PFAS Exposure May Nearly Double Risk of Aggressive Breast Cancer, NIH Says

WHO:

The Boston Globe - The National Institutes of Health (NIH) researchers studied women with elevated blood levels of PFOA and PFOS, two per- and polyfluoroalkyl substances (PFAS).

The Boston Globe - Dr. Alexandra White, an NIH investigator who led the study, said the findings indicate that PFOA and PFOS are associated with higher risk of estrogen receptor-negative (ER-negative) breast cancer.

The Boston Globe - Dr. Timothy Rebbeck, a professor of cancer prevention at Dana-Farber Cancer Institute and Harvard, said human evidence so far shows correlation, not causation.

Science Daily - Its report described an NIH study of common “forever chemicals” and aggressive breast cancer.

WHAT:

The Boston Globe - Women with the highest PFOA levels had a 67 percent higher rate of ER-negative breast cancer than women with the lowest levels; for PFOS, the rate was 93 percent higher.

Science Daily - The study found up to a 93% higher rate of an aggressive form of breast cancer among women with high levels of two common forever chemicals.

The Boston Globe - Researchers found no clear association between PFOA or PFOS and breast cancer overall.

The Boston Globe - ER-negative tumors lack receptors through which estrogen helps cancer cells grow; NIH said this cancer type tends to be more aggressive and have worse outcomes.

The Boston Globe - The study was published in the *Journal of Clinical Oncology* and confirmed its findings using a meta-analysis of earlier research.

WHERE:

The Boston Globe - PFOA and PFOS were used in products including non-stick cookware, food packaging, and stain-resistant clothes. They have mostly been phased out in the United States but remain widespread.

The Boston Globe - The Sister Study enrolled women in the United States and Puerto Rico.

WHEN:

The Boston Globe - PFOA and PFOS have mostly been phased out in the United States since the early 2000s.

The Boston Globe - The Sister Study enrolled participants from 2003 to 2009; CDC data show blood PFOS levels fell by more than 85 percent and PFOA levels by more than 70 percent between 1999 and 2019.

WHY:

The Boston Globe - PFOA and PFOS are called “forever chemicals” because they break down slowly and can remain in the human body for years.

HOW:

The Boston Globe - Researchers compared blood samples from 1,609 women who later developed breast cancer with samples from 2,269 other women. Samples were collected years before diagnosis.

The Boston Globe - The Sister Study enrolled more than 50,000 women ages 35–74; each had a sister diagnosed with breast cancer, but participants did not have the disease when they enrolled.

The Boston Globe - Nearly all people in the United States have PFAS in their blood, according to the CDC.

The Boston Globe - Researchers did not establish how PFAS might contribute to breast cancer; they suggested possible effects on immune-system processes or gene activity. White said further research is needed, especially on newer replacement PFAS.

The Boston Globe - White said PFAS exposure is potentially modifiable and that reducing exposure could open avenues for prevention; Rebbeck said it is too early to know whether lowering exposure would reduce breast-cancer risk.

(UPDATED November 13, 2026 01:10 UTC)

NIH researchers linked higher levels of two forever chemicals with increased risk of aggressive breast cancer. Rates were up to 93 percent higher, but researchers stressed the findings show association, not causation. No clear link emerged for breast cancer overall, and further research is needed.