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PFAS and Public Water Contamination


A recent article by Julie Turkewitz in the New York Times reports that a group of chemicals called per- and polyfluoroalkyl substances (PFAS) have leached into at least 55 drinking water systems at military bases around the globe. The contaminated water may be causing illness in those drinking it, including tumors, thyroid problems, and debilitating fatigue.

The problem is not confined to military bases. As many as 10 million people could be drinking water laced with PFAS, according to the article.

Per- and polyfluoroalkyl substances (PFAS) are a group of man-made chemicals that are used for a large number of purposes around the globe, and they are present in many common consumer items. “There is evidence that exposure to PFAS can leads to adverse human health effects,” as the Environmental Protection Agency puts it. (Environmental Protection Agency, 2018) They are not on the list of toxic chemicals monitored by the EPA, however. After an outcry and concerted campaign by public health scientists, the EPA has agreed to do a comprehensive study of the human health effects of exposure to the chemicals, and to survey exposure levels across the country. (Davenport, 2019)

On the other hand, PFAS represent $19.7 billion in sales to chemical manufacturers, according to another article. (Lipton and Abrams, 2015) DuPont, one of the primary manufacturers, maintains that years of study and experience have proven that the chemicals are safe for their intended use. (Davenport, 2019)

Of course, leaching into the public water supply is not one of their intended uses.

Well, this blog is not about looking into the controversy around this group of chemicals. I thought I’d look and see if I could find any databases that document exposure to them. Lo-and-behold, I did. The EPA’s report on The Third Unregulated Contaminant Monitoring Rule (UCMR 3): Data Summary, January 2017 contains some information. The National Environmental Public Health Tracking Network contains more.

The data in the EPA report only has reports on PFAS from public water systems serving fewer than 10,000 people. Thus, it represents a small fraction of all public water systems, and an even smaller fraction of the number of people served by public water systems. On the other hand, the data mapped by the National Environmental Public Health Tracking Network includes many of the largest public water systems, and covers a substantial portion of the population, at least in Missouri.

In both sets of data, the group of chemicals are listed individually, and it is not clear how much the water systems contaminated by one overlap those contaminated by another. Finally, for several of the chemicals no reference level has been determined. Think of a reference level as something similar to the maximum safe exposure level. Some of these chemicals have not yet been studied that way, that’s why the EPA is undertaking the study mentioned above.

Table 1 lists the chemicals and the number of public water systems in which they were detected from the EPA report:

Table 1. Public Water Systems Contaminated with PFAS:

Chemical Number of Water Systems in Which It Was Detected
PFOA 117
PFHx5 55
PFHpA 86

Data Source: Environmental Protection Agency, 2017.

Figures 1-3 map the locations of water systems where PFAS were detected, from the National Environmental Public Health Tracking Network. Each map is labelled with the specific chemical being mapped. The orange dots show a single system, the grey dots with numbers show locations where more than one water system had PFAS, but the scale of the map is too small to show them both. The number inside the grey circle shows the number of water systems in that locale where the chemical was detected.

Figure 2. PFOS and PFOA Contamination. Source: Centers for Disease Control, 2019.

Figure 1. PFHpA and PFBS Contamination. Source: Centers for Disease Control, 2019.

Figure 3. PFNA and PFHxS Contamination. Source: Centers for Disease Control, 2019.

Although 87 public water systems in Missouri were sampled, none reported detectable PFAS. The sample covered public water systems that served 3,802,254 people, and included the City of St. Louis Public Water System, the Missouri American St. Louis-St. Charles County Water System, the Kansas City Public Water System, 2 Jackson County Public Water Systems, the Springfield Public Water System, as well as many other large public water systems. The sampling included the Ft. Leonard Wood water system, and no contamination was detected.

For right now, this data seems to suggest that the public drinking water in Missouri may not be contaminated with these chemicals. I wouldn’t say this is the last word, however. The EPA study will hopefully give us a more comprehensive analysis of what the health effects of these chemicals are, how much exposure of what kind is safe, and how much contamination is out there.


Centers for Disease Control. 2019. National Environmental Public Health Tracking Network. Viewed online 2/22/2019 at https://ephtracking.cdc.gov/DataExplorer/#/.

Davenport, Coral. 2019. “E.P.A. Will Study Limits on Cancer-Linked Chemicals. Critisc Say the Plan Delays Action.” The New York Times, 2/14/2019. Viewed online 2/22/2019 at https://www.nytimes.com/2019/02/14/climate/epa-chemical-plan-pfas.html?module=inline.

Environmental Protection Agency. 2018. Basic Information on PFAS. Viewed online 2/22/2019 at https://www.epa.gov/pfas/basic-information-pfas.

Environmental Protection Agency. 2017. The Third Unregulated Contaminant Monitoring Rule (UMCR 3): Data Summary, January 2017. Viewed online 2/22/2019 at https://www.epa.gov/sites/production/files/2017-02/documents/ucmr3-data-summary-january-2017.pdf.

Lipton, Eric, and Rachel Abrams. 2015. “Commonly Used Chemicals Come Under New Scrutiny.” The New York Times, 5/1/2015. Viewed online 2/22/2019 at https://www.nytimes.com/2015/05/01/business/commonly-used-chemicals-come-under-new-scrutiny.html?module=inline.

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