Women who switched to paraben- and phthalate- free shampoos, lotions, soaps and deodorants had fewer cancer-associated changes to breast tissue cells.
Ashley James for the Environmental Health News
It's well established that high estrogen exposure is a major breast cancer risk factor.
Endocrine-disrupting chemicals that mimic estrogen, also known as xenoestrogens, have been associated with increased breast cancer risk, even at low doses.
The two most common xenoestrogens, phthalates and parabens, are used widely in personal care products such as shampoo, deodorant, lotion, nail polish, fragrances and more.
While most toxicology cancer research uses animal models or cancer cell lines,
the new study,
published in Chemosphere, aimed to
understand how reducing real-world exposure to these toxics affects early
markers of breast cancer in people’s bodies.
Breast cancer survivors and researchers partnered to recruit cancer-free women who used personal care products with parabens and phthalates daily. Randomly assigning some women as controls, they collected blood, urine and breast tissue cells from participants at the start and end of a 28-day intervention period, where non-control participants switched to phthalate- and paraben-free products.
They observed significant
reversal of known cancer-associated cell signaling pathways, significant shifts
of known cancer-associated genes to a ‘normal’ profile, and significant
reduction in phthalate and paraben urine levels post-intervention.
“For us [breast cancer survivors] this study changes the paradigm for breast cancer research,” Polly Marshall, executive director of Breast Cancer Over Time and a co-author of the study, told Environmental Health News (EHN). “Instead of looking at correlations, we found a way to actually study causation in people's bodies.”
A community-based shift for breast cancer research
As a community-based participatory research
project, breast cancer survivors were involved in all steps of the study, from
generating research questions to recruiting and educating participants.
The study design is a strength beyond being
performed on humans. The fact that pre- and post-intervention samples came from
the same women keeps outside factors that could otherwise skew results, such as
diet and exposure to pollution, constant. Researchers were also able to see
results in a short period of time rather than waiting decades to follow a
cohort of women.
Funding for cancer research typically goes toward finding a cure and treatment rather than prevention. However, the potential to protect future generations is what motivated both the survivors and participants, most of whom had a loved one with breast cancer.
“There are a lot of people out there who want to move beyond awareness and pink ribbons and actually do something to prevent breast cancer,” Marshall said.
Next steps in breast cancer research
The researchers said the study needs to be
replicated in a larger study to confirm results.
According to Shanaz Dairkee, a cancer
researcher at Sutter Health and the lead investigator on the paper, this pilot
study opens many doors for future research. “This study design could be applied
to other suspect chemicals in conjunction with other accessible human tissues
with risk of cancer or other diseases,” she told EHN. Dairkee also
believes that future research should assess the combined health impact of
chemical reduction from multiple sources, such as personal care products and
diet.
Authors say this type of research could also help close the research gaps necessary for chemical regulation. Organizations, such as Breast Cancer Prevention Partners, have advocated for safer personal care products since the early 2000s.
While there has been
some recent progress with
the passing of the Modernization of Cosmetics Regulations Act, which improves
ingredient transparency and requires adverse-event reporting, the federal
government has yet to ban or restrict chemicals linked to breast cancer and
other chronic diseases.
Kaley Beins, a senior scientist at the
Environmental Working Group, focuses on improving public health by reducing
chemical exposure from personal care products. “Intervention-based studies like
this one, that link behavior changes not only to exposure reduction but
potentially to mechanisms of risk reduction, will support the importance of
regulating consumer products overall,” she told EHN.
