Dr. Laurel Shader, a senior scientist at the Silent Spring Institute, gave a public presentation in Nantucket explaining what per- and polyfluoroalkyl substances (PFAS) are, how people are exposed and what communities and individuals can do to reduce risk. "PFAS stands for per- and polyfluoroalkyl substances," Shader said, describing the class as persistent "forever chemicals" that resist environmental breakdown.

Shader laid out three key lines of evidence scientists use to learn about chemical harms—epidemiology, toxicology and lab-based (in vitro) studies—and said combining those approaches strengthens confidence in links between PFAS exposures and health effects. She cited consistent findings associating PFAS with immune effects (reduced vaccine antibody response in children), altered thyroid hormones, metabolic changes such as higher cholesterol, some reproductive and developmental impacts, and elevated risks for certain cancers in prior studies.

On exposure routes, Shader said drinking water, food and consumer products are the major contributors. She named specific product sources—nonstick cookware, stain-resistant textiles (Scotchgard), waterproof clothing (Gore-Tex) and some food packaging—and noted consumer products can raise indoor dust levels that contribute to exposure. Workplaces such as fluoropolymer plants and firefighters using AFFF firefighting foam remain groups with higher exposure potential.

Shader summarized two research efforts tied to Massachusetts: STEEP (Sources, Transport, Exposure and Effects), a multi-institution private-well study that tested wells across Cape communities and found correlations between PFAS and wastewater markers (nitrate, boron), and the CDC/ATSDR-funded multisite epidemiological study led in part by Silent Spring that enrolled adults and children in communities with a history of water contamination to measure blood PFAS and health markers. She said early results show communities with contaminated water (for example, Hyannis) have higher blood PFAS than the general U.S. population.

Shader also reviewed the regulatory landscape. She described a history of evolving EPA advisories and guidelines, and noted EPA's recent enforceable maximum contaminant levels for PFOS and PFOA (4 parts per trillion) while observing that some related standards and implementation timelines have been delayed. Massachusetts set a combined PFAS6 standard at 20 parts per trillion in 2020, she said, and state-level approaches vary by which PFAS compounds they include.

To help residents interpret testing and clinical results, Shader recommended the PFAS Exchange (an online resource developed by Silent Spring and partners) and highlighted a continuing medical education course for clinicians that can improve patient care for people with elevated PFAS exposures. She urged people with clinical concerns to discuss testing and follow-up with their own physicians.

Shader closed by urging both individual and institutional actions—testing private wells when appropriate, reducing reliance on nonessential PFAS-containing products and pursuing procurement policies at municipal and institutional levels to limit PFAS purchases.

The presentation was recorded; slides and a recording will be posted by the Nantucket Health Department.