Sunday, July 30, 2023

PFAS in 20% of Private Wells

The below summarizes and quotes the finding and results from the USGS study

from USGS

On March 14, 2023, EPA announced the proposed National Primary Drinking Water Regulation (NPDWR) for six Per- and Polyfluoroalkyl Substances (PFAS) including perfluorooctanoic acid (PFOA), perfluorooctane sulfonic acid (PFOS), perfluorononanoic acid (PFNA), hexafluoropropylene oxide dimer acid (HFPO-DA, commonly known as GenX Chemicals), perfluorohexane sulfonic acid (PFHxS), and perfluorobutane sulfonic acid (PFBS). EPA anticipates finalizing the regulation by the end of 2023.

PFAS do not occur in nature, they are an entirely synthetic substance. Yet, most people in the United States have been exposed to PFAS and have PFAS in their blood, especially perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA). There are thousands of PFAS chemicals, and they are found in many different consumer, commercial, and industrial products. This category of chemical has been widely used for over 80 years mainly for their ability to repel oil, grease, water, and heat.

We have all been exposed to PFAS in everyday life. Stain-resistant carpeting, nonstick cookware, grease- and water-proof food packaging, fabric softeners, waterproof clothing, cosmetics, and through our diet and water. These forever chemicals are washed out of our clothing, carpeting, pans, skin and end up in our wastewater. There are numerous sources of exposure including: industrial emissions, PFAS-containing consumer products, contaminated drinking and surface water, house dust and food.

Though very water soluble, PFAS are resistant to degradation and simply flow through the wastewater treatment plant or septic leach field. PFAS remains in the biosolids and effluent. That is how it has spread throughout society and into our food supply. When the U.S. EPA was developing the regulations they utilized the Unregulated Contaminant Monitoring Rule (UCMR) program to collect data for contaminants suspected to be present in drinking water, but that do not yet have health-based standards set under the Safe Drinking Water Act (SDWA).  

EPA had public water systems serving more than 10,000 people gather data on a handful of  PFASs. The EPA found 4% of the large US drinking-water treatment plants tested had detectable PFAS. However, this probably vastly underestimated the extent of contamination because of the high level of detection limits (10–90 ng/L depending on individual PFAS) used in the analysis in that testing and a limited number of PFAS tested for (Hu et al., 2016).

The national testing programs, the UCMR3 focused only on community water supplies serving ≥ 10,000 consumers, and did not include private-wells and information from rural communities (52 million people rely on small water supplies serving < 10,000).  Data on PFAS exposure and potential human-health effects is does not exist for over one-third of the US population- the 40 million on private wells and the 52 million who get their water from small community water systems. 

There is limited information is available on PFAS concentrations at the  point-of-use tap water for all users. Most of the drinking-water studies only looked at samples from the source waters (McMahon et al., 2022; Sims et al., 2022) or pre-distribution samples from community water supplies. The distribution system and plumbing materials contribution was largely ignored; and there was a lack of data available for private-wells across the US.  Now the U.S. Geological Survey has completed a multi-year sampling program and created a model to estimate the probable concentrations of 32 PFASs at point of use for  water systems and private wells.

 The study tested for 32 individual PFAS compounds using a method developed by the USGS National Water Quality Laboratory. The most frequently detected compounds in this study were PFBS, PFHxS and PFOA. The interim health advisories released by the EPA in 2022 for PFOS and PFOA were exceeded in every sample in which they were detected in this study because the level of detections was higher than the final regulatory limit. So, the probability model conservatively estimates the occurrence of those chemicals. 

Scientists collected tap water samples from 716 locations representing a range of low, medium and high human-impacted areas. The low category includes protected lands; medium includes residential and rural areas with no known PFAS sources; and high includes urban areas and locations with reported PFAS sources such as industry or waste sites.  

At least one PFAS was detected in 20% of private-well (55/269) and 40% of the public-supply (182/447) samples collected throughout the US. A similar pattern was reported in groundwater from the eastern US, in which 60% of the public-supply wells and 20% of monitoring wells contained at least one PFAS (McMahon et al., 2022). Median cumulative PFAS concentrations (estimated given the detection limits) were comparable between public-supply (median = 7.1 ng/L) and private–well point-of-use tap water (median = 8.2 ng/L ).

I am one of the approximately 40 million people in the US that rely on private-wells for drinking-water and responsible for maintaining a safe water supply for my family. I plan to test my well as soon as a reliable test below the regulatory limit is commercially available and the labs have gotten more experience with the sample handling protocols. Don’t panic. If you feel you must do something, now. Then you could try testing your well yourself. Many laboratories and universities offer water quality testing services to homeowners. Most of these institutions will ship you a sampling kit and you return the samples to them for analysis. Four that I know of are: Cyclopure, Tap Score, Freshwater Future, and WaterCheck. The Virginia Tech water clinics do not yet test for PFASs. Also, the most effective removal system is reverse osmosis, but the disposal of any PFAS removed is problematic at this time.

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