcinogenic gas—in people's homes and commercial buildings close to fracking sites has increased dramatically over the last decade.