More Private Wells Exceed "Imminent Hazard" PFAS Threshold

Another private well on Nantucket has tested above the state’s “imminent hazard” threshold for the so-called “forever chemicals” known as PFAS, and a second was so close to the limit that the state is also treating it as an imminent hazard.

After a sample collected from a private well at Hummock Pond Road and Burnt Swamp Lane tested above the imminent hazard threshold in May, the Massachusetts Department of Environmental Protection (MassDEP) returned to the island in early June to sample another 11 homes in the area of the detection. One sample from a home on Oak Hollow Lane tested at 171 parts per trillion (ppt) of PFAS, almost double the imminent hazard threshold of 90 ppt and over eight times higher than the 20 ppt MassDEP has set as the public drinking water standard, also called the Massachusetts Maximum Contaminant Level (MMCL).

Another sample, from a home on Hummock Pond Road, tested at 87 ppt, just below the imminent hazard threshold.

“Even though this did not exceed the [imminent hazard] threshold of 90 ppt, MassDEP is treating this as an [imminent hazard] detection,” town environmental contamination coordinator Andrew Shapero wrote in an email to the Current. “From my perspective, there is no difference between 87 ppt and 90 ppt in terms of health. It’s just a regulatory distinction.”

Shapero said that the MassDEP is providing bottled water to both homes and is sampling additional homes in the vicinity.

Like the hotspot at Toms Way, the source of the new detections has not yet been determined.

The hazardous concentrations are both outside of known PFAS hotspots near Nantucket Memorial Airport and Toms Way in the mid-island area, as was the earlier imminent hazard detection from the sample collected in April. And yet, other wells nearby these detections were found to have relatively low PFAS concentrations, suggesting that concentrations remain highly unpredictable.

“This is a pattern we have seen in other parts of the island, where high detections can be close to relatively low detections of PFAS,” Shapero said. “This highlights the importance of getting your own well tested, even if you are not near a known contamination hotspot. MassDEP recommends that all well owners test their wells for PFAS every 10 years.”

MassDEP identified another sample on Burnt Swamp Lane with a concentration of 20.1 ppt, just above the 20 ppt MMCL. The other eight residences tested had PFAS levels below the 20 ppt threshold.

Used to manufacture stain- and water-resistant products, the family of chemicals known as PFAS is suspected to increase the risk of kidney and testicular cancers, as well as other health conditions. They are often called "forever chemicals" because they do not break down and remain present in the environment. The chemicals are used in a wide range of products, from non-stick pans to fast food wrappers to firefighting foam.

There are thousands of PFAS, but MassDEP only tests for six, known as PFAS6, meaning that actual PFAS concentrations could be higher than what the official testing shows.

Shapero will give an update on PFAS sampling efforts at the Board of Health meeting this Thursday, including samples purchased through the Health Department.