More than 16 million Americans get their drinking water from public systems contaminated with industrial chemicals known as PFASs or PFCs, and at levels high enough to concern the U.S. Environmental Protection Agency because of the risks to public health.
Although the problem is spread across 30 states (and three territories), three-fourths of the contaminated systems are in just 13 — including Minnesota. For more than 6 million people, the concentrations are at or above the EPA’s recommended safety maximum.
Those are the sobering conclusions of new research from the Harvard School of Public Health that attracted significant if scattered national coverage last week, as well as brief treatment locally. (Bring Me The News gathered a useful selection of excerpts and the Star Tribune published most of a short Washington Post story.)
PFASs have been linked to a range of medical problems from birth defects and endocrine disruption to immune-system suppression, from obesity and elevated blood cholesterol to cancer.
They have become widely dispersed over six decades of proliferating use, and are very long-lived in both the environment and the human body. There is no good way as yet for getting them back out of drinking water.
In May 2015, an international group of 200 scientists called for major new research into the health effects, as well as precautionary restrictions on their use until the risks were better understood.
However, most remain essentially unregulated in the U.S. in regard to environmental exposure, if by “regulated” we mean that water systems delivering unsafe amounts of a toxin must either remove it, dilute it or switch to a less contaminated source. An exception is certain “long-chain” varieties that were banned a dozen years ago after successful lawsuits forced the EPA to act.
This lack of protection may surprise readers familiar with the long legal struggle over underground plumes from the 3M Co.’s manufacturing operation in Cottage Grove — or, more recently, the settlement between the Minnesota Pollution Control Agency and a St. Louis Park metal-plating firm, Douglas Corp., over runoff contaminating Lake Calhoun.
But when it comes to drinking water contamination — the most significant source of human ingestion — there still are no legal limits on the chemicals (although some believe the EPA may be moving in that direction). There is only a level at which the EPA requires their presence to be reported, and a higher limit that it recommends as a safety maximum but does not enforce.
PFAS compounds share the special and useful property of repelling both water and oil, and are now found in more products than we have space today to list, from fire suppressants and flame retardants to cardboard coatings, from cleaning products and paints to nonstick cookware linings such as Teflon.
They are typically known by their abbreviations, which form a thick alphabet soup; as a group they are often referred to as PFASs (for polyfluoroalkyl or perfluoroalkyl substances), and sometimes more simply as PFCs (for perfluorinated chemicals).
For the new study, published Aug. 9 in the journal Environmental Science & Technology Letters, the Harvard team looked at six specific members: Perﬂuorobutanesulfonic acid (PFBS), perﬂuorohexanesulfonic acid (PFHxS), perﬂuoroheptanoic acid (PFHpA), perﬂuorooctanoic acid (PFOA), perﬂuorooctanesulfonic acid (PFOS), and perﬂuorononanoic acid (PFNA).
The EPA has only been tracking their new presence in water supplies since 2013, when it lowered the recommended maximum safe level to 70 parts per trillion (70 nanograms per liter), and Harvard scientists examined the numbers for the years 2013 to 2015. A highly readable summary in the Harvard Gazette lays out the key findings concisely:
The study found that PFASs were detectable at the minimum reporting levels required by the EPA in 194 out of 4,864 water supplies in 33 states across the United States. Drinking water from 13 states accounted for 75 percent of the detections: California, New Jersey, North Carolina, Alabama, Florida, Pennsylvania, Ohio, New York, Georgia, Minnesota, Arizona, Massachusetts, and Illinois, in order of frequency of detection.
Sixty-six of the public water supplies examined, serving six million people, had at least one water sample that measured at or above the EPA safety limit of 70 parts per trillion (ng/L) for two types of PFASs, perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA). Concentrations in some locations ranged as high as 349 ng/L for PFOA and 1,800 ng/L for PFOS.
“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,” said Elsie Sunderland, senior author of the study. …
Linking contaminants to sources
In addition to identifying water systems with high contamination slevels, the Harvard team attempted to correlate them with probable sources of PFASs, which fall into three main categories: industrial plants that make them or apply them to products, military bases or civilian airports where the firefighting products are used in training, and wastewater treatment plants which, somewhat perversely, tend to concentrate them because the compounds resist removal by currently available methods.
This part of the study was complicated because the intake points for many large public water systems are secret, for national security reasons, which meant researchers had to rely on geographic matching at the level of ZIP codes. This sometimes led to imprecise attribution of contamination, they said — for example, in “systems that draw water upstream from point sources, such as Minneapolis and St. Paul in Minnesota.”
There also was no way to factor in additional sources beyond the main three types, such as landfills where PFASs used in, say, food packaging are leaching into groundwater, or farmland where sludge produced in wastewater treatment is spread as fertilizer.
In general, systems that drew their supplies from groundwater seemed twice as likely to have PFAS contamination than those that drew from lakes and rivers. The association with different contamination sources was complex, but researcher Xindi Hu summarized it neatly in an interview with Think Progress:
Researchers also found that being near a manufacturing site makes a public water system 81 percent more likely to have elevated levels of PFAS pollution. “That’s a big increase,” said Hu. Military sites carry a 35 percent increase. She said, while wastewater treatment plants bring a much lower risk of some 2 percent. Proximity to an airport brought no statistically significant risk.
As for do-it-yourself treatment, the Harvard Gazette quotes Hu as explaining that activated carbon filters and reverse osmosis are not yet up to the task of removing PFASs, although some show promise. No technology for large-scale treatment is on the near horizon.
Hu also pointed out another significant limitation of the study: Because EPA’s tracking program doesn’t concern itself with contamination of private wells, which provide water for 44.5 million Americans, or of the smaller public systems that serve another 52 million, nearly 100 million of us are exposed to PFASs at levels that no one has begun to quantify.
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The full paper, “Detection of Poly- and Perfluoroalkyl Substances (PFASs) in U.S. Drinking Water Linked to Industrial Sites, Military Fire Training Areas, and Wastewater Treatment Plants,” can be read and downloaded here without charge.