PFAS Panel Discussion Summary

On October 14, 2020, more than 100 people gathered by Zoom to listen as an expert panel discussed PFAS in drinking water and answered questions from residents. This post provides a summary of the speakers’ comments, links to their slides, a link to the video of the event, and answers to audience questions that remained unanswered when the time available for the live event ran out. 

Links: 

• Video of October 14 Green Acton / LWV panel discussion 
• Dan Groher’s slides
• Sandra Baird’s slides
• Matthew Mostoller’s slides
• Slides from October 21 PFAS panel sponsored by 495/MetroWest
• Access all Green Acton’s PFAS coverage 

The PFAS panel discussion and the Green Acton website coverage of PFAS are activities of the Green Acton Water Committee. The committee welcomes new people at our monthly meetings and on our email discussion list; reach out to water-contact@greenacton.org 

Summary

The program began with a welcome from the sponsoring organizations: Green Acton and the League of Women Voters–Acton Area.

Dan Groher, an Acton resident and environmental engineer, provided an overview of what PFAS are, where they come from, how they behave in the environment, and what approaches are available to remediate them. Since the accidental discovery of Teflon in 1938, PFAS have been used in apparel, electronics, fire fighting foam, and many other industrial and consumer products. There are thousands of compounds in the PFAS family of chemicals; they all share the basic structure of a chain of carbon atoms with fluorine atoms attached. PFAS are an emerging contaminant type, with rapidly evolving science and many unanswered questions. These chemicals travel easily through groundwater and surface water, and do not readily degrade with time. However, water suppliers do have effective technologies for treating PFAS in drinking water. The first PFAS treatment plant in Massachusetts, in Ayer, began operation earlier this month.

Dr. Sandra Baird, a toxicologist and environmental analyst from the Massachusetts Department of Environmental Protection (MassDEP) Office of Research & Standards, discussed the Commonwealth’s newly established Maximum Contaminant Level (MCL) for PFAS in drinking water, and the lines of evidence used to establish such limits. Regulatory agencies consider risk information from animal toxicology studies and human epidemiological studies, along with practical realities of how easily and accurately the contaminant can be detected and how effectively it can be treated. MassDEP chose to regulate six long-chain PFAS chemicals that are toxic at low exposure levels, persist in the environment, are water-soluble, and are associated with both cancer and non-cancer health effects. The state MCL requires that the sum of the concentrations of all six PFAS together must be kept below 20 parts per trillion (ppt). This MCL is broader and/or more stringent than in the other nine states that have established standards (see table below). The federal EPA (Environmental Protection Agency) and most other states still have merely a non-enforceable “health advisory” metric. The Massachusetts MCL was announced on September 24, 2020, and comes into effect in 2021. 

Matthew Mostoller, the Environmental Manager of the Acton Water District (AWD), provided an update on the situation here in Acton, including actions taken by the AWD since the emergence of PFAS as a contaminant of concern. The first testing for PFAS in Acton water was done in 2013–2014; with laboratory techniques available at the time, no PFAS were detected. In 2019, the two EPA Superfund sites that impact Acton’s groundwater, WR Grace and NMI, found PFAS in some of their monitoring wells. Alerted by the EPA findings, AWD began its own testing program in January 2020. All of the AWD sources have now been tested multiple times, with results shown in the graph below.

In immediate response to these findings, AWD removed the highest-PFAS sources from service and notified local government and townspeople. Next, the AWD conducted a comparison test of the effectiveness of six different filtration media on Acton’s most-PFAS-impacted water sources. These findings are being used to plan modifications of the North Acton Water Treatment Plant to add PFAS treatment to the existing system. Finally, the AWD has joined with many other drinking water providers in litigation against the manufacturers of PFAS. Residents who want to receive email updates about PFAS from the AWD can sign up by emailing wq@actonwater.com.

Answers to Additional Questions 

The audience generated dozens of heartfelt and insightful questions, most of which you can hear answered in the video. A few questions remained unanswered when the event time expired, and the panelists and moderator later provided answers by email. Some questions and answers have been lightly edited.

Q: [paraphrased by moderator] What are the pros and cons of reactivating the Assabet 3 well on the edge of the WR Grace Superfund site?

Mostoller: The pros of using this source include: it has been previously permitted, in 2009, for use by the District; the South Acton treatment plant was designed to accommodate its future volume of water; and early indications show lower PFAS levels than existing [active] Assabet wells. The cons are: capital costs to connect to the treatment plant and make the well operational; potential for changes in 1,4-dioxane levels; and extra permitting to convince MassDEP to expand withdrawal capacity for this well, which historically sustained >1 million gallons per day.

