Over 57,000 US Sites Likely Contaminated With “Forever Chemicals”

A new study has mapped over 57,000 sites in the US that are likely contaminated with per- and polyfluoroalkyl substances (PFAS) – also known as “forever chemicals”. The study is published in Environmental Science & Technology Letters.

PFAS are a risk to human health

PFAS are a group of over 12,000 chemicals first produced in the late 1930s. Referred to as “forever chemicals” due to their durability, they are useful in non-stick cookware coatings, waterproof clothing and firefighting foams. However, these qualities also make them almost impossible to destroy meaning that PFAS can accumulate in the environment, contaminating water, air and even our blood.

Research in recent decades has revealed numerous health implications of PFAS such as increased risk of cancer, decreased fertility, low birth weight and high cholesterol levels. Despite this, there is a notable lack of data regarding the extent and severity of PFAS contamination in the US.

Federal efforts to test for PFAS in the US have focused on large drinking water systems, excluding private wells and having high reporting thresholds – meaning that the scale of known PFAS contamination is likely an underestimate of actual contamination.

Dr. Alissa Cordner, co-director of the PFAS Project Lab and senior author of the study, explained the importance of monitoring for PFAS contamination: “Testing for PFAS is essential in order to understand the scope of PFAS contamination across the globe, and it also is necessary to protect public health in specific communities. There can be disincentives for PFAS testing – for example, testing is expensive, there are currently no federal regulatory levels for PFAS in drinking water and so it's not always clear what action should be taken when PFAS are detected, and remediation can be extremely costly. However, we also know that PFAS appear to be toxic at extremely low levels of exposure, so it is essential that more testing is done to identify where PFAS contamination poses a risk to the public.”

The researchers in the current study set out to build a map of presumed PFAS contamination sites in the US, based on likely sources of PFAS in the absence of costly large-scale testing. Cordner says these findings “will let decision-makers prioritize locations for future testing and regulatory action.”

Mapping presumed contamination

The researchers combined high-quality geocoded information (i.e., with precise geographical coordinates) on sites that are likely contaminated with PFAS to build the presumptive contamination map.

“We used already published scientific studies and government research programs that have identified specific types of locations that were sources of PFAS contamination – for example, extensive testing at Department of Defense sites suggests that military bases are presumptive sites of PFAS contamination because of the use of fluorinated firefighting foams,” explained Cordner. “We then gathered all of the publicly available, high-quality, nationwide data we could on the different types of presumptive PFAS contamination sites, and we kept in only the data that was specific enough in terms of its geolocation data that we could use it to create a nationwide map.”

In total 57,412 sites were identified – this included 49,145 industrial facilities, 4,255 wastewater treatment plants, 3,493 military sites and 519 major airports. This reflects the applications and implications of PFAS as they are used in industrial manufacturing, in extinguishing fuel-based fires and are released in contaminated effluent after wastewater treatment. An interactive web version of the map can be found here.

These findings were validated by cross-referencing them with a list of 503 sites that are known to be contaminated with PFAS. 35% of these sites were observed by the map, and a further 37% were “expected” sites, but could not be mapped due to the limitations of the data – meaning the total accuracy was 72%.

Is this still an underestimation?

Nevertheless, the authors state that this map of presumptive PFAS-contaminated sites remains a vast underestimate. For example, around 23% of the identified industrial facilities had to be excluded as they lacked geographical information. There is also a lack of publicly available information on other locations where PFAS are commonly used such as firefighting training sites, fuel storage facilities and locations of railroad or airplane crashes.

“[Our] model is designed to be conservative, so there are many types of industrial facilities that are possible sources of PFAS contamination, but we didn't feel confident that every single one of those facilities was a probable source of contamination – for example, dry cleaners, ski shops, septage businesses, etc. As more testing is done related to these industrial facilities, we may expand the types of industrial facilities included in our model,” Cordner elaborates.

The researchers hope that this map of presumptive PFAS-contaminated sites can fill in the gaps left by the laborious nature of PFAS testing and identify hotspots to drive future monitoring and regulation of contamination. In the future, Cordner and colleagues hope that similar maps of presumptive PFAS exposure or PFAS-mediated illness could also be produced.

Dr. Alissa Cordner was speaking to Sarah Whelan, Science Writer for Technology Networks.

Reference: Salvatore D, Mok K, Garrett KK, et al. Presumptive contamination: a new approach to PFAS contamination based on likely sources. Environ Sci Technol Lett. doi: 10.1021/acs.estlett.2c00502