At least six million Americans in 33 states are being exposed to unsafe levels of industrial perfluorooctanoic acid (PFOA) chemicals in their drinking water, found a study published Tuesday in the journal Environmental Science and Technology Letters.

"Virtually all Americans are exposed to these compounds. They never break down. Once they are released into the environment, they are there."

—Xindi Hu, Harvard University"And the available water data only reveals the tip of the iceberg of contaminated drinking water," said study co-author Dr. Philippe Grandjean of the Harvard School of Public Health to the Charleston Gazette-Mail.

The Washington Post details the researchers' findings:

194 of 4,864 water supplies across nearly three dozen states had detectable levels of the chemicals. Sixty-six of those water supplies, serving about six million people, had at least one sample that exceeded the EPA's recommended safety limit of 70 parts per trillion for two types of chemicals — perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA).

PFOA and PFOS chemical compounds—including C8, popularly known as the Teflon chemical—are extremely dangerous to human health, and despite an EPA advisory released earlier this year and increasing calls for action, research shows they are near-ubiquitous in the United States.

"Virtually all Americans are exposed to these compounds," said Xindi Hu, the study's lead author and a doctoral student at Harvard's Department of Environmental Health, to the Post. "They never break down. Once they are released into the environment, they are there."

Moreover, the study also notes that research suggests "that exposure to these chemicals can make people sick, even at or below the concentration recommended as acceptable under the EPA health advisory," according to the Gazette-Mail.

"The EPA advisory limit ... is much too high to protect us against toxic effects on the immune system," said Grandjean to the Gazette-Mail.

PFOAs are the contentious center of a years-long legal battle against DuPont, which manufactured the chemical for decades—and dumped it into public waterways—despite knowing that it was severely harmful to human health and the environment. Thousands of personal injury cases are currently pending against the chemical giant.

The Gazette-Mail further reports:

DuPont and other companies have agreed on a voluntary phase-out of the chemical, but researchers noted in this week's study that declines in production in the U.S. and Europe have been offset by increases in developing regions such as Asia. Scientists have also been increasingly concerned about chemical contamination of consumer products, and the new study provides important details about the potential threats from waste disposal practices and varying uses of the substances.

The dire situation is a result of decades of weak or no regulations, as Hu remarked to the Harvard Gazette: "For many years, chemicals with unknown toxicities, such as [PFOAs], were allowed to be used and released to the environment, and we now have to face the severe consequences."

"In addition, the actual number of people exposed may be even higher than our study found," Hu continued, "because government data for levels of these compounds in drinking water is lacking for almost a third of the U.S. population—about 100 million people."