Q: Are the six PFAS/PFOAs [those included in the MassDEP regulation] good indicators, or representative of other PFAS — in terms of presence of other PFAS and or in terms of toxicity?

Baird: The MassDEP PFAS6:

• were selected from the PFAS measured during the testing for unregulated contaminants [UCMR3 / EPA’s Third Unregulated Contaminant Monitoring Rule] and by the current analytical methods;
• include PFAS detected in Massachusetts drinking water;
• include the PFAS that are the most-studied, meaning those with high historic use) — PFOA and PFOS and PFAS that are structurally very similar, with 8 (+2) carbons; and
• exclude one PFAS that is included in the structurally similar group that has evidence of low toxicity and doesn’t appear to accumulate in people — PFHxA.

PFAS in the environment is a relatively new area of study; thus, analytical methods reflect the PFAS that scientists know to look for, and the analytical techniques they have for looking at very-low concentrations. Toxicity information is limited; there is some data availability for fewer than 10–20 PFAS. We [MassDEP Office of Research & Standards] make extrapolations across the PFAS6 based on toxicological similarity and persistence in people, and because, historically, chemicals with very similar structures behave more like each other than chemicals with different structures.

Q: Is there work being done on synergy with other contaminants, such as arsenic and PFAS, or are these issues being dealt with separately?

Mostoller: The arsenic notice from July was isolated to one treatment plant. The filters at that site typically are effective at reducing arsenic; normal operations had been resumed relative to arsenic removal by the time the notice was mailed to customers. This is not viewed as an ongoing issue. It should be noted that the facility with the arsenic breakthrough is also our facility currently utilizing granular activated carbon and has exhibited no detectable PFAS6 in the treated water.

Baird: At this time I am unaware of any research that has evaluated the effects of PFAS and another contaminant, such as arsenic or 1,4-dioxane, following exposure to both. The research effort on PFAS is still relatively new, and made more challenging by the number of PFAS substances that need testing. In general, when exposure to two substances occurs, with both at low concentrations, the effects are those that would be expected from each individually. The amount allowed in drinking water is intended to result in no health effects, even to sensitive populations. Note that the 1,4-dioxane ORSG [Office of Research & Standards Guideline] of 0.3 micrograms per liter (ug/L) is based on a cancer risk of one-in-one-million additional cancer risk for a lifetime of exposure. The non-cancer based ORSG for 1,4-dioxane is 210 ug/L, 700 times higher than the cancer ORSG.

Q: Were PFAS found in the Clapp or Whitcomb wells, which are located near private wells in Boxborough?

Mostoller: The Clapp and Whitcomb wells, located on the Boxborough town line, have exhibited concentrations of PFAS ranging from 7.99 to 23.28 parts per trillion. The treated water from these sources has been non-detect for PFAS6.

Q: The notice also suggested that PFAS becomes concentrated with boiling. Are there additional concerns for cooking purposes? 

Mostoller: The notice indicated that cooking food such as rice and pasta, which absorb water, could be a concern for food prepared for the sensitive subpopulation. 

Baird: PFAS are concentrated with boiling water because boiling releases steam (water in vapor form), which decreases the amount of water in the pot while the amount of PFAS stays the same. I think that this statement is included in the [MassDEP-provided language in the] notice because many people are familiar with boil water orders when there is concern about bacterial contamination. In the case of elevated PFAS levels, boiling would not be helpful.

Q: Do bedrock wells in general lead to lower PFAS levels?

Mostoller: This is not definitive. It will depend on the sources of PFAS contributing to a well, the hydrogeology, and even the well construction. Our bedrock well exploration is looking at depths up to 600 feet below grade, thereby providing water which is likely “older” and has not been exposed to PFAS in the environment. I am aware of private and public bedrock wells in the area that have ben impacted by PFAS. Additionally, some overburden wells have none-to-few PFAS impacts.

Q: If we want to test our water at home, what should we do?

Kastens (moderator): The Green Acton web post PFAS: News You Can Use includes a section on getting private well water tested, including a link to MassDEP’s list of approved testing labs, costs, and contact information for vendors who can provide a home water testing kit. Because PFAS concentrations are so minuscule (parts per trillion) and PFAS are so ubiquitous, there is a strong risk of cross-contamination when gathering samples, so follow the directions included with the kit scrupulously.