By Granite State Report
New, state-level research presented this week confirms what many families in southern New Hampshire have suspected for years: kidney cancer diagnoses in Merrimack are significantly higher than expected, and Manchester may also have an emerging cluster. The findings revive urgent questions about long-standing PFAS (“forever chemicals”) contamination and what state and local leaders will do next.
What’s new
A Dartmouth epidemiology team reported that Merrimack saw a 38% excess of kidney cancer cases from 2013–2021, with an additional 18% excess in Manchester over the same period. Hudson had an 83% excess in 1995–2003 that later returned to expected levels. The researchers emphasized the study confirms elevated rates but does not determine a cause; more funding and granular exposure data are needed. (New Hampshire Bulletin)
Why it matters
PFAS chemicals have shadowed the region for nearly a decade, after state testing tied widespread contamination to emissions from the now-demolished Saint-Gobain Performance Plastics facility in Merrimack. The company closed the plant in 2023 and finished demolition in 2025 under regulatory scrutiny and a consent decree to provide clean water hookups, but long-term cleanup and exposure histories remain complex. (New Hampshire Bulletin)
Globally, the science has moved: the World Health Organization’s cancer agency now classifies PFOA (a common PFAS) as carcinogenic to humans and PFOS as possibly carcinogenic, with renal (kidney) cell carcinoma among the cancers of concern. (IARC)
At the policy level, the EPA finalized the first national drinking-water standards for PFAS in April 2024, setting legally enforceable limits and timelines for compliance; New Hampshire was already among the earliest states to set strict PFAS standards in 2019. (Environmental Protection Agency)
What the data show (and don’t)
The Dartmouth team used the New Hampshire State Cancer Registry to compare kidney cancer rates in Merrimack and eight surrounding towns against the rest of the state across three time windows. The signal in Merrimack (2013–2021) is consistent with earlier New Hampshire DHHS work that also found a statistically significant excess and recommended deeper study. The new analysis additionally flags Manchester’s excess—especially among women—while urging caution until more detail is available. (New Hampshire Bulletin)
Researchers say the next step is to link people’s residential histories and water testing records to exposure data—work that is doable but intensive and dependent on sustained funding. (New Hampshire Bulletin)
Community context
Residents have long pointed to PFAS as a likely culprit, given contamination in soil and groundwater and years of air emissions from Saint-Gobain. While the plant is gone, the remediation picture is unfinished; even routine construction in parts of Merrimack is complicated by guidance to keep contaminated soils contained until clear disposal pathways are set. (New Hampshire Bulletin)
What Granite Staters can do right now
- If you’re on a private well: NHDES recommends testing, and the state offers a request pathway for sampling and, in some cases, rebates for PFAS removal systems. Start with the PFAS Response site and private-well guidance. (pfas.des.nh.gov)
- If you want to understand the cancer data: New Hampshire DHHS posts methods, SIR (standardized incidence ratio) explainers, and the 2023 Merrimack cancer report. (dhhs.nh.gov)
- If you’re on public water: Your utility must meet EPA’s new standards on a federal timeline; watch for monitoring notices and treatment updates as systems move toward compliance. (Environmental Protection Agency)
What to watch next
- Whether state and federal partners fund the expanded exposure-history study researchers say is necessary to test environmental links. (New Hampshire Bulletin)
- How NHDES implements PFAS treatment projects and soil management around Merrimack and Manchester, and whether additional community health surveillance is added. (New Hampshire Bulletin)
- Utility upgrades to meet EPA’s PFAS drinking-water standards by the required deadlines. (Environmental Protection Agency)
Further reading (evidence)
- Today’s study coverage: New Hampshire Bulletin report with town-by-town details and methods notes. (New Hampshire Bulletin)
- Plant demolition & background: Saint-Gobain demolition update; consent-decree context and prior DHHS findings. (New Hampshire Bulletin)
- PFAS and cancer classifications: IARC on PFOA/PFOS carcinogenicity. (IARC)
- Rules & standards: EPA’s 2024 national PFAS drinking-water rule; New Hampshire’s 2019 MCLs. (Environmental Protection Agency)
Watch: explainers and local meetings (YouTube)
- NHDES/Merrimack PFAS informational meeting (background, standards, consent decree): https://www.youtube.com/watch?v=YUdHZZAJOAw (YouTube)
- Dana-Farber explainer: “What is the connection between PFAS and cancer?” https://www.youtube.com/watch?v=Nfxu1gWxzDE (YouTube)
- Merrimack TV coverage: PFAS virtual public meeting (state session with Q&A): https://www.youtube.com/watch?v=8EzVNSCgu0g (YouTube)
- A broader science explainer on PFAS persistence and exposure pathways (Veritasium): https://www.youtube.com/watch?v=SC2eSujzrUY (YouTube)
