Certain common chemicals associated with higher odds of cancer in women
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.
The study, published late 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 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 impacting 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 University of California-San Francisco Program
on Reproductive Health and the Environment, the University of Southern
California, and the University of Michigan.
(This story is co-published with the Guardian.)