Women exposed to several widely used chemicals appear to face increased odds for ovarian and other types of cancers, including a doubling of odds for melanoma, according to new research funded by the US government. Using data collected by the Centers for Disease Control and Prevention (CDC), a team of academic researchers found evidence that women diagnosed with some “hormonally driven” cancers had exposures to certain per- and polyfluoroalkyl substances (PFAS), which are used in thousands of household and industrial products, including in stain- and heat-resistant items. They found similar links between women diagnosed with cancer and high exposures to phenols, which are commonly used in food packaging, dyes and personal care products. PFAS have been dubbed “forever chemicals” due to their longevity in the environment. The study, published late on Sunday in the Journal of Exposure Science and Environmental Epidemiology, did not find similar associations between the chemicals and cancer diagnoses in men. PFAS chemicals, in particular, may disrupt hormone functions specific to women – a potential mechanism for increasing their odds of hormone-related cancers, the researchers determined. Hormonally active cancers are common and hard to cure, making deeper inquiry into potential environmental causes critical, the researchers said. “People should care about this because we know that there is widespread human exposure to these chemicals and we have documented data on that,” said Max Aung, assistant professor of environmental health at the USC Kreck School of Medicine and a senior author of the study. “These chemicals can increase the risk of various different health outcomes and they can alter your biological pathways … That is important to know so that we can better prevent exposures and mitigate risks,” Aung said. It’s nearly impossible to avoid exposure to PFAS, because the chemicals are so widespread in the environment. Sometimes called “forever chemicals” because they do not naturally break down, PFAS residues can persist in water, soil, air and food. An estimated 97% of Americans have PFAS in their blood, according to the CDC. The US Geological Survey (USGS), a unit of the US Department of Interior, says that 45% of US drinking water is contaminated with PFAS. Notably, the research team found differences in women from different racial groups – links between PFAS and ovarian and uterine cancers were seen mainly in white women, while associations between chemicals known as phenols and breast cancer were seen largely in non-white women. The researchers said it was not clear exactly why such differences exist, but could be due to dietary habits and proximity to contaminated drinking water sources, among other factors. The new study is based on analysis of data collected through a CDC biomonitoring program from 2005 to 2018 involving more than 10,000 people. Researchers looked at prior cancer diagnoses and levels of PFAS and phenols in blood and urine collected from study participants. The researchers said the data showed that women with higher exposure to a long-chained PFAS compound called PFDE had double the odds of having a prior melanoma diagnosis, while women with higher exposure to two other long-chained PFAS compounds, PFNA and PFUA, had nearly double the odds of a prior melanoma diagnosis. Researchers said they also found a link between PFNA and uterine cancer. The work does not prove that exposure to PFAS and phenols led to these cancer diagnoses, the researchers said, but is a strong sign that the chemicals play a role and should be studied further. The study is part of ongoing research funded by the National Institutes of Environmental Health to “better understand” how PFAS chemicals are affecting human health. There are thousands of different types of PFAS, and research on their health effects is still evolving, though certain types of PFAS have already been linked through prior scientific research to multiple health problems including cancer, decreased fertility and kidney disease. In addition to Aung, the study was conducted by researchers affiliated with the Program on Reproductive Health and the Environment at the University of California, San Francisco; the University of Southern California; and the University of Michigan. This story is co-published with the New Lede, a journalism project of the Environmental Working Group