High levels of chemicals shown to cause cancer and other health problems are laced in the drinking water of six million Americans, according to a team of researchers from Harvard’s School of Public Health. Their findings, published in the journal Environmental Science & Technology Letters, reveal those living near industrial sites, military bases, and wastewater treatment plants are most at risk for drinking contaminated water.

Researchers focused on searching for six different types of widely-used chemicals polyfluoroalkyl and perfluoroalkyl (PFASs) in 36,000 water samples collected by the Environmental Protection Agency (EPA) from 2013-2015. As a result of chemical sludge leaking into the groundwater, roughly six million Americans across 33 different states drank water that measured at or above the EPA's safety limit, with the highest levels found in California, New Jersey, North Carolina, Alabama, Florida, Pennsylvania, Ohio, New York, Georgia, Minnesota, Arizona, Massachusetts, and Illinois. And those who lived near industrial sites were at the greatest risk for consuming chemical discharges from plants that utilize PFASs in their products.

"For many years, chemicals with unknown toxicities, such as PFASs, were allowed to be used and released to the environment, and we now have to face the severe consequences," said the study’s lead author Xindi Hu, a doctoral student in the department of Environmental Health at Harvard Chan School, in a statement. "In addition, the actual number of people exposed may be even higher than our study found, 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."

Over the last 60 years, manufacturers have been using chemicals PFASs in food wrappers, pizza boxes, backpacks, clothing, and pots and pans, ultimately increasing Americans' exposure. PFASs were designed to resist high temperatures and remain durable; however, the human body has a maximum toxic threshold that these manmade chemicals currently exceed.

According to the Centers for Disease Control and Prevention, aside from causing cancer, PFASs have also been linked to increased cholesterol, changes in the immune system, decreased fertility, developmental delays in unborn babies and abnormalities in growth, as well as learning and behavioral problems in children.

The study’s senior author Elsie Sunderland, an associate professor at Harvard, concluded: "These compounds are potent immunotoxicants in children and recent work suggests drinking water safety levels should be much lower than the provisional guidelines established by EPA."

Source: Sunderland E and Hu X, Andrews DQ, et al. Detection of Poly- and Perfluoroalkyl Substances (PFASs) in U.S. Drinking Water Linked to Industrial Sites, Military Fire Training Areas, and Wastewater Treatment Plants. Environmental Science & Technology Letters. 2016.