Sunday, November 12, 2023

Your Water Contains PFAS. Now What?

My younger brother lives in Massachusetts where in 2020, the department of environmental protection (MassDEP) published its PFAS public drinking water standard or Massachusetts Maximum Contaminant Level (MMCL) of 20 nanograms per liter (ng/L), or parts per trillion (ppt) for the sum of the concentrations of six specific PFAS. The six PFAS are: PFOS, PFOA, PFHxS, PFNA, PFHpA, and PFDA. MassDEP abbreviates this set of six PFAS as “PFAS6” and has all public water systems test for them. 

This list of PFAS6 is from the national UCMR 3 (an US EPA  Safe Drinking Water program used to identify emerging contaminants of concern). Roughly 5,000 water systems monitored  for six PFAS back then and according to EPA, 63 water systems serving an estimated 5.5 million individuals detected PFOA and/or PFOS at levels above EPA’s 2016 health advisory level of 70 ppt (separately or combined). Several states took action on their own to protect their citizens. As the US EPA did not take additional action for a decade. Then in March 2023, EPA proposed drinking water standards for PFOA and PFOS at extremely low levels and  higher levels for perfluorobutane sulfonic acid (PFBS), perfluorononanoic acid (PFNA), perfluorohexane sulfonic acid (PFHxS), and hexafluoropropylene oxide dimer acid (HFPO-DA) and its ammonium salt (also known as the GenX chemicals). EPA has not finalized their regulations and the methods of analysis for the regulatory levels has not been yet achieved.

Nonetheless, in Massachusetts my brother received a notice from his water company that they had found a PFAS6 result that exceeded the Massachusetts Maximum Contaminant Level (MCL) for drinking water. He and his partner asked me what they should do. A little background.

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. PFOS and PFOA found in Scotch Guard and an ingredient in Teflon and traditional Aqueous Film-Forming Foam (AFFF) - the Class B firefighting foam used to fight aviation and other chemical fires -were the first to become widely commercially successful.

PFAS was also used in spray coatings for cans and food packaging. Wash water from light manufacturing or processing. Stain resistant and flame resistant treatments to carpeting, upholstery, clothing. Food with PFAS containing packaging picked up traces of PFAS and it was passed onto people that way, too. Basically, PFAS us ubiquitous. When 3M the former manufacturer of PFOS took blood samples of people exposed to PFAS, they could not find a control group that did not have PFAS in their bloodstream.

MassDEP is working with small public water systems like his to implement treatment for PFAS so that all community drinking water will meet the MCLs. PFAS can effectively be removed by treatment systems at least below the MassDEP MCL, but it is not known how effective they are at achieving the US EPA proposed SDW limit.

Right now the technology out there to remove PFAS is: activated carbon treatment, anion exchange, nanofiltration or reverse osmosis.

Activated carbon treatment is the most studied treatment for PFAS removal. Activated carbon is commonly used to adsorb natural organic compounds, taste and odor compounds, and synthetic organic chemicals in drinking water treatment systems. Adsorption is both the physical and chemical process of accumulating a substance, such as PFAS, at the interface between liquid and solids phases. Activated carbon is an effective adsorbent because it is a highly porous material and provides a large surface area to which contaminants may adsorb. Activated carbon (GAC) is made from organic materials with high carbon contents such as wood, lignite, and coal; and is often used in granular form called granular activated carbon (GAC). At analysis levels available in the past, GAC has been shown to effectively remove PFAS from drinking water when it is used in a flow through filter mode after particulates have already been removed.

Another treatment option is anion exchange treatment, or resins. There are two broad categories of ion exchange resins: cationic and anionic. The positively charged anion exchange resins (AER) are effective for removing negatively charged contaminants, like PFAS. Of the different types of AER resins, perhaps the most promising is an AER in a single use mode followed by incineration of the resin. Once more limitations of analytical method has hindered verification, but like GAC, AER removes 100 percent of the PFAS for a time.

High-pressure membranes, such as nanofiltration or reverse osmosis, have been extremely effective at removing PFAS.  Reverse osmosis membranes are tighter than nanofiltration membranes.  This technology depends on membrane permeability.  A standard difference between the two is that a nanofiltration membrane will reject hardness to a high degree, but pass sodium chloride; whereas reverse osmosis membrane will reject all salts to a high degree exactly how high a degree needs to be confirmed when the test methods are available.  

Though my brother’s water company suggested using bottled water for at risk populations, that may not be a good idea. A study published in August 2021  and led by Johns Hopkins University researchers, found PFAS substances in 39 out of more than 100 different brands of bottled water tested.  Since, I know that his partners is very risk adverse, I advised an interim measure: use a low cost system activated carbon filtration. A couple of years back the Environmental Working Group tested home systems for effectiveness at removing PFAS. Once more they were limited by the then available test methods to know how much PFAS was removed. The systems EWG recommends were inexpensive and 100% effective to the limit of analysis of removing PFAS.

So, you can just go the EWG website and click through one of the less expensive water filters and give it a try.  After a reliable test method and verification of removal takes place you can reevaluate this decision.

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