Toxic chemicals associated with cancer and other health issues have been discovered at unsafe levels in the drinking water that supplies 6 million Americans, new research finds.
Researchers from Harvard T.H. Chan School of Public Health and the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) found levels of an industrial class of chemicals – polyfluoroalkyl and perfluoroalkyl substances (PFASs) – exceeded federally recommended safety levels.
“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,” says lead author Xindi Hu, a doctoral student in the Department of Environmental Health at Harvard Chan School and Environmental Science and Engineering at SEAS.
“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,” she adds.
PFASs are a class of man-made chemicals that are widely used to make commercial products more stain-resistant, waterproof, and nonstick – ranging from food wrappers to clothing and pots and pans.
Both chemicals are very persistent in the environment and the human body – that is, they do not break down when exposed to air, water, or sunlight – which means people can become exposed to PFASs manufactured months or years in the past or emitted from production facilities thousands of miles away.
The accumulative nature of PFASs remaining in the body for long periods can lead to adverse health effects. Studies indicate that PFASs are linked to reproductive and developmental, liver and kidney, and immunological effects such as tumors, changes in cholesterol levels, low birth weight, liver tissue damage, obesity, and development of testicular, pancreatic and liver cancers.
Blood sampling data over recent years have shown that exposures to PFASs are decreasing in the U.S. population due to the decline and discontinued use by several major manufacturers. However, the chemicals continue to persist in people and wildlife, with drinking water a primary route for exposure.
Using data from more than 36,000 water samples collected by the U.S. Environmental Protection Agency (EPA) from 2013-2015 in drinking water supplies nationwide, the team observed concentrations of six types of PFASs.
The researchers also looked at industrial sites, such as military fire training sites and civilian airports where fire-fighting foam containing PFASs is used, and wastewater treatment plants.
The plants are unable to remove PFASs from wastewater and discharges by standard treatment methods, which allows for contamination of not only groundwater, but also any sludge that the plants generate, which is often used as fertilizer.
In 194 out of 4,864 water supplies in 33 states across the U.S., PFASs were detectable at the minimum reporting levels required by the EPA.
Drinking water from 13 states accounted for 75 percent of the detections. In order of frequency of detection, they were: California, New Jersey, North Carolina, Alabama, Florida, Pennsylvania, Ohio, New York, Georgia, Minnesota, Arizona, Massachusetts, and Illinois.
Xindi Hu and colleagues found that 66 public water supplies, serving 6 million people, had at least one water sample that measured at or above the EPA safety limit of 70 ng/L for two types of PFASs. Perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) – two kinds of PFASs – were seen at concentrations ranging as high as 349 ng/L for PFOA (Warminster, PA) and 1,800 ng/L for PFOS (Newark, DE).
“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.”
Elsie Sunderland, senior author and associate prof. in both the Harvard Chan School and SEAS
The researchers note that the highest levels of PFASs were located in watersheds near industrial sites, military bases, and wastewater treatment plants where these chemicals are often used.