Researchers say this migration spurred by PFAS could contribute to cancer metastasis in animals and humans.
Forever chemicals or per-and poly-fluoroalkyl substances (PFAS) are found virtually everywhere. Scientists suggest nearly 50% of private wells and public drinking water sources in the United States contain some level of PFAS contamination, and approximately 200 million people have drinking water sources that harbor unsafe PFAS levels. Even healthy food items such as kale may contain these chemicals.
Scientists have linked PFAS to thyroid cancer, immune system issues, and infertility. The Centers for Disease Control and Prevention says PFAS exposure may lead to changes in liver enzymes, elevated cholesterol levels, and a higher risk of testicular and kidney cancer.
Yale School of Public Health researchers suggest that there may be a relationship between PFAS exposure and colorectal cancer. Firefighters who are routinely exposed to PFAS have a higher rate of this type of cancer than the general public.
While the links between cancer and PFAS exposure are known, it's unclear how these chemicals might contribute to cancer development.
In a new study published in Environmental Science & Technology, Yale University scientists focused on perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) — two PFAS chemicals the International Agency for Research on Cancer (IARC) recently classified as possibly carcinogenic to humans. These specific PFAS are found in firefighting foam and other materials.
The investigators conducted various experiments, including immersing two types of colorectal cancer cells — an unmutated and mutated KRAS gene type — in a PFAS solution for seven days.
The researchers found that exposure to the PFAS solution caused the cancer cells to migrate and penetrate membranes. Further experiments showed that cancer cells exposed to PFAS could migrate across lines the researchers drew in Petri dishes.
Metabolic changes also occurred in the cancer cells. Specifically, they produced amino acids, fatty acids, and signaling proteins in patterns that previous research linked to cancer metastasis. The cells exposed to forever chemicals also downregulated cancer-fighting small-chain fatty acids.
The scientists say this increased cell motility with PFAS exposure and metabolic changes observed were consistent with cancer metastasis.
In a Yale news release, lead investigator Caroline Johnson, Ph.D., an associate professor of epidemiology at the Department of Environmental Health Sciences, Yale School of Public Health, said, "It doesn't prove it's metastasis, but they have increased motility, which is a feature of metastasis."
Some changes the researchers observed were more pronounced in the KRAS-mutated cancer cells. The scientists suggest these findings could indicate that cancers with this particular mutation may be more prone to metastasizing after PFAS exposure.
Since the researchers used cancer cells cultured in a lab, it's unclear if the same migration would occur in the human body.
"Many in vitro studies can't be translated into humans," Johnson said. "But I think understanding first the mechanisms of how they can actually affect cancer cell growth is important."
Because this study used PFAS at levels similar to what firefighters and other people with frequent exposure to forever chemicals face, the research team plans to test cancer cells at levels closer to what the general population might encounter. The scientists also plan to look closer at how exposure to PFAS might impact the outcomes of people with colon cancer.
- CDC. What are the health effects of PFAS?
- Firefighter Cancer Support Network. The Training Brief.
- Environmental Science & Technology. Perfluorooctanesulfonic Acid and Perfluorooctanoic Acid Promote Migration of Three-Dimensional Colorectal Cancer Spheroids.
- International Agency for Research on Cancer. IARC Monographs evaluate the carcinogenicity of perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS).
- Yale School of Public Health. Yale Study: "Forever Chemicals" Promote Cancer Cell Migration